page_title: Brontomerus
section_title: Paleobiology
hierarchical_section_title: Brontomerus / Paleobiology
caption_attribution_description: English: Brontomerus mcintoshi may have had a powerful kick due to large abductor muscles. Here an adult is protecting a juvenile from a Utahraptor.
context_page_description: Brontomerus is a possibly dubious genus of camarasauromorph sauropod which lived during the early Cretaceous. 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 "Jack" Stanton McIntosh.
context_section_description: Dr. Michael Taylor, one of the dinosaur's describers, hypothesizes that the strong thigh muscles of Brontomerus were probably used for functions other than speed. He points out that for fast movement, the strong muscles would be oriented at the back of the leg to pull it along, but the actual positioning of the muscles indicates they were more likely used to deliver a kick. This is due to the apparent anchoring of large femoral protraction muscles, which would have been used to move the leg forward powerfully. Large femoral retraction muscles, on the other hand, are needed for fast forward locomotion, and the ilium of Brontomerus offers little attachment area for these, though this does not necessarily imply weak retraction muscles as these would have been mostly anchored on the tail-base rather than the ilium. The supposed kicks would have possibly been used for fighting over mates or in defense against predators, such as Utahraptor and Deinonychus.
  Dr. Matthew Wedel, assistant professor of anatomy at the Western University of Health Sciences in Pomona, California, has stated that since it has been commonly been assumed that sauropods tend to prefer drier, upload areas, perhaps Brontomerus may have used its powerful leg muscles for traversing rough, hilly terrain. He described the theoretical use of such muscles in this terrain as "a sort of dinosaur four-wheel drive."
  In addition to powerful protraction muscles, the ilium of Brontomerus would have also anchored abductor muscles, which are muscles used for drawing the leg laterally away from the body. These muscles would have been necessary for creating abduction torque when standing, and could have theoretically aided in an occasional bipedal stance or even limited bipedal walking. Another possible explanation for the proportionally large leg muscles is that they were used to control unusually long legs. While no material from the legs is known, the large anterior expansion of the scapula provides only weak support for this hypothesis. If this interpretation is correct, however, the morphology of Brontomerus may have resembled that of a giraffe.
  Despite these theories, the actual data on the ilium and its powerful muscles indicates only that the animal was "unusually athletic for a sauropod", and there is minimal speculation that Brontomerus may have been predatory and would require extra power in locomotion to feed; it would be the first carnivore among any sauropod discovered. The authors acknowledge that while the unusual qualities of the hipbone probably have some functional significance, it is difficult to assess without further information about the pelvis, femora and proximal caudals.
caption: Reconstruction of Brontomerus using its strong femoral protraction muscles to deliver a kick to a Utahraptor
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