| Lophostropheus | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Superfamily: | †Coelophysoidea |
| Genus: | †Lophostropheus Ezcurra &Cuny, 2007 |
| Species: | †L. airelensis |
| Binomial name | |
| †Lophostropheus airelensis (Cuny &Galton, 1993) | |
| Synonyms | |
| |
Lophostropheus (pronounced: "LOAF-oh-STRO-fee-us") is anextinctgenus ofcoelophysoidtheropoddinosaur that lived approximately 205.6 to 196.5million years ago during the boundary between theLate TriassicPeriod and theEarly JurassicPeriod, in what is nowNormandy,France.Lophostropheus is one of the few dinosaurs that may have survived theTriassic–Jurassic extinction event.
Lophostropheus was a small to medium-sized, moderately-built, ground-dwelling,bipedalcarnivore, that could grow up to 3 m (9.8 ft) long. Over the years it had been incorrectly classified asHalticosaurus andLiliensternus, but was later recognized as a new genus and was reassigned toLophostropheus in 2007.
Lophostropheus was described and named byArgentinepaleontologist Martin Ezcurra (Museo Argentino de Ciencias Naturales) and French paleontologist Gilles Cuny of theUniversité Pierre et Marie Curie in2007, and thetype species isLophostropheus airelensis. The composite termLophostropheus is derived from theGreek 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. Thespecific name, "airelensis" is a reference to the locality where the specimen was discovered, the Airel Quarry.
Estimates suggest thatLophostropheus 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 ofHalticosaurus.
Lophostropheus differs from othertheropods in several ways. It has features reminiscent of morederived theropods, such as having aball connection to the front of its neck vertebrae, a socket connection to the front of its tail vertebrae, and a vertical ridge on theilium. These characteristics have all been interpreted asconvergences, 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, unlikeLiliensternus.[5] It was closer to thecoelophysids, including the well-knownCoelophysis, than toLiliensternus.[4] It has been assigned to the superfamilyCoelophysoidea. An analysis of early dinosaurs by Baron, Norman and Barrett (2017) placedLophostropheus in a position close to the derived theropodsSinosaurus andCryolophosaurus.[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.
According to Ezcurra and Cuny (2007),Lophostropheus can be distinguished based on the following characteristics:
In 1966, the French paleontologists Claude Larsonneur andAlbert-Félix de Lapparent described a partial theropod skeleton from the Triassic-Jurassic boundary of Normandy, found in 1959 by Claude Pareyn, asHalticosaurus sp.[7] This specimen consisted of atooth, fiveneck vertebrae, two vertebrae from the back, foursacral vertebrae,tail vertebrae, portions of all thepelvic bones, and an unidentified fragment.[4] It was reinterpreted in 1993 by Gilles Cuny andPeter Galton as belonging to a newspecies, assigned toLiliensternus and namedL. airelensis.[8] Other researchers began to notice differences betweenL. airelensis and thetype species,L. liliensterni,[5][9] such as those observed in thepleurocoels of the cervical vertebrae,[5] and in 2007, Martin Ezcurra and Gilles Cuny assigned it to its own genus,Lophostropheus.[4]
Lophostropheus, as a coelophysoid, would have been a small to medium-sizedbipedalcarnivore,[10] probably comparable in size and habits toLiliensternus (best specimen estimated at 5.15 meters long, or 16.9 feet).[11] Very few dinosaurs are known from its time period; in fact, it is the only theropod genus known from good remains at the Triassic-Jurassic boundary.[4]
The remains of the type specimen ofLophostropheus airelensis was recovered in the Airel Quarry locality of theMoon-Airel Formation, in Basse-Normandie,France. The specimen was collected by Pareyn in 1959 in sandy claystone and lenticular, sandy limestone that was deposited on the boundary of theRhaetian stage of theTriassic period and theHettangian stage of theJurassic period, approximately 205.6 to 196.5 million years ago. It is one of the few dinosaurs known to have lived during the Triassic-Jurassic boundary.Lophostropheus is one of the few dinosaurs that may have survived the Triassic–Jurassic extinction event when at least half of the known species living on Earth became extinct. This specimen is housed in the collection ofCaen University in Normandy, France, and has not been assigned a collection number.
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