Brontomerus

Brontomerus (from Greek bronte meaning "thunder", and merós meaning "thigh") is a genus of camarasauromorph sauropod which lived during the early Cretaceous (Aptian or Albian age, approximately 110 million years ago). It was named in 2011 and the type species is Brontomerus mcintoshi. It is probably a fairly basal camarasauromorph, though the taxon is difficult to resolve due to incompleteness of the material. It is most remarkable for its unusual hipbones, which would have supported the largest thigh muscles, proportionally, of any known sauropod. The specific name is in honor of physicist and North American sauropod expert John Stanton McIntosh.

==Description== thumb|left|Preserved bones of Brontomerus (in white), with missing elements based on Camarasaurus Brontomerus is known from two fragmentary specimens differing in size, likely a juvenile and an adult. The researchers speculate that the adult may have been the mother of the juvenile. The type specimen, OMNH 66430, is represented by the left ilium of the smaller individual. Other recovered fossils include a crushed presacral centrum, several caudal vertebrae, a right-side dorsal rib, a large scapula, and two partial sternal plates. The adult specimen is thought to have weighed around six tonnes, and probably measured around 14 meters (46 ft) in length. The juvenile specimen had about a third of this length, and probably weighed around 200 kilograms and measured 4.5 meters (15 ft) in length. Its assignment to a new species is based on several noteworthy autapomorphies, including an oddly-shaped hipbone which would have permitted the attachment of unusually massive leg muscles. This unique ilium would have given it the largest leg muscles of any sauropod dinosaur. The ilium is unusual in being very deep and having a front part that is much larger than the part behind the hip socket.