Sarcosaurus

Sarcosaurus () is a genus of basal neotheropod dinosaur, roughly long. It lived in what is now England and maybe Ireland and Scotland during the Hettangian-Sinemurian stages of the Early Jurassic, about 199-196 million years ago. Sarcosaurus is one of the earliest known Jurassic theropods, and one of only a handful of theropod genera from this time period. Along with Dracoraptor hanigani it is one of the two described neotheropods from the lowermost Jurassic of the United Kingdom.

==Description== left|thumb|Size comparison of the two known partial skeletons of Sarcosaurus woodi (restored as a basal neotheropod) The holotype is NHMUK PV R4840 a partial skeleton that includes a posterior dorsal vertebra, partial left and right ilia, that are fused to the proximal portion of the pubis, lacking the femoral head. The specimen shows some evidence of skeletal maturity, meaning it is not an early juvenile, but its exact ontogenetic stage cannot be ascertained. Referred specimens include the non mature NHMUK PV R3542 (holotype of Sarcosaurus andrewsi) that includes a complete right tibia; WARMS G667–690, a partial skeleton of a single individual that includes posterior dorsal vertebra, middle caudal vertebra, dorsal rib fragments, left ilium, right and left pubes, femora and tibiae, proximal end of left fibula, probable distal half of fibula, distal portions of metatarsals IV, II or III proximal half of left pedal phalanx II-1, and three indeterminate bone fragments. Sarcosaurus shares certain morphological conditions with other neotheropods, including Liliensternus liliensterni (collateral fossae of the metatarsal II with similar development and shape on both sides, larger ratio on the centrum) and Dilophosaurus wetherilli (lateral collateral fossa is bigger than the medial one in the metatarsal, middle caudal series proportionately lower and narrower than the middle−posterior dorsal vertebra). Sarcosaurus was a bipedal predator, probably able to run fast and catch small prey. The holotype belonged to a 3.5-metre-long animal whose weight was no greater than 50–60 kg. NHMUK PV R3542 belonged to a larger animal, estimated to have had a maximum length of 5 m and a weight of 140 kg.