Brontomerus

Brontomerus fights with the hind leg from a predatory Utahraptor (live reconstruction).

• United States, Utah ( Cedar Mountain Formation)

• Brontomerus mcintoshi

Brontomerus is a genus of sauropod dinosaur in the group of Macronaria from the Lower Cretaceous of North America. So far, only a few bone fragments are known to originate from the Cedar Mountain Formation in eastern Utah (USA) and the Aptian to Albian (before about 126.3 to 100.5 million years ago) are dated. The exact systematic position of the genus within the Macronaria is unclear - it currently is listed as not representative of the unclassifiable Camarasauromorpha. From other sauropods Brontomerus be different due to the unique morphology of the ilium ( ilium ), which provided attachment points for large and strong adductor muscles of the hind leg muscles. Only species is B. mcintoshi.

Description

The holotype ( specimen number OMNH 66430 ) is a fragmentary left ilium. More of this type, attributed fossils include fragmentary shoulder blade (scapula ), two sternum ( sternum), three vertebrae (two tail vertebrae and the broken fragment of a Präsakralwirbels ( a vortex from the region in front of the pelvis) ), a rib and bone fragments with a. Although all bones are from the same quarry, they belonged to at least two different individuals, like the very different size of the bones suggests. Thus, the shoulder blade rest is 98 inches long, with the original total length of this bone is estimated to be 121 centimeters. While scapula and ilium are at the Titanosaurier Rapetosaurus approximately the same length, measured the iliac found by Brontomerus only one-third the length of the shoulder blade. Probably belonged ilium, Präsakralwirbel and sternum to a cub while the scapula and other bones from a larger individual come.

This genus can be explained by five unique features ( autapomorphies ) distinguished from other genera: So did the präacetabulare blade of the ilium ( the front of the hip joint socket ( acetabulum ), this part of the bone) 55 percent of the total length of the ilium, and is thus longer than any other sauropods. In addition, the präacetabulare shovel was moved by 30 percent relative to the sagittal plane. The postacetabulare ( located behind the acetabulum ) blade was against largely reduced. Below this blade joined the the ischium ( ischium ) facing style ( " ischiadic peduncle " ), which was reduced to a very low hump. Further, the ilium was higher than other sauropods.

Paleobiology

The enlarged presacral blade of the ilium offered starting points for very large muscles of the thigh, which allowed a vigorous forward movement of the hind leg. About the function of these muscles can be enlarged merely speculation. They may suggest that Brontomerus possessed unusually strong limbs for locomotion. They could also have enabled powerful kicks with the hind leg. Another possibility is that Brontomerus has developed a rear on the hind legs, to which muscles are needed that allow a lateral spreading of the legs; these muscles also are attached to the ilium. On the other hand, could the enlarged muscles also indicate relatively long legs.

System

Brontomerus is classified as not representative of the unclassifiable Camarasauromorpha, a group that includes, among others, Camarasaurus, the Brachiosauridae and Titanosauria with. A cladistic analysis could not define stable systematic position within this group - the most likely variant Brontomerus However, as basal ( original ) Representatives of Somphospondyli, as relatives of Euhelopus and Titanosauria.

History of discovery and naming

The fossils date from the Hotel Mesa Quarry, a quarry in Grand County in eastern Utah. This quarry was first investigated scientifically in 1994 by Richard Cifelli - more fossils were collected in 1995. The quarry was long been known fossils private collectors, which a majority of the fossils already took away - the researchers call a significant loss of information. More fossils of this quarry include various fish, several species of crocodiles as well as remains of theropod dinosaurs and ornithopods with a. The quarry is located in the upper portion of the Ruby Ranch member, a layer member of the Cedar Mountain Formation, a major fossil site.

Brontomerus 2011 was described by Michael P. Taylor, Mathew J. Wedel and Richard L. Cifelli first time scientifically. The name Brontomerus ( gr bronto - "thunder", gr Meros - " leg " ) means something like " thunder thighs ", which points to the very strong muscles of the thigh bone, which can get a glimpse at the morphology of the ilium. The second part of the species name, mcintoshi, honors the significant paleontologists and sauropod expert John S. McIntosh.