Decoding Nature’s Riddle: Unveiling the Thoracosaur – When a Croc Isn’t Really a Croc

Life reconsturction of the long-snouted Thoracosaurus, a fish-eating reptile from the Mesozoic era. Credit: Jacob Baardse

Image

The fearsome Thoracosaurus, a dinosaur-era reptile from North America with jaws like giant pincers, bears an uncanny resemblance to a modern fish-eating croc called a gharial.

However, new research led by Flinders University shows that these similarities are all due to convergent evolution, which has repeatedly fooled scientists trying to reconstruct the family tree of crocodiles.

When is a croc not a croc? When it’s a thoracosaur

The Indian gharial and ‘false’ gharial both have long, narrow snouts for grabbing fish underwater.

Their similar DNA demonstrates that both gharials are close relatives – hence the so-called ‘false’ gharial is actually a true gharial.

The genetic evidence further suggests that gharials are a very young group that evolved alongside modern mammals, perhaps 30 million years ago.

Historical material of cf. Thoracosaurus from the Maastrichtian of Denmark provides new insight into the K/Pg distribution of Crocodylia - ScienceDirect

This scenario is at odds with the occurrence of ancient gharial-like fossils from the Mesozoic era called “thoracosaurs,” which lived more than 70 million years ago.

A new study in Proceedings: Biological Sciences has resolved this dilemma, using new Bayesian techniques for inferring evolutionary trees which, unlike other methods, take into consideration both the anatomy and geological age of fossils.

New Jersey State Museum on X: "#Museum30 Day 27: Broken Most of the fossils that are collected and brought to the NJSM are broken and need some repair. This 56 million yr

These analyses show that the ancient thoracosaurs are not closely related to living gharials after all, but are a totally separate group of ancient reptiles which had adopted a similar fish-eating lifestyle, and evolved pincer-like snouts to match.

Thus, as predicted by the DNA data, gharials did not exist in the Mesozoic; the presumed fossils were merely gharial mimics.

Luigi on X: "Lower jaw material from Thoracosaurus neocesariensis (Croc taxon from Hell Creek, Maastrichtian age). #FossilFriday #Crocodyliforms https://t.co/vwd0VyRe1i" / X

“The DNA of living gharials indicates they are a young group, which evolved well after the dinosaurs – but then why are there gharial-like fossils older than T-rex?” says lead author Professor Michael Lee, from Flinders University and the South Australian Museum.

“Either the DNA evidence is wrong, or we’ve misinterpreted these ancient thoracosaurs.”

“Our work suggests we’ve got the fossils wrong, after being misled by convergent evolution.”

Thoracosaurus, an up to 8 meter long crocodylomorph that lived with Tyrannosaurus and Triceratops in the Hell Creek Formation : r/Naturewasmetal

Convergent evolution is when animals in similar habitats evolve similar adaptations, such as fins in whales and fish, and wings in bats and birds.

The study’s co-author Dr. Adam Yates, from the Museum of Central Australia in the Northern Territory, says the “long pincer-like jaws are ideal for grabbing fish underwater, as they can slam shut rapidly with minimal water resistance.”

“It is not surprising that thoracosaurs and modern gharials both convergently evolved almost identical snouts, for feeding in a similar way and on similar prey,” Dr. Yates says. “It seems the thoracosaurs are the ‘true’ false gharials.”

Sia

Related Posts

Lost Titan Resurrected: Brazil’s Largest Dinosaur Emerges from 60-Year Hiatus, Rewriting History in Unbelievable Cupboard Discovery

Brazil’s largest ever dinosaur is found: Fossils discovered in a cupboard after 60 years shed light on 82ft-long beast] A South American dinosaur of truly magnificent proportions…

Lost Titan Resurrected: Brazil’s Largest Dinosaur Emerges from 60-Year Hiatus in Unbelievable Cupboard Discovery, Rewriting History

Brazil’s largest ever dinosaur is found: Fossils discovered in a cupboard after 60 years shed light on 82ft-long beast] A South American dinosaur of truly magnificent proportions…

Unearthing Jurassic Wonders: Delving into Eype Starfish Bed on the Jurassic Coast for Incredible Fossil Discoveries

Between Seatown and Eype, on the West Dorset coast (part of the Dorset and East Devon Coast World Heritage Site), there is a remarkable layer of rock…

Unearthing Ancient Wonders: Exploring Jurassic Coast’s Eype Starfish Bed for Spectacular Prehistoric Fossil Finds

Between Seatown and Eype, on the West Dorset coast (part of the Dorset and East Devon Coast World Heritage Site), there is a remarkable layer of rock…

Thailand’s Treasures: Remarkable Neornithischian Dinosaur Fossil Revealed in Astonishing Prehistoric Discovery

Minimocursor phunoiensis is the earliest known neornithischian dinosaur from Southeast Asia as well as one of the best-preserved dinosaurs ever found in the region. Reconstruction of Minimocursor…

Thailand’s Prehistoric Surprise Unveiled – Newly Discovered Neornithischian Dinosaur Rewrites Evolutionary Tale

Minimocursor phunoiensis is the earliest known neornithischian dinosaur from Southeast Asia as well as one of the best-preserved dinosaurs ever found in the region. Reconstruction of Minimocursor…

Leave a Reply

Your email address will not be published. Required fields are marked *