Dinosaurs: New Findings & Theories

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#1
Skull study sheds light on dinosaur diversity


With their long necks and tails, sauropod dinosaurs—famous as the Sinclair gasoline logo and Fred Flintstone's gravel pit tractor—are easy to recognize, in part because they all seem to look alike.

The largest animals known to have walked the earth, sauropods were common in North America during the middle of the dinosaur era but were thought to have been pushed to extinction by more specialized plant-eaters at the end of that era. New discoveries, however, are showing that one lineage of sauropods diversified at the end of the dinosaur era, University of Michigan paleontologist Jeffrey Wilson says.

Wilson's recent restudy and reconstruction of the skull of a Mongolian sauropod adds to a growing body of evidence for sauropod diversity at the end of the dinosaur era. Wilson described the reconstruction and the conclusions he drew from it in a paper published Aug. 24 in the Journal of Systematic Palaeontology.

He based the reconstruction on two nearly complete skulls that were found in the Gobi Desert in the 1950s and 1960s but whose evolutionary relationships have remained enigmatic. In the 1990s and early 2000s, Wilson restudied the skulls and found characteristics identifying them as skulls of titanosaurs, a late surviving sauropod lineage.

"Titanosaurs, which were surprisingly common at the end of the dinosaur era, were really the only sauropod lineage that flourished. All the others went extinct," said Wilson, an assistant professor of geological sciences and an assistant curator at the University of Michigan Museum of Paleontology. But as prevalent as titanosaurs were, they left behind surprisingly few skulls. Paleontologists have found plenty of other titanosaur bones, providing a picture of a group of sauropods with specialized limb bones.

Wilson began to appreciate the finer points of titanosaurs as a graduate student, when he and another student studied fossilized sauropod tracks and titanosaur limb anatomy. From those studies, Wilson concluded that unlike other sauropods, titanosaurs walked with their feet planted far from the middles of their bodies, an unusual style of "wide gauge" locomotion.

"Most animals walk with a narrow gauge, with their feet close to the midline, because it's energetically more efficient to walk that way. But some sauropod trackways tell us that a group of sauropods were walking with a new wide-gauge stance. We can identify characteristics of titanosaurs that would have allowed that stance, and we can tie the appearance of those features with the proliferation of wide gauge tracks everywhere in the fossil record at the end of the dinosaur era." Wilson wonders if the change in locomotion—from typical sauropod narrow-gauge walking to titanosaur wide-gauge walking—corresponded to lifestyle changes, such as different feeding habits. But without skulls to study, it has been hard to draw conclusions about how and what titanosaurs ate.

With his work and that of researchers at the State University of New York, Stony Brook who announced the discovery of a complete titanosaur skeleton in 2001, sauropod specialists finally can start piecing together a clearer picture of the dinosaurs' lives.

One feature of the skulls is particularly intriguing. "They have elongate, sort of horse-like skulls with many openings and grooves on the outer surface of their snouts," said Wilson, who worked closely with U-M Museum of Paleontology artist Bonnie Miljour over the course of a year preparing the paper's many illustrations of the skull reconstruction. "Blood vessels and nerves passed through these holes and may suggest an especially sensitive snout. This probably had some role in feeding, but we haven't investigated it at all."

Oddly, a group of distantly related sauropods evolved a similarly grooved snout. "Apparently, these two different branches of sauropods gravitated toward similar anatomical structures, perhaps because they were specialized for eating certain types of vegetation."

Source: University of Michigan
http://www.physorg.com/news6540.html
Edit to amend title.
 
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#2
Dinosaur eggs fail to reveal life

Dinosaur eggs fail to reveal life

A medical scan of three fossilised dinosaur eggs by experts hoping to find life in them has proved inconclusive. The eggs were brought to England from China before exports of the rare specimens were banned.

They are encased in one piece of rock and are normally on display at a gem shop in Tunbridge Wells, Kent.

Owner Graham Bell said images from the scan appeared to show parts of the shell, but the Natural History Museum would be investigating further.


It had been hoped that the hadrosaur eggs, which are at least 70 million years old, would yield a glimpse of a dinosaur embryo.

The eggs came from a clutch found in a nesting site in the mongolian desert.

They were spotted in the shop by someone from a local medical centre who offered Mr Bell the chance of putting them through a state-of-the-art scanner usually used for checking out people's heart disease.

Mr Bell said: "As the images emerged so more things became visible and we saw what we first thought were bones... but we think they were probably parts of the shell that had collapsed into the egg before petrification."

He added that the eggs would eventually be sold, which had been always been his original intention.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/e ... 292676.stm

Published: 2005/09/29 08:37:05 GMT

© BBC MMV
 
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#3
Dino reputation 'is exaggerated'

Dino reputation 'is exaggerated'
The Velociraptor dinosaur made famous by the Hollywood movie Jurassic Park may not have been quite the super-efficient killer we all thought.
Like other dinos in its family, it had a distinctive sickle-shaped claw on the second toe which many have assumed was employed to disembowel victims.

But tests on a mechanical arm suggest this fearsome-looking appendage was probably used just to hang on to prey.

UK scientists report their experiments in the journal Biology Letters.

"This dispels the myth in place for some 40 years that this was a disembowelling claw - this is not the case," says Dr Phil Manning, from the Manchester Museum, University of Manchester.

"I'm saying that the primary function of this claw was to hold on to the predator, effectively like a climber's crampon," the curator of palaeontology told the BBC News website.

Dino kick

Velociraptor belonged to the Dromaeosauridae , a family of small to medium-sized, lightly built and fast-running dinosaurs from the Cretaceous Period (146 million to 65 million years ago) who appear from the fossil record to have been very effective predators.

There is even evidence some, such as Deinonychus , hunted in packs.


It's effectively like a fatal embrace
Dr Phil Manning

They all possessed a large, curved claw on their big toes that could rotate through an arc in excess of 200 degrees.
By kicking and slashing, it has been widely thought these creatures could quickly open up their unfortunate victims, either killing them outright or making them bleed so profusely death followed very quickly.

Dr Manning and his team tested the reputation on a robotic arm fitted with a life-like Dromaeosaur claw. The set-up was based on detailed fossil measurements.

The mechanical limb mimicked the sort kick that might have come from a 2m-long, 40kg Velociraptor . The Kevlar and carbon-fibre-coated aluminium claw was thrust into the flesh from pig and crocodile carcasses.

Skin impact

Instead of producing the expected slashing wounds, the robotic impacts created only small, rounded punctures.


What is more, the way the skin tissue bunched under the impacts prevented the claw from withdrawing easily.
The punctures had a depth of about 30-40mm.

"It seems highly unlikely that wounds of this depth would have posed a danger to the vital organs of a large herbivorous dinosaur, though they would obviously be fatal to small prey," the team writes in Biology Letters.

Dr Manning does not want people to think less of Velociraptor or Deinonychus because of the research.

Its killing efficiency may not have matched their Hollywood image but the creatures would still have presented a terrifying prospect.

Deadly pack

"It's effectively like a fatal embrace," he told the BBC News website.

"These claws were used to hook into the flanks of prey larger than them so the jaws could do the despatching.


"Imagine the scene: it's the Lower Cretaceous, and Tenontosaurs (large, plant-eating dinosaurs) are grazing on ferns or cycads, going about their everyday business," he added.
"Unbeknown to them, you've got a pack of predators stalking them.

"First, [the Dromaeosaurs ] try to separate the animal they wish to kill by running into the pack.

"The lead attacker then jumps on to the flanks of the animal, followed by maybe two or three others, hooking the huge claws in their feet into the animal and holding on with the re-curved claws on their hands.

"And once they're hooked into their prey, the razor sharp teeth of their jaws go to work causing as much blood loss as possible to weaken the animal.

"Eventually, the other animals come over for the kill, probably ripping open the throat and stomach with their teeth - not their claws."

The results of research were first shown on The Truth about Killer Dinosaurs, a BBC television production.

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/s ... 332272.stm

Published: 2005/10/11 23:18:47 GMT
 
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#4
Ichthyosaur bones found off U.K. coast

Ichthyosaur bones found off U.K. coast

LYME REGIS, England, Oct. 14 (UPI) -- The snout, teeth, vertebrae and ribcage of a 15-foot reptile that lived off the coast of England 190 million years ago have been found.

Geologist Paddy Howe, who is monitoring work on the site in Lyme Regis, says the ichthyosaur looked a bit like a dolphin but was a reptile that swam in the sea at the same time dinosaurs roamed the land, the BBC reported Friday.

The remains were found during work to prevent landslides along the coastline and took months to painstakingly remove.

"Now it's a case of waiting to identify the exact species and how rare the fossil is before deciding whether or not to try and find the rest of it," Howe said. "We hope that the fossil will eventually go on display at Lyme Regis Museum."

Ichthyosaur
[/code]
 
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#5
Researcher Identifies Tracks Of Swimming Dinosaur In Wyoming

Researcher Identifies Tracks Of Swimming Dinosaur In Wyoming

The tracks of a previously unknown, two-legged swimming dinosaur have been identified along the shoreline of an ancient inland sea that covered Wyoming 165 million years ago, according to a University of Colorado at Boulder graduate student.

Debra Mickelson of CU-Boulder's geological sciences department said the research team identified the tracks of the six-foot-tall, bipedal dinosaur at a number of sites in northern Wyoming, including the Bighorn Canyon National Recreation Area. "It was about the size of an ostrich, and it was a meat-eater," she said. "The tracks suggest it waded along the shoreline and swam offshore, perhaps to feed on fish or carrion."

Mickelson will present her findings at the Geological Society of America's annual meeting Oct. 16-19 in Salt Lake City. She collaborated on the project with researchers from CU-Boulder, Indiana University, Dartmouth College, Tennessee Technological University and the University of Massachusetts.

Mickelson said scientists have previously reported evidence of swimming dinosaurs in other parts of the world and at other times in the geologic record. But the new findings by the team are the only known evidence of any dinosaurs in the Wyoming region during the middle Jurassic, she said.

The dinosaur does not have a name, although Mickelson is continuing to look for bones and other remains that could be used to identify and name the new species. "This dinosaur is similar to a Coelosaur," she said. "It is a dinosaur with bird-like characteristics and is a possible ancestor of birds. It lived in a much earlier time period and was very different from larger dinosaurs like T-Rex or Allosaurus."

The tracks are embedded in a layer of rock known as the Middle Jurassic Bajocian Gypsum Spring Formation, a 165- to 167-million-year-old rock formation that contains fossilized remains of a marine shoreline and tidal flats. Geologists believe an inland sea, called the Sundance Sea, covered Wyoming, Colorado and a large area of the western United States during the Jurassic period from about 165 million years ago to 157 million years ago.

Mickelson said the sea might have been warm and relatively shallow, much like the Gulf of Mexico today.

"The swimming dinosaur had four limbs and it walked on its hind legs, which each had three toes," Mickelson said. "The tracks show how it became more buoyant as it waded into deeper water -- the full footprints gradually become half-footprints and then only claw marks."

Mickelson explained the tracks are found among the traces left by many animals, including ancient crocodiles and marine worms. "The tracks of the ancient crocodiles are very different," she said. "They walk on four legs and have five digits."

Since summarizing preliminary findings last spring, Mickelson and the research group have expanded their study area, which she said contains millions of dinosaur tracks in a number of Gypsum Spring Formation rock outcrops in northern Wyoming.

The tracks are of different sizes and were deposited at about the same time, according to Mickelson, revealing that the dinosaurs likely traveled in packs and exhibited some variation in overall size. "Further research into the geologic record and depositional history of the region supports our conclusion that the dinosaurs were intentionally swimming out to sea, perhaps to feed," she said.

Source: University of Colorado at Boulder


http://www.physorg.com/news7313.html
 
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#6
Wright Brothers Upstaged! Dinos Invented Biplanes

Wright Brothers Upstaged! Dinos Invented Biplanes

The evolution of airplanes from the Wright Brothers' first biplanes to monoplanes was an inadvertent replay of the much earlier evolution of dinosaur flight, say two dino flight experts.

According to paleontologist Sankar Chatterjee and retired aeronautical engineer R.J. Templin, a small early Chinese dinosaur called Microraptor gui used a two-level, biplane wing configuration to fly from tree to tree in the early Cretaceous.

Among the evidence for the early biplane is that Microraptor had unmistakable flight feathers on its hind limbs as well as on its wings, says Chatterjee, a distinguished professor at Texas Tech University in Lubbock. The Chinese paleontologists who first reconstructed Microraptor had guessed that its four wings were used in tandem, similar to those of dragonfly.

Chatterjee presented the new biplane flight findings Sunday, 16 October, at the Annual Meeting of the Geological Society of America in Salt Lake City.

"The most unusual thing is that they have flight feathers not only on the hand section, but also on foot," said Chatterjee. Flight feathers differ noticeably from other feathers in that they are asymmetrical with interlocking barbules to keep their shape. The leading edge of each long feather was narrower than the trailing edge, which helped streamline the body in flight. The hooked, interlocking barbs gave strength and flexibility to the feather and prevented air from passing through it in flight.

Some present-day birds, especially raptors as well as the earliest Jurassic bird Archaeopteryx, also have (or had) feathers on their legs, Chatterjee says. But these are not flight feathers and appear adapted to streamline the legs during catching and carrying prey so they don't interfere with flight.

Another key element to discovering Microraptor's flight secrets was setting some realistic limitations on how the dinosaur could move its hindlimbs – something that was initially overlooked by Chinese researchers who found the fossil. Chatterjee and Templin studied its anatomy and found that like any dinosaurs, Microraptor held their hindlimbs in erect, vertical plane, permitting forward and backward motion.

"The problem we faced is that the legs of Microraptor, like on any dinosaur, could not be splayed sideways," as the Chinese paleontologists assumed. That means Microraptor could not have extended its rear limbs to form a wing directly behind the front wing. More likely, and more aerodynamically stable, would have been a rear wing that was held lower than the front wing – what from the side would look like a staggered biplane configuration, Chatterjee explains.

Chatterjee and Templin fed Microraptor's flight data into a computer simulation that they have previously used to successfully analyze the flying abilities of pterosaurs and Archaeopteryx. Based on the aeronautical analysis, it appears that Microraptor flights looked rather like those seen today among some "monoplane" forest birds -- something called undulating phugoid gliding, Chatterjee said. In other words, Microraptor launched from a high branch and dove off, falling head-first until it reached a speed that created lift on its wings. With that lift the feathered dino then swooped upwards and landed in the branches of another tree without having to flap its wings and expend muscular energy.

"The biplane wing configuration was probably a very first experiment in nature," says Chatterjee of the early flying technique, which was also used by another feathered dinosaur from China, Pedopenna, he said. Archaeopteryx achieved fully powered flight with monoplane configuration, as its wing became even larger than those of Microraptor, but foot feathers were lost.

"It is intriguing to contemplate that perhaps avian flight, like aircraft evolution, went through a biplane stage before the monoplane was introduced, said Chatterjee. "It seems likely that Microraptor invented the biplane 125 million years before the Wright 1903 Flyer."

The discovery of Microraptor and other small, exquisitely preserved feathered dinosaurs from China also helps to settle a century-old controversy over whether avian flight began in trees (trees-down theory) or on the ground (ground-up theory). These fossils show various transitional stages–from wingless, tree-dwelling theropod dinosaurs to fully winged, active flyers, Chatterjee said.

The central theme of the trees-down theory is that gravity was the source of energy: a small climbing dinosaur first parachuted down, then began to stay aloft longer by gliding, and finally acquired powered flight. As those abilities developed, feathers became larger and more specialized, providing greater lift and thrust. The Chinese feathered dinosaurs show these transitional stages of flight.

In contrast, the ground-up theory has a theropod struggling toward flight directly from the ground, against gravity, without any gliding stage. Such long feathers around the feet would make it hard for Microraptor to run on the ground, says Chatterjee, supporting the idea that it was a tree dweller, thus reinforcing the trees-down theory.

http://www.physorg.com/news7358.html
 
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#8
Taking A Bite Out Of The Problem: Researchers Devise Dinosau

Source: Washington University in St. Louis
Date: 2005-11-10
http://www.sciencedaily.com/releases/20 ... 084537.htm

--------------------------------------------------------------------------------

Taking A Bite Out Of The Problem: Researchers Devise Dinosaur Classification Method
What do you get when you cross Carcharodontosaurus with Majungatholus? Good luck telling the two apart. Owing to paltry numbers of whole specimens that fail to illuminate a range of intraspecies morphological variation, dinosaur classification can be a task as gargantuan as some of its famed species. But Josh Smith, Ph.D., assistant professor of earth and planetary sciences at Washington University in St. Louis, has concocted a mathematical scheme for identifying dinosaurs based upon measurements of their copious Mesozoic dental droppings. His method could help paleobiologists identify and reconstruct the lives of the creatures that roamed our terra firma many millions of years ago.

Smith, who claims he's "not very good at math," and his coauthors, David R. Vann and Peter Dodson of the University of Pennsylvania, devised a quantitative methodology by which an isolated tooth of a predatory dinosaur — a theropod — can be correlated with a given genus. They used a variety of measurements — some of which had been defined by previous workers — that describe the basic size and general shape of the teeth as well as devised functions that help quantitatively describe the shapes of the curved surfaces possessed by the teeth. The result was a preliminary but rigorous method of classifying theropod teeth with established genera. Smith and his colleagues published their in work in a recent issue of The Anatomical Record (Vol. 285, 2005).

"My whole point was to take an isolated tooth and figure out what dinosaur it belonged to," Smith explained. "The questions I'm interested in are different than 'what did this thing eat?' I'm interested more in teeth as tools for dinosaur identification rather than the teeth as teeth themselves."

Teeth as hardy identifiers

People like teeth. The same mineral that helps us chaw our way to Thanksgiving bliss allows paleontologists like Smith to study a time period so far removed from our own that traces of bones and enamel are among the only clues to the past. Mesozoic-aged dinosaurs, living between 225 and 65 million years ago, are referred to as polyphyodont animals because they continually shed and replaced teeth throughout their lives. Tooth replacement introduces the hardest and most resilient substance in the vertebrate body, enamel, into the local environment many times over as old teeth are lost and fall from the mouths of their owners into streams and onto the forest floor. After countless tooth replacements and millions of years of sedimentation, Smith and his colleagues have uncovered an ample data set of preserved dinosaur enamel: Smith's Rosetta stone of theropod classification.

"The problem is that theropod teeth are simple enough that everyone has ignored them for the last 200 years, " Smith said. He said that the simple shapes of theropod teeth have complicated previous rigorous attempts to use them for classification.

The mathematical tedium Smith claims to have spared while devising the methods was not lost on tooth examination: Smith collected measurements and curvature data from about 2,000 teeth, scrutinizing dinosaur chops as a dentist would a root canal. Thousands of measurements ultimately boiled down into a data set of just under 300 usable teeth. The dataset is comprised of measurements of teeth from genera that are known with certainty; it thus forms a standard of comparison against which unknown teeth can be compared.

Smith then ran statistics on the database to correlate the shapes of unknown teeth with the most similar tooth of known origin. During a test of the methods, most of the time the model worked, correctly identifying known, and even similar-looking teeth as the correct genus.

"I've created the beginnings of a standard of comparison; a data set with teeth that we know where they came from, against which to compare isolated teeth. That's basically all I've done," Smith said.

He said that the model, although functional, isn't without its weaknesses. To properly correlate a tooth with a species, the species that the tooth belongs to must be represented in the data set; otherwise, the analysis will try to match the tooth with the species that most resembles the unknown.

Increasing the data set

"So now I'm working on making the method better and increasing the size of the data set," Smith adds.

Dinosaur identification is critical for paleontologists trying to accurately reconstruct the Mesozoic Period. Teeth can reveal dinosaur eating habits and biology if the tooth is associated with its rightful owner.

"We're taking a potential data set — that is, isolated teeth — that has the potential to be really powerful," Smith said, "Until now, the data have largely been overlooked but we're trying to make use of them. And it looks like it's working. Which is only really significant because everybody said it wouldn't."
 

lawofnations

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#9
First time post - and in anger

I'm a long time lurker, first time poster.

Josh Smith used to supervise my fiancée during the one year she spent as a PhD student at Washington University in St Louis. She was forced to leave the PhD at Wash U due to the behaviour of "Professor" Smith, who, amongst his many other sins (perhaps his wife would care to know about his "field work") assaulted my fiancée and stole research ideas from students and allowed other students to steal research ideas from close friends of my fiancée. As most board members with connections with academia will know, there is no greater professional sin than plagiarism.

Identification of dinosaur species from morphometric analysis of isolated samples of dinosaur teeth was my fiancées proposed PhD dissertation. Josh Smith dismissed this as unworkable and not worth studying. My fiancée countered that there were many isolated specimens and that no-one else was doing this work. Smith said that there was a reason no-one was doing it, because it wouldn't work, and also because it is computers and maths that no-one would understand.

Now I see that Smith has decided to steal her research (no change from his standard behaviour), and still claims he doesn't understand the math, unlike my fiancée, who does. I note the article does not mention the computer programs that would be required to be used for this morphometric analysis. Doubtless Smith has decided to perform the analysis manually with calipers - my fiancée suggested using a powerful suite of computer programs called TPS.

I am sorry if this isn't really in the spirit or purpose of this thread, but I am so damn angry at the moment it's not funny.

Apologies to everyone for this rant. Grrrrrrrrr.
 

rynner2

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Re: First time post - and in anger

lawofnations said:
I'm a long time lurker, first time poster.
I am sorry if this isn't really in the spirit or purpose of this thread, but I am so damn angry at the moment it's not funny.
.................................
Apologies to everyone for this rant. Grrrrrrrrr.
No need to apologise for this interesting insight into the ways of academia.

There are selfish, thieving gits in all fields of human endeavour, sadly.
 
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#12
Missing Fossil Link 'Dallasaurus' Found

Source: Southern Methodist University
Date: 2005-11-16
http://www.sciencedaily.com/releases/20 ... 173945.htm

--------------------------------------------------------------------------------

Missing Fossil Link 'Dallasaurus' Found

When amateur fossil finder Van Turner discovered a small vertebra at a construction site near Dallas 16 years ago, he knew the creature was unlike anything in the fossil record. Scientists now know the significance of Turner’s fossil as the origin of an extinct line of lizards with an evolutionary twist: a land-dwelling species that became fully aquatic.

Turner took the remains to paleontologists at the Dallas Museum of Natural History, but it took several years before scientists dubbed the find Dallasaurus turneri. Word of Dallasaurus is now reaching the scientific community with a special issue of the Netherlands Journal of Geosciences, featuring an article by Southern Methodist University paleontologist Michael Polcyn and Gordon Bell Jr. of Guadalupe National Park in Texas.

They describe Dallasaurus, a three-foot long lizard who lived 92 million years ago in the shallow seas and shores of what was then a stretch of Texas mostly under water, and also used the fossil to better understand the mosasaur family tree. Polcyn and Bell painstakingly pieced together an understanding of the anatomy and natural history of Dallasaurus from the bones Turner discovered and from some matching skeletal remains at the Texas Memorial Museum at the University of Texas in Austin.

Dallasaurus represents a missing link in the evolution of a group of creatures called mosasaurs, prehistoric animals that started out on land, but evolved in the seas and dominated the oceans at the same time dinosaurs ruled the land. One aspect of Polcyn and Bell’s research is the revelation that Dallasaurus retained complete limbs, hands and feet suitable for walking on land, whereas later mosasaurs evolved their limbs into flippers.

“This is pretty close to the beginning of the mosasaur family tree,” says Dallas Museum of Natural History Earth Sciences Curator and SMU Adjunct Professor of Paleontology Anthony R. Fiorillo, Ph.D. “It is the most complete mosasaur retaining all of its limbs found in North America.”

Mosasaurs, every bit as prolific, fascinating and nearly as big as some dinosaurs, are becoming more popular for paleontologists to study. Mosasaurs lived and became extinct alongside dinosaurs, but few paleontologists specialize in them. Later mosasaurs grew as large as their dinosaur brethren, reaching up to 45 feet in length. Until the discovery of Dallasaurus, however, only five primitive forms with land-capable limbs were known, all of them found in the Middle East and the eastern Adriatic.

“Lizards had nearly 150 million-year-long history on land; then in the Late Cretaceous, the final stage of the age of dinosaurs, one group moved into the sea and rose to the very top of the food chain,” explains Polcyn, director of SMU’s Visualization Laboratory, part of the university’s geological sciences department. “Starting out as small animals like Dallasaurus, they mastered their new marine environment and rose to become the top predator in their ecosystem, the T. Rex of the ocean.”

The Late Cretaceous period was a time of hot house temperatures and rising sea levels.

“As the earth warmed and the seas rose, small land-dwelling lizards took to the oceans and developed increasing levels of seagoing capabilities, and over 30 million years, eventually evolving into the top predator of their domain before becoming extinct some 65 million years ago” says Polcyn.

The advanced fin-bearing mosasaurs have been grouped into three major lineages. Although a small number of primitive mosasaur have been known to retain land-capable limbs, they were thought to be an ancestral group separate from the later fin-bearing forms. Dallasaurus represents a clear link to one lineage of the later forms and the first time researchers can clearly show mosasaurs evolved fins from limbs within the different lineages of mosasaurs.

With the aid of computer science and SMU’s visualization laboratory, Polcyn has been able to simulate what Dallasaurus looked like, and how, based on his skeletal remains, he would swim and move from land to sea. An artist has taken Polcyn’s visualization work even one step further by creating a life-sized model of Dallasaurus, a work that is soon to be on display at the Museum along with the computer simulation.

When funds become available for reconstructing a suitable exhibit, the bones of Dallasaurus will be displayed at the Dallas Museum of Natural History. The work, however, will take several more years of additional efforts and substantial funding. A nearly 30-foot long mosasaur, some 75 million years old, already is on display at the Dallas Museum.

Major dinosaur finds are frequently the result of creatures dying in groups through flooding or drought, situations that lend themselves fairly well to more complete preservation and conservation of their bones, and much slower deterioration. Mosasaur fossils, in contrast, are rarely found in large groupings, and are only found in areas once covered by seas. Remains were quick to deteriorate under ocean currents; their bodies often fell victim to the ravages of other sea life, such as sharks, who would pick away at carcasses for food. Because of their mostly shallow sea and seaside habitats, the remains of early mosasaurs are even more rare and much harder to find.

But in the last two decades, many new discoveries and significant advances have been made in the understanding of mosasaur evolution and how they lived. Dallasaurus significantly advances that understanding by filling in a long missing piece of mosasaur evolution, specifically a time at which they transition from land to sea.

The importance of Turner’s discovery isn’t lost on the researchers putting together the pieces of the mosasaur puzzle. In fact, they predict the legacy of Turner’s discovery will live on. His contribution was honored by naming the species, “turneri,” after his last name. “Not all major discoveries are made by highly trained paleontologists,” notes Dallas Natural History Museum Curator Fiorillo. “The observant individual, even kids, can still make an important find,” he says. “Once this goes mainstream, and people begin to recognize what mosasaurs are, we’ll be finding more and more.”

# # #

SMU is a private university in Dallas with more than 10,000 students and offers degree programs through seven schools. More information about SMU is available at www.smu.edu.

The Dallas Museum of Natural History, a Smithsonian Institution affiliate, is a research and exhibition institution devoted to natural history research and public education. It is funded by public government, companies and by private foundations and individual donations, including the City of Dallas, the state of Texas, the Microsoft Foundation, the Junior League, American Airlines and the Dallas Morning News. With over 280,000 specimens, it is among the largest natural history museums in the country. Located in historic Fair Park in Dallas, the museum is open daily, 362 days annually. The Museum’s website is www.dallasdino.org.
 
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#13
Dinosaurs had appetite for grass
A study of fossil dinosaur dung has for the first time confirmed that the ancient reptiles ate grass.
Grass was previously thought to have become common only after the dinosaurs died out 65 million years ago.

But grasses were probably not a very important part of dinosaur diets - the fossilised faeces show the big beasts ate many different types of plants.

However, the Science journal study suggests grass was possibly an important food for early mammals.

Caroline Strömberg from the Swedish Museum of Natural History and her colleagues studied phytoliths (mineral particles produced by grass and other plants) preserved in fossil dinosaur dung from central India.

Theory dumped

The 65-67 million-year-old dung fossils, or coprolites, are thought to have been made by so-called titanosaur sauropods; large, vegetarian dinosaurs.


"It's difficult to tell how widespread [grass grazing] was," Ms Strömberg told the BBC News website, "Dinosaurs seem to have been indiscriminate feeders."
The study also sheds new light on the evolution of grass. Grasses are thought to have undergone a major diversification and geographic proliferation during the so-called Cenozoic, after the dinosaurs had gone extinct.

But the researchers found at least five different types of grass in the droppings.

This suggests grasses had already undergone substantial diversification in the Late Cretaceous, when the giant beasts still walked the Earth.

Defence mechanism

Many grasses today contain high levels of silica, which makes them tough and hard to chew. One theory proposes that this is an evolutionary defence against being eaten by herbivores.

This defence is traditionally thought to have been a response to large-scale grazing by mammals in the Cenozoic. But, if the theory is correct, it raises the possibility that grasses first began developing this defence in response to grazing by dinosaurs.

However, small mammals living alongside the dinosaurs may also have been grass feeders.

An enigmatic group of extinct mammals known as sudamericid gondwanatherians, which lived during the Late Cretaceous, show possible signs of adaptation to a grassy diet.

Their teeth are ideally suited for handling abrasive materials like grass. But because of grass's patchy presence in the fossil record, these features were interpreted as an adaptation to a semi-aquatic, or burrowing, lifestyle like that of modern beavers.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/s ... 443696.stm

Published: 2005/11/17 18:55:57 GMT

© BBC MMV
 
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#14
Oldest bird had dinosaur feet
19:00 01 December 2005
NewScientist.com news service
Jeff Hecht

Enlarge image
With jagged teeth and raptor-like features, the feathered archaeopteryx is unlike any modern species of bird (Image: G Mayr/Senckenberg)
Enlarge image
Ultraviolet light enhances details of a complete foot, showing that archaeopteryx had an extensible claw on its second toe – a hallmark of raptors – which is absent in all known birds (Image: G Mayr/Senckenberg)The oldest known bird was closer to a dinosaur than previously thought – a discovery that confuses the evolutionary tree as we currently understand it.

An exceptionally well preserved new fossil reveals a foot and skull that more closely resemble those of a group of two-legged predatory dinosaurs called the known as dromeosaurs, than modern birds.

With jagged teeth and a dinosaur-like skeleton, the archaeopteryx is unlike any modern species of bird. But flight feathers on its long front limbs have led palaeontologists to identify the creature as the oldest known species of bird.

Nine previously known specimens of archaeopteryx have led palaeontologists to conclude that birds probably evolved from small meat-eating dinosaurs, and are closely related to the dromeosaurs, a group that includes the velociraptor. Yet precisely how archaeopteryx is related to the raptors has remained unclear – key pieces of these previous specimens are missing.

But the newly revealed fossil appears to fill in many of the gaps. The specimen comes from the private collection of a worker at the Solnhofen limestone quarries in Germany, where the first archaeopteryx fossil was discovered. It has remained unknown to science until its owner's death, when the new owner made it available to scientists at the Wyoming Dinosaur Center in the US.

Computer model
A complete foot reveals that archaeopteryx had an extensible claw on its second toe, which is a hallmark of raptors, but is absent in all known birds. Its first toe, or "hallux", is also at the side of the foot and not reversed as it is in perching birds, which use it to grasp branches.

The skull is also well preserved and shows that the animal had a skull bone known as the "palatine", which is shaped in the same way as in many two-legged dinosaurs.

The new traits were added to a computer model, enabling palaeontologists to analyse the relationship between extinct species. "It's now very difficult to distinguish between [early] birds and [early] dromeosaurs," says Gerald Mayr of the Senckenberg Research Institute in Frankfurt, Germany, who studied the specimen.

Question of class
Mayr told New Scientist that there are no unique traits shared by archaeopteryx and other early bird-like fossils that are not present in dinosaurs. This would either mean that archaeopteryx cannot be classed within the same evolutionary group as birds or that this group needs to be redefined.

But Peter Makovicky of the Field Museum of Natural History in Chicago, US, says those results are shaky because Mayr's group considered only three bird-like creatures; archaeopteryx, confuciusornis and a primitive bird called Rahonavis, that lived much later.

In October 2005, Makovicky carried out a separate study that links Rahonavis directly to the dromeosaurs and suggests this species may have evolved flight separately from archaeopteryx and other birds. Makovicky told New Scientist he found no change in the shape of his evolutionary tree when he added the new traits found for archaeopteryx.

Journal reference: Science (Vol 310, p 1483)

http://www.newscientist.com/article.ns?id=dn8408

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Science
http://www.sciencemag.org/
Field Museum of Natural History
http://www.fieldmuseum.org/
Senckenberg Research Institute
http://www.senckenberg.de/
 
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#15
One Size Didn't Fit All for Early Dinosaur, Study Says

James Owen
for National Geographic News

December 15, 2005
One size didn't fit all for the early dinosaur Plateosaurus, a new study suggests.

Fossils show the giant plant-eaters experienced sudden growth spurts, with some adults dwarfing others.


The study team estimates that the biggest individuals measured 33 feet (10 meters) in length and weighed almost 4 tons. Other dinos of the species were twice as small, managing an adult body length of only 15 feet (4.8 meters).

Researchers say the animal, which lived some 200 million years ago, had growth patterns like those seen in living reptiles but unlike those of other, later dinosaurs.

Scientists at the University of Bonn in Germany analyzed growth rings found in the fossilized leg and pelvic bones of Plateosaurus, a long-necked, two-legged dino once common across Europe.

The study, which appears tomorrow in the journal Science, suggests that adults grew at different rates and that their growth occurred either in rapid spurts or slow stretches depending on environmental conditions.

The scientists add that this growth model in such a large dino species means that Plateosaurus possibly marks an initial step in the evolution of genuinely warm-blooded dinosaurs.

Size Range

Mammals grow "in accordance with a genetically programmed blueprint," said Martin Sander, a University of Bonn palaeontologist and lead study author.

Humans, for example, can reach different sizes as adults, but individuals' growth rates will be fairly predictable over time.

Dinosaurs were thought to have had steady growth patterns similar to mammals, but "our findings have thrown this conception into disarray, at least for one dinosaur," Sander said.

Sander and his colleagues say Plateosaurus probably had a similar metabolism to living reptiles. Like today's lizards, crocodiles, and turtles, the dinosaur's growth "was affected by environmental factors such as climate and food availability," the researchers report.

Some individuals hit upon excellent conditions for piling on the pounds, while others fell on lean times.

Dinosaur researcher Paul Barrett, of the Natural History Museum in London, agrees that the study appears to provide "nice evidence of some kind of temporary growth spurt rather than continued, similar rate of growth throughout the animal's lifetime."


This "might correlate with greater instances of food or maybe a warmer summer," Barrett said. "That would make sense in interpreting [Plateosaurus] in a crocodile- or lizardlike model."

Growth spurts and big size differences within a species are characteristic of ectothermic animals—those with a metabolism dependent on external conditions. Lizards, for instance, are active when it's hot but become sluggish in cold weather.

Meanwhile mammals and birds, which have growth rates largely independent of outside factors, are endothermic—they heat and cool their bodies internally.

Which of these two camps dinosaurs belonged to has long been a bone of contention among experts.

Sander says Plateosaurus was probably somewhere between the two, with the animal perhaps representing a first stage in the evolution of endothermic dinosaurs.

Warm-Blooded

Barrett of the Natural History Museum says early large dinosaurs such as Plateosaurus were not endothermic, but likely were warm-blooded.

"They're probably warm-blooded because they're big and they produce a lot of heat through digestion and through muscular action," he said.

"They have a relatively small surface area to their volume ratio, and any excess heat they generated just by accident would mean they have a higher body temperature than the outside environment."

Based on their body structure, some later, smaller dinosaurs also appear to have been endothermic.

"It's a size argument," Barrett said. "Because they are small and active, it looks like they should be warm-blooded to fuel their active lifestyle."

"Some of these little dinosaurs are now known to have had an insulating covering—feathers or fuzz of some kind," he added. "This suggests they were generating heat internally and were trying to retain it."

These small theropod dinosaurs are on the evolutionary line that leads eventually to birds, Barrett says.

"Certainly, by the time you get to birds, [the animals] are generating heat internally," he added.

"Birds are only modified dinosaurs, and at some point in their ancestry you need to switch [endothermy] on. Deciding when that happened is quite difficult, as we can't just go and measure the temperature of an extinct dinosaur."

Dino
 
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#16
Duck-bill dinosaur mystery finally solved

A University of Toronto scientist has concluded duck-billed dinosaurs' large, hollow crests had nothing to do with olfaction.

David Evans, a University of Toronto-Mississauga doctoral zoology student, has used a reconstructed brain cavity to rule out one of the most popular theories: that the crests evolved to increase the animal's sense of smell.

"From the brain case, there's no indication that the nerves curled upward into the crest, as we would expect if the crest was used for the sense of smell," Evans says. "It appears the brain changed very little from their non-crested dinosaur ancestors, and the primary region of the sense of smell was located right in front of the eyes -- and, coincidentally, that's where it is in birds, crocodiles, mammals and basically all four-legged animals."

Evans research adds weight to two other popular theories: the crests were used to create resonant sounds to attract mates or warn of predators, or they were used for visual display in mate selection or species recognition.

The study appears in the journal Paleobiology.

http://www.physorg.com/printnews.php?newsid=10212
 
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#17
Oldest T. rex relative unveiled
By Rebecca Morelle
BBC News science reporter



The forefather of the mighty Tyrannosaurus rex has been discovered, scientists report. The 160 million-year-old fossil is the oldest tyrannosaur ever found. The researchers were surprised to learn the 3m long dinosaur sported a spectacular crest on its head which may have been brightly coloured.

The discovery, unveiled in the journal Nature, might reveal how early tyrannosaurs evolved into the T. rex 100 million years later. The new species was found in the Junggar Basin, an area rich in dinosaur fossils, in the far north-west corner of China.

'Crowned dragon'

A local labourer, hired to search for ancient bones, happened upon two dinosaur skeletons: a 12-year-old adult and a six-year-old juvenile. Both were found to be remarkably intact.

The international team have named the dinosaur, which hails from the Late Jurassic period, Guanlong wucaii ( G. wucaii ) which is derived from the Chinese for "crowned dragon".


We suspect that the crest was highly coloured and probably a display structure of some kind
Prof James Clark, George Washington University

Professor James Clark, an author on the paper and a palaeontologist at George Washington University, US, told the BBC News website of the discovery.

"We found two skeletons of what we call a therapod dinosaur. When we looked at them very closely we found that they are a relative of Tyrannosaurus rex - making them the most primitive tyrannosaur relatives that we have seen," he explained.

Tyrannosaurs were the dominant group of predators during the Late Cretaceous period. This era, about 65 to 100 million years ago, marked the final chapter before dinosaurs became extinct.

It was during this time the T. rex roamed. The most famed member of the tyrannosaur family; its immense size of between 9 to 13m, huge teeth and tiny but savagely-clawed forearms have made it the beast of choice for many Hollywood films.

Evolution clues

Professor Clark described how the G. wucaii would have looked: "The most obvious thing was that it had a big crest in the middle of its head. For carnivorous dinosaurs that's pretty unusual.

"We suspect that the crest was highly coloured and probably a display structure of some kind."

He said that it shared some features with the later tyrannosaurs, such as the T. rex . It had sharp teeth, similar muscle scars on its hips and probably ran on two legs.


But the G. wucaii differed markedly in terms of its size: at three metres it was much smaller. In addition, its more primitive skull and pelvic features would suggest that that it was intermediate animal between tyrannosaurs and the coelurosaurs - an even older related group of dinosaurs which are also the predecessors to modern birds.

The researchers hope that the find will reveal more about the primitive phase of tyrannosaur evolution.

" Guanlong shows us how the small coelurosaurian ancestors of tyrannosaurs took the first step that led to the giant T. rex almost 100 million years later," Prof Clark said.

Most of the tyrannosaur fossils that have been found date to the latter years of tyrannosaurs' existence, and there are very few early specimens.

Prior to the discovery of the G. wucaii , the 130 million-year-old feathered Dilong paradoxus ( D. paradoxus ) reported in 2004, was the oldest tyrannosaur known.

Dr Paul Barrett, a palaeontologist at the Natural History Museum, commented: "The discovery of this new animal pushes the origin of the group containing T. rex further back in time and also shows that early tyrannosaurs had a much wider distribution than previously thought."

The researchers believe the G. wucaii , with its bizarre crest, will begin to fill in some of the gaps of our knowledge of tyrannosaurs.

"This is 160 million years old, there are almost 100 million years of fossil records between it and T. rex and there are only a few tyrannosaurs that we know of between that," said Professor Clark

"It is telling us that we are just getting into finding the missing records of these early tyrannosaurs."


The Guanlong lies at the base of the lineage of tyrannosaurides
The Eotyrannus was dwarfed by other predators in its environment
The T. rex was a member of the Tyrannosauridae family


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/s ... 692962.stm

Published: 2006/02/08 18:00:26 GMT
 

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#18
The dino-daddy of all meat eaters

THE biggest, and possibly the baddest predatory dinosaur of them all was not the fabled Tyrannosaurus rex, or even its slightly larger rival Gigantosaurus, but a long-jawed, sail-backed creature called Spinosaurus.

An examination of some newly obtained fossils shows that Spinosaurus stretched an impressive 17 metres from nose to tail, dwarfing its meat-eating relatives. As well as being longer than its rivals, Spinosaurus also had stronger arms with which to catch its prey, unlike the puny-armed T. rex and its ilk.

Until 10 years ago, T. rex held the mantle of the biggest predatory dinosaur. Of the 30 specimens collected so far, the largest and most complete is a fossil called Sue, kept at the Field Museum of Natural History in Chicago. She measures 12.8 metres long and is thought to have weighed 6.4 tonnes when alive 67 million years ago.

Enter Gigantosaurus, a meat-eating dinosaur that lived in what is now Argentina. Reconstruction of a partial skeleton indicated that it stretched 13.7 metres. It lived about 100 million years ago at around the same time as two other huge predatory dinosaurs were stalking other continents. The slightly smaller Carcharodontosaurus lived in Africa while Acanthosaurus lived in North America, the only one of the three dinosaurs for which we have more than a handful of fragmentary fossils. All three predators were closely related to Allosaurus, a 9 to 12-metre-long predator of a lighter build than T. rex which was common in North America 150 million years ago.

However, Spinosaurus has been casting its fearsome shadow over all these beasts for some time. German palaeontologist Ernst Stromer discovered the first and best specimen in 1912 in Egypt. He identified it as a long-snouted giant predator which he believed was bigger than T. rex, and published a detailed study of the bones, including a partial backbone with long spines on the vertebrae, which may have supported a sail. Stromer's fossils were obliterated when allied bombers hit a Munich museum in 1944. Since then, all that has been discovered are some specimens of related smaller spinosaurs, as well as some isolated bones of Spinosaurus itself.

But a new examination of two skull fragments of Spinosaurus has confirmed its early reputation. Cristiano Dal Sasso of the Civic Natural History Museum in Milan, Italy, and his colleagues analysed a snout the museum acquired from an Italian collector, and previously unidentified bones from the upper rear of the skull collected by the University of Chicago, both of which were originally unearthed in Morocco.

“With their long, slender snouts and interlocking teeth, spinosaurs were like theropods with crocodile mouths”After measuring their sizes, he estimates that the 99-centimetre-long snout came from a skull 1.75 metres long. From what we know of the body shapes of other spinosaurs, Dal Sasso calculates that the new Spinosaurus was 17 metres long and weighed 7 to 9 tonnes (Journal of Vertebrate Paleontology, vol 14, p 888).

Spinosaurus lived alongside Carcharodontosaurus in Africa 100 million years ago, and like T. rex and Giganotosaurus was a theropod, the group of dinosaurs that gave rise to birds. But Dal Sasso says spinosaurs, with their very long and slender snouts are more like "theropods with crocodile mouths". Their long teeth interlocked to catch prey, and a sawfish vertebra stuck between a tooth socket and an emerging tooth in one fossil specimen supports the idea that Spinosaurus preyed largely on fish. Other specimens also suggest that spinosaurs had arms "strong enough to be used in catching prey", says Eric Buffetaut of France's National Centre for Scientific Research in Paris, who collaborated with Dal Sasso.

T. rex and Gigantosaurus "were doing very different things", says palaeontologist Larry Witmer of Ohio University in Athens. T. rex had puny arms, but its stout skull had massive banana-shaped teeth that could crunch through bone, where Giganotosaurus had a much more slender skull, with blade-like teeth to slice through flesh.

http://www.newscientist.com/article.ns? ... 925384.600
 

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#19
Dinosaurs were 'poisoned'


Scientists claim dinosaurs were poisoned to extinction and not killed off by an asteroid collision with Earth.

Researchers say the animals became extinct when arsenic and other toxic metallic elements were released into the atmosphere during volcanic eruptions.

The emissions, mainly in India and New Zealand, happened 500 to 800 years before an asteroid hit the Gulf of Mexico 65 million years ago.

The team at Vienna's Natural History Museum and the Russian Academy of Sciences came to this conclusion by examining earth samples taken from Styria in Austria.

http://www.ananova.com/news/story/sm_17 ... ?menu=news. scienceanddiscovery
 
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#20
North Sea fossil is deepest dino

The first dinosaur fossil discovered in Norway is also the deepest one that has been found anywhere in the world. The 195-210-million-year-old specimen was found 2.3km (1.4 miles) below the floor of the North Sea by an offshore oil drilling platform.

Norwegian palaeontologist Jorn Harald Hurum, from the University of Oslo, identified the fossil as the knucklebone of a plateosaur.

Details of the discovery are to appear in the Norwegian Journal of Geology.


We knew there was food there, so something must have been eating it. But we didn't know what animals were there
Jorn Harald Hurum, University of Oslo

"It's the first time a dinosaur bone has ever been found in such a deep core," Dr Hurum told the BBC News website.
Marine reptile fossils have been found in some previous North Sea drill cores, but to find a terrestrial animal at such a depth is rare.

"To drill through a terrestrial animal is much rarer because there are so many more marine sediments there," Dr Hurum, assistant professor of vertebrate palaeontology at Oslo's Natural History Museum, explained.

The crushed knucklebone was identified in a long cylinder of rock drilled out from an exploration well at Norway's Snorre offshore field.

Enigmatic specimen

The geologists who drilled the core spotted the curious specimen in 1997; but they were discouraged by colleagues who thought it was plant matter and tucked it away in a drawer.

Only in 2003 did they pass the specimen to Hurum, who thought it looked like a dinosaur.


After consulting palaeontologists at the University of Bonn in Germany, a microscopic examination of the specimen showed it to be identical in structure to bones from a Plateosaurus species.
This dinosaur is the most common type found in Europe. At the time it lived, there was a desert between Norway and Greenland crossed by meandering rivers.

"We knew there was food there, so something must have been eating it; but we didn't know what animals were there," Dr Hurum said.

Dr Hurum describes himself as Norway's only dinosaur researcher. Successive ice ages have eroded dinosaur-bearing rocks in mainland Norway.

But the scientist thinks fossils could be found on the northern island of Spitsbergen.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/s ... 950540.stm

Published: 2006/04/27 15:13:49 GMT

© BBC MMVI
 
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#21
Hot And Heavy Dinos Rules The Earth

View of left side of Dakosaurus andiniensis skull. Credit: Diego Pol, Ohio State University.
by Staff Writers
Gainesville FL (SPX) Jul 13, 2006
If you think dinosaurs are hot today, just think back to about 110 million years ago when they really ran hot and heavy. One of the larger animals, a behemoth called Sauroposeidon proteles, weighed close to 120,000 pounds as an adult. Now, a new study led by the University of Florida suggests it may have had a body temperature close to 48 degrees Celsius.
That is a 118-degree Fahrenheit normal temperature, about as hot as most living creatures can get before the proteins in their bodies actually begin to break down.

In fact, the size of the largest dinosaurs may ultimately have been limited by their body temperatures, according to a team of scientists from the UF Genetics Institute, the National Center for Ecological Analysis and Synthesis in Santa Barbara and the University of New Mexico writing this week in the online journal PLoS Biology.

One of the first things to strike me about our results was that larger dinosaurs, for their size, were much more active than contemporary reptiles, said Andrew Allen, a researcher with the NCEAS. If these animals functioned at temperatures of 35 or 40 degrees centigrade, it suggests that they operated at a rate more like today s mammals and birds. While the largest dinosaurs may not have been running around as fast as in Jurassic Park, they certainly were very active given their extreme size.

Tyrannosaurus rex, one of the more familiar dinosaurs considered by the researchers, probably had a cruising temperature of about 33 degrees Celsius, which is just over 91 degrees Fahrenheit, according to lead researcher James Gillooly, an assistant professor in UF s department of zoology. Humans have a normal temperature around 98.6 degrees Fahrenheit and redline at about 108 degrees.

Researchers determined dinosaur temperatures - long a subject of debate in biology - by combining their understanding of relationships among body size, temperature and growth rates with newly available fossil data on the growth rates of eight dinosaur species. Using a mathematical formula, they produced the first prediction of dinosaur body temperatures based on direct fossil evidence.

When a dinosaur started small and grew large, its body temperature changed dramatically through its lifespan, unlike any animals we know today, Gillooly said. It increased by about 5 degrees Fahrenheit for species weighing about 661 pounds as adults and nearly 36 degrees for those reaching about 27 tons.

This dramatic difference in body temperature between the largest and smallest dinosaurs probably resulted in major differences in how these species lived, because we know a difference of 18 degrees Fahrenheit results in a nearly 300 percent change in rates of population growth, lifespan and population density.

For many years, scientists had assumed that dinosaurs were cold-blooded, or ectotherms, with a slow metabolism that required the sun s heat to regulate temperature. But in the late 1960s, the notion emerged that dinosaurs, like mammals and birds, might have been warm-blooded, or endotherms, with relatively constant, high body temperatures that were internally regulated.

The new findings show that even though dinosaurs were cold-blooded reptiles, large dinosaurs dissipated body heat more slowly, and thus maintained higher, more constant body temperatures similar to today s birds and mammals. The researchers show that this increase in body temperature with size has been observed in modern crocodiles.

The study is an important contribution to the scientific discussion about dinosaurs, because it is the first that uses evidence directly derived from fossils - rather than from theoretical models - to conclude that many of the larger dinosaurs were indeed warm reptiles, said Frank Seebacher, of the School of Biological Sciences at the University of Sydney, who did not take part in the research.

These findings clearly show that mammal-like endothermy is not a necessary prerequisite for ecological success. Dinosaurs inhabited all latitudes, and although the climate in the age of dinosaurs 65 (million) to 150 million years ago was much warmer than today, the animals could nonetheless maintain high body temperatures in polar climates with freezing or near-freezing conditions.

The advantages of being a warm reptile are that no energy has to be expended to produce metabolic heat to keep warm; in other words, if we were warm reptile-like ectotherms, we would save a lot of money on the grocery bill.

In the meantime, the research team continues to investigate what are proving to be universal relationships among size, growth rate and temperature.

There are differences between mammals and invertebrates, but within a group, from a mouse to an elephant, or plankton to a large fish, we have found growth rate can be explained by how warm the animal is and how big the animal is, Gillooly said. If we know the growth rate and size, we can determine temperature. If we know size and temperature, we can make predictions about the rate at which an organism lives and reproduces. This simple little equation has turned out to be tremendously useful to understanding the biological time clock.

www.terradaily.com/reports/Hot_And_Heav ... h_999.html
 
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#22
Source: University of Alberta

Posted: July 13, 2006

Tyrannosaur Survivorship -- Tough Times For Teens

A massive Albertosaurus death bed in Alberta has helped map out the dinosaur's life span and thrown doubt on long-held theories about how the species lived, according to new research conducted in part at the University of Alberta.


Bones like these are helping U of A researcher Dr. Philip Currie track the life-cycle of the Albertosaurus sarcophagus. (Image courtesy of University of Alberta)Ads by Google Advertise on this site


New research is throwing doubt on the theory that a catastrophic event wiped out the species.

"One of the surprises to me was that the overall pattern of survivorship fits closer to an attritional model rather than the catastrophic model we were expecting," said world-renowned paleontologist Dr. Philip Currie, a professor in the U of A Department of Biological Sciences. "Hopefully this will help us to unravel the cause of death of so many carnivores at one location.

"It's also surprising that something like this study has never been done before."

For decades, scientists believed dinosaurs were bigger versions of living reptiles but this new research, published in the current issue of Science, shows that the life pattern of the Albertosaurus is closer to that of living large mammals. The pattern also shows that if the Albertosaurus lived until the age of two, it enjoyed a low death rate until its teenage years, when mortality increased.

In 1910, a collecting party from the American Museum of Natural History floated down Alberta's Red Deer River. Led by Barnum Brown, the team excavated skeletons of nine Albertosaurus sarcophagus from a single quarry. It is the best evidence that exists to suggest that tyrannosaurids may have been pack animals. An almost complete lack of herbivore bones from the excavation suggests it was probably not a predator trap. Recognizing the importance of the site, Currie led an expedition in 1997 to try to find Brown's original quarry, and returned annually with a group from the Royal Tyrrell Museum in Drumheller, Alberta, to excavate the site. The remains of at least 22 Albertosaurus individuals are at the site, ranging from two to almost 10 metres in length.

For this latest paper, Currie collaborated with Dr. Gregory Erickson from Florida State University to produce the first age-standardized ecological life table for a non-avian dinosaur population. They selected leg and foot bones from individuals and used growth line counts to estimate ages at death.

They found that the complex survivorship pattern is remarkably similar to that seen in large mammals. High newborn mortality rates due to predation alone subside by the age of two, once a threshold size is reached, said the research team. The mortality rates remained low until about the 13th year of life, at which point the dinosaurs had reached total lengths of six metres, or 60 per cent of their maximum recorded size. At that point, mortality rates escalated to more than 23 per cent a year, when the dinosaurs likely died because of old age, just like most mammals.

Seventy per cent of the animals surviving to two years of age were still alive at age 13, which would help explain why so few bones of young adults have been found. "One implication of these findings is that the previously mysterious rarity of sub-adult tyrannosaur specimens is due to their exceptionally low mortality rates," said Currie.

Some people have speculated that tyrannosaurs must have rocketed to adult size in a few years or less, leaving only a small fraction of development that juveniles could have contributed to the fossil record. "However, this notion is inconsistent with our growth curve," say the researchers in the paper. "Instead, we suggest that these young animals simply had low mortality, just like older juveniles and subadults of most large terrestrial mammals today."

The estimated survivorship curve also provides a possible explanation for the rarity of individual giants - just two per cent of the population lived long enough to attain maximal size and age for the species.


http://www.sciencedaily.com/releases/20 ... 233840.htm
 
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#23
Reptile named after electrician

Plesiosaurs used to roam the North Yorkshire coast millions of year ago
A 70 million-year-old plesiosaur may be named after the electrician who discovered it, experts said.
Nigel Armstrong from Doncaster found the marine reptile fossil's skeleton on land south of Filey in 2002.

The 4m-long "sea dragon" is the first of its age to be found and provides a missing link in its evolution, a Rotunda Geology Group spokeswoman said.

The new species may be named after Mr Armstrong but scientists had yet to make that decision, she added.

Convention would mean its name would include the word "Armstrongi" as it has to become Latinised.

Academics from across the world are expected to study the remains of the creature when they go on show at the Scarborough Campus of the University of Hull on 26 July.

At the time of the discovery, amateur palaeontologist Mr Armstrong said he saw a single vertebra and then traced the fossil up the cliff.

This plesiosaur is a new one and will need a new name all of its own

Plesiosaur expert, Mark Evans

"I was pleased when I found one of the back bones at the bottom of the cliff, but when I traced the remains up to the main skeleton I was over the moon," he said.

Mark Evans, a plesiosaur expert from Leicester Museums, said it was one of the few plesiosaur skeletons from the early part of the Cretaceous period.

"We know about earlier plesiosaurs from the Jurassic period and ones from later on in the Cretaceous, so this new specimen fills a gap in our knowledge very nicely" he said.

"Although it looks like it belongs to a group of plesiosaurs with long necks, this plesiosaur is a new one, and will need a new name all of its own."

The skeleton will be displayed in the redeveloped Rotunda Museum in Scarborough when it reopens in 2007 and form a star exhibit in the Shell Geology Now Gallery.


http://news.bbc.co.uk/2/hi/uk_news/engl ... 201326.stm
 
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#24
Published online: 4 September 2006;
| doi:10.1038/news060904-2

Happy hunting predicted for dinosaur seekers
Two-thirds of all species groups are yet to be unearthed.
Jim Giles

Thanks to movies such as Steven Spielberg's Jurassic Park and visits to natural history museums, 'dinosaur hunter' is one scientific job that schoolchildren aspire to. And according to a study of dinosaur diversity, these budding palaeontologists will have plenty to do: researchers estimate that more than 1,000 new groups of dinosaur species remain to be discovered.

"It's a safe bet that a child born today could expect a very fruitful career in dinosaur palaeontology," says Peter Dodson, an author of the estimate and a palaeontologist at the University of Pennsylvania in Philadelphia.

So far, 527 dinosaur genera — the plural of genus, a group of species that share similar characteristics — have been identified from fossils. But the rate of discovery is growing, with scientists now finding about 20 genera per year (see Dinosaur count), raising the question of how many more species remain to be discovered.

Dodson attacked the problem by teaming up with Steve Wang, a statistician at Swarthmore College in Pennsylvania. They combed through the fossil record to see how often new finds dropped into existing genera, and how often they necessitated the naming of a new one. A lot of instances of the former would indicate that the range of dinosaurs has already been well sampled, whereas a lot of the latter would suggest that scientists are still just scratching the surface of dinosaur diversity.

After trawling the 2004 edition of The Dinosauria, a book co-authored by Dodson that lists known dinosaur species, together with more recent additions described in scientific papers, Wang and Dodson conclude that more than 1,300 new species groups remain to be discovered.

Counting up

The actual number of dinosaur types that lived is probably higher than that, Dodson says, but some will probably remain undiscoverable for various reasons — perhaps because the bones have not been preserved, for example, or are only to be found in inaccessible locations.

The estimate, published in the Proceedings of the National Academy of Sciences1, is higher than the researchers had previously thought. In 1990, when 285 genera were known, Dodson estimated that there were some 900 to 1,200 new genera left to find.

The increase is in part due to new scientists entering the field and unearthing fossils from previously unexplored parts of the world, says Dodson. Most dinosaur taxonomy has been the purview of the western world, he says, but, "with the recent explosion of dinosaur palaeontology in places like China, Mongolia and South America, that is clearly no longer the case".

The result is good news for dinosaur hunters, but some note that the estimates need to be treated with caution. David Weishampel, a palaeontologist at Johns Hopkins University in Baltimore, Maryland, says he is glad to know that "I'm going to live out my life with plenty to find". But he also points out that the error bars on Dodson's successive estimates are getting bigger. This suggests that the methods used to create the estimate are subject to a great deal of uncertainty.

So the true amount of dinosaur diversity remains unknown; but it is certain that discoveries will inevitably one day peter out. Dodson says that although today's children have plenty to unearth, their children's grandchildren will see the rate of new discoveries start to decline in the early twenty-second century.

References
Wang S. C., Dodson P. et al. P. Proc. Natl Acad. Sci., 103. 13601 - 13605 (2006).


Story from [email protected]:
http://news.nature.com//news/2006/060904/060904-2.html
 

lawofnations

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#25
Should have published earlier...

Sounds quite similar to the work Mrs Lawofnations was doing two years ago. The same sort of work her supervisor rubbished. See http://news.bbc.co.uk/1/hi/sci/tech/3475915.stm. Mrs Lawofnations would like to point out that she never actually said 500 species, she was working with completeness percentages of the fossil record.

Interestingly, her supervisor was himself supervised during his PhD by Peter Dodson!

And an update on the lying, vindictive, aggressive, bullying, violent, plagiarising, manipulative, womanising "Prof" Smith of Washington University (see my post on the first page). He's been fired. After numerous complaints from students about his behaviour. Which included inappropriate sexual relations with his students. The kind he rather forcibly tried to have with Mrs Lawofnations within days of her arrival in the US.

Karma's a good thing...
 
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#26
--------------------------------------------------------------------------------

NEWS
Prehistoric puzzles
A sculptor pieces together ancient fossils

By Laura Buchholz

http://www.the-scientist.com/news/display/24780/

[Published 15th September 2006 03:13 PM GMT]


--------------------------------------------------------------------------------

Think you've seen all there is to see of the dinosaurs? Not so fast: a new statistical study by Drs. Steven C. Wang and Peter Dodson of Swarthmore College has revealed that 71% of dinosaur genera on earth still remain to be discovered. That's good news for paleontologists and amateur dinosaur enthusiasts. But it's also good news for Richard Webber, a New York sculptor who has carved out a professional niche reconstructing fossilized remains.

Webber worked on the renovation of the American Museum of Natural History's fossil hall in the mid-90s, where he built the Indricotherium, the world's largest land mammal, and helped to re-mount the museum's Tyrannosaurus rex. These days, he works from his studio in Greenpoint, Brooklyn, amidst a menagerie of half-assembled creatures. A borrowed ribcage of a zebra stands hoisted at attention; a model of a beaky Titanus pecks its way around a desk cluttered with art supplies; a Struthiomimus pelvis perches on a support, waiting for legs; the bones of a 50-million-year-old Oligocene Sespia line up on a dusty yellow legal pad; a metal barracuda hangs from the ceiling, ever-vigilant for bait. But the star of the studio at the moment is a four-million-year-old Odobenus rosmarus -- a walrus -- that Webber is reconstructing for the San Diego Natural History Museum.

Webber's walrus is named Ayveq, after the sole male walrus at the New York Aquarium. Webber watched Ayveq the Living for hours over many days to inspire his own portrayal of Ayveq the Fossil. Webber described the process as more experiential than analytic. "I usually end up not observing the animal, but being the animal," he said.

Just as paleontologists must recreate history using an incomplete set of data, Webber's job often requires him to reconstruct whole animals using an incomplete set of bones. (Once he was assigned to assemble an entire dinosaur from a single claw.) To do this, he creates a custom armature for each fossilized bone and then mounts each bone in correct alignment and articulation with the others. The remaining body, movement, and attitude of the creature is then filled in by his graceful metal work.

Webber's armature technique allows him to avoid drilling into the ancient fossils to make mounts. "I would never drill into raw material," he said. "Something that's been in the ground for 5 million, 400 million years, and all of a sudden it's in your hands...There's something spiritual about that."

Nor does Webber like to use vertical supports, which he believes make the fossils look like "carousel horses." Instead, he disguises his mount points by placing them at the animal's natural contact points with the earth. As a result, his animals seem to float through space gracefully and under their own power. And there is a scientific payoff to Webber's artistry as well: his customized armatures allow scientists to remove and study individual bones without damaging them.

In addition to Ayveq the Walrus, Webber's most recent work includes a Pleistocene horse, an Oligocene tortoise, an Oligocene Sespia, and an Eocene Protoreodont for the San Diego Natural History Museum. If Wang and Dodson's predictions are correct, he'll have a lot more work to do in the future.

"We're currently living in a dinosaur renaissance, with unprecedented numbers of discoveries every year," according to Wang. Perhaps some of these discoveries will make their way to Richard Webber's studio. After their long journey, they'd be lucky to end up in such good hands.

Laura Buchholz
[email protected]


Links within this article

Estimating the diversity of dinosaurs
http://www.pnas.org

American Museum of Natural History - Fossil Hall
http://www.amnh.org/exhibitions/permanent/fossils/

Odobenus rosmarus
http://www.mnh.si.edu/mna/image_info.cfm?species_id=228

San Diego Natural History Museum - Fossil Mysteries Exhibit
http://www.sdnhm.org/exhibits/mystery/index.html

Ayveq the Walrus (New York Aquarium)
http://www.nyaquarium.com/nyaanimals/286497
 
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#27
Dinosaur's reputation challenged

Coelophysis is not the first dinosaur to face reassessment


Enlarge Image

A US study has bruised the fearsome reputation of a popular dinosaur.
Coelophysis, a carnivore that lived more than 200 million years ago, has often been presented in books and museum exhibits as a cannibal.

The view is based on Coelophysis fossils that have preserved stomach contents interpreted as being the chewed up remains of its own kind.

But now a re-examination has suggested those contents may be crocodile, a Royal Society journal reports.

Indeed, one purported meal could even be an accident of geology - one Coelophysis simply dying on top of another, giving the impression the underlying animal's remains were inside the top creature's gut.

"Ideas always need testing; they've been around for a while and we've got to take a close look at how we think these animals really lived," said Sterling Nesbitt from the American Museum of Natural History (AMNH), New York; and Columbia University.

Nesbitt and colleagues report their findings of a re-examination of Coelophysis fossils in Biology Letters.

Give-away bones

The creature's cannibalistic reputation stems from the classic find in 1947 of literally hundreds of skeletons of the species Coelophysis bauri at a site near Ghost Ranch in north-central New Mexico, US.

A whole group of animals had died en masse in some catastrophe. Two of the more complete specimens when examined revealed collections of bones inside their body cavities.

It's not completely outrageous to say these guys were cannibals, it's just the evidence to say that they were, is no longer there now

Sterling Nesbitt, AMNH
The clear inference was that these bones represented last meals - and the gruesome assessment at the time was that this dino diet consisted of other Coelophysis.

But Mr Nesbitt's speciality is early crocodile-like animals, and he says one of the specimens contains tell-tale bones that puncture the cannibal legend.

"There are a few bones in there which we call diagnostic. One is a femur. It's what fits into the hip socket; and in dinosaurs and crocodiles, it does it in completely different ways.

"Then there's part of the pelvis. All dinosaurs have what we call an open-hip socket and this specimen has a closed-hip socket, just like a crocodilian-hipped animal."

The second specimen, Nesbitt's team contends, does not even show gut contents. The researchers say their new analysis demonstrates the way two animals have been fossilised, one on top of the other, gives the illusion that one ate the other.

Motor mouth

Mr Nesbitt believes his team's findings put a big question mark against the popular image of Coelophysis - all the books, TV programmes and museum displays may have to change their content.

"It's not completely outrageous to say these guys were cannibals, it's just the evidence to say that they were, is no longer there now.


Coelophysis was about 3m in length


Enlarge Image

"The Coelophysis skeletons were the major piece of evidence we have that dinosaurs were cannibalistic. There are examples of animals that have bite marks on them from the same species but you can never be sure if that was cannibalism or just scavenging."

This type of reassessment is nothing new in palaeontology. As new finds are made and old specimens looked at again, ideas have to be updated.

The most famous dino of them all, T. rex, is itself the centre of a robust debate about its lifestyle. Many scientists believe its terrifying reputation has also been overstated; it may have been more of a scavenger than a predator, these researchers argue.

An animatronic Coelophysis - complete with dino dinner hanging from its mouth - can be seen at London's Natural History Museum, in its Dino Jaws exhibition.

The special presentation runs until April next year.




http://news.bbc.co.uk/2/hi/science/nature/5361170.stm
 
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#28
'Monster' fossil find in Arctic
By Paul Rincon
Science reporter, BBC News



One find has been nicknamed "The Monster"


Enlarge Image

Norwegian scientists have discovered a "treasure trove" of fossils belonging to giant sea reptiles that roamed the seas at the time of the dinosaurs.

The 150 million-year-old fossils were uncovered on the Arctic island chain of Svalbard - about halfway between the Norwegian mainland and the North Pole.

The finds belong to two groups of extinct marine reptiles - the plesiosaurs and the ichthyosaurs.

One skeleton has been nicknamed The Monster because of its enormous size.

These animals were the top predators living in what was then a relatively cool, deep sea.

These sites are very unusual. To find that many individuals is a remarkable thing - that's a bonanza

Dave Martill, University of Portsmouth

Palaeontologists from the University of Oslo's Natural History Museum discovered the fossils during fieldwork in a remote part of Spitsbergen, the largest island in the Svalbard archipelago.

Jorn Harald Hurum, co-director of the dig, said he was taken aback by the sheer density of fossil remains in one area.

"You can't walk for more than 100m without finding a skeleton. That's amazing anywhere in the world," he told BBC News.

Dr Dave Martill, a palaeontologist at the University of Portsmouth commented: "These sites are very unusual. To find that many individuals is a remarkable thing - that's a bonanza."


The "Monster" may measure more than 8m (26ft) in length


Enlarge Image


Ichthyosaurs bore a passing resemblance to modern dolphins, but they used an upright tail fin to propel themselves through the water.

Plesiosaurs are said to resemble descriptions of Scotland's mythical Loch Ness monster. They used two sets of powerful flippers for swimming and came in two varieties - one with a small head and very long neck, and another with a large head and short neck.

The short-necked varieties are known as pliosaurs.

The discovery of a gigantic pliosaur, nicknamed The Monster, was one of the most remarkable discoveries of the expedition.

Its skeleton has dinner-plate-sized neck vertebrae, and the lower jaw has teeth as big as bananas.

Tooth in the neck

The skeleton is not yet fully excavated, but its skull is about 3m long, suggesting the body could be more than 8m from the tip of its nose to its tail.

"What's amazing here is that it looks like we have a complete skeleton. No other complete pliosaur skeletons are known anywhere in the world," said Dr Hurum.


See the marine reptile finds from Svalbard


In pictures

The researchers even found evidence of an attack on one of the creatures. An ichthyosaur tooth is embedded in a neck vertebra from one plesiosaur belonging to the genus Kimmerosaurus.

The fossil hoard comprises 21 long-necked plesiosaurs, six ichthyosaurs and one short-necked plesiosaur. The bones were unearthed in fine-grained sedimentary rock called black shale.

"Everything we're finding is articulated. It's not single bones here and there, and bits and pieces - these are complete skeletons," said Dr Hurum.

After death, the carcasses came to rest in mud at the bottom of the deep ocean, where little or no oxygen was present.

Dr Hurum said an unusual chemistry of the mud could have been responsible for the remarkable preservation of the specimens: "Something happened with the chemistry that's really good for bone preservation. Some skeletons are pale white even though they're in black shale - they look like roadkill."

The marine reptiles found in the Norwegian archipelago are very similar to ones known from southern England. Dr Hurum said the animals could have been living in the same ocean and he now plans to compare the Arctic finds with those from Britain.

The Svalbard excavation was led by Dr Hurum and Hans Arne Nakrem, also of Oslo's Natural History Museum. The museum plans to return to the field site in the summer of 2007 to resume excavations.

[email protected].


http://news.bbc.co.uk/2/hi/science/nature/5403570.stm
 
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#29
Dino-Era "Sea Monster" Found on Arctic Island
James Owen
for National Geographic News

October 6, 2006
A dinosaur-era Davy Jones's locker of large, predatory sea reptiles—including a giant that scientists have nicknamed "the Monster"—has been discovered by fossil hunters on an Arctic island.

The ancient graveyard once lay deep underwater during the Jurassic period, about 200 million to 145 million years ago (take a virtual swim with Jurassic sea monsters).

The site now sits on the island of Spitsbergen, part of the Norwegian-owned Svalbard archipelago, which lies about 600 miles (966 kilometers) from the North Pole (map of Norway).

In total, 28 well-preserved skeletons of marine reptiles that lived some 150 million years ago have been identified at the site, reports a team from the University of Oslo Natural History Museum in Norway.

The fossil haul includes the Monster, an estimated 33-foot-long (10-meter-long) pliosaur that has not yet been fully excavated. (See images of the newly found sea monster.)

Pliosaurs were the top marine predators during a time when the oceans were teeming with large, meat-eating reptiles.

"It was the T. rex of the ocean," said Jørn Hurum, co-leader of the research team. "It would have eaten everything."

So far the team has found the Monster's skull, which measures 6.9 feet (2.1 meters) in length, along with dinner plate-size neck vertebrae and portions of the lower jaw containing teeth as thick as cucumbers.

The fossil specimen may represent the largest complete pliosaur ever found, Hurum says.

"It looks very promising, because we've got 6 meters [20 feet] of vertebrae and the skull and part of a flipper, so it's probably complete," Hurum said.

Black Mud

In addition to the Monster, the researchers uncovered 6 ichthyosaurs and 21 plesiosaurs during a two-week expedition to Spitsbergen in August.

Pliosaurs are believed to be closely related to plesiosaurs. But pliosaurs had short necks and massive jaws that would have been capable of lifting a car and biting it in half.

Such strength likely helped the pliosaurs hunt prey such as plesiosaurs and ichthyosaurs, another group of marine reptiles.

Ichthyosaurs resembled dolphins but used an upright tail fin, as opposed to dolphins' sideways tail fins, to propel themselves through the water.

Most ichthyosaurs averaged 13 to 20 feet (4 to 6 meters) in length, but some reached 75 feet (23 meters).

The new find follows up on fieldwork on Spitsbergen in 2004, when University of Oslo researchers excavated parts of the skulls of an ichthyosaur and two plesiosaurs.

The fossils from both digs were found in a layer of black shale—a type of sedimentary rock—that is between 65 to 100 feet (20 to 30 meters) thick.

"There's something special about the chemistry of the shale which has preserved all the bones in this layer," Hurum said.

According to Hurum, when the reptiles died they probably sank to the ocean floor, where conditions were right for preserving their bodies.

"It's deep water and black mud that they fell into. There were no animals living close to the bottom that could eat these big things that were decaying," he said.

"One specimen [we found] was probably scavenged before it fell to the bottom, but the others look quite complete, and that's amazing," Hurum said.

This summer marine reptile expert Pat Druckenmiller, of Montana State University in Bozeman, accompanied the team to Svalbard.

Druckenmiller, who identified the large pliosaur, said that "it is certainly likely that some of these animals represent new types of plesiosaurs and ichthyosaurs that are unknown to science."

The paleontologist says that many of the fossil reptiles are well articulated.

"This means that if you find the tail sticking out of the hill and you follow it in, you have a good chance of finding the rest of the skeleton—including the all-important skull—also attached," he said.

"This type of preservation, in black shale, is one of the settings considered likely to preserve traces of the animals' soft tissues, such as skin impressions," he added.

Dreams of Eggs

Druckenmiller says that the find shows that the Svalbard island chain is "significant at a global level," in terms of the quality of fossil preservation and the number and different types of marine reptiles found.

The site also provides "a relatively complete chapter from the late Jurassic, about 150 million years ago," he added.

"This age is considered one of the heydays of marine reptile life, but what we know of life from this specific window of time only comes from scattered sites around the globe."

The Oslo team is hopeful that the fossil graveyard will yield important new clues to the history and biology of these ocean predators.

"The dream is that one of the plesiosaurs or the pliosaur was pregnant" when it died, the University of Oslo's Hurum said. "A pregnant one, or one with eggs inside, is not known anywhere in the world."

Researchers still aren't sure if these creatures gave birth to live young underwater or if they hauled themselves on land to lay eggs like modern sea turtles.

Also, having the remains of both young and adult plesiosaurs could shed light on how the reptiles grew and matured, Hurum adds.

The researchers will return to the Arctic island next summer, when they plan to finish excavating the pliosaur and several other specimens.


http://news.nationalgeographic.com/news ... tiles.html
 
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#30
Ancient 'Jaws' had monster bite

Ancient 'Jaws' had monster bite

The fish would have been a formidable predator
A prehistoric "Jaws" that roamed the seas 400 million years ago had the most powerful bite of any known fish.
The extinct creature, Dunkleosteus terrelli, could bring its jaws together with a remarkable force of 5,000 Newtons (1,100lbs-force).

This performance surpasses all living fish, including today's great white shark, and puts it up with some of the most powerful bites in all animals.

Details appear in the UK Royal Society journal Biology Letters.

US researchers Mark Westneat and Philip Anderson tell the journal that higher bite forces have only been reported for some large alligators and dinosaurs.

T. rex, for example, could clamp down on its meal with a crushing force of 13,000 Newtons (3,000lbs-force); but a modern spotted hyena, by comparison, exerts a force of only 2,000 Newtons (500lbs-force) when it cracks bones in its mouth.

The team developed its biomechanical model of Dunkleosteus by studying the fossil remains of the fish, which probably grew up to 10m (30ft) in length.

The scientists say the way its teeth were organised in the jaw meant it could focus its bite into a small area - the fang tip - with the incredible pressure of nearly 150 million Pascals (22,000lbs per sq inch).

Even more surprising is the fact that Dunkleosteus could also open its mouth very quickly - in just one fiftieth of a second - which created a strong suction force, pulling fast prey into its mouth.




"This heavily armoured fish was both fast during jaw opening and quite powerful during jaw closing," said Westneat, who is curator of fishes at The Field Museum in Chicago.
"This is possible due to the unique engineering design of its skull and different muscles used for opening and closing."

Usually, a fish has either a powerful bite or a fast bite, but not both.

The formidable fish was a placoderm, a diverse group of armoured fish that dominated aquatic ecosystems during the Devonian Period, from 415 million to 360 million years ago.

"Dunkleosteus was surrounded by possible prey that all required really high bite force," said Anderson, who works out of the University of Chicago.

"There were free-swimming, fast animals that all had a hard armour; most of the other fish were other placoderms which had the same hard bony covering. And then there were large molluscs with hard shells and really large crustaceans," he told BBC News.




http://news.bbc.co.uk/2/hi/science/nature/6195188.stm
 
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