Messes of Information

There are usually only a few topics of interest on Wednesdays to pick from and extrapolate. Allosaurus gives us a copious amount of information to draw from and discuss today. We could discuss ontogeny or pathology or perhaps even the overall scope of the paleobiological implications of Allosaurus and its environment. One of the more interesting topics that has been delved into, in my opinion, is the laying of eggs. Medullary tissues in leg bones (tibia material) from the Cleveland-Lloyd Quarry has been studied and determined to be representative of a gravid female. These findings were reported in comparison to gravid female birds mineralization in long bones. The tissue is used by the female birds, and purportedly by the female theropods, to calcify the shell layers that are laid around eggs as the shells were formed in the oviduct. Sexual maturity was dependent on Allosaurus size, according to some sources, but at 15 years of age maximum size was reached, based on histological analyses; these same analyses determined that bone deposition in Allosaurus slows and stops between 22 and 28 years of age. Regardless of the age of sexual maturity, a clutch of destroyed eggs discovered in Colorado is hypothesized to belong to Allosaurus and comparison of any remaining molecular data in the eggs and Allosaurus bones that have been recovered. Should these eggs turn out to be those of Allosaurus, the life cycle of Allosaurus would be completely represented in fossil assemblages; that means, of course, that juveniles and adults of all ages and sizes have been fairly well represented.

Allosaur life stages; Natural History Museum of Utah