Were S. stenops and S ungulatus at all separated geographically or chronologically?

[andrewsaurus rex]

i was just wondering if it could be a case of sexual dimorphism rather than them being 2 distinct species.   Has this possibility very been ruled out?

[Sim]

Maidment considers the two to be one species, but I'm not aware of any justification for this and the two are scientifically different.
Stegosaurus stenops comes from the middle Morrison while Stegosaurus ungulatus is from the upper Morrison.  Additionally, S. stenops is found in Colorado while S. ungulatus is found in Wyoming.

[andrewsaurus rex]

thanks......in light of that they obviously don't represent sexual dimorphism.  Perhaps just a bit of an evolution of stenops.

[Torvosaurus]

It's roughly 300 miles between where the two were found, and I believe S. ungulatus has also been found in Utah, around Dinosaur National Monument. I suspect that either species probably spread across the entire region from New Mexico to Montana without any problems. The time difference between the mid and upper Morrison is what really distinguishes the two species.

Torvo

[Newt]

It should be pointed out that the majority of stegosaur fossils from the Morrison are not diagnostic to species, or often even to genus (Hesperosaurus and Alcovasaurus were also present). This is partly due to the incompleteness of many fossils, but also to the apparently high variability of stegosaurs.

Add to that the difficulty of determining the relative ages of different Morrison outcrops, and it becomes very difficult to make any firm statements about biogeography or chronology.

[bmathison1972]

The geographic separation is insignificant. Temporal differences are more important, but as Newt pointed out, that could be hard to discern.

Until there is solid evidence to the contrary, I am considering them two different species.