Nothogenus

*Nothogenus* 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. The name *Nothogenus* derives from the Greek words *nothos* (meaning "false" or "spurious") and *genus* (referring to a group or kind), reflecting its initial classification as a misidentified or atypical thalattosaur. Fossil remains of *Nothogenus* have been discovered primarily in North America, particularly in the southwestern United States, including regions of Arizona and New Mexico.

*Nothogenus* is characterized by its elongated, streamlined body adapted for aquatic life, similar to other thalattosaurs. It possessed a long neck, a broad snout, and sharp teeth, suggesting a diet primarily consisting of fish and other small marine prey. The skull of *Nothogenus* is notably robust, with a distinctively shaped jaw that distinguishes it from closely related genera. Paleontologists have identified at least two species within the genus: *Nothogenus clarki* and *Nothogenus robertsi*, though taxonomic classifications may vary based on ongoing research.

*Nothogenus* is significant in the study of thalattosaur evolution, providing insights into the ecological diversity of Late Triassic marine ecosystems. Its fossils offer clues about the adaptation of reptiles to fully aquatic lifestyles, including specialized features for swimming and hunting. The genus is often compared to other contemporaneous thalattosaurs, such as *Thalattosaurus* and *Pachypterygius*, to understand broader trends in thalattosaur morphology and behavior.

Fossil evidence of *Nothogenus* has been recovered from marine sedimentary deposits, indicating that it inhabited coastal and shallow marine environments. Its presence aligns with the broader distribution of thalattosaurs during the Late Triassic, a time marked by significant marine biodiversity before the mass extinction event that marked the end of the Triassic period. Ongoing paleontological research continues to refine the understanding of *Nothogenus* and its role within the evolutionary history of marine reptiles.