Pachagnathus ("earth jaw") is an extinct genus of non-pterodactyloid pterosaur from the late Norian–early Rhaetian-aged Quebrada del Barro Formation of Argentina. It lived in the Late Triassic period (217-201 million years ago), and is one of the only known definitive Triassic pterosaurs from the southern hemisphere (along with the contemporaneous and related Yelaphomte). It is also one of the few known continental Triassic pterosaurs, indicating that the absence of early pterosaurs in both the southern hemisphere and terrestrial environments is likely a sampling bias, and not a true absence.
Pachagnathus ("earth jaw") is an extinct genus of non-pterodactyloid pterosaur from the late Norian–early Rhaetian-aged Quebrada del Barro Formation of Argentina. It lived in the Late Triassic period (217-201 million years ago), and is one of the only known definitive Triassic pterosaurs from the southern hemisphere (along with the contemporaneous and related Yelaphomte). It is also one of the few known continental Triassic pterosaurs, indicating that the absence of early pterosaurs in both the southern hemisphere and terrestrial environments is likely a sampling bias, and not a true absence.
==Discovery and naming== The type and only known specimen of Pachagnathus, PVSJ 1080, was collected during fieldwork by the Museo de Ciencias Naturales of the Universidad Nacional de San Juan from 2012 to 2014. It consists of only a broken portion of the front end of a lower jaw along its mandibular symphysis preserved in three dimensions and undistorted, including a partial tooth crown as well as several tooth roots and alveoli. The specimen was discovered at the 'Quebrada del Puma' locality of the Quebrada del Barro Formation within the Marayes–El Carrizal Basin of Northwestern Argentina, part of the Caucete Department in the San Juan Province. The 'Quebrada del Puma' locality occurs in the upper layers of the Quebrada del Barro Formation in its southern outcrops, and has been roughly dated to around the late Norian into the Rhaetian based on its faunal assemblages. PVSJ 1080 was discovered in a horizon of reddish muddy sandstone just 30 m below the top of the formation, beneath the unconformably overlying Cretaceous aged El Gigante Group.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).