Thursday, April 23, 2015

Sexual Dimorphism in Stegosaurus

Evidence for Sexual Dimorphism in the Plated Dinosaur Stegosaurus mjosi (Ornithischia, Stegosauria) from the Morrison Formation (Upper Jurassic) of Western USA.. 2015. PLoS ONE

Stegosaurs plates may have differed between males and females.
Stegosaurus, a large, herbivorous dinosaur, lived roughly 150 million years ago and had two staggered rows of bony plates along its back. Some individuals had tall plates and others had wide plates, which could be up to 45% larger than the tall plates.

Evan Saitta found that the tall-plated Stegosaurus and the wide-plated Stegosaurus were not two distinct species, nor were they individuals of different age: they were actually males and females. CT scanning and microscope analysis of the plates showed that the differences were not a result of growth, as the bone tissues had ceased growing in both varieties.

The presence of sexual dimorphism in an extinct species may provide scientists with a much clearer picture Stegosaurus behavior than would otherwise be possible. PR