Monthly Archives: December 2023

Gulo: Reconstructing the Most Ferocious Predator of the North

Arctoidea, Mustelidae

A medium dog-sized carnivore that is able to take down on its own ungulates, survives the harshest winters far north and does not hibernate..

Well, there is an actual animal like that, the wolverine (Gulo gulo).

Wild wolverine in Finland. Image: pixabay

The wolverine is a great example of an opportunistic predator and scavenger. It will feast on anything it stubles on, taking huge advantage of any opportunity given..  While most of the time it’s looking for smaller prey and carrion, it can take down ungulates much larger than itself such as reindeer. It’s also a scavenger, with a very acute sense of smell, capable of detecting carcasses covered up by snow with great accuracy.

With frost and water resistant fur and paws of very large size, that help them to stay on top of deep snow, its anatomy is greatly adjusted to the conditions of arctic and boreal forests.

Its lifestyle and habits are reflected in the skull and dentition. When compared to their closest relatives, it posseses enormously enlarged carnassials (P4 and m1) to crush bones and also, the upper molars are rotated in 90° angle which enables them to tear off frozen solid meat. Overall, the skull looks like that of an absolutely formidable predator.

Image:http://digimorph.org/specimens/Gulo_gulo/female/

The wolverine is a member of Mustelidae, that means that it’s basically a giant marten or a weasel rather than a small bear. The members of the weasel family are known to have absolutely enormous capabilities relatively for their body size, which is only confirmed in this species.

To look a little bit at its background and history, among mustelids, the wolverine is most closely related to martens (Martes) and fisher (Pekania). Together forming the subfamily Guloninae. To whose of these is the wolverine more closely related isn’t 100% sure. It’s likely that their common ancestor looked similar to the fisher Pekania occulta.

The wolverine might have evolved from a fisher-like ancestor. Image: https://www.eopugetsound.org/articles/fisher-pekania-pennanti Photo by: Jessica Hoffman

I had the idea of reconstructing some of its ancestors, or closely related extinct species. What came to my interest, is this fragment of the lower jaw of the ancestor of wolverine, being classified in its own species Gulo schlosseri, from Żabia cave in Poland.

Image:https://www.researchgate.net/publication/259810350_Early_Pleistocene_fauna_and_sediments_of_the_Zabia_Cave

To highlight the proportions and life appearance of this animal with the best possible accuracy, I combined this material with skeleton of modern wolverine, which gave me a good base for my drawing.

With a decent “strolling” pose and proportions, the muscles were added very roughly. I chose it yawning, to show its stunning hypercarnivorous dentition mentioned above. 

Since the animal, in life would be all covered in fur, no muscular anatomy would be visible. This has made the job a bit easier. Here’s the outline of it.

Then, the details…

And finally, coloration. Althought color variations in individual wolverines can be suprisingly variable, for this one, I chose more darkly-toned individual. Perhaps, all these populations were darkly colored because of their shared ancestry with the fishers (Pekania)? This is a matter of speculation :).

Here we have it. The reconstruction of Gulo schlosseri, an ancestral wolverine from Early Pleistocene. Acting more or less like its living descendants, it surely would have been an amazing experience encountering one of these in their natural habitat.

References:

Devinophoca: Miocene Seal from Slovakia

Arctoidea, Phocidae, Pinnipedia

Believe it or not, during the early Middle Miocene (here, I focus on roughly 16-14 million years ago, but overall it was for a longer period of time), large parts of Slovakia and Eastern Europe were covered by a massive sea called the Paratethys, with Carpathian mountains being just an archipelago within this massive inland water body!

It was in this setting, where numerous fossils of small-sized earless seals (Phocidae) were discovered. In the outskirts of Bratislava, near the peak of Devínska Kobyla, two species of one of these seals were described. Devinophoca claytoni and D. emryi. Together forming a now completely extinct subfamily Devinophocinae that possessed mixed characteristics with the other extant subfamilies of seals.

The holotype skull of Devinophoca emryi, picture from the study: https://riviste.unimi.it/index.php/RIPS/article/download/6399/6445/0

Here is shown my reconstruction of D. emryi. It was a seal of rather small size, being close to the Baikal seal. The missing parts of the skeleton and the general appearance is based on bunch of other extant seals such as Phoca, Pusa, Monachus and Neomonachus.

The reconstruction of Devinophoca emryi (skull lenght 11.95 cm)

Althought, it would look a lot like its modern counterparts, D. emryi possesed proportionally smaller skull and longer flippers. The latter might have been an unsuccessful evolutionary adaptadion that led to the eventual demise of this group. It has been suggested that Devinophoca might actually represent a very primitive relict of the common ancestors of other phocid seal species. That would mean that this is how we can imagine some of the first earless seals to look like. It lived in a tropical -subtropical environment of transitional shallow marine waters with coral-reef zones.

A sketch showing a pair of Devinophoca emryi in the Slovakian Central Paratethys.

Seals of the subfamily Phocinae can be divided into 5 exact groups based on morphology and ecology. (Representatives of other subfamilies can also be assigned, but its group can differ based on what criteria are used, as in Medditerrean monk seal (Monachus monachus)). Our seal, Devinophoca emryi, althought not belonging to Phocinae, based on morphology alone, falls exactly into the group 3. It’s reasonable to speculate that it was a bottom feeding seal, preying mostly on invertebrates such as mollusks, crabs, shrimp, amphipods and also fish.

The still-living Ribbon seal also falls into the ecomorphological group 3. Image: Michael Cameron
Devinophoca lived in a tropical-subtropical environment, similar to that of Hawaiian monk seal. Image: Kent Backman

Both species D. emryi and D. claytoni fall into different ecomorphological groups, therefore it is totally possible that they coexisted without any competition and niche overlap (for example hunting in different depths) as it’s also seen in some modern seals.

There is so much that could be additionally said, but for now, my time is up. Hoping to get back to this!

References:

The “Wolf-Like” Dog Skull that I Found

Canidae
The skull in lateral and ventral view (scale bar 10 mm)
The orbital angle

Some time ago, in a forest near one village in Slovakia, I’ve found this skull. After looking at it for a bit, and drawing it, I suppose, that it most likely belongs to a dog, with a wolf-like head, perhaps a german shepherd, wolfdog, some northern breed or a mongrel of them… But not totally excluding the posibility of a wolf.

The lenght of the skull is a little smaller (21,1 cm) than that, what I found to be the average for the wolf as a species (23 – 28 cm), althought I’m not aware of the local wolves’ average sizes. The individual was already mature and probably not the youngest, since the teeth (P4, M1, M2) show large wear.

One characteristic commonly used to distinguish between wolves and the first domesticated dogs, is the orbital angle (shown in the picture above). The sharper the angle is the more “wolf-like” the head becomes. Some disagreement exists however, because apparently it’s a very variable feature, that must be taken with a grain of salt. I applied it to my skull, and it falls within the lower edge of a domesticated dog standards and higher edge of wolf’s.

As this is a very quick overview, and I’m an amateur on Canis skull morphology, feel free to refer to anything I missed out on!

References: