A "new" species of Allosaurus

[Halichoeres]

These specimens have been kicking around in collections for a long time, but they've finally been given a description and name. Meet Allosaurus jimmadseni from the lower Morrison:



The crests on the lacrimals definitely look different from the ones on A. fragilis. The specific name honors Jim Madsen, who did a big monograph on Allosaurus in the 70s.

Chure & Loewen, open access in PeerJ: https://peerj.com/articles/7803.pdf

[Funk]

Also, this is the species "Big Al", known from the WWD special, belongs to. I wonder how many Allosaurus toys actually show A. jimmadseni?

Seems it would include at least the 2006 Sleich figure, which seems based on the documentary's design: http://dinotoyblog.com/2010/10/08/allosaurus-schleich/

[Sim]

It's great to finally see this species get named.  It's the one that has been represented as Allosaurus sp. in Scott Hartman's Allosaurus comparison: https://www.deviantart.com/scotthartman/art/Allosaur-comparison-173333349

@Funk, I think the Favorite soft model series 2 Allosaurus represents A. jimmadseni.  It contrasts with the series 1 version that appears to represent A. fragilis.  Both versions of the Favorite soft model Allosaurus can be seen in this review: http://dinotoyblog.com/2018/04/26/allosaurus-soft-model-series-1-by-favorite-co-ltd/

[Funk]

Could be right, one feature that sets jimmadseni apart from fragilis is that the lower margin of the upper jaw almost stays straight, whereas it gets much deeper by the jugal (below the eye region) in fragilis, which also seems to sets the two Favorite figures apart (though not too pronounced):

[Pachyrhinosaurus]

Very interesting that the species has only been officially described now. I thought it's been an established species for some time. I remember reading about Allosaurus jimmadseni at least a decade ago.

[Sim]

Looking at newer figures, the CollectA 2020 Allosaurus looks like A. jimmadseni while the Safari 2019 version looks like A. fragilis.

[SidB]

This makes me appreciate the old Battat series that made the point of including the species designation on their belly stamps.

[Sim]

@Halichoeres, are you going to have a figure of both Allosaurus fragilis and Allosaurus jimmadseni in your collection?  I intend to have a figure of both in my collection.

[MLMjp]

This isn't really a "new species", I have heard the A. jimmadseni name for quite a while. This is basically making it into an actual valid species, instead of a proposed species like it was before.

[Halichoeres]

I think the Toyway Allosaurus would also represent A. jimmadseni, right? http://dinotoyblog.com/2016/09/22/allosaurus-walking-with-dinosaurs-by-toyway/

This isn't really a "new species", I have heard the A. jimmadseni name for quite a while. This is basically making it into an actual valid species, instead of a proposed species like it was before.

Yes, that's right, that's why I put "new" in quotes. It's been known for a long time, it just wasn't formally described and named. Still, all future citations of this name will say "Allosaurus jimmadseni, Chure & Loewen 2020"

@Halichoeres, are you going to have a figure of both Allosaurus fragilis and Allosaurus jimmadseni in your collection?  I intend to have a figure of both in my collection.

@Sim Hmm, I'm not sure. It seems like it would be easy enough by adding the new CollectA. That said, I already have a pretty bad case of theropod fatigue...

[Funk]

I think the Toyway Allosaurus would also represent A. jimmadseni, right? http://dinotoyblog.com/2016/09/22/allosaurus-walking-with-dinosaurs-by-toyway/

Looks like a botched ''fragilis''; note the sharp downwards angle of the jugal bone in relation to the maxilla, whereas in ''jimmadseni'' its lower margin is almost straight continuously from the lower margin of the maxilla, which is one of its diagnostic features.


From the paper: "In particular, whereas the ventral margin of the jugal of Allosaurus fragilis has pronounced sigmoidal convexity, the ventral margin is virtually straight in Allosaurus jimmadseni." https://peerj.com/articles/7803

[Halichoeres]

@Funk, for sure, I wasn't going based on the actual anatomy, only that the species that "Big Al" ought to pertain to is A. jimmadseni.

[Funk]

Oh yeah, the WWD Big Al is certainly jimmadseni, but the "regular" WWD episode Allosaurus was very different, in for example incorrectly having the horns directly above the eyes instead of in front of them and no ridges along the nasals. So it looks like the Toyway figure is based on the episode Allosaurus rather than the Big Al special version.

WWD episode:

Big Al special:

[Dinoguy2]

Interestingly, the original Carnegie Allosuarus looks more like fragilis (boxy skull, slightly downturned jugal) while the resculpted 1995 version looks like it may have been based more on the skull of Big Al 1 (narrower snout, no downturn or even an upturn in the jugal).

[HD-man]

I'm surprised no 1 else has mentioned the best part of A.jimmadseni being described: Atuchin's illustration.

[ITdactyl]

So sleek, it's so easy to miss the peach fuzz.

[Shonisaurus]

Magnificent allosaurus jimmadseni. I really like Andrey Atuchin because his paleoartistic works are very finished and are superrealistic.

[Sim]

For me the best part of Allosaurus jimmadseni being described is it being named and described.

[SidB]

Remarkable how our minds have such a passion for order and categorization.

[Nanuqsaurus]

A few days ago I was at the Museum of Natural Sciences in Brussels, and they have a spectacular looking Allosaurus named Arkhane there. Seems to be a pretty recently set up exhibit too. The signs mentioned this is a new species of Allosaurus, but I couldn't really find out if Arkhane is A. jimmadseni or an yet another new species. Does anyone have info on that?