Make a crocodile out of taffy. Grab his head and pull it until his neck is a few feet above his body. If you squint, it could be what a strange looking Triassic reptile called it Tanystropheus looked like. More or less.
This animal’s assortment of ridiculously long fossilized neck bones has puzzled paleontologists for nearly 170 years. Using CT scans to extract the crushed skulls from the reptiles’ remains, the researchers finally resolved some nagging questions surrounding this strange animal in August last year.
Copies of Tanystropheus can grow to over 5 meters in length, with its tail about a third of its length and its body perhaps a quarter. The rest is all necks.
Tanystropheus sizes compared to a human. (Spiekman, et al., Current Biology, 2020)
Tanystropheus looked like a stocky crocodile with a very, very long neck, ‘said paleontologist Olivier Rieppel of Chicago’s Field Museum.
Why this reptile evolved so extensively is a complete mystery. The fact that no one could figure out whether it would rather be submerged in water or trudged on land only made it more difficult to reach a decision.
Part of its peculiarity is the shape of the neck bones. Unlike those in a snake or lizard, the cervical vertebrae are in it Tanystropheus fossils stretch out like those of a giraffe. When its remains were first discovered in 1852, the scattered bones were believed to be the elongated wing bones of a flying pterosaur.
Not all the individuals we dug up are also not as big as a crocodile. A number are much smaller, leading paleontologists to question whether some of the specimens in their records belong to juveniles or represent a completely different species.
This is a common problem in paleontology – the diminutive fossil of a dwarf species can be nearly identical to the stunted bones of a youngster. Separating them requires looking for clues as to whether the skeleton has not yet reached full size or has yet to grow.
Fortunately, such clues can be found deep in the fossils. Just as the rings in a tree’s trunk indicate their age, bones can do the same.
To find these, Rieppel and his colleagues used X-rays on an assortment of Tanystropheus skeletons, which turn the scans into 3D models using high-resolution computer tomography (CT) technology.
“The power of CT scanning allows us to see details that would otherwise be impossible to see in fossils,” said lead author Stephan Spiekman, an expert in Triassic reptile evolution at the University of Zurich.
The growth rings revealed the smaller ones Tanystropheus bodies were indeed of adults, making it quite clear that what the researchers were holding were two different types.
To distinguish them, the team named the bigger one T. hydroides, after the hydra in Greek mythology. Its smaller cousin kept the original generic name T longobardico
Converting the scans into digital models also provided the researchers with a way to rearrange the crushed bones in a clearer configuration, making it much easier to get a good look at the creature’s entire anatomy.
“From a severely crushed skull, we have been able to reconstruct an almost complete 3D skull, revealing crucial morphological details,” said Spiekman.
With all its bone fragments in the right place, it seems Tanystropheus would be well versed in the water.
The reptile’s skull has its nostrils on top, much like a crocodile’s snout – just what an ambush predator keeps a lung full of air while waiting for a meal to pass by.
(Spiekman et al., Current Biology, 2020)
What was a jumbled pile of pointed teeth can also be seen as a fairly efficient trap for grabbing a cephalopod, at least for the king-size kind.
“The small species probably fed on small animals, such as shrimp, as opposed to the fish and squid that the large species ate,” said Spiekman.
“This is really remarkable, because we were expecting the bizarre neck Tanystropheus specialized for a single task, such as a giraffe’s neck. But it actually made different lifestyles possible. This completely changes the way we look at this animal. “
An illustration shows T. hydroides hunt. (Emma Finley-Jacob)
The fact that the two very similar species had so different ways of using their tall bodies made it much easier for them to live in the same habitats and share their environment without competing for the same food resources.
We can almost imagine that the animal’s squatting, crocodile-like body lay against the bottom of a shallow shoreline some 242 million years ago, with its head raised to the surface so that its nostrils could siphon air down, its bushy beak slightly hopped open, waiting for a stray squid to stumble past.
No matter how familiar the scene feels, Tanystropheus is still a weird beast.
This research is published in Current Biology
A version of this article was first published in August 2020.