Scientists finally know how an ancient reptile lived with such an absurdly long neck

Make a crocodile out of taffy. Take his head and pull on it until his neck extends a few feet from his body. If you squint, it could be what a strange Triassic reptile called it Tanystrophy looked like. More or less.

This animal’s assortment of ridiculously long fossilized neck bones has confused paleontologists for nearly 170 years. Using CT scans to unwrap crushed skulls from reptile remains, researchers finally resolved some nagging questions surrounding this strange animal in August of last year.

Specimens of Tanystrophy can reach over 5 meters (16 feet) in length, with its tail being about a third of its length and its body perhaps a quarter. The rest is all around the neck.

Tanystropheus sizes compared to a human. (Spiekman, et al., Current Biology, 2020)

“Tanystrophy looked like a stocky crocodile with a very, very long neck, ”said paleontologist Olivier Rieppel of the Field Museum in Chicago.

Why this reptile evolved such expansive dimensions is a complete mystery. The fact that no one could tell if they would rather be submerged in water or wander around on land only made it harder to draw conclusions.

Part of its quirk is the shape of the neck bones. Unlike those of a snake or a lizard, the cervical vertebrae Tanystrophy the fossils are spread out like those of a giraffe. In fact, 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 of the individuals we have found are the size of a crocodile either. A number are much smaller, making paleontologists question whether any of the specimens in their archives are juvenile 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 young one. To separate them, you have to look for clues as to whether the skeleton has not yet reached its actual size or if it still has work to do.

Fortunately, such clues can be found deep in the fossils. Just as the rings inside a tree trunk show evidence of their age, so can bones.

To find them, Rieppel and his colleagues used x-rays on an assortment of Tanystrophy skeletons, transforming scans into 3D models using high-resolution computerized tomography (CT) technology.

“The power of CT scans allows us to see details that are otherwise impossible to see in fossils,” said lead author Stephan Spiekman, an expert on Triassic reptile evolution at the University of Zurich.

Growth rings revealed the smallest Tanystrophy the bodies did indeed belong to adults, indicating quite clearly that what the researchers had in their hands were two distinct species.

To distinguish them, the team named the largest T. hydroids, after the hydra in Greek mythology. Its little cousin has retained the original name of the species T longobardico.

Turning the scans into digital models also provided the researchers with a way to rearrange the crushed bones into a clearer configuration, which made it much easier to see the creature’s anatomy well.

“From a heavily crushed skull, we were able to reconstruct an almost complete 3D skull, revealing crucial morphological details,” said Spiekman.

With all of his bone fragments in their place, he looks like Tanystrophy would be nice at home in the water after all.

The reptile’s skull has its nostrils perched on top, much like a crocodile’s snout – just enough for an ambushing predator to keep a lung full of air while waiting for a meal to pass.

(Spiekman et al., Current Biology, 2020)

What had been a bunch of tangled sharp teeth can also be seen forming a fairly effective trap for catching a cephalopod, at least for large species.

“The small species probably fed on small shelled animals, like shrimp, unlike the fish and squid that the large species ate,” Spiekman said.

“It’s really remarkable, because we expected the bizarre neck of Tanystrophy be specialized for a single task, like the neck of a giraffe. But in fact, it enabled several ways of life. It completely changes the way we look at this animal. “

An illustration showing T. hydroids hunt. (Emma Finley-Jacob)

The fact that the two very similar species have such different ways of using their long bodies made it much easier for them to exist in the same habitats, sharing their surroundings without competing for the same food sources.

One can almost imagine the stocky body of the crocodile-shaped animal lying against the ground of a shallow coast some 242 million years ago, its head rising very high to the surface for its nostrils could siphon air, its spiky mouth gaping slightly in anticipation of a wandering squid to stumble.

As familiar as the scene seems, Tanystrophy is still a strange creature.

This research was published in Current biology.

A version of this article was first published in August 2020.