Field Museum paleontologist leads study on two new dinosaurs ...(osaurs are a lineage of theropods that e...)

With an estimated body mass of almost 1400 lbs. (626 kg), Beishanlong is one of the largest ornithomimosaurs yet described, rivaling the Late Cretaceous ornithomimosaur Gallimimus in size. Bone microstructure analysis on a cross section of one of the lower leg bones of the principal specimen by co-author Gregory Erickson of Florida State University reveals that the holotype individual was not yet fully grown when it died. According to Dr. Erickson, "Growth line counts revealed that the animal perished during its 14th year of life. Although it is hard to fathom, this giant was still actively growing when it died. Growth line spacing in the bones of the teen-giant show only moderate decreases in width towards the periphery. Somewhere out there are even larger specimens awaiting discovery."

Beishanlong was equipped with hand claws up to six inches in length and relatively powerful forelimbs compared to most other ornithomimosaurs. "We know the forelimbs could not be brought far forward or elevated too much" says Makovicky, who is the lead author on the study, "but their range of motion and the shape of the claws suggest they may have been used for digging or raking the ground."

Other dinosaurs found together with Beishanlong and Xiongguanlong include the beaked and probably herbivorous therizinosauroid theropod Suzhousaurus, primitive relatives of duck-billed dinosaurs, the small horned dinosaur Auroraceratops, and both small and large sickle-clawed theropods. Most of the famous Cretaceous dinosaur faunas of China and Mongolia, like the ones that include Velociraptor and Protoceratops, comprise members of the same dinosaur lineages as those found in Gansu, but very few others. Interestingly, horned dinosaurs and sickle-claw
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