Gnathovorax, a new very complete Herrerasaurid

[Ikessauro]

Besides being very complete, this animal was also found in association with other triassic fauna from the Santa Maria Formation, in southern Brazil.
https://blogs.scientificamerican.com/laelaps/stunning-skeleton-reveals-early-carnivorous-dinosaur/

[Newt]

That's fantastic! I'm always excited to see new Triassic dinosaur remains, and especially anything as complete as this guy. The phylogenetic results are interesting - support for the old idea that herrerasaurids are non-theropod, non-sauropodomorph basal saurischians. I'm interested too by the sisterhood of Tawa and Chindesaurus they recovered - I don't believe I've seen that before.


I'm a little confused by Black's assertion (not made in the paper) that sauropodomorphs were the main competitors with herrerasaurids as predators. The contemporary predatory sauropodomorphs were smaller than herrerasaurs, and there were many other non-dinosaurian predators (phytosaurs, poposaurs, rauisuchids, assorted paracrocodylomorphs) that were more serious competition for herrerasaurs. I'm sure Black was just trying to point out the interesting fact that early sauropodomorphs were predatory, but it was awkwardly phrased.


Speaking of which, the authors of the paper make a point that Carnian-age saurischian faunas contain only herrerasaurs and sauropodomorphs. There are two problems with this; one is the very contentious position of the Carnian-Norian boundary in the Chinle Group (if the "long Norian" hypothesis is incorrect, the definite theropod Camposaurus arizonensis from the traditionally Carnian-aged Placerias Quarry is more or less coeval with the herrerasaurs). More serious is the fact that, if theropods and sauropodomorphs are sister groups, then it is impossible for one group to be older than the other, and therefore there must have been theropods in the Carnian, whether their remains have been discovered or not.


Anyway, just my two cents.



Paper (open access) is here.

[eion129]

The dinosaur remains the biggest creature in the world and we all don't want to have them in real world again.

[Loon]

The article was pretty interesting. I'm not sure I every saw the word "faunivorous" before. But, I gotta saw, this guy got quite the lively skeletal:

[Newt]

"Faunivorous" is a good catchall for carnivores, piscivores, and invertivores, especially since it is often unclear what a predator's main food source was.

[Sim]

This is a great find!  This Gnathovorax is a beautiful specimen.  The phylogenetic analysis in the paper was very interesting.  It supports theropods and sauropodomorphs being each other's closest relatives (in Saurischia) with herrerasaurids and a few others like Tawa being non-theropod, non-sauropodomorph saurischians.  It also finds Eoraptor to be a sauropodomorph and some silesaurids to be ornithischians!  These last two have been found before, but I'm happy to see them again as I think this is most likely their correct placement.  I wonder if the lack of Carnian theropods is because herrerasaurids and others like Eodromaeus are actually theropods.

[SidB]

Please correct me if I'm mistaken, but was there not an analysis several years or so ago that proposed re-aligning the dinosaur family tree with Sauropodmorpha differentiating at an earlier date from Dinosauria than a later split of Ornithischia and Theropoda from a common ancestoral Ornithoscelida? I never saw that paper, and am wondering a) how much traction it got in the paleontological community, and, b) what the potential relationship of Gnathovorax might be to that new picture, if anyone has made a conjecture on this point?

[stargatedalek]

Please correct me if I'm mistaken, but was there not an analysis several years or so ago that proposed re-aligning the dinosaur family tree with Sauropodmorpha differentiating at an earlier date from Dinosauria than a later split of Ornithischia and Theropoda from a common ancestoral Ornithoscelida? I never saw that paper, and am wondering a) how much traction it got in the paleontological community, and, b) what the potential relationship of Gnathovorax might be to that new picture, if anyone has made a conjecture on this point?

That paper left a lot of people confused, but I think that's because a lot of it was more semantic than people assumed. It didn't really move sauropods or Herrerasaurs around, rather it changed the "cutoff point" for "being a theropod" to be later along the line (as otherwise all dinosaurs would have been theropods). The new part was the placement of Ornithischia.

I can't see this species changing any of that around.

[brontosauruschuck]

Thanks for posting this!

[SidB]

Please correct me if I'm mistaken, but was there not an analysis several years or so ago that proposed re-aligning the dinosaur family tree with Sauropodmorpha differentiating at an earlier date from Dinosauria than a later split of Ornithischia and Theropoda from a common ancestoral Ornithoscelida? I never saw that paper, and am wondering a) how much traction it got in the paleontological community, and, b) what the potential relationship of Gnathovorax might be to that new picture, if anyone has made a conjecture on this point?

That paper left a lot of people confused, but I think that's because a lot of it was more semantic than people assumed. It didn't really move sauropods or Herrerasaurs around, rather it changed the "cutoff point" for "being a theropod" to be later along the line (as otherwise all dinosaurs would have been theropods). The new part was the placement of Ornithischia.

I can't see this species changing any of that around.

I'm certainly one of the confused ...  would you be able to guide me in the direction of current papers or blog discussions grappling with the placement of Ornithischia?