Brontosaurus Morphs?

[ZoPteryx]

I was reading the Princeton Field Guide to Dinosaurs by GSP and happened to notice something interesting under the Apatosaurus enteries.  In the text, he refers to "Brontosaurus morphs" on several occassions; what is he talking about?  Is this similar to the robust and gracile (likely female/male) morphs of T. rex , or something else entirely?

[wings]

I was reading the Princeton Field Guide to Dinosaurs by GSP and happened to notice something interesting under the Apatosaurus enteries.  In the text, he refers to "Brontosaurus morphs" on several occassions; what is he talking about?  Is this similar to the robust and gracile (likely female/male) morphs of T. rex , or something else entirely?

I think Paul is referring to A.parvus, A.excelsus and A.louisae (see the word Brontosaurus in brackets, and his notes on the A.parvus entry, he mentioned brontosaurus is the shorter, narrower-necked version of Apatosaurus...) being the Brontosaurus morph whereas A.ajax is a different morph (form) to the rest (see the anatomical description for A.ajax which highlight the differences). This is probably different to the robust and gracile morphs because often these terms would normally be referring to animals of the same species.

[ZoPteryx]

Awe, I see. Thank you.

[wings]

I've often found Paul's descriptions are rather vague and "less than useful" in most occasion for classification. Take this "Brontosaurus morph" for example, unless you have all/most of the skeletal of all the different species (i.e. A.parvus, A.excelsus, A.louisae and A.ajax) in front of you to make the comparison there is no way for you to distinguish these animals. Let's say you are lucky enough to find an isolated but complete Apatosaurus' hip and thigh, based on Paul's description, it would be close to impossible to tell the species apart (i.e. hips sail not especially tall. arm and leg long. Pelvis not as large as earlier apatosaurs). There are more "useful/solid" morphological (form) differences between these species (like the form of the neck ribs, A.excelsus has an extension in front of the neck rib where A.louisae doesn't. Or the shape of the shoulder blades, the distribution/shape of the hollow out areas on the vertebrae for example), however, you probably need to do a bit more digging around for info if you are really interested in these species.