Dinosaurs: New Findings & Theories

EnolaGaia

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ramonmercado

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Not so nifty on their feet.

How does an animal as big as a semitruck move around?

That’s a question scientists have long asked about sauropods, the largest known dinosaurs, which may have weighed as much as 70 tons. Did they walk like a giraffe, picking up their two left and right legs in a dignified march? Or like an elephant, lifting and placing one front foot, then the opposite back foot to amble along?

Neither, according to a new analysis of fossilized footprints. Instead, the giant beasts kept one foot down on each side while leisurely swinging their diagonal legs, much like a beaver or a hedgehog does today.

The approach of analyzing trackways could be used to reconstruct the gaits of other dinosaurs as well, says Cary Woodruff, a sauropod paleontologist at the Great Plains Dinosaur Museum and Field Station, who was not involved with the study. “The way they did this tells us a lot about how these animals were moving,” he says. “It’s really neat.”

Fossilized bones can reveal the shape of an extinct animal’s body, but paleontologists look to footprints and other evidence to deduce things like behavior and locomotion. Past studies posited that sauropods, a group of long-necked dinosaurs that lived between 201 million and 66 million years ago, walked with a “pace gait,” like a giraffe, where the left or right legs hit the ground at once.

But that motion didn’t make sense to Jens Lallensack, a paleontologist at Liverpool John Moores University. If a sauropod walked this way, he says, it would risk falling over as it shifted its gargantuan weight to each side. “If a 30 to 40-ton animal falls, it’s going to be dead.” ...

https://www.science.org/content/art...biggest-dinosaurs-walk-footprints-offer-clues
 

ramonmercado

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Interesting, I wonder if Nessie is a spinosaur?

A fierce group of predatory dinosaurs may have done much of their hunting in the water.

An analysis of the bone density of several sharp-toothed spinosaurs suggests that several members of this dino group were predominantly aquatic, researchers report March 23 in Nature.

That finding is the latest salvo in an ongoing challenge to the prevailing view that all dinosaurs were land-based animals that left the realms of water and air to marine reptiles such as Mosasaurus and flying reptiles such as Pteranodon. But, other researchers say, it still doesn’t prove that Spinosaurus and its kin actually swam.

Back in 2014, Nizar Ibrahim, a vertebrate paleontologist now at the University of Portsmouth in England, and colleagues pieced together the fossil of a 15-meter-long Spinosaurus from what’s now Morocco. The dinosaur’s odd collection of features — a massive sail-like structure on its back, short and muscular legs, nostrils set well back from its snout and needlelike teeth seemingly designed for snagging fish — suggested to the researchers that the predator might have been a swimmer (SN: 9/11/14). In particular, it had very dense leg bones, a feature of some aquatic creatures like manatees that need the bones for ballast to stay submerged.

In the new study, Ibrahim and his team returned to that question of bone density to assess whether it’s a reliable proxy for how much time a creature spends in the water. The team assembled “a massive dataset” of femur and dorsal rib bone densities from “an incredible menagerie of extinct and living animals, reaching out to museum curators all around the world,” Ibrahim says. ...

https://www.sciencenews.org/article/spinosaurus-bones-dinosaur-swim-paleontology
 

EnolaGaia

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Why did T. rex have such ludicrously small forelimbs (i.e., "arms")?

This newly published study suggests the tiny arms were an evolutionary innovation to prevent injury during feeding frenzies.
Wild New Paper Suggests T. Rex Had Short Arms So Friends Wouldn't Bite Them Off

The teeny tiny arms of Tyrannosaurus rex have been the butt of jokes for many scientists and non-scientists alike. We have various hypotheses: perhaps its arms were vicious slashing machines or a way to help grasp on during sex, but it's hard to work out these sorts of evolutionary questions from a pile of 66 million-year-old bones.

A new paper now presents a wild hypothesis – that these dinosaurs evolved short arms to lower the risk of accidental bites by other T. rex while engaging in feeding frenzies. Put simply, short arms are less likely to be chomped on by friends.

"What if several adult tyrannosaurs converged on a carcass? You have a bunch of massive skulls, with incredibly powerful jaws and teeth, ripping and chomping down flesh and bone right next to you. What if your friend there thinks you're getting a little too close? They might warn you away by severing your arm," says Kevin Padian, integrative biologist at the University of California, Berkeley and the author of the new paper.

"So, it could be a benefit to reduce the forelimbs, since you're not using them in predation anyway." ...
FULL STORY: https://www.sciencealert.com/wild-s...h-short-arms-so-their-friends-didn-t-eat-them
 

EnolaGaia

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Here are the bibliographic details and abstract from the published study. The full study report is accessible at the link below.


Padian, K. 2022.
Why tyrannosaurid forelimbs were so short: An integrative hypothesis.
Acta Palaeontologica Polonica 67 (1): 63–76.

The unusually shortened limbs of giant theropods, including abelisaurids, carcharodontosaurids, and derived tyranno- sauroids such as Tyrannosaurus rex have long been an object of wonder, speculation, and even derision on the part of both paleontologists and the public. Two questions commonly asked are “Why did the forelimbs become so short?” and “What did the animals use such short forelimbs for, if for anything?” Because basal tyrannosauroids and their outgroups, as well as the outgroups of other giant theropods, had longer forelimbs, the foreshortening of these elements in derived taxa was secondary, and it ostensibly involved a shift in developmental timing of the forelimb elements. Factors proposed to have influenced the evolutionary foreshortening include natural selection, sexual selection, energetic compensation, ontogenetic vagaries, and rudimentation due to disuse. Hypotheses of use have varied from a supporting anchor that allows the hindlimbs a purchase to stand from a reclining position to a pectoral version of pelvic claspers during inter- course to a sort of waving display during sexual or social selection. None of these hypotheses explain selective regimes for reduction; at best, they might argue for maintenance of the limb, but in all cases a larger limb would have suited the function better. It is likely that we have been looking the wrong way through the telescope, and that no specific function of the forelimbs was being selected; instead, another crucial adaptation of the animal profited from forelimb reduction. Here I propose, in the context of phylogenetic, ontogenetic, taphonomic, and social lines of evidence, that the forelimbs became shorter in the context of behavioral ecology: the great skull and jaws provided all the necessary predatory mech- anisms, and during group-feeding on carcasses, limb reduction was selected to keep the forelimbs out of the way of the jaws of large conspecific predators, avoiding injury, loss of blood, amputation, infection, and death. A variety of lines of evidence can test this hypothesis.

SOURCE: https://www.app.pan.pl/article/item/app009212021.html
 

Nemo

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Tanis: 'First dinosaur fossil linked to asteroid strike'

Scientists have presented a stunningly preserved leg of a dinosaur.

The limb, complete with skin, is just one of a series of remarkable finds emerging from the Tanis fossil site in the US State of North Dakota.
But it's not just their exquisite condition that's turning heads - it's what these ancient specimens purport to represent.
The claim is the Tanis creatures were killed and entombed on the actual day a giant asteroid struck Earth.
The day 66 million years ago when the reign of the dinosaurs ended and the rise of mammals began.
Very few dinosaur remains have been found in the rocks that record even the final few thousand years before the impact. To have a specimen from the cataclysm itself would be extraordinary.
The BBC has spent three years filming at Tanis for a show to be broadcast on 15 April, narrated by Sir David Attenborough.
(c) BBC. '22
 
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ramonmercado

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Limping dino.

In a subtropical wetland in what is now Spain, a 5-ton dinosaur with a limp walked in shallow waters surrounded by grazing fish. Scientists uncovered this moment in prehistoric time from just six preserved footprints the animal left behind in the limestone of an ancient fossil bed east of Madrid, some 129 million years ago.

When paleontologists started to study the peculiar footprints in the La Huérguina Formation 6 years ago, they knew their age and they knew a dinosaur made them. But they weren’t sure the same animal made all of them: The left and right footprints showed different lengths, as if a toe was missing in the left foot. Poor preservation could also explain the disparity. To find the real answer, the researchers used a special 3D scanner to obtain detailed measurements—depth, width, and length—of each footprint. They then compared them with another 75 sets of dinosaur footprints from around the world.

https://www.science.org/content/article/mysterious-dinosaur-had-limp-ancient-footprints-reveal
 

ramonmercado

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Our feathered friends were around longer than we originally thought.

The idea that dinosaurs sported colorful feathers, once outlandish, has become conventional wisdom.

Now, a new study of a Brazilian fossil suggests that pterosaurs—leathery winged, flying reptiles only distantly related to dinosaurs—were also clad in tiny feathers of varying hues. The finding suggests feathers may have evolved more than 150 million years before the heyday of the dinosaurs, probably for display, the authors say. “In their very earliest forms, feathers were colored … presumably for signaling,” says paleobiologist Maria McNamara of University College Cork, who led the study.

The paper “reinforces the idea that pterosaurs were ‘fluffy,’ and indicates at least some of them probably had complex colorful patterns—which is fantastic,” says Rodrigo Pêgas, a paleontologist at the Federal University of ABC, São Bernardo do Campo, in Brazil. But Pêgas is not convinced that feathers originated as early as McNamara thinks—and some other researchers doubt the structures are feathers at all.

How feathers arose has been a big question in paleontology for more than 150 years, since the first Archaeopteryx—a feathered dinosaur once thought to be the first bird—was found in Germany. Many researchers think feathers arose for insulation and were co-opted only much later for flight and other uses, such as courtship displays. As for pterosaurs, researchers had previously reported their bodies were covered in pycnofibers, single-stranded structures that formed a “fuzz,” presumably for warmth. ...

https://www.science.org/content/art...aunted-colorful-plumage-long-reign-dinosaurs?
 

Comfortably Numb

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Our feathered friends were around longer than we originally thought.
From a related, 'Science News' article...

Screenshot_20220430-101346.jpg


:)

https://www.sciencenews.org/article...lored-feathers-heads-fossil-skull-soft-tissue
 

Erinaceus

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I was sitting outside earlier, watching the young starlings begging for food, and and had a probably unsolvable thought.
Now it is accepted that birds evolved from dinosaurs and many dinosaurs had feathers of some kind, did hatchling dinosaurs show a yellow gape to prompt the parents to feed them?
 

madmath

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I was sitting outside earlier, watching the young starlings begging for food, and and had a probably unsolvable thought.
Now it is accepted that birds evolved from dinosaurs and many dinosaurs had feathers of some kind, did hatchling dinosaurs show a yellow gape to prompt the parents to feed them?
There is the possibility that, if a fossilized hatching was well-preserved, some of the color pigment chemistry may be preserved.
 

Nemo

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Remains of 'immense' killer dinosaur found in UK.

The ‘White Rock spinosaurid’ would have weighed several tonnes.


The remains of Europe’s largest ever land-based hunter which measured more than 10 metres long and lived 125 million years ago have been found on the Isle of Wight. Several prehistoric bones belonging to the two-legged, crocodile-faced spinosaurid dinosaur were discovered on the island off the south coast of England and have been analysed by scientists from the University of Southampton.


The spinosaurid would have lived at the beginning of a period of rising sea levels and would have stalked lagoonal waters and sandflats in search of food. PhD student Chris Barker said: “This was a huge animal, exceeding 10m (32.8ft) in length and probably several tonnes in weight.


“Judging from some of the dimensions, it appears to represent one of the largest predatory dinosaur ever found in Europe – maybe even the biggest yet known. It’s a shame it’s only known from a small amount of material, but these are enough to show it was an immense creature.”


The discovered bones of the ‘White Rock spinosaurid’ – named as such because of the geological layer in which the remains were found – include huge pelvic and tail vertebrae.
(C) WoL. '22
 

Lord Lucan

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A new dino discovery from Japan:


New Dinosaur Species With Massive Knife-Like Claws Found In Japan: Study

A bipedal dinosaur with knives for fingers roamed around the shores of Asia between 66 million and 145 million years ago, a new study has revealed.

According to Live Science, the new genus and species of the dinosaur that lived during the Cretaceous period was identified from the fossilised remains unearthed on Hokkaido, the northern island of Japan. The fossil is the first to be found in Asia in marine sediments, researchers from the United States and Japan informed.
https://www.ndtv.com/world-news/new...knife-like-claws-found-in-japan-study-3060061
 

Nemo

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Rise of the dinosaurs traced back to their adaptation to cold.


Covering of feathers left them able to cope when other creatures died off in mass extinction event, scientists say.

Fossil hunters have traced the rise of the dinosaurs back to the freezing winters the beasts endured while roaming around the far north.

Footprints of the animals and stone deposits from north-west China suggest dinosaurs became adapted to the cold in polar regions before a mass extinction event paved the way for their reign at the end of the Triassic.

With a covering of fuzzy feathers to help keep them warm, the dinosaurs were better able to cope and to take advantage of new territories when brutal conditions wiped out great swaths of more vulnerable creatures.

“The key to their eventual dominance was very simple,” said Paul Olsen, the lead author on the study at the Lamont-Doherty Earth Observatory at Columbia University. “They were fundamentally cold-adapted animals. When it got cold everywhere, they were ready, and other animals weren’t.”

The first dinosaurs are thought to have emerged in the temperate south more than 230m years ago, when most of Earth’s land made up a supercontinent called Pangaea. The dinosaurs were initially a minority group, living mainly at high altitudes. Other species, including ancestors of modern crocodiles, dominated the tropics and subtropics.

But at the end of the Triassic, about 202m years ago, more than three-quarters of land and marine species were wiped out in a mysterious mass extinction event linked to vast volcanic eruptions that sent much of the world into cold and darkness. The devastation set the stage for the reign of the dinosaurs.
(C) The Guardian. '22.
 

ramonmercado

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More on this topic.

Dinosaurs lived in an endless summer, surrounded by steaming jungles and lush swamps—at least if movies such as Fantasia and Jurassic World are to be believed.

But that classic image is changing. Paleontologists now know some dinosaurs lived in comparatively chilly habitats with months of darkness and occasional snow on the ground. Frigid conditions like these, a controversial new study argues, may have helped them survive one of Earth’s worst extinctions.

“There are several interesting ideas thrown in the mix of the new paper,” says Alfio Alessandro Chiarenza, a paleontologist at the University of Vigo who was not involved with the work. But more evidence is needed to bear out some of the study’s broad claims, he and others say.

Scientists led by Columbia University paleontologist Paul Olsen zeroed in on the events of approximately 201 million years ago. Around this time, at the end of the Triassic period and just prior to the following Jurassic period, many geologists think massive volcanic eruptions cooled Earth, triggering a mass extinction on land and in the seas. Some kinds of organisms fared better than others. Although all existing groups of dinosaurs walked through the disaster virtually unscathed and went on to wildly proliferate through the Jurassic, many other forms of reptiles and amphibians perished. Adaptations to life in colder habitats, the new paper proposes, is what separated the survivors from those that went extinct.

https://www.science.org/content/art...nosaurs-survive-one-earth-s-worst-extinctions
 

blessmycottonsocks

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New species of giant therapod predatory dinosaur discovered, featuring a huge skull and ridiculously tiny arms.

Scientist Peter Makovicky said the dinosaur's arms were "literally half the length of the skull and the animal would not have been able to reach its mouth".
Mr Makovicky said he believed the species' massive heads were the main predatory tool, taking on the functions that arms would have had in smaller species.

https://www.bbc.co.uk/news/science-environment-62088874
 

PeteByrdie

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New species of giant therapod predatory dinosaur discovered, featuring a huge skull and ridiculously tiny arms.

Scientist Peter Makovicky said the dinosaur's arms were "literally half the length of the skull and the animal would not have been able to reach its mouth".
Mr Makovicky said he believed the species' massive heads were the main predatory tool, taking on the functions that arms would have had in smaller species.

https://www.bbc.co.uk/news/science-environment-62088874
So, how did he scratch his nose? Did they have to hang out in pairs and scratch each other's noses?
 

ramonmercado

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Reach for the skies.

Ever since pterosaur fossils were discovered more than two centuries ago, paleontologists have wondered how these gawky-looking reptiles launched themselves into the air.

Experts have recently focused on a “quad launch” hypothesis, which envisions pterosaurs rocking back and forth on their arms to jump into the air using a pole vault–like motion, whether from land or water. Direct physical evidence of this technique has been elusive, but now a small pterosaur from the Jurassic rocks of Germany is helping solve the mystery.

The sparrow-sized fossil, described by Natural History Museum of Los Angeles paleontologist Michael Habib and his colleagues in Scientific Reports, features unusually well-preserved bones and skin impressions of a pterosaur type called an aurorazhdarchid. The paleontologists used a process known as laser-stimulated fluorescence to detect the fossilized tissues, including a wing membrane and webbed feet. Analyzing these structures let the researchers determine how the pterosaur could have used them to take off.

Prior research indicates pterosaurs were not strong swimmers, Habib notes—so this fossil's soft tissues “are best interpreted as water-launch adaptations” rather than swimming gear. These structures offer the first physical evidence that pterosaurs could take off using quad launch, he says; until now the best evidence came from biomechanical models of skeletons. The skin impressions along the arms suggest that, when folded, the pterosaur's wings could help the reptile push off from the water's surface. The researchers found that the wings and webbed feet combined would have been enough to propel the animal from a resting position.

https://www.scientificamerican.com/...have-pole-vaulted-into-flight-from-the-water/
 

EnolaGaia

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Newly reported discoveries in Patagonia indicate a new and previously-unknown lineage of armored dinosaurs.
Small, prickly dinosaur discovered in South America reveals an unknown lineage

Fossils of a small, prickly dinosaur recently discovered in South America may represent an entire lineage of armored dinosaurs previously unknown to science.

The newly discovered species, Jakapil kaniukura, looks like a primitive relative of armored dinosaurs like Ankylosaurus or Stegosaurus, but it came from the Cretaceous, the last era of the dinosaurs, and lived between 97 million and 94 million years ago. That means a whole lineage of armored dinosaurs lived in the Southern Hemisphere but had gone completely undetected until now, paleontologists reported in a new study.

J. kaniukura weighed about as much as a house cat and had a row of protective spines running from its neck to its tail and probably grew to about 5 feet (1.5 meters) long. It was a plant eater, with leaf-shaped teeth similar to those of Stegosaurus. ...

Paleontologists at the Félix de Azara Natural History Foundation in Argentina uncovered a partial skeleton of a subadult J. kaniukura in the Río Negro province in northern Patagonia. The dinosaur likely walked upright and sported a short beak capable of delivering a strong bite. It probably would have been able to eat tough, woody vegetation, the researchers reported Thursday (Aug. 11) in the journal Nature Reports ...
FULL STORY: https://www.livescience.com/new-armored-dinosaur-south-america
 

EnolaGaia

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Here are the bibliographic details and abstract from the published research report. The full report is accessible at the link below.


Riguetti, F.J., Apesteguía, S. & Pereda-Suberbiola, X.
A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs.
Sci Rep 12, 11621 (2022).
https://doi.org/10.1038/s41598-022-15535-6

Abstract
The early evolution of thyreophoran dinosaurs is thought to have occurred primarily in northern continents since most evidence comes from the Lower and Middle Jurassic of Europe and North America. The diversification into stegosaurs and ankylosaurs is obscured by a patchy fossil record comprising only a handful of fragmentary fossils, most with uncertain phylogenetic affinities. Here we report the discovery of a new armoured dinosaur from the early Late Cretaceous of Argentina, recovered phylogenetically using various datasets either as a basal thyreophoran or a stem ankylosaur, closely related to Scelidosaurus. It bears unusual anatomical features showing that several traits traditionally associated with the heavy Cretaceous thyreophorans did not occur universally. Jakapil kaniukura gen. et sp. nov. is the first definitive thyreophoran species from the Argentinian Patagonia. Unlike most thyreophorans, it seems to show a bipedal stance, as in Scutellosaurus. Jakapil also shows that early thyreophorans had a much broader geographic distribution than previously thought. It is a member of an ancient basal thyreophoran lineage that survived until the Late Cretaceous in South America.

SOURCE / FULL REPORT: https://www.nature.com/articles/s41598-022-15535-6
 
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