Yet another Carnegie mount I’m afraid. Those who have been to the museum since the refurbishment are probably getting sick of them by now. But this was truly fascinating for me because despite my travels in Europe and Asia, we simply don’t have many American classics over here and getting to see them all was superb fun and an education. So I’m afriad you’re stuck with this for a few more weeks as I have yet to hit up all the theropods, or the ceratopsians and I want to cover the museum as a whole and some of it’s other superb exhibits.
For now though, you’ll have to be content with a Herrerasaurus. This is one of those somewhat ‘benchmark’ taxa that crop up again and again in phylogenies as the outgroup because it’s nice and old and nice and basal and nice and complete, all the things you want really. Even so, it has moved around a bit in various analyses especially early on, and I recall a time where (a little like Archaeopteryx now) each new analysis seemed to place it slightly further up or lower down than the last one, and while it never moved far it dotted around the base on the dinosaurs, just outside Dinosauria, as a basal theropod etc. That last position seems to look like it’ll be the settled one, but with new things like Panphagia and Eoraptor turning up, it can always move again.