ioniparitus

Ioniparitus 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 marine lizards but distinct in their evolutionary lineage. Fossil remains of Ioniparitus have been primarily discovered in what is now the southwestern United States, particularly in the Chinle Formation of Arizona and New Mexico.

The name *Ioniparitus* derives from the Greek words *ion* (meaning "goat") and *paritus* (meaning "bearing"), likely referencing the distinctive shape of its skull, which resembles that of a goat. This genus is characterized by its elongated, streamlined body, adapted for swimming, and a robust skull with sharp teeth suited for capturing fish and other marine prey. Estimates suggest that Ioniparitus could reach lengths of up to 2 meters (6.6 feet), though most specimens are smaller.

Like other thalattosaurs, Ioniparitus likely spent much of its time in coastal waters, using its powerful limbs for propulsion. Its fossilized remains provide valuable insights into the ecological diversity of Late Triassic marine ecosystems, particularly the transition between terrestrial and aquatic environments during this time. The genus is one of several thalattosaurs studied to understand the evolutionary adaptations that allowed reptiles to colonize marine habitats before the rise of true marine mammals.