The discovery of Turnersuchus hingleyae follows the impressive discovery of fossils on the Jurassic Coast in Dorset, UK, including part of the head, spine and limbs. In fact, the find in the Charmouth Mudstone Formation was so successful that Turnersuchus is the only thalattosuchian of its age dated to the Early Jurassic, Plensbachian period, about 185 million years ago complete enough to be named today.
Published in the peer-reviewed Journal of Vertebrate Paleontology, experts say the discovery of this new predator helps fill a gap in the fossil record and suggests that thalattosuchians, along with other crocodilians, should have originated at the end of the Triassic period – around 15 million years further back in time than when Turnersuchus lived.
Co-author Dr. Eric Wilberg, Assistant Professor in the Department of Anatomical Sciences at Stony Brook University says “We should now expect to find more thalattosuchians of the same age as Turnersuchus and older”.
In fact, during the publication of our paper, another paper was published describing a thalattosuchian skull discovered in the roof of a cave in Morocco from the Hettangian/Sinemurian (the period preceding the Pliensbachian where Turnersuchus was found) which confirms this idea. I expect we will continue to find more ancient thalattosuchians and their relatives. Our analyzes suggest that thalattosuchians probably first appeared in the Triassic and survived the mass extinction at the end of the Triassic.
However, no excavations have yet found thalattosuchians in Triassic rocks, implying that there is a ghost lineage (the period during which we know the group must have existed, but have yet to discover fossil evidence). Until the discovery of Turnersuch, this ghost line stretched from the end of the Triassic to the Toarcian, in the Jurassic, “but now we can reduce the ghost line by several million years”, according to the team of experts.
Thalattosuchians are colloquially referred to as “sea crocodiles” or “sea crocodiles”, although they are not members of Crocodylia, but are more distantly related. Some thalattosuchians are very well adapted to life in the oceans, with short finned limbs, a shark-like caudal fin, salt glands, and potentially the ability to live birth (rather than lay eggs).
Turnersuchus is interesting because many of these recognized thalattosuchian features had yet to fully evolve. He lived in the Jurassic Ocean and fed on marine animals. And given its relatively long, slender snout, it would have looked similar to the currently living gharial crocodiles, which are found in all the major river systems of the northern Indian subcontinent.
Says co-author Dr. Pedro Godoy of the University of São Paulo in Brazil, “unlike crocodiles, this approximately 2-meter-long predator lived purely in coastal marine habitats. And although their skulls look superficially similar to modern gharials, they were built quite differently.”
Thalattosuchians had particularly large supratemporal fenestrae – the area of the skull that houses the jaw muscles. This suggests that Turnersuchus and other thalattosuchians had enlarged jaw muscles that probably allowed for rapid biting; most of their likely prey were fast-moving fish or cephalopods.
It is also possible, as in modern crocodilians, that the supratemporal region of Turnersuchus had a thermoregulatory function – helping to balance the temperature of the brain.
Its name ‘Turner’suchus ‘hingley’ae’ comes from those who discovered and donated the specimen to Lyme Regis Museum: Paul Turner and Lizzie Hingley, who discovered the fossil in 2017. The ending “suchus” is the Latinized form of “soukhos”, Greek for crocodile. The specimen is currently on display at the Lyme Regis Museum in Lyme Regis, Dorset, England.
Colleagues from the Charmouth Heritage Coast Center also took part in the excavation, helping to unite the pieces. These cliffs and beaches on the south coast of England have become synonymous with such finds, with the discovery of ichthyosaurs and plesiosaurs, as well as the best-preserved and most complete dinosaur ever found in Britain, Scelidosaurus, to name but a few.
Written by: Vaishali Verma
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