Make a caramel crocodile. Take her head and pull her until her neck extends a good few feet from her body. If you squint, this could be what a strange looking Triassic reptile called Tanystropheus looked like. So so.
The ridiculously long array of fossilized neck bones from this animal has puzzled paleontologists for nearly 170 years. By using CT scans to unpack the crushed skulls from the reptile remains, the researchers finally solved some nagging questions about this strange animal in August of last year.
Specimens of Tanystropheus It can reach over 5 meters (16 feet) long, with its tail making up about a third of its length and its body perhaps a quarter. The rest is all neck.
“Tanystropheus it looked like a chubby crocodile with a very, very long neck, “said paleontologist Olivier Rieppel of the Field Museum in Chicago.
Why this reptile evolved in such vast dimensions is a complete mystery. The fact that no one could figure out whether he preferred to dive into the water or to walk heavily on land only made it more difficult to draw conclusions.
Part of its rarity is the shape of the neck bones. Unlike those of a snake or lizard, the cervical vertebrae in Tanystropheus the fossils spread out like those of a giraffe. In fact, when its remains were first discovered in 1852, the scattered bones were assumed to be the elongated wing bones of a flying pterosaur.
Nor are all the individuals we have unearthed the size of a crocodile. Some are much smaller, leading paleontologists to wonder if some of the specimens in their archives are juveniles or represent an entirely different species.
This is a common problem in paleontology: the tiny fossil of a dwarf species can be almost identical to the immature bones of a youngster. Separating them requires looking for clues as to whether the skeleton has not yet reached its full size or has yet to grow.
Fortunately, these clues can be found inside fossils. Just as the rings within a tree trunk keep track of its age, bones can do the same.
To find them, Rieppel and his colleagues used X-rays on a variety of Tanystropheus skeletons, converting the scans into 3D models through high-resolution computed tomography (CT) technology.
“The power of computed tomography allows us to see details that would otherwise be impossible to observe in fossils,” said lead author Stephan Spiekman, an expert on Triassic reptile evolution at the University of Zurich.
The growth rings revealed the smallest Tanystropheus In fact, the bodies belonged to adults, which makes it quite clear that what the researchers were dealing with were two different species.
To distinguish them, the team named the greatest T. hydroides, after the hydra in Greek mythology. His younger cousin kept the original species name of T. longobardicus.
Transforming the scans into digital models also gave the researchers a way to rearrange the crushed bones into a clearer configuration, making it much easier to get a good look at the entire anatomy of the creature.
“From a heavily crushed skull, we have been able to reconstruct a nearly complete 3D skull, revealing crucial morphological details,” Spiekman said.
With all its bone fragments in their correct place, it seems Tanystropheus it would be fine at home in the water after all.
The reptile’s skull has its nostrils perched on top, much like a crocodile’s snout, just what an ambush predator needs to keep a lung full of air while waiting for a meal to pass.
What had been a messy pile of pointed teeth can also be seen forming a fairly efficient trap for catching a cephalopod, at least for the giant species.
“The small species probably fed on small, shelled animals, such as shrimp, in contrast to the fish and squid that the large species ate,” Spiekman said.
“This is really remarkable, because we expected the strange neck of Tanystropheus specialize for a single task, such as a giraffe’s neck. But in reality, it allowed for various lifestyles. This completely changes the way we look at this animal. “
The fact that the two very similar species had such different ways of using their long bodies made it much easier for them to exist in the same habitats, sharing their environment without competing for the same food sources.
We can almost imagine the squat, crocodile-like body lying against the ground on a shallow shore some 242 million years ago, its head rising to the surface so that its nostrils can suck in air, its bristly mouth slightly open. in anticipation of a stray squid to stumble upon.
As familiar as the scene feels Tanystropheus it is still a strange creature.
This research was published in Current biology.
A version of this article was first published in August 2020.