Lophostropheus (pronounced: "LOAF-oh-STRO-fee-us") is an extinct genus of coelophysoid theropod dinosaur that lived approximately 205.6 to 196.5 million years ago during the boundary between the Late Triassic Period and the Early Jurassic Period, in what is now Normandy, France. Lophostropheus is one of the few dinosaurs that may have survived the Triassic–Jurassic extinction event.
Lophostropheus was a small to medium-sized, moderately-built, ground-dwelling, bipedal carnivore, that could grow up to 3 m (9.8 ft) long. Over the years it had been incorrectly classified as Halticosaurus and Liliensternus, but was later recognized as a new genus and was reassigned to Lophostropheus in 2007.
Lophostropheus was described and named by Argentine paleontologist Martin Ezcurra (Museo Argentino de Ciencias Naturales) and French paleontologist Gilles Cuny of the Université Pierre et Marie Curie in 2007, and the type species is Lophostropheus airelensis. The composite term Lophostropheus is derived from the Greek words "lophè" (λόφη) meaning "crest" and the word "stropheus" (στροφεύς) meaning "pertaining to the vertebrae";[1] thus, "crest vertebrae". This naming is a reference to the prominent dorsal and ventral laminae observed in the cranial cervical vertebrae. The specific name, "airelensis" is a reference to the locality where the specimen was discovered, the Airel Quarry.
Estimates suggest that Lophostropheus was at best 3 m (10 ft) long and weighed 100 kilograms (220 pounds) at most.[2] In 2016 Molina-Pérez and Larramendi gave a higher estimation of 5.2 meters (17 ft) and 136 kg (300 lbs).[3] It is based on a partial skeleton first described in 1966 as a specimen of Halticosaurus.
Lophostropheus differs from other theropods in several ways. It has features reminiscent of more derived theropods, such as having a ball connection to the front of its neck vertebrae, a socket connection to the front of its tail vertebrae, and a vertical ridge on the ilium. These characteristics have all been interpreted as convergences, however.[4] It also has prominent crests on the tops and bottoms of its neck vertebrae (for which it was named),[4] and an extra pair of cavities in its neck vertebrae, unlike Liliensternus.[5] It was closer to the coelophysids, including the well-known Coelophysis, than to Liliensternus.[4] It has been assigned to the superfamily Coelophysoidea. An analysis of early dinosaurs by Baron, Norman and Barrett (2017) placed Lophostropheus in a position close to the derived theropods Sinosaurus and Cryolophosaurus.[6]
A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism or group.