Search the Community

I took these photos of a replica of the Allosaurus jimmadseni specimen "Big Al 2" at the Lewis Science Center in Orange Coast College earlier this year. Like the referred A. jimmadseni specimen "Big Al", it was excavated at Howe Quarry in Wyoming in the 1990s.

A very long time coming, over a decade in discussion, Allosaurus jimmadseni has finally been described in the attached OPEN paper The abstract says it best "Allosaurus is one of the best known theropod dinosaurs from the Jurassic and a crucial taxon in phylogenetic analyses. On the basis of an in-depth, firsthand study of the bulk of Allosaurus specimens housed in North American institutions, we describe here a new theropod dinosaur from the Upper Jurassic Morrison Formation of Western North America, Allosaurus jimmadseni sp. nov., based upon a remarkably complete articulated skeleton and skull and a second specimen with an articulated skull and associated skeleton. " https://peerj.com/articles/7803/ National Park Service article https://www.nps.gov/dino/learn/nature/allosaurus-jimmadseni.htm Article https://phys.org/news/2020-01-species-allosaurus-utah.html Collectors For those of us that collect teeth I'm sure that these teeth are indistinguishable from other Allosaurus species like Allosaurus fragilis and all teeth should all be identified as Allosaurus sp. including bones. Also please do not get taken by sellers claiming to offer Allosaurus jimmadseni teeth. Unless one comes off an identifiable skull its bogus.

While doing research on dino stratigraphy in the Morrison Formation, I noted that Hesperosaurus has been found at the bottom of the Morrison Formation and also the Salt Wash Member near Howe Quarry (where a specimen of Stegosaurus armatus has been found), roughly the same level as the plethora of Stegosaurus specimens found at Como Bluff Quarry 13. At the same time, I've noticed that the primitive apatosaurine Eobrontosaurus has been found to coexist with the advanced diplodocine Diplodocus in Garden Park, Colorado. Since the most primitive Morrison dinos (Eobrontosaurus, Hesperosaurus, "Allosaurus jimmadseni") are found in the lower part of the Salt Wash Member and coexist with the their more advanced counterparts at the Howe Quarry (which is situated near the boundary between the Salt Wash and Brushy Basin Members), would it be reasonable to assume that the rate of faunal turnover for dinosaurs in the Morrison Formation was a gradual one, with Hesperosaurus and Eobrontosaurus being eventually replaced by Diplodocus and Stegosaurus in the Brushy Basin Member?