Fossil Friday: Colorado's State Fossil
Stegosaurus was named the state fossil of Colorado in 1982 due to its history of discovery. Many specimens have been found in state including the holotype specimen.
Stegosaurus lived in the Kimmeridgian to early Tithonian of the Late Jurassic period, between 155 and 150 million years ago, in the western United States and Portugal. It is one of the most recognizable dinosaur types due to their back plates and tail spikes (thagomizers).
It was first found and named during the Bone Wars in 1877 by Othniel Charles Marsh north of Morrison Colorado; (Marsh 1877) the original species named was Stegosaurus armatus but the type specimen was too fragmentary and the species is now considered a nomen dubium. It was replaced by S. stenops as the type species, and the only other valid species are S. ungulatus (Galton 2010) and S. sulcatus. (Gilmore and 1914)
Stegosaurus had the largest plates of any stegosaur with some plates pushing 1 m (3.3 ft) in height. The arrangement of their plates was controversial for a long time, no one knew if they were in one or two rows and if they were in pairs or alternating. A specimen from Cañon City, Colorado, indicates that reconstructions with two alternating rows was the correct arrangement.
Just as the arrangement of their dorsal plates was a mystery for the longest time so was their function with theories ranging vastly. The most realistic answer to their purpose is likely a mix of many roles including species recognition, display, defense and thermoregulation. There appears to be a size difference between the plates of S. stenops and S. ungulatus who lived together.
Thank you for reading and happy Fossil Friday, remember to wish our dig team luck as they currently work at several localities in the Morrison Formation.
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