Paleonews

Il blog dedicato ai Paleontologi !!!!

2009-05-10 – Utah, USA: ritrovata una tartaruga fossile incinta (fossil pregnant turtle)

Rare prehistoric pregnant turtle found in Utah

At least three eggs are visible from the outside of the fossil, and Montana State University researchers this week have been studying images taken from a CT scan in search of others inside.

Montana State graduate student Michael Knell says the turtle was probably about a week from laying her eggs when she died and became entombed for millions of years in sandstone.

The fossil was found in 2006 in a remote part of Grand Staircase-Escalante National Monument. The eggs weren’t discovered until after it sat in storage for two years and was being re-examined by a volunteer.

This image provided Montana State University shows CT technician, Tanya Spence preparing to run a 75 million-year-old turtle fossil through a CT scanner at Deaconess Hospital in Bozeman, Mont. (AP Photo/Montana State University, Kelly Gorham)

This image provided Montana State University shows CT technician, Tanya Spence preparing to run a 75 million-year-old turtle fossil through a CT scanner at Deaconess Hospital in Bozeman, Mont. (AP Photo/Montana State University, Kelly Gorham)

Annunci

maggio 10, 2009 Posted by | - Rettili, 1 Cretaceo, America Northern, An. Vertebrates, Articolo sc. di riferimento, Mesozoic, P - Preservazione eccezionale, P - Ritrovamenti fossili, Paleontology / Paleontologia, X - Nature | , , , , , , , , , | Lascia un commento

2009-03-07 – Coahuila, MEX: the oldest chelonid turtle

Oldest sea turtle fossil unveiled in Mexico

“It is the oldest sea turtle of its kind and it belongs to the chelonia family. The oldest specimen of this species up to now was 65 million years old and was found in New Jersey, United States,” the INAH said in a statement.

The fossils of seven sea turtles were found at different sites in Coahuila, the state that Mexican scientists call “the paradise of paleontology.”

The sea turtle inhabited the northern region in the late Cretaceous period, 72 million years ago, and is the ancestor of the present day green turtle, the institute said.

It was one meter (yard) long, 70 centimeters (28 inches) wide and distinguished from other turtles by its rounded head.

source: AFP

marzo 7, 2009 Posted by | - Rettili, 2 Jurassic / Giurassico, America Central, An. Vertebrates, Mesozoic, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , | Lascia un commento

2009-02-14 – Aurorachelys, tartaruga fossile dalla Groenlandia (Greenlad, turtle fossil)

February 13, 2009

Ancient turtle fossil found on Axel Heiberg Island

Shell dates from warm period 90 million years ago

NUNATSIAQ NEWS

Geologists from the University of Rochester have uncovered a 90 million-year-old fossil of a tropical freshwater Asian turtle in Nunavut’s High Arctic.

The fossil was found in a slab of ancient basalt on Axel Heiberg Island.

The turtle, dubbed Aurorachelys, or aurora turtle, lived in the region 90 million years ago when polar temperatures averaged above 14 C, similar to those found in today’s northern Florida.


2009-02-14-aurorachelys
Turtles swam in Nunavut’s High Arctic 90 million years ago, say geologists who announced the find of this fossil turtle shell this week.
(PHOTO COURTESY OF THE UNIVERSITY OF ROCHESTER)

A paper on the fossil, published in the Feb. 1 journal Geology, suggests that carbon dioxide pouring into the atmosphere from volcanic activity during that period may have caused a “super-greenhouse” effect, boosting temperatures in the polar region.

“We’re talking about extremely warm, ice-free conditions in the Arctic region, allowing migrations across the pole,” said John Tarduno, professor of geophysics at the University of Rochester and leader of the team that found the turtle fossil, in a news release on the find.

The turtle resembles a kind of freshwater turtle found in Mongolia, so its presence in the High Arctic suggests that it may have migrated from Asia to North America by floating on a freshwater layer on top of the then-warm, salty Arctic Ocean.

Tarduno’s team found the fossil in 2006 when they went to the Arctic to study paleo-magnetism- that is, the Earth’s magnetic field in the far distant past.

Tarduno said study of the magnetism in rocks where the fossil was found rules out the possibility that the fossil came from southern waters. The turtle was clearly a native of the area, Tarduno noted.

At the time the aurora turtle lived, the Arctic Ocean was probably even more separated from the global oceanic circulation system than it is today, Tarduno said, and rivers would have poured fresh water into the ancient sea.

Fresh water is lighter than sea water, so Tarduno thinks fresh water may have rested on top of the salty water, allowing a freshwater animal such as the aurora turtle to migrate.

According to the news release, Tarduno also believes volcanoes could have produced a series of islands along an underwater mountain range in the Arctic Ocean called the Alpha Ridge.

If the ridge poked out above the surface of the water at one time, it would have given the turtles and other species the ability to island-hop all the way from ancient Russia to Canada, Tarduno said.

In recent years, Tarduno has uncovered fossils of other warm-water species in the High Arctic, such as crocodile-like beasts, which once thrived there 90 million years ago.

source: http://www.nunatsiaq.com/news/climate/90213_1907.html

febbraio 14, 2009 Posted by | - Rettili, 1 Cretaceo, An. Vertebrates, Mesozoic, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , | Lascia un commento

2009-02-03 – La tartaruga fossile e il polo “tropicale” (Turtle fossil and tropical Artic)

CLIMA: CANADA; FOSSILE TARTARUGA PROVA ANTICO EFFETTO SERRA

L’Artide 90 milioni di anni fa era un posto molto piu’ temperato: senza ghiacci e con passaggio migratorio degli animali preistorici. Lo sostengono alcuni scienziati dopo la scoperta di un fossile di tartaruga asiatica nell’Artide canadese. Secondo i ricercatori, tra cui Donald Brinkman del Royal Tyrell Museum dell’Alberta, la tartaruga tipica della Mongolia, chiamata ‘tartaruga aurora’, con il guscio quasi perfettamente rotondo, esistente all’epoca dei dinosauri e da tempo estinta, avrebbe percorso migliaia di chilometri dal suo habitat originario nelle acque dolci dell’Asia passando non dall’Alaska ma direttamente dal polo Nord. Questo proverebbe che nel polo Nord le temperature in passato erano molto piu’ temperate, al punto da rendere l’Artide un percorso migratorio delle creature preistoriche. Secondo i ricercatori un ‘super effetto serra’, forse originato da eruzioni vulcaniche, causo’ 90 milioni di anni fa un’enorme emissione di anidride carbonica scaldando i poli ed aprendo nuovi passaggi per gli animali migratori, comprese le tartarughe. (ANSA). COR-DI
02/02/2009 19:47

fonte: http://www.ansa.it/ambiente/notizie/notiziari/natura/20090202194734816739.html

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Turtle fossil shows how ‘super-greenhouse effect’ created tropical Arctic

The discovery of a fossilised ancient turtle reveals the North Pole was once “extremely” warm and tropical, scientists said.

Turtle fossil shows how 'super-greenhouse effect' created tropical Arctic
The North Pole: “extremely” warm and tropical millions of years ago Photo: GETTY IMAGES

Animals migrated from Asia to North America directly across the formerly frost-free Arctic Ocean, new evidence shows.

Geologists made the breakthrough after discovering the fossil of a freshwater Asian turtle – dating back millions of years – in Canada.

John Tarduno, a US-based professor of geophysics at the University of Rochester, said: “We’ve known there’s been an interchange of animals between Asia and North America in the late cretaceous period, but this is the first example we have of a fossil in the High Arctic region showing how this migration may have taken place.

“We’re talking about extremely warm, ice-free conditions in the Arctic region, allowing migrations across the pole.”

Numerous rivers from the adjacent continents would have poured fresh water into the ancient Arctic sea, he said.

Fresh water, which is lighter than marine water, may have rested on top of the salty ocean water allowing animals such as the turtle to migrate with relative ease.

The professor, who published his findings in the journal Geology, added: “We found this turtle right on top of the last flood basalts – a large stretch of lava from a series of giant volcanic eruptions.

“That leads us to believe that the warming may have been caused by volcanoes pumping tremendous amounts of carbon dioxide into the Earth’s atmosphere.

“There is evidence that this volcanic activity happened all around the planet – not just the Arctic.

“If it all happened on a short-enough timescale, it could cause a super-greenhouse effect.”

The research team plans to return to the Arctic to look for more fossils.

source: http://www.telegraph.co.uk/earth/environment/climatechange/4419843/Turtle-fossil-shows-how-super-greenhouse-effect-created-tropical-Arctic.html

febbraio 3, 2009 Posted by | - Rettili, 1 Cretaceo, An. Vertebrates, Antartide, Lang. - Italiano, Mesozoic, P - Paleoclimatologia, Paleontology / Paleontologia | , , , , , , , , , | Lascia un commento

2008-11-24 – Eileanchelys waldmani: la prima tartaruga acquatica ? (sea-turtle missing link)

Reperti fossili di un genere di tartaruga ritrovati nel Giurassico scozzese aiutalo a comprendere il passaggio da una vita terrestre ad una marina.

I reperti di Eileanchelys waldmani rappresentano infatti una foma di passaggio in quanto sebbene adattati alla vita acquatica (ritrovati in sedimenti di laguna assieme a squali e altri organismi marini) presentno caratteristiche del cranio tipiche di esemplari terresti.

Inoltre sono comunque molto somiglianti a un genere attuale a prova della “bontà” del progetto evolutivo delle tartarughe acquatiche.

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Scottish turtle is missing link

Monday, 24 November 2008
Cosmos Online

LONDON: Turtles normally evoke images of tropical seas, but palaeontologists have found the 164-million-year-old remains of one of the first known water-dwelling turtles on a chilly Scottish island.

These unique fossils bridge what has been a 65-million-year gap in the fossil record primitive land-based turtles and modern turtles, many of which live in the open ocean, said Jérémy Anquetin, based at both University College London (UCL) and the Natural History Museum, in England.

Rugged an beautiful

Against the rugged and beautiful backdrop of the Isle of Skye, his team have unearthed six fossils of a species called Eileanchelys waldmani. The discoveries are described in the British journal the Proceedings of the Royal Society B.

Similar fossils from the Middle Jurassic have been found in the U.S., Argentina, and Russia, but Anquetin’s are the most complete yet discovered and offer new clues about the tricky transition from land to water.

Though it seems an unlikely place to find tropical animals today, “Scotland was much farther south [in the Jurassic]… its position would not have been tropical, but its climate may have been,” said Anquetin.

These turtles would have shared their lagoon and lake environment with sharks and salamanders, whose remains have also been found at the site, he said.

Remarkable similarities

Despite the antiquity of the fossils, the species have some remarkably similar features to turtles found today, particularly a primitive freshwater species called the red-eared slider, found in the southeast of the U.S. and Mexico.

One major difference is that the skull of the fossil is more “reptilian” than modern turtles, said Anquetin. However, the overall body shape, or morphology of these turtles has changed very little over million of years, especially when compared with the transformations seen in mammals.

“I like to think [turtles] are an evolutionary success … because their body plan is still working,” said Anquetin, who added that (like crocodiles) they have outlived many catastrophes including numerous ice ages and mass extinctions.

The exciting research is helping plug a 65 million year gap in the fossil record, commented Walter Joyce a vertebrate palaeontologist and fossil turtle expert at the University of Tuebingen in Germany.

“The new fossil is finally giving us a glimpse of how early turtles evolved,” he said. “The authors make a compelling case that by this stage in evolution turtles had started moving into aquatic habitats.”

http://www.cosmosmagazine.com/news/2367/scottish-turtle-missing-link

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Scientific article:

Jérémy Anquetin, Paul M. Barrett, Marc E.H. Jones, Scott Moore-Fay and Susan E. Evans
Abstract

 The discovery of a new stem turtle from the Middle Jurassic (Bathonian) deposits of the Isle of Skye, Scotland, sheds new light on the early evolutionary history of Testudinata. Eileanchelys waldmani gen. et sp. nov. is known from cranial and postcranial material of several individuals and represents the most complete Middle Jurassic turtle described to date, bridging the morphological gap between basal turtles from the Late Triassic–Early Jurassic and crown-group turtles that diversify during the Late Jurassic. A phylogenetic analysis places the new taxon within the stem group of Testudines (crown-group turtles) and suggests a sister-group relationship between E. waldmani and Heckerochelys romani from the Middle Jurassic of Russia. Moreover, E. waldmani also demonstrates that stem turtles were ecologically diverse, as it may represent the earliest known aquatic turtle.

Additional electronic material (free access) – PDFHTML

novembre 24, 2008 Posted by | - Rettili, 2 Jurassic / Giurassico, Articolo sc. di riferimento, Europa, Italiano (riassunto), P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , , , , , | 1 commento

2008-10-08 – L’origine del carapace delle tartarughe (origin of the turtle’s shell, Chinlechelys tenertesta, New Mexico USA)

Fossil reveals how the turtle got its shell

  • 11:22 08 October 2008
  • NewScientist.com news service
  • Ewen Callaway

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

Royal Society)

Chinlechelys tenertesta - The gradual origin of the turtle shell with two hypothetical ancestors, from an animal with isolated lumps of armour, to one with a complete shell (Image: Royal Society)

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)

Evolution – Learn more about the struggle to survive in our comprehensive special report.

Source: http://www.newscientist.com/article/dn14892-fossil-reveals-how-the-turtle-got-its-shell.html?DCMP=ILC-hmts&nsref=news4_head_dn14892

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A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell

Proceedings of the Royal Society B
free previewPDF 
Authors
Walter G. Joyce1, Spencer G. Lucas2, Torsten M. Scheyer3, Andrew B. Heckert4, Adrian P. Hunt2

1 Peabody Museum of Natural History, Yale University, New Haven, CT 06520, USA
2 New Mexico Museum of Natural History and Science, Albuquerque, NM 87104, USA
3 Paläontologisches Institut und Museum, Universität Zürich, 8006 Zürich, Switzerland
4Department of Geology, Appalachian State University, Boone, NC 28608, USA

Abstract

 A new, thin-shelled fossil from the Upper Triassic (Revueltian: Norian) Chinle Group of New Mexico, Chinlechelys tenertesta, is one of the most primitive known unambiguous members of the turtle stem lineage. The thin-shelled nature of the new turtle combined with its likely terrestrial habitat preference hint at taphonomic filters that basal turtles had to overcome before entering the fossil record. Chinlechelys tenertesta possesses neck spines formed by multiple osteoderms, indicating that the earliest known turtles were covered with rows of dermal armour. More importantly, the primitive, vertically oriented dorsal ribs of the new turtle are only poorly associated with the overlying costal bones, indicating that these two structures are independent ossifications in basal turtles. These novel observations lend support to the hypothesis that the turtle shell was originally a complex composite in which dermal armour fused with the endoskeletal ribs and vertebrae of an ancestral lineage instead of forming de novo. The critical shell elements (i.e. costals and neurals) are thus not simple outgrowths of the bone of the endoskeletal elements as has been hypothesized from some embryological observations.

Keywords

Triassic, New Mexico, Testudinata, Chinlechelys tenertesta, origin of the turtle shell

ottobre 8, 2008 Posted by | - Rettili, 3 Triassico, America Northern, Articolo sc. di riferimento, P - Evoluzione, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , , , , , , , , , , | 2 commenti

2008-08-27 – Tartaruga incinta dal Cretaceo del Canada

Fossilized Pregnant Turtle Found 75 Million Years After Death

Wednesday, August 27, 2008

A turtle that toddled alongside the dinosaurs died just days before laying a clutch of eggs. Now, about 75 million years later, paleontologists are announcing their find of the fossilized mother-to-be and the eggs tucked inside her body.

Scientists from the Royal Tyrrell Museum of Palaeontology in Canada discovered the turtle in 1999 in a mud-filled channel in the badlands of southeastern Alberta. Then, in 2005, University of Calgary scientists found a nest of 26 eggs laid by another female of the same species in the same region.

Both specimens, described this week in the journal Biology Letters, belong to an extinct turtle in the Adocus genus, a large river turtle that resembles today’s slider and cooter turtles.

The pregnant turtle represents the first fossil turtle to be unearthed with eggs still inside the body cavity, the scientists say.

“Although it is relatively rare to find the eggs and babies of extinct animals, it is even rarer to find them inside the body of the mother,” said researcher Darla Zelenitsky, a geoscientist at the University of Calgary in Alberta, who was also involved in the first discovery of a dinosaur with eggs inside its body.

It was almost by accident that scientists realized that the fossil turtle had been pregnant.

“The reason we knew she was pregnant was because when the fossil was found the body was broken,” Zelenitsky told LiveScience, “so there was egg shell on the ground just below the fossil, it was falling out of the body.”

The team spotted at least five crushed eggs within the body of the fossilized female, and computed tomography (CT) scans revealed more eggs hidden beneath the turtle’s shell. The turtle, estimated to be about 16 inches (40 cm) long, could have produced about 20 eggs.

When still intact, the eggs would have been spherical and about 1.5 inches (4 cm) in diameter. The eggs from the nearby nest were about the same size and shape. Both sets of eggs also had extremely thick and hard shells, especially compared with most modern turtles whose shells are either thinner or soft.

Thick-shelled

The thick eggshell may have evolved to protect the eggs from drying out or from voracious predators that lived during the Age of Dinosaurs.

The pregnant turtle and nest specimens, the researchers say, shed light on the evolution of reproductive traits of modern turtles.

“Based on these fossils, we have determined that the ancestor of living hidden-necked turtles, which are most of today’s turtles and tortoises, laid a large number of eggs and had hard, rigid shells,” said François Therrien, the Museum’s Curator of Dinosaur Palaeoecology, who worked on the turtle report in the journal.

http://www.foxnews.com/story/0,2933,411962,00.html

Additional links:

http://gauntlet.ucalgary.ca/story/12654 (see for pictures)

World’s 1st pregnant turtle fossil found in Alberta
CBC.ca – 28 ago 2008
The Alberta find is the first time the fossil of a pregnant turtle has been discovered anywhere in the world. (CBC) A 75 million-year-old fossilized
Tyrrell shows off unique pregnant turtle fossil
Calgary Herald – 28 ago 2008
A pregnant prehistoric turtle is about to go on display in the Tyrrell Museum in Drumheller. The 75-million-year-old item is the first fossilized pregnant
University of Calgary unveils fossil first: a pregnant turtle
TheChronicleHerald.ca – 28 ago 2008
By The Canadian Press CALGARY — A 75-million-year-old fossil of a pregnant turtle was officially introduced to the public Tueday, nine years after it was
Fossilized Pregnant Turtle Found 75 Million Years After Death
FOXNews – 27 ago 2008
By Jeanna Bryner A turtle that toddled alongside the dinosaurs died just days before laying a clutch of eggs. Now, about 75 million years later,
First Prehistoric Pregnant Turtle And Nest Of Eggs Discovered In
Science Daily (press release) – 27 ago 2008
ScienceDaily (Aug. 27, 2008) — A 75-million-year-old fossil of a pregnant turtle and a nest of fossilized eggs that were discovered in the badlands of
Pregnant turtle fossil find unique
Lethbridge Herald – 28 ago 2008
By Jeff Wiebe That was Alberta, 75 million years ago. It was also home to the Adocus turtle, and the fossil of one such animal was revealed to the public
Fossils helping to uncover turtle’s evolution secrets
Canoe.ca – 28 ago 2008
By JENNA MCMURRAY, SUN MEDIA New ideas regarding the evolution of egg-laying and reproduction in turtles and tortoises is emerging from fossils of a
Researchers discover first fossilized pregnant turtle in southern
The Canadian Press – 27 ago 2008
CALGARY — Nine years after its discovery in the badlands of southeastern Alberta, the 75-million-year-old fossil of a pregnant turtle finally made its

settembre 20, 2008 Posted by | - Rettili, 1 Cretaceo, America Northern, P - Preservazione eccezionale, P - Ritrovamenti fossili, Paleontology / Paleontologia | , , , , , , , , , | Lascia un commento