Turtle Fossils

ramonmercado

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Fossil reveals how the turtle got its shell
Turtle
by Ewen Callaway

A newly identified fossil could explain one of evolution's biggest mysteries – the origin of the turtle's shell.

Bone fragments from a 210-million year-old, land-dwelling reptile from New Mexico suggest that the earliest turtles didn't have much of a shell at all.

Over millions of years, rows of protective armour plates gradually fused together and to the reptile's vertebrae, eventually creating a complete shell.

"Turtles ultimately originated from something that looked like an armadillo," says lead author Walter Joyce, a palaeontologist at the Peabody Museum of Natural History in New Haven, Connecticut.

His colleague Spencer Lucas, of the New Mexico Museum of Natural History and Science in Albuquerque, discovered a neck-bone fragment of the new reptile more than a decade ago, but its provenance remained debatable because the skeleton was so small, Joyce says.

However, recent erosion revealed enough pieces of Chinlechelys tenertesta – Latin for thin-shelled turtle – to remove any doubt.

Unlike turtle fossils dating from the later Jurassic era – "they're so common people stopped collecting them," Joyce says – Triassic turtles are few and far between. That's probably because they lived on land, where fossilisation is far less likely to happen, he says.

The new animal is about 30 centimetres long, with a shell only a millimetre wide. "This one's by far the thinnest ever found," Joyce says.

More importantly, the reptile's dorsal ribs aren't fully fused to its shell – or carapace – as is the case in later fossils and in modern turtles.

"This is a crucial new discovery," says Guillermo Rougier, at the University of Louisville in Kentucky, who uncovered the first Triassic turtles in northwest Argentina. These and other early turtles had already gained their carapaces and offered few clues as to its origin.

C. tenertesta, on the other hand, points to the body form that must have given rise to the shell. "This new guy is an animal that belong to the lineage of turtles, it's a proto-turtle in a way," he says.

Exactly why turtles evolved their shell remains a mystery, Joyce says. A full shell might offer added protection and stability. And the proof could be in the pudding – their body plan is the world's oldest, changing little over 200 million years. "For some reason just being a turtle is an idea that came along and just really works," he says.

Journal reference: Proceedings of the Royal Society B (DOI: 10.1098/rspb.2008.1196)
http://publishing.royalsociety.org/index.cfm?page=1569

Evolution - Learn more about the struggle to survive in our comprehensive special report. http://www.newscientist.com/channel/life/evolution

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Weblinks

Spencer Lucas, New Mexico Museum of Natural History and Science
http://www.nmnaturalhistory.org/science ... lucas.html
http://www.yale.edu/peabody/collections ... joyce.html

Walter Joyce, Peabody Museum of Natural History
Guillermo Rougier, University of Louisville
http://louisville.edu/medschool/anatomy ... ugier.html

Edit to amend title.
 
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ProfessorF

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So, uh, God didn't just create them that way then?
Oh.
 

Xanatico

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I thought there would be a nice little Kipling story about it.
 

ramonmercado

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Ancient Giant Turtle Fossil Was Size of Smart Car
http://www.sciencedaily.com/releases/20 ... 131650.htm

Reconstruction of Carbonemys preying upon a small crocodylomorph. (Credit: Artwork by Liz Bradford)

ScienceDaily (May 17, 2012) — Picture a turtle the size of a Smart car, with a shell large enough to double as a kiddie pool. Paleontologists from North Carolina State University have found just such a specimen -- the fossilized remains of a 60-million-year-old South American giant that lived in what is now Colombia.

The turtle in question is Carbonemys cofrinii, which means "coal turtle," and is part of a group of side-necked turtles known as pelomedusoides. The fossil was named Carbonemys because it was discovered in 2005 in a coal mine that was part of northern Colombia's Cerrejon formation. The specimen's skull measures 24 centimeters, roughly the size of a regulation NFL football. The shell which was recovered nearby -- and is believed to belong to the same species -- measures 172 centimeters, or about 5 feet 7 inches, long. That's the same height as Edwin Cadena, the NC State doctoral student who discovered the fossil.

"We had recovered smaller turtle specimens from the site. But after spending about four days working on uncovering the shell, I realized that this particular turtle was the biggest anyone had found in this area for this time period -- and it gave us the first evidence of giantism in freshwater turtles," Cadena says.

Smaller relatives of Carbonemys existed alongside dinosaurs. But the giant version appeared five million years after the dinosaurs vanished, during a period when giant varieties of many different reptiles -- including Titanoboa cerrejonensis, the largest snake ever discovered -- lived in this part of South America. Researchers believe that a combination of changes in the ecosystem, including fewer predators, a larger habitat area, plentiful food supply and climate changes, worked together to allow these giant species to survive. Carbonemys' habitat would have resembled a much warmer modern-day Orinoco or Amazon River delta.

In addition to the turtle's huge size, the fossil also shows that this particular turtle had massive, powerful jaws that would have enabled the omnivore to eat anything nearby -- from mollusks to smaller turtles or even crocodiles.

Thus far, only one specimen of this size has been recovered. Dr. Dan Ksepka, NC State paleontologist and research associate at the North Carolina Museum of Natural Sciences, believes that this is because a turtle of this size would need a large territory in order to obtain enough food to survive. "It's like having one big snapping turtle living in the middle of a lake," says Ksepka, co-author of the paper describing the find. "That turtle survives because it has eaten all of the major competitors for resources. We found many bite-marked shells at this site that show crocodilians preyed on side-necked turtles. None would have bothered an adult Carbonemys, though -- in fact smaller crocs would have been easy prey for this behemoth."

The paleontologists' findings appear in the Journal of Systematic Palaeontology. Dr. Carlos Jaramillo from the Smithsonian Tropical Research Institute in Panama and Dr. Jonathan Bloch from the Florida Museum of Natural History contributed to the work. The research was funded by grants from the Smithsonian Institute and the National Science Foundation.

Story Source:

The above story is reprinted from materials provided by North Carolina State University, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Edwin Cadena, Dan Ksepka, Carlos Jaramillo, Jonathan Bloch. New pelomedusoid turtles from the late Palaeocene Cerrejon Formation of Colombia and their implications for phylogeny and body size evolution. Journal of Systematic Palaeontology, 2012 (in press)
 
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ramonmercado

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Turtles fossilised in sex embrace
By Jonathan Amos
Science correspondent, BBC News

The turtles were found in male-female pairs

Related Stories

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How the turtle's shell developed

Turtles killed as they were having sex and then fossilised in position have been described by scientists.

The remains of the 47-million-year old animals were unearthed in the famous Messel Pit near Darmstadt, Germany.

They were found as male-female pairs. In two cases, the males even had their tails tucked under their partners' as would be expected from the coital position.

Details are carried in the Royal Society journal Biology Letters.

Researchers think the turtles had initiated sex in the surface waters of the lake that once existed on the site, and were then overcome as they sank through deeper layers made toxic by the release of volcanic gases.

The animals, still in embrace, were then buried in the lakebed sediments and locked away in geological time.

"We see this in some volcanic lakes in East African today," explained Dr Walter Joyce of the University of Tübingen.

"Every few hundred years, these lakes can have a sudden outburst of carbon dioxide, like the opening of a champagne bottle, and it will poison everything around them."

The turtles described in Biology Letters are of the extinct species Allaeochelys crassesculpta.

They are about 20cm in length; the females are slightly bigger than the males.

Their nearest living relatives are probably the pig-nosed turtle (Carettochelys insculpta), a much bigger species that swims in waters around Australia and Papua New Guinea.

A. crassesculpta is just one of thousands of exquisitely preserved fossil creatures pulled from Messel Pit, which has Unesco World Heritage status because of its palaeontological significance.

Nine pairs of turtles have been unearthed at the site over the past 30 years.

In most of the couples, the individuals were discovered in contact with each other. For the pairs that were not, the individuals were no more than 30cm apart.

"People had long speculated they might have died while mating, but that's quite different from actually showing it," said Dr Joyce.

"We've demonstrated quite clearly that each pair is a male and a female, and not, for example, just two males that might have died in combat.

"This fact combined with the observation that their back ends are always orientated toward one another, and the two pairs with tails in the position of mating - that's a smoking gun in our view."

It is said to be the only example in the fossil record of vertebrates being preserved in the act of having sex.

For invertebrates, there are numerous examples in the scientific literature of copulating insects being caught in amber, or fossilised tree resin.

The closest living relative is probably the distinctive pig-nosed turtle.

http://www.bbc.co.uk/news/science-environment-18495102
[email protected]. and follow me on Twitter
 
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ramonmercado

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Fossil turtle from Colombia round like car tire
July 11th, 2012 in Other Sciences / Archaeology & Fossils

The round shape of a new species of fossil turtle found in Cerrejon coal mine in Colombia may have warmed readily in the sun. Credit: Liz Bradford
Paleontologist Carlos Jaramillo's group at the Smithsonian Tropical Research Institute in Panama and colleagues at North Carolina State University and the Florida Museum of Natural History discovered a new species of fossil turtle that lived 60 million years ago in what is now northwestern South America. The team's findings were published in the Journal of Paleontology.

The new turtle species is named Puentemys mushaisaensis because it was found in La Puente pit in Cerrejón Coal Mine, a place made famous for the discoveries, not only of the extinct Titanoboa, the world's biggest snake, but also of Carbonemys, a freshwater turtle as big as a smart car.


Paleontologists unearth the carapace of the giant turtle, Puentemys, which lived 60 million years ago in a hot tropical forest environment. Credit: Edwin Cadena

Cerrejon's fossil reptiles all seem to be extremely large. With its total length of 5 feet, Puentemys adds to growing evidence that following the extinction of the dinosaurs, tropical reptiles were much bigger than they are now. Fossils from Cerrejon offer an excellent opportunity to understand the origins of tropical biodiversity in the last 60 million years of Earth's history.

The most peculiar feature of this new turtle is its extremely circular shell, about the size and shape of a big car tire. Edwin Cadena, post-doctoral fellow at North Carolina State University and lead author of the paper, said that the turtle's round shape could have discouraged predators, including Titanoboa, and aided in regulating its body temperature.

The width of the turtle's shell probably exceeded the maximum expansion of the Titanoboa's mouth. Its circular, low-domed shape would have increased the area of the body exposed to the sun, helping the cold-blooded turtle warm to a temperature at which it was more active.

http://phys.org/news/2012-07-fossil-tur ... a-car.html

More information: Cadena, E.A., Bloch, J.I., and Jaramillo, C.A. 2012. New Bothremydid turtle (Testudines, Pleurodira) from the Paleocene of Northeastern Colombia. Journal of Paleontology, 86(4):689-699.

Provided by Smithsonian Tropical Research Institute
 
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Comfortably Numb

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New Discovery of 96-Million-Year Old Turtle Species and Hints at Intercontinental Migrations

New 96-million-year old turtles from Texas connect North America with Asia and the Southern Hemisphere, suggesting vast intercontinental migrations during this time.

Source: Midwestern University/scitechdaily.com
Date: 23 December, 2019

The Arlington Archosaur Site (AAS) of Texas preserves remnants of an ancient Late Cretaceous river delta that once existed in the Dallas-Fort Worth area. Known for discoveries of fossil crocodiles and dinosaurs, a multi-institution research team has described four extinct turtle species, including a new river turtle named after AAS paleontologist Dr. Derek Main and the oldest side-necked turtle in North America. These new turtles include an intriguing combination of native North American forms alongside Asian and Southern Hemisphere immigrants, suggesting extensive intercontinental migration of turtles during this time.

Originally discovered by amateur fossil hunter Art Sahlstein in 2003, the AAS is a prolific fossil locality found in the middle of a suburban subdivision. The AAS preserves remnants of an ancient Late Cretaceous river delta around 96 million years ago in what is today the Dallas-Fort Worth area. It preserves a record of a freshwater wetland that sat near the shore of a large peninsula, including a diverse assemblage of crocodile relatives, dinosaurs, amphibians, mammals, fish, invertebrates, and plants, several of which are also new species awaiting description. “Until this discovery, there were very few turtle fossils from this time period discovered in Appalachia,” says Dr. Heather Smith, one of the authors of the paper. The research team describing these discoveries includes Brent Adrian, M.F.A., Heather F. Smith, Ph.D., and Ari Grossman, Ph.D., from Midwestern University in Glendale Arizona, and Christopher Noto, Ph.D., from University of Wisconsin-Parkside.

https://scitechdaily-com.cdn.amppro...ies-and-hints-at-intercontinental-migrations/
 

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Bizarre' turtle managed to survive asteroid that wiped out dinosaurs

Source: Fox News / Scientific Reports
Date: 6 February, 2020

The asteroid that wiped out the dinosaurs 65 million years ago also caused nearly 75 percent of all species on the planet to go extinct. However, a new study suggests one "bizarre" form of life managed to survive — a land turtle.

Fossils of the turtle, known as Laurasichersis relicta, were recently discovered in northern France. The fossils date to around 56 million years ago, 10 million years after the asteroid hit Earth in the Yucatan Peninsula in Mexico. The asteroid may have also acidified Earth's oceans, according to a study published in October 2019.

At this point, it's unclear why or how L. relicta survived the impact blast, according to the study's lead author, palaeontologist Adán Pérez García. "The reason why Laurasichersis survived the great extinction, while none of the other primitive North American, European or Asian land turtles managed to do so, remains a mystery," Pérez García said in a statement.

https://www-foxnews-com.cdn.ampproj...-turtle-survived-asteroid-wiped-out-dinosaurs
 

EnolaGaia

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Turtles fossilised in sex embrace
Here's a photo of the mating turtles fossil ... It represents the oldest known fossil of vertebrate animals doing the nasty.

mating-turtles-fossil.jpg
The oldest known vertebrates to be fossilized while mating are a pair of 47 million-year-old turtles, which were attached by their genitals as they got buried alive.​
SOURCE: https://www.cnn.com/2021/09/20/world/dinosaur-sex-lives-scn/index.html
 
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