Triassic Reptiles with Extraordinarily Long Neck were Decapitated by Predators, Paleontologists Say

Paleontologists have studied the unusual necks of two species of Tanystropheusa type of aquatic reptile that lived during the Triassic period some 242 million years ago and had an extraordinarily long and stiffened neck that was almost three times the length of its torso.

Tanystropheus were first described as a single species, Tanystropheus longobardicusin 1852.

These aquatic reptiles were up to 6 m (20 feet) long, and had unique necks composed of 13 extremely elongated vertebrae and strut-like ribs.

Consequently, they likely possessed stiffened necks and waited to ambush their prey. But Tanystropheus’ predators apparently also took advantage of the long neck for their own gain.

Careful examination of their fossilized bones now shows that the necks of two existing specimens representing different Tanystropheus species with severed necks have clear bite marks on them, in one case right where the neck was broken.

“Paleontologists speculated that these long necks formed an obvious weak spot for predation, as was already vividly depicted almost 200 years ago in a famous painting by Henry de la Beche from 1830,” said Dr. Stephan Spiekman, a paleontologist at the Staatliches Museum für Naturkunde Stuttgart.

“Nevertheless, there was no evidence of decapitation — or any other sort of attack targeting the neck — known from the abundant fossil record of long-necked marine reptiles until our present study on these two specimens of Tanystropheus.”

Dr. Spiekman and colleagues recognized that the two Tanystropheus species lived in the same environment, one small species, about 1.5 m (4.9 feet) in length, likely feeding on soft-shelled animals like shrimp, and a much larger species of up to 6 m long that fed on fish and squid.

They also found clear evidence in the shape of the skull that Tanystropheus likely spent most of its time in the water.

It had been well known that two specimens of these species had well-preserved heads and necks that abruptly ended.

It had been speculated that these necks were bitten off, but no one had studied this in detail.

In the new study, Dr. Spiekman and co-authors concluded that the necks had clearly been bitten off.

“Something that caught our attention is that the skull and portion of the neck preserved are undisturbed, only showing some disarticulation due to the typical decay of a carcass in a quiet environment,” said Dr. Mujal, also from the Staatliches Museum für Naturkunde Stuttgart.

“Only the neck and head are preserved; there is no evidence whatsoever of the rest of the animals.”

“The necks end abruptly, indicating they were completely severed by another animal during a particularly violent event, as the presence of tooth traces evinces.”

“The fact that the head and neck are so undisturbed suggests that when they reached the place of their final burial, the bones were still covered by soft tissues like muscle and skin.”

“They were clearly not fed on by the predator. Although this is speculative, it would make sense that the predators were less interested in the skinny neck and small head, and instead focused on the much meatier parts of the body.”

“Taken together, these factors make it most likely that both individuals were decapitated during the hunt and not scavenged, although scavenging can never be fully excluded in fossils that are this old.”

“Interestingly, the same scenario — although certainly executed by different predators — played out for both specimens, which remember, represent individuals of two different Tanystropheus species, which are very different in size and possibly lifestyle,” Dr. Spiekman said.

The findings will be published in the journal Current Biology.

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Stephan Spiekman et al. 2023. Decapitation in the long-necked reptile Tanystropheus (Archosauromorpha, Tanystropheidae). Current Biologyin press; doi: 10.1016/j.cub.2023.04.027