Daspletosaurus wilsoni, is a newly described transitional species from the Judith River Formation

[Faelrin]

Daspletosaurus wilsoni is described as a transitional species between D. torosus and D. horneri. The holotype specimen is BDM 107, and material consists of parts of the skull, and a few other scant remains.

Here's the paper (which is not paywalled):

https://peerj.com/articles/14461/

And here's another article explaining the stuff inside the paper:

http://dickinsonmuseumcenter.com/badlands_research-2022newtyranno/

Some artwork by Andrey Atuchin as well:



And a pic of the skull parts:

[Sim]

Thanks for sharing this Faelrin!  It's nice to see a new tyrannosauroid known from good remains after the nonsense of Dynamoterror, Thanatotheristes and Timurlengia.

It's interesting to have a new species of Daspletosaurus, that genus really is turning out to be the one with the most tyrannosauroid species.  If this new species is intermediate between D. torosus and D. horneri, I wonder where the unnamed Dinosaur Park Formation Daspletosaurus fits in?  And on that note I hope to see that one get named soon!

The paper also includes a comparison between the three named Daspletosaurus species' skulls:

[Faelrin]

@Sim I'm actually wondering that as well, and also hoping to see that get described and named at some point too.

[andrewsaurus rex]

it's my understanding that D. torosus is considered to be the direct ancestor of T. rex.  So it seems there was a split in the lineage at D. torosus, with one line continuing on with new Daspletosaurus species and another evolving into T. rex.  But D. torosus is relatively more heavily built than T. rex and has proportionally larger teeth.  It doesn't make sense to me that T. rex would evolve to be significantly larger but at the same time leaner and smaller toothed (relatively).   I can maybe see it being leaner, in an attempt to keep from getting overly heavy in its new larger size, but what evolutionary advantage would there be to evolving relatively smaller teeth?

[Dynomikegojira]

I don't think anybody considers Daspletosaurus to be the a direct ancestor of T.rex anymore especially since more tyrannosaurids have been discovered. I personally think T.rex ancestors hail from Asia.

[Sim]

I've never heard of Daspletosaurus torosus being considered the ancestor of Tyrannosaurus rex.  I've heard of T. rex's ancestor being asian and recently that Daspletosaurus horneri is an ancestor of T. rex.  My understanding is D. torosus evolved into D. wilsoni which evolved into D. horneri which leads to T. rex.

Daspletosaurus torosus is not more heavily built than Tyrannosaurus rex and it doesn't have proportionally larger teeth either.  Supporting this is Scott Hartman's skeletals of D. torosus and T. rex:

[andrewsaurus rex]

i guess my knowledge is out of date then.  Greg S Paul is one of the proponents of D. torosus being T. rex's direct ancestor.   Here's an article from 2017 that reiterates that:  https://magazine.scienceconnected.org/2017/03/dinosaur-gave-rise-tyrannosaurus-rex/

I guess 5 years is a long time in paleontology these days....   That plus there often seem to be a variety of differing opinions circulating at the same time.

[Newt]

Greg Paul is virtually always at odds with the rest of paleontology when it comes to taxonomy and phylogeny. It's one of his charms.