Wednesday, November 22, 2017

An Aelurodon of My Own

Aelurodon ferox chasing Neohipparion, by Mauricio Anton
You know, I never blogged about my SVP 2017 experience, more out of sloth than anything else. I can wrap up my thoughts with this sentence: it was fun but very lonely. For me, perhaps the most enjoyable part of the conference was the silent auction. I should have stayed for the following “real” auction because photos posted to social media afterward made it look insane, but I had a bunch of meds to do and an early start the next morning. I bid on several items in the silent auction, most of them 3D prints of interesting fossils, but I was quickly outbid past my own point of comfort for most of them. However, I was able to secure this nifty specimen:

Lateral view of MOR 1724 (cast).
That is a very nice cast of MOR 1724, the holotype of Aelurodon montanensis. I recognized the name at the time but couldn’t place it—I’d later realize that Aelurodon is a multi-species genus of borophagine dog. Borophagines are really cool; I learned about them in the excellent book Dogs: Their Fossil Relatives and Evolutionary History by Wang & Tedford (2010) with gorgeous illustrations by Mauricio Anton.

Medial view of MOR 1724 (cast)
Borophagines were the canid versions of hyenas,* developing a hypercarnivorous diet and bone-crunching molars, although never to the same extent as modern hyenas. They never got all that big; Epicyon was five feet long and it is one of the largest canids. Meanwhile, Borophagus, the mostly solidly-built borophagine, was only the size of a coyote. However, they were powerfully built, with especially strong necks and large heads. As the group became better-adapted at bone-crunching, the heads changed shape: the forehead became more prominent and the snout shortened. Aelurodon falls somewhere between a typical canid (like a wolf) and Borophageus, which had the most bone-crushing adaptations.

There are many species of Aelurodon, which appear to have two subgroups within the genus: an A. taxoides species group and an A. saevus species group. I don’t know enough about this animal to tell you what the difference is, but that’s not why I’m writing this blog post.

Note there is no medial view of the upper jaw fragment.
This cast has been sitting in my office ever since. Well, just yesterday, while falling into a Wikipedia hole, I came across Wang et al.(2004), which describes my specimen! It is the holotype of a new species, A. montanensis, and is the only representation of the genus in Montana. However, I was surprised to find that, while my lower jaw fragment matches the photos in the description, my upper jaw fragment differs considerably, as if my cast has a lot more bone connecting the teeth than the specimen as figured in the paper. In particular, there is a chunk of bone holding the canine in place with a distinct foramina on the lateral side. On the medial side, there seems to be a more or less continuous strip of bone going from the canine to the anterior half of P4. Additionally, my cast features a chunk of small chunk of bone surrounding the root of M1.

Was more material found than was figured in the description, perhaps later? It’s a bit of a puzzle, but I am very happy that my cast was actually described and that it represents a new species of Aelurodon. It’s inspiring me to learn more about borophagine dogs and in fact, I’ve downloaded this massive monograph (Wang, Tedford & Taylor, 1999) and I intend to at least skim the whole thing.

Quality casts and 3D prints of fossils are so important for education and outreach. I’ve said this before, but I’m stressing it again here. It’s one thing to read about a specimen and look at pretty photographs of it, but it’s another thing entirely to actually hold the thing and inspect it firsthand. Thank you to the Museum of the Rockies (I assume) for donating this excellent cast to the silent auction!

*But aren't hyenas a kind of dog? Turns out they're not! They're sitting neatly on the feline branch of the Carnivora. I know, I was surprised when I found this out, too.

1 comment:

  1. I wonder if your fossil assemblage is actually parts from two different discoveries? also; Hyenas are amazing all on thier own. damn near impossible to poison!!