Lycorhinus

Lycorhinus is a genus of heterodontosaurid ornithischian dinosaur that lived during the Early Jurassic, in the Sinemurian. It is known from a single species L. angustidens, that was named in 1924 by Sidney H. Haughton as a cynodont for a partial jaw found in the Upper Elliot Formation of South Africa. The genus name is derived from the Ancient Greek words for "wolf" and "nose". The limited material available, which has degraded over time to only be represented now by a single original tooth and the impression of the remaining jaw and teeth, has resulted in multiple different interpretations of the diagnostic nature and synonymy of Lycorhinus, including the treatmens of the type species of Heterodontosaurus, Abrictosaurus, and Lanasaurus as either species of Lycorhinus or synonyms. The latest review of Lycorhinus accepted the synonymy of Lanasaurus scalpridens, named in 1975 by Christopher Gow for a maxilla from Golden Gate Highlands National Park, with Lycorhinus angustidens, and also the referral of a partial skull found at the same locality as the original holotype decades later. Tentative specimens from the Clarens Formation have also been considered allied with Lycorhinus, but they may be better treated as remains of indeterminate heterodontosaurids.

History and naming Prior to 1914, Dr. Martin Ricono collected multiple specimens from the "Red Beds" of Paballong, Mount Fletcher district of South Africa, sending them to the South African Museum. Among this material was a lower jaw fragment identified and described in 1924 by Sidney H. Haughton as the holotype of a new cynodont, SAM 3606. This partial jaw showed a canine tooth and 11 molars (four as impressions), and the partial jaw bone supporting them. Only the inner side of the jaw could be seen because of the rock surrounding the specimen, but Haughton gave it the new binomial name Lycorhinus angustidens. From the same deposits within a 0.40 km (0.25 mi) Ricono and Alexander du Toit also collected material of the cynodont Tritheledon and thecodont Sphenosuchus. The genus name comes from the Ancient Greek words λύκος (lykos), meaning "wolf", and ῥῑνός (rhinos), meaning "nose". Robert Broom revisited Lycorhinus in a 1932 review of South African early mammals, incorrectly identifying the type locality as Witkop near Burgersdorp. He noted that the original specimen is no longer in the same condition, with the jaw and all of the molars being lost and only remaining as an impression of the external surface within the bone; only the canine remained as original fossil. Broom had also mentioned the species "Lycorhinus parvidens" in passing in 1913 as a therocephalian from the Permian of South Africa, but this was a mistaken identity of Alopecorhinus parvidens. The identity of Lycorhinus as a cynodont was maintained until 1962, when Alfred Walter Crompton and Alan Jack Charig described the new Triassic ornithischian Heterodontosaurus, and reidentified Lycorhinus as well after being alerted to it by John Attridge. The "Red Beds" of South Africa are now known as the Elliot Formation, with the locality of Paballong located at 30°26′S 28°31′E and within the Upper Elliot Formation. Historically the entire Elliot Formation has been considered Triassic in age, but reevaluations of the fauna has resulted in the Upper Elliot Formation to be interpreted as Early Jurassic, which would make it one of few fossiliferous formations to span the End-Triassic mass extinction event. Uranium-lead dating done in 2020 confirmed that the Upper Elliot Formation spans approximately 10 million years of the Early Jurassic, from approximately the Triassic-Jurassic boundary 201.3 mya until at least the late Sinemurian 191.9 mya. The exact age of Lycorhinus is uncertain as its locality is approximate, but it is likely from the younger sediments of the Upper Elliot Formation.

Heterodontosaurus and Abrictosaurus

… excerpt ends here. Continue reading the full article.