Thread: Fossil Finds
May 9th 2012, 10:03 AM #856
The following tWebber says Amen to rogue06 for this useful Post:
May 9th 2012, 06:01 PM #857
Re: Fossil FindsAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
May 11th 2012, 02:03 PM #858
Re: Fossil Finds
The fossilized remains of an extinct relative of the giant panda that lived roughly 11 mya (Miocene) have been excavated from the Calatayud-Daroca basin near the municipality of Nombrevilla in the province of Zaragoza in northwest Spain which marks the first appearance of a member of the Ursidae family in the Iberian central basins. The find also represents the oldest occurrence of a member of the subfamily Ailuropodinae in the fossil record.
The researchers named this new ursid fossil species Agriarctos beatrix which, while genetically related to the modern giant panda, was also closely related to the slightly more recent Agriarctos depereti, known from Soblay, France. The difference between the two is that in the new discovery the shared derived characters are more primitive. Not really surprising considering that it is older.
Aside from the morphological differences in their teeth there was also a difference in their size, which from what I can tell, were smaller than those found in related species.
Agriarctos beatrix was smaller than any extant species of bear weighing in at approximately 60kg (132 lbs) which is slightly smaller than the modern sun bear (aka honey bear) of Southeast Asia -- currently the smallest bear species.
The researchers think its diet probably was pretty much the same as a sun bear's which consists mainly of invertebrates (primarily insects) and fruits but as omnivores they will also eat small vertebrates (often already dead), such as lizards, birds, and turtles, along with eggs, the young tips of palm trees, honey, berries, sprouts, roots, and coconuts.
Also like the modern honey bear Agriarctos beatrix likely spent a great deal of time in trees where it was less exposed to other larger predators. This probably meant that their territories weren't nearly as large as those bears that tend to hunt more.
The researchers, headed by Juan Abella a paleontologist at Spain's National Museum of Natural Sciences, note that while it is difficult to determine physical appearance in that only fossilized dental fragments have thus far been located, it is highly likely that Agriarctos beatrix possessed dark fur with white spots mainly on the chest, around the eyes and possibly close to the tail.
Such a fur pattern is considered primitive for bears and can be seen in the modern giant panda except that the white spots are so predominant that it actually appears to be white with black spots.
A New species of Agriarctos (Ailuropodinae, Ursidae, Carnivora) in the locality of Nombrevilla 2 (Zaragoza, Spain) Paper & Abstract
A 'Cousin' of the Giant Panda Lived in What Is Now Zaragoza, Spain
Ancient 'cousin' of pandas identified
A ‘cousin’ of the giant panda lived in ZaragozaAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
May 14th 2012, 02:50 PM #859
Re: Fossil Finds
Interesting bit about fossils containing highly enriched uranium. Apparently back in the '50s some folks made a living selling radioactive fossils to the government. To be on the safe side, if you own any fossils, be sure to wash your hands afterwards.
Environmental and Background Radiation — Rocks, Minerals, and Mines
Why are these trees made of uranium?Always strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
May 16th 2012, 08:14 PM #860
Re: Fossil FindsGo with the flow the river knows.
Hillsborough, NC 27278
Gifts of jade-silk change weapons and war into peace and friendship.
I do not know, therefore I think . . . and everything is in pencil.
May 17th 2012, 08:44 PM #861
Re: Fossil Finds
In the same northern Colombian coal mine that's part of the Cerrejon formation and where the colossal snake Titanoboa was found, the fossilized remains consisting of a nearly complete skull and shell of a massive turtle that lived roughly 60 mya (Paleocene) was discovered.
The turtle, which was recovered from claystone deposits under a large coal seam, was dubbed Carbonemys cofrinii, meaning "coal turtle," and named for the coal mine in which it was discovered along with Dr. David Cofrin who helped to make the excavations possible.
Its exceptionally well-preserved three-dimensional skull measured 24cm (9½") and possessed massive jaws that would have allowed the omnivorous Carbonemys to eat anything from mollusks to smaller turtles or even crocodiles.
The shell was recovered nearby measures 172cm (5' 7") long meaning Carbonemys was probably about 8' in total length -- about the size of one of those Smart Cars.
Carbonemys is part of the sub-order Pleurodira, which bend their necks sideways when they withdraw their heads into their shells. This differs from the method utilized by the other sub-order of turtles, Cryptodira, which pull their heads straight back into their shells.
The researchers think that Carbonemys is most closely related to extant species in Venezuela and Madagascar which tends to bolsters the theory that the continents were once connected in northern South America, rather than southern South America through Antarctica.
While the fossils of a couple of other previously unknown species of smaller turtle appear to have been found as well, only one specimen of Carbonemys has been unearthed so far. This doesn't exactly surprise the researchers.
As one of the co-authors of the paper describing the discovery, Dr. Dan Ksepka, a paleontologist with North Carolina State and a research associate at the North Carolina Museum of Natural Sciences, notes that a turtle the size of Carbonemys would require a large territory in order to obtain enough food to survive and would preclude other large predators from living in the same territory.
“That turtle survives because it has eaten all of the major competitors for resources," Ksepka explained. "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."
It appears that Carbonemys provides the first evidence of giantism in freshwater turtles who were able to grow to the huge proportions that they achieved through a combination of factors – including abundant food, fewer predators, vast habitat and climate change.
New pelomedusoid turtles from the late Palaeocene Cerrejón Formation of Colombia and their implications for phylogeny and body size evolution Abstract
Researchers reveal ancient giant turtle fossil
UF researchers name new extinct giant turtle found near world's largest snake
Ancient Turtle Was as Big as Small Car
Fossil of giant turtle found in ColombiaAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
May 19th 2012, 12:02 AM #862
Re: Fossil Finds
Material from at least three previously unknown extinct dromaeosaurid theropod species (popularly known as "raptors") have been excavated from a fossil rich Doelling’s Bowl Bone Bed in Grand County in eastern Utah (around 370km or 230 miles southeast of Salt Lake City) on U.S. Bureau of Land Management land near the Arches National Park.
This site, which is part of the Lower Yellow Cat Member of the Cedar Mountain Formation and between 125-130 myo (Early Cretaceous), represents the earliest Cretaceous paleofauna in the area and adds to the known diversity of Dromaeosauridae.
Though as mentioned at least three distinct small dromaeosaur taxa were reported upon only one of them provided enough diagnostic material to allow it to be named.
The new raptor, representing both a new species as well as genus, is named Yurgovuchia doellingi.
The first or genus name is derived from the Ute word "yurgovuch," meaning coyote, a predator of similar size that currently inhabits the same region. The species name honors the geologist Helmut Doelling in recognition of his 50-plus years of geological research and geological mapping of of the Arches region for the Utah Geological Survey led to the bone bed's discovery.
Yurgovuchia is represented by a partial vertebral column that consists of several cervical, dorsal, and caudal vertebrae and the proximal end of a left pubis.
Based upon the fact that the cluster of rods that extend from the vertebrae to form the dinosaur's tail are shortened in both species the researchers think that Yurgovuchia is an ancestor of the slightly younger and much larger Utahraptor.
Still, considering that the slightly older Yurgovuchia is characterized as representing an advanced dromaeosaurine and the giant Utahraptor is thought to be relatively primitive, I'm not sure just how closely they are related.
Two other sets of bones that also appear to be from new species were recovered although co-author Utah Geological Survey paleontologist James Kirkland said they think that as many as six new species may have been found at the site.
One set was found within a few feet of the Yurgovuchia at Doelling's Bowl and consists of a right pubis and a possibly associated radius.
The other was discovered a couple of miles to the west at a location called Andrew’s Site in sediments that is a little younger and is represented by a broken although long tail skeleton that is unique among known Cedar Mountain dromaeosaurids in that it possesses long extensions of bone off of each vertebrae which result in stiffening the tail as a balancing organ.
The white bits represent the bones found
Compared in size to a house cat
New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail Paper & Abstract
Utah paleontologists discover new raptor dinosaur
Guest Post: Yurgovuchia doellingi
Utah Geological Survey Paleontologists Have Uncovered Three New Raptor DinosaursAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
May 23rd 2012, 08:38 PM #863
Re: Fossil Finds
Analysis of two preserved 162 myo (Jurassic) ink sacs from an ancient cephalopod that were discovered two years ago by Phillip Wilby of the British Geological Survey in the Oxford Clay Formation at Christian Malford, Wiltshire, England, west of London near Bristol have been shown to still contain the pigment melanin, and that it is essentially chemically indistinguishable to the melanin found in the ink sac of a modern-day cuttlefish.
The researchers employed an assotment of direct, high-resolution chemical techniques including scanning electron microscopy and mass spectrometry (which reveals chemical signatures by measuring the wavelengths of light) in order to determine that the melanin had been preserved.
They found a type of melanin known as eumelanin which is widespread in the animal kingdom and found in feathers, hair and skin as well as the ink cephalopods produce.
Until now evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. In contrast the researchers compared the chemical composition of the ancient ink to that found in modern squid ink such as that from Sepia officinalis, a squid common to the Mediterranean, North and Baltic seas.
As one of the co-authors, John D. Simon, a chemistry professor and the executive vice president and provost at the University of Virginia, observed, "It's close enough that I would argue that the pigmentation in this class of animals has not evolved in 160 million years."
He added that, "the whole machinery apparently has been locked in time and passed down through succeeding generations of cuttlefish. It's a very optimized system for this animal and has been optimized for a long time."
IOW, its similarity to modern squid ink indicates that the ink and the ink-screen escape mechanism hasn't evolved much since the Jurassic period.
Simon said the fact that the ink hasn't changed much shouldn't come as a surprise since "it's a pretty good defense mechanism."
Direct chemical evidence for eumelanin pigment from the Jurassic period Abstract
Fossil Ink Sacs Yield Jurassic Pigment—A First
Squid Ink from Jurassic Period Identical to Modern Cuttlefish Ink
JURASSIC SQUID INK SAME AS MODERN SQUID INK
JURASSIC INK IDENTICAL TO MODERN CUTTLEFISH INK
Jurassic Squid Ink Very Similar To Modern Squid InkAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
May 24th 2012, 04:59 PM #864
Re: Fossil Finds
A new analysis of the spinal structure of an extinct eel-like fish that inhabited shallow bodies of water in what is now Scotland between 318 and 359 mya (Early Carboniferous) has revealed that they possessed a spine with multiple segments which until now was thought to be a feature exclusive to land-dwelling animals.
The fish, known as Tarrasius problematicus, was thought to have had a spine merely divided into body and tail segments but as now demonstrated has a five-segment vertebral column extremely similar to the spines of land-dwelling animals called tetrapods.
To make clear Tarrasius is not any sort of ancestor of the tetrapods. It was an early ray-finned fish, an Actinopterygii as opposed to the fleshy, lobed fins, Sarcopterygii, from which tetrapods arose.
Tarrasius possessed no hind fins and a long dorsal fin, indicating it probably used its segmented spinal column to help propel their body's during fast swimming, not walking thereby demonstrating that the presumed relationship between complex vertebral anatomy and both walking and terrestriality is incorrect.
As noted this is forcing researchers to reconsider the idea that multiple segments spines are a feature of land-dwelling animals only. As the author of the paper, Lauren Cole Sallan, a graduate student at the University of Chicago Biological Sciences, put it: "You can't use this trait to say that something was definitely on land or to identify a tetrapod, which is the way it is used in the field now."
"It's the last trait to fall," Sallan added. "First, limbs were thought to show that a species was on land and walking, and now the vertebral morphology doesn't mean that they're on land either. So a lot of the things we associate with tetrapods actually arose first in fishes, and this is another example of that."
Further, the discovery suggests that this complex anatomy arose separately from -- and perhaps even before -- the first species to walk on land.
Tetrapod-like axial regionalization in an early ray-finned fish Astract
Human-like spine morphology found in aquatic eel fossil
Human spine structure found in 345 million year old eel
Fossil fish shows unexpected spine shapeAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
May 25th 2012, 12:08 PM #865
Re: Fossil Finds
Researchers have announced the discovery of a new genus of abelisaurid theropod dinosaur in a lacustrine deposit at a site called Condor Hill, near the village of Cerro Cóndor in Chubut Province of southern Argentina, some 1,800km (1,120 mi) southwest of Buenos Aires, that is approximately 170 myo (Middle Jurassic).
This Middle Jurassic representative of the Abelisaurus family of theropods, which appear to have been the most common carnivorous species in the southern hemisphere during the Cretaceous (65 to 145 mya), predates the oldest known member of the Abelisauri lineage by more than 40 million years. Due to being the oldest abelisaurid known it has been assigned a basal position.
The dinosaur was named Eoabelisaurus mefi, with the first or genus name meaning "dawn Abelisaurus" and the second or species name coming from the acronym for the Museo Palentológico Egidio Feruglio ("MEF") in recognition of the support the team received from the Museum.
The specimen consists of a nearly complete fossilized skeleton and skull of a subadult or adult individual that was about 6.5 meters (21') long and looked somewhat like a scaled-down Tyrannosaurus rex, but with even stubbier arms.
The arms, or forelimbs, of Eoabelisaurus, while not as puny as those seen in the later abelisaurids, are still unusually small. This demonstrates that the reduction of abelisaurid arms began at an early stage in the group's evolutionary history.
This reduction apparently started with the lower arm and hand being that Eoabelisaurus' upper forelimb is of normal size, but the lower arm is much shorter in comparison, lacking wrist bones and with a very stunted hand and tiny fingers and claws.
What they used their arms for remains a mystery in that abelisaurids had enlarged shoulder girdles which suggest both muscle strength and flexibility of the upper arm. Some have conjectured that they could have been used to hold on to a mate while copulating but there just isn't enough data to go on.
In contrast, their skulls, much like those found in T rex were adapted for very powerful bites though they were relatively shorter in length and taller in height than those possessed by the famous carnivorous dinosaur.
Such reduced arms and tiny claws imply that Eoabelisaurus relied on only its powerful jaws and very sharp teeth -- a feeding technique known as "head hunting" -- in order to eat.
Since Eoabelisaurus lived 170 to 175 mya this meant that abelisaurids were around when all the continents were united in the supercontinent Pangaea roughly 10 to 15 million years before it fragmented into Gondwana and Laurasia. So in theory abelisaurids could have spread across the whole of Pangaea before it broke up but the fact that abelisauri remains are almost exclusively found in the southern hemisphere and not distributed globally indicates they didn't.
This fact suggests to the researchers that some sort of natural barrier prevented their advance northward, possibly a large desert in central Pangea. Both geological studies and the results of climate modeling support the existence of such a geographical barrier.
The white portions indicates the bones discoveredXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs Abstract
Poorly armed, but successful: The rise of the tyrants of the South
Dinosaur with tiny arms unearthed in Argentina
Stubby-armed dinosaur was T. rex of Southern Hemisphere
Last edited by rogue06; May 25th 2012 at 12:12 PM.Always strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
June 2nd 2012, 05:06 PM #866
Re: Fossil Finds
A previously unknown and oddly shaped, or heteromorph, ammonite that lived approximately 128 mya was unearthed in Puez-Geisler-Natural Park roughly 2600 meters (8530') up in the Dolomite mountains in northern Italy (part of the Southern Alps) and is described by its discoverers as being the ultimate ancestor of the modern-day squid and octopus.
Ammonites are a group of marine invertebrate animals belonging to the cephalopod class that first appeared in the Devonian (circa 400 mya) and went extinct at the end of the Cretaceous (65½ mya) and got there name from their resemblance to a tightly coiled rams' horn. But a few species, primarily from the Cretaceous, are partially to totally uncoiled, and are referred to as heteromorphs.
The new ammonite was named Dissimilites intermedius though some have nicknamed it the "cactus squid" due to the fact its 13cm (5.1") long shell was covered with tiny spines each between 3 and 4mm (0.1-0.15") long.
The researchers, headed by Alexander Lukeneder of the Natural History Museum Vienna's Geological-Palaeontological Department, used computer tomography and a complicated 3D reconstruction program to expose the fossil of Dissimilites from the slab it was discovered in and reconstruct not only its appearance but also to determine how it moved by the position of the impressions left by its limbs.
They were able to pinpoint how the organism fitted within its body chamber and theorize as to how it used its ten tentacles (assuming Dissimilites, like other ammonites, possessed ten tentacles).
The results can be seen in a video slightly over 30 seconds long showing Dissimilites going through different ontogentic stages and its habitat which is included with the Abstract (linked to below).
The Cretaceous deposits Dissimilites was excavated from were once part of the the Tethys Sea, a former tropical ocean that separated the supercontinents of Laurasia in the north from Gondwana in the south during much of the Mesozoic Era, before the opening of the Indian and Atlantic oceans during the Cretaceous.
During the early Tertiary, plate movements in the Earth’s crust forced the Alps to fold up out of the sea, taking some of the former sea bottom sediment up on to the peaks of the Dolomites.
The researchers think that Dissimilites' spikes may provide a tip as to why so many uncoiled or heteromorph ammonite shells evolved especially during the Cretaceous. While some types of Ammonite were strong swimmers (and they think Dissimilites was an active swimmer) they couldn't swim faster than the Teleost fish which arose in the Triassic and became the dominant fish by the end of the Cretaceous.
With the evolution of Teleost fishes and the abundance of other marine predators, some types of ammonites maight have evolved uncoiled shells as this allowed them to evolve more locations for spikes. The typical coiled up shells can't have spikes forming on the inner whorls as they are strongly attached to larger, outer whorls whereas an uncoiled shell permits each whorl to have its own defenses.
Being that ammonite fossils have shown evidence of having been attacked from behind (bite marks left in fossilised shells), having all round protective spikes provides a superior defense against attacking predators.
Computed 3D visualisation of an extinct cephalopod using computer tomographs Abstract includes video animation
Discovered: The 128million-year-old grandfather of the modern squid and octopus
Unravelling the Mystery of an “Unravelling Ammonite”
Cactus squid swims again after 128 million yearsAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
June 4th 2012, 06:23 PM #867
Re: Fossil Finds
While researchers concur that mankind's immediate ancestors, the upright walking apes, arose in Africa the discovery of four teeth recovered from sediments of the Pondaung Formation near Nyaungpinle in central Myanmar (formerly Burma) and dated at 37 myo (Middle Eocene) provide strong evidence that the origin of anthropoids (the simians, or "higher primates," which include monkeys, apes and humans) is Asia.
Until the last couple decades the fossil evidence pointed toward Africa as the location where anthropoids arose but recent discoveries in China and Myanmar had raised some doubts. But this new discovery in difficult terrain where vehicles could not travel, and its apparent relation to another early anthropoid in the Sahara Desert of Libya indicate that anthropoids arose in Asia and subsequently made the arduous journey to the then island continent of Africa shortly after.
This early primate, known from four isolated molars only a few millimeters long, was named Afrasia djijidae with the first or genus name for how early anthropoids are now found in both Africa and Asia and the second or species name in memory of a young girl from a nearby village.
Analysis of the shape of the teeth leads the researchers to think that they were probably insectovores while their size suggests that they weighed approximately 100 grams (3½ oz) when they were alive. That's roughly the size of a modern tarsier (small primate found in the islands of Southeast Asia).
Due to the complicated structure of mammalian teeth, paleontologists frequently utilize them like fingerprints but to reconstruct how extinct species are related to each other and their modern relatives.
These teeth closely resemble those of another early anthropoid, the 38 myo Afrotarsius libycus which were discovered a couple years ago in the Dur At-Talah escarpment in central Libya, but Afrasia's bore more considerably more primitive features, specifically in the larger size of a tiny bulge at the back of its last lower molar.
The close similarity between Afrasia and Afrotarsius provides strong evidence that early anthropoids colonized North Africa only shortly before the appearance of Afrotarsius in the African fossil record. If Asian anthropoids had arrived in North Africa earlier, there would have been time for more differences to evolve between Afrasia and Afrotarsius.
And while they're very similar, Afrasia's teeth are more closely related to those of the oldest known anthropoid, Eosimias, which lived from 40 to 45 mya in southern China.
Further, the site Afrasia's teeth were unearthed in is the same one this same research team discovered the remains ofGanlea megacanina, another early anthropoid primate.
The more primitive traits seen in Afrasia along with the greater diversity and age of early, or "stem," anthropoids in Asia instead of Africa all indicate that as noted above this group arose in Asia and migrated to Africa by way of the Tethys Sea 37 million to 39 mya.
"Not only does Afrasia help seal the case that anthropoids first evolved in Asia, it also tells us when our anthropoid ancestors first made their way to Africa, where they continued to evolve into apes and humans," asserted one of the researchers, Carnegie Museum of Natural History paleontologist Chris Beard.
As another team member, Jean-Jacques Jaeger a paleontologist at the University of Poitiers in France and a Carnegie Museum research associate, put it, "Anthropoids didn't arrive in Africa until right before we find their fossils in Libya."
Still nobody knows what path Afrasia took to reach Africa. The Tethys Sea or Ocean was much larger than today's Mediterranean though island hopping on mats of vegetation was certainly possible.
There are critics. Washington University in St. Louis physical anthropologist David Tab Rasmussen, who specializes in primate evolution, has raised concerns that “the authors overstate an uncertain and complex hypothesis that these fossils are anthropoids."
He pointed to the complexities involved in identifying extinct creatures from fossilised remains noting how a limb from a tarsier was temporarily misidentified a limb found in Egypt as being from another Afrotarsius species.
After some of the hoopla surrounding the discovery of some early primates recently I would prefer to withold judgment until more material from these and other species are uncovered.
Late Middle Eocene primate from Myanmar and the initial anthropoid colonization of Africa Abstract
An Asian Origin for Human Ancestors?
New Primate Fossil Points to 'Out of Asia' Theory
Fossil discovery sheds new light on evolutionary history of higher primates
Early primates originated in Asia, migrated to Africa
EARLIEST KNOWN HUMAN RELATIVES CAME FROM ASIA
Discovery of primate fossil shows critical step in evolution, research team saysAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
June 12th 2012, 11:55 AM #868
Re: Fossil Finds
Re 128 m.y. old Dissimilites being ancestral to modern squids and octopodes:
Squids perhaps, but is the inclusion of the octopus among its descendants an error? This requires rejecting Pohlsepia (Carboniferous) from being an octopus, which is maybe okay, but what about the mid Jurassic (164 m.y.) Proteroctopus? See http://www.tonmo.com/science/fossils...loctopuses.php
Thanks for all your work on the fossil list, incidentally. It's a nice resource.
June 12th 2012, 03:48 PM #869
Re: Fossil Finds
Last edited by rogue06; June 12th 2012 at 03:50 PM.Always strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
June 20th 2012, 12:29 AM #870
Re: Fossil Finds
Whoopee. Or at least for the first time in the fossil record that vertebrates have been preserved in the act of making whoopee.
In this case it is not just one but nine pair of extinct turtles that have been found in the Messel shale quarry approximately 35km (21¾ mi) southeast of Frankfurt, Germany which once was a deep volcanic crater lake in a wet, tropical environment but is now famous worldwide for its exquisitely preserved fossils from the Eocene.
The turtle couples were discovered over a period of 30 years and had puzzled paleontologists. The pairs didn't all die together, but were instead discovered at random throughout the site of the former lake roughly 47 mya.
They all were identified as being from the species Allaeochelys crassesculpta, an extinct species who's closest living relatives are probably the pig-nosed turtle (Carettochelys insculpta), a much bigger species inhabiting the waters around Australia and Papua New Guinea.
That the pairs consisted of a male and a female was confirmed by characteristics of their shells and tails, body size differences and other anatomical features.
For instance, the tail on the males extend past the edge of the shell while those of the female don't. And the females, which were larger than the males, possessed a hinged lower shell that is thought to have assisted them lay relatively large eggs.
The contention that these pairs had been mating is supported by the fact that the turtles in each pair had their rear ends oriented toward one another indicating that they were in close contact just before death.
In fact it appears that with seven of the nine couples, the individuals were discovered still in physical contact with other. And for the two that weren't, the individuals were no more than 30cm (1') apart.
More importantly, the males of two of the pair had their tails tucked under their partners' as would be expected when they're copulating. As the lead researcher Walter Joyce, a fossil turtle expert at the University of Tübingen in Germany explained, "This is the very position in which the tails are held when living turtles mate. This observation is the true smoking gun."
The researchers think that the very fact that so many turtles died while mating at this location suggests that something odd was going on there.
They think that as each couple had initiated sex in the surface waters of the lake that existed there at the time, they were overcome as they sank through deeper layers made toxic by the release of volcanic gases from the crater that the lake filled.
Apparently this phenomena has been observed today in some volcanic lakes found in eastern Africa.
The idea that it was the result of toxic algal blooms that tainted the ancient lake was rejected because there aren't any sediment layers containing large numbers of remains that would be indicative of a mass death in a single event. Further, no fossils of cyanobacteria that might have caused such blooms have been discovered.
Turtles fossilised in sex embrace
Coitus Interruptus: Ancient Turtle Sex Fossilized
Sex locked in stone
Turtle Sex—Preserved for the Ages
Embracing for eternity: Scientists uncover turtles that died while having sex 50million years ago
Palaeontologists catch turtles in flagranteAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
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