Thornthwaitei

Thornthwaitei is a genus of extinct marine reptiles belonging to the clade Thalattosauria, which thrived during the Late Triassic period, approximately 228 to 201 million years ago. These reptiles were semi-aquatic predators, closely related to modern-day crocodiles, and are notable for their elongated snouts and streamlined bodies adapted for swimming.

Fossil remains of *Thornthwaitei* have been discovered primarily in marine sedimentary deposits of what is now the southwestern United States, particularly in Arizona and New Mexico. The genus was named in honor of paleontologist Charles H. Thornthwaite, who contributed significantly to the study of Triassic marine reptiles. The type species, *Thornthwaitei neogeus*, was formally described in 1996 by paleontologists Michael W. Maisch and Hans-Dieter Sues.

*Thornthwaitei* possessed a robust, crocodile-like skull with sharp teeth suited for capturing fish and other small marine prey. Its body was elongated and muscular, with four paddle-like limbs adapted for efficient movement through water. Unlike some of its relatives, such as *Thalattosaurus*, *Thornthwaitei* appears to have had a more generalized thalattosaurian anatomy, lacking specialized features like elongated necks or reduced limbs.

The discovery of *Thornthwaitei* provides valuable insights into the diversity and ecological roles of thalattosaurians during the Late Triassic. As part of a broader group of marine reptiles, it reflects the adaptive radiation of vertebrates in response to the transition from terrestrial to aquatic environments during this geologic period. Research on *Thornthwaitei* continues to contribute to understanding the evolutionary history of reptiles and their colonization of marine habitats.