Prehistoric crocodilians known as Thoracosaurus were likely capable of crossing the Atlantic Ocean. A study published Wednesday in the journal Palaeontology reveals that these extinct reptiles possessed physiological adaptations specifically suited for marine environments.
CT Scans Reveal Salt-Processing Anatomy
Researchers used CT scans to examine two Thoracosaurus isorhynchus specimens from Northern France and Southern Sweden, alongside one Eothoracosaurus mississippiensis from Mississippi. These animals lived between 80 and 60 million years ago, a window that includes the asteroid impact that wiped out non-avian dinosaurs.
The imaging identified large, spherical protrusions near the eye sockets. These structures, which are absent in modern crocodilians, resemble features found in other extinct marine reptiles. According to KU Leuven researcher Sophie Boerman, the position and shape of these cavities suggest they were linked to salt-processing mechanisms, allowing the animals to process salt water and survive extended periods at sea.
Evidence for a Transoceanic Predator
Finding these fossils in marine sedimentary rock bolsters the theory that Thoracosaurus was a sea-bound predator. This lifestyle explains why the same genus appears on both sides of the Atlantic. During the late Cretaceous, the Atlantic Ocean was significantly narrower, likely facilitating migration for a reptile adapted to salt water.
The researchers stop short of claiming absolute proof. “We naturally do not find a salt gland itself in a fossilized skull,” Boerman stated. Regardless, the anatomical evidence serves as the strongest indicator yet that these creatures were specialized for life in the open ocean.
Auditory Adaptations and Diving Limits
The study also scrutinized the inner ear structures to interpret the behavior of these ancient reptiles. The analysis uncovered large air channels within the skull, suggesting that Thoracosaurus was not a deep-diving species.
Researchers hypothesize that these internal cranial structures may have played a role in the perception or production of underwater sound. While the findings offer a clearer picture of how Thoracosaurus interacted with its environment, the team noted that further research is required to determine the precise function of these unique auditory adaptations.
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