While the enigmatic Andrewsarchus is a fairly popular prehistoric mammal, much of the identity of this animal remains a mystery.

It is only known from a single skull, though from that it can at least be gathered that it was an artiodactyl (hooved mammal.) One study places Andrewsarchus in Cetancodontamorpha, the clade which includes whales, hippos, and entelodonts, while classically it was placed with the more wolf-like Mesonychians. Like entelodonts, they were probably omnivorous, but seemed to lean more towards predation or scavenging carcasses than digging for roots. Since we only have one massive (three foot long!) skull, it can’t be said for sure, but depending on how its body was built Andrewsarchus could have been the largest predatory land mammal of all time.

It lived in Inner Mongolia during the Eocene, and while Basilosaurus was ruling the seas, it was busy ruling the land.

Daeodon shoshonensis was an entelodont, which are commonly called “Hell Pigs” or “Terminator Pigs,” but are actually closer related to hippos and whales than pigs.

Daeodon shoshonensis was the largest entelodont at almost 7 feet at the shoulder. While they had large tusks and strong incisors, they were most likely omnivores like modern pigs, eating tough roots, nuts, bark, fungi, and carrion. Their jaws could open unusually wide, a feature seen in their hippo relatives, so they may have similarly used their gape to intimidate rivals and jaw-wrestle. The large bony growths on the skull seem to vary between individuals, so it’s speculated that only males may have had the impressive “cheekbones” to protect their faces during sparring matches.

Daeodon lived in Miocene Nebraska, USA, in a floodplain environment, alongside camels, chalicothere, bear-dogs, land beavers, and small rhinoceroses.

(You also may know Daeodon as the terrifying face peering through a peephole in a certain meme)

And one more whale, the freakishly long Basilosaurus cetoides. One of the top predators, if not THE top predator, of the Tethys Sea, Basilosaurus was the largest animal in the Paleogene at up to 66 feet long. It preyed on sharks, marine mammals, large fish, and other cetaceans like Dorudon.

Finally continuing my simplistic synapsid series and starting on mammals. School is intense right now and I’m trying to nail down a schedule that allows me to get everything done yet still have some free time. So yeah I’ll still be working on these, but won’t be able to come up with new ones as often as I was before.

Anyway, with that out of the way, here is Ambulocetus natans!

Ambulocetus was one of the first cetaceans (whales) to take to the water, living a semi-aquatic lifestyle similar to otters or crocodiles. These sea lion-sized ungulates lived in modern day India, which used to be a tropical island before colliding with the rest of Asia. They lived in coastal brackish mangrove swamps alongside sharks, turtles, crocodiles, and other early cetaceans like Pakicetus.

Well, I’ve already posted this on Instagram before I started on the non-mammals, so I guess we’ll start my mammal series with Aenocyon dirus, the Dire Wolf!

In case you haven’t heard yet, some Dire Wolf DNA was able to be examined and it was found that Dire Wolves are actually not just larger, bulkier gray wolves… in fact they’re not even wolves at all! They belong to their own genus, Aenocyon, and would have probably looked like older species of dog and been more suited for temperate climates rather than tundra.

For this one in particular, I combined coloration of bush dogs, jackals, African wild dogs, and maned wolves. Though it sorta ended up looking like a long-legged wolverine. 😅

And that’s it for my first venture into non-mammalian synapsids! Here’s a size chart with all of the ones I’ve drawn now. As usual please take it with a grain of salt as I just kinda eyeballed their general sizes from other size charts.

This was really fun; I’d never drawn any of these species before and it was fun to kinda learn as I went along. I’ll be putting some of these up as stickers on Redbubble btw, and since I actually drew them a bit larger than usual this time, maybe I’ll venture into some other products as well. ¯\_(ツ)_/¯

Anyway, my next project is mammalian synapsids, so we’re not venturing back into dinosaur land quite yet!

Therocephalians were a group of synapsids closely related to the cynodonts: the ancestors of mammals. While they looked somewhat similar to gorgonopsids, they were a bit more advanced, and more diverse.

Pristerognathus vanderbyli was a dog-sized therocephalian from the woodlands of middle Permian South Africa. It had a long, narrow skull with saber teeth and likely preyed on smaller synapsids and reptiles.

Lycaenops ornatus was a fox-sized gorgonopsid from the mid to late Permian South Africa. Like all gorgonopsids, Lycaenops had saber teeth in powerful jaws, which it used to pierce and tear through flesh. It likely hunted small reptiles and dicynodonts.

Gorgonopsids were cat-like, saber-toothed synapsids from the late Permian, and Inostrancevia were the largest of them.

Here I’ve drawn the Russian Inostrancevia alexandri, which was about as large as a grizzly bear and no doubt the apex predator of its environment. Gorgonopsids had very flexible jaws, and could have opened their mouths at a 90° angle if necessary.

Like Dimetrodon, Secondontosaurus was another sail-backed Sphenacodontid from early Permian Texas. Unlike Dimetrodon, it had long slender jaws, which seemed to have been specialized for catching fish or poking into burrows. Also unlike dimetrodon, Secondontosaurus seems to have been pretty rare, and as its fossils are rarely found I didn’t have much information to go off of! But I wanted to include just one more “sail back” and I think Secondontosaurus is a pretty unique one.

Arguably the most famous non-mammalian synapsid is Dimetrodon. There are over a dozen species of Dimetrodon, and for my first one I’ve chosen D. grandis. (mostly just due to the fact that there was a skeletal readily available.)

Famous for its tall spine, Dimetrodon is often confused for a dinosaur and seen as a contemporary, though it lived long before dinosaurs existed. As a synapsid, it is more closely related (though not a direct ancestor) to mammals than reptiles. Larger species would have probably been the apex predators of their environments, while smaller species would have filled different niches.

Dimetrodon grandis was the second largest species of Dimetrodon, and had serrated teeth specialized in slicing through flesh. It lived in early Permian Texas.

Because I APPARENTLY want to suffer I’ve chosen four different sail-backed synapsids to include in this series. The first is Edaphosaurus, specifically Edaphosaurus cruciger.

Edaphosaurus is one of the earliest known large herbivorous tetrapods (four-limbed land vertebrates.) A number of synapsids from the early Permian had similar bony sails on their backs, but Edaphosaurus was unique in that it had supportive cross-bars on the spines, and little spikes possibly sticking out on either side (this could have also been covered by skin.) It had a small, triangular head, with muscular jaws fit for cropping away at tough plants.

My next synapsid is another dinocephalian, this time the bizarre Moschops capensis. These things were about the size of a large pony. With a huge, barrel-shaped body, muscular neck, and hard, domed skull, they likely used their thick heads for head-butting. Their teeth and large guts indicate they were grazers, and it’s speculated they may have been semi-aquatic, like a hippopotamus. Their elbow joints were also more flexible than many other dinocephalians, allowing them to move and bend their legs in a more mammal-like manner, possibly to make moving their thicc bodies around a little easier.

(Btw It’s really hard to make something that looks like a Star Wars alien mixed with Patrick Stewart seem like a real animal.)

My next non-mammalian synapsid is the absolutely unnerving dinocephalian Estemmenosuchus. There were at least two species of Estemmenosuchus, the hippopotamus sized E. uralensis, and the lion-sized E. mirabilis. (I’ve drawn the smaller mirabilis here, as it has more impressive headgear.) Though they boasted some scary tusks, they were likely omnivorous or herbivorous, probably filling a similar niche to a wild boar or hippopotamus.

I wanted to do one more dicynodont to show just how diverse these guys were. Yes I could have done Diictodon… but instead I chose Bulbasaurus phylloxyron. Did I choose it just for that name? Maybe.

Apparently, Bulbasaurus was not originally named after the Pokémon bulbasaur, but rather for the “bulbous” headgear on its nose. However, its describers have admitted that its name and similarity to the Pokémon “may not be entirely coincidental.”

Also, “phylloxyron” means Razor Leaf. Apparently also maybe possibly a coincidence as it relates to its leaf-cutting beak. But I think we all know paleontologists are a bunch of nerds, so…

The largest dicynodont species (that we know of) was Lisowicia bojani. Found in Poland and hailing from the Late Triassic, it was about the size of an Asian elephant and estimated to have weighed between 5 and 6 tons. Rather than tusks, it had these weird bony protrusions on either side of its face. It was even more unique in that it stood in an erect posture, rather than with its legs sprawled to the side like other dicynodonts, probably due to its weight. It may have been a high-browsing competitor to early sauropodomorphs, and was preyed upon by the mysterious predatory archosaur Smok.

My next three non-mammalian synapsids will be dicynodonts. Surviving the great Permian extinction into the Triassic, dicynodonts basically ruled the world for a time. There are over 70 genera known, ranging from rat sized to elephant sized, and filling in every herbivorous niche. However, only four groups survived the Great Dying. Of these genera, Lystrosaurus was the most widespread, with many different species covering most of the Southern Hemisphere. At one point in the early Triassic, one species of Lystrosaurus made up 95% of all land vertebrates! Imagine going for a walk outside and every land animal you see is a tusked, beaked, lizard pig.

This one species is Lystrosaurus curvatus, which I chose for its weird, flat face (and easy access of reference material.) L. curvatus wasn’t as specialized as other Lystrosaurs, and was thus able to live in a wide variety of environments, burrowing and hibernating in colder climates, and surviving much longer into the Triassic than most other dicynodonts.

My next non-mammalian synapsid (we really gotta come up with a better name ya’ll) is Cynognathus crateronotus. Cynognathus was a cynodont, a clade with a large variety of animals, all of which have gone extinct except one group: mammals.

Cynognathus was a wolverine-sized predator with a large distribution across the Southern Hemisphere; and it looked very mammalian. Paleontologists believe Cynognathus had hair, whiskers, warm blood, and even the ability to give live birth, long before its mammalian cousins did.

(I’m going to be drawing some Non-mammalian synapsids in my usual simplified “Archovember” style, just to maintain it and also so when November comes around again it doesn’t take all my followers on Instagram by surprise when my feed suddenly becomes all dinosaur all the time. 😅)

For my first Non-mammalian synapsid, I chose Cotylorhynchus, specifically Cotylorhynchus hancocki, the Big One. (Yea this is the first non-mammalian synapsid I’ve drawn. Ever. I’ve never even drawn dimetrodon) I had to draw Cotylorhynchus because it just makes me laugh every time I’m reminded of its existence. It’s so ridiculous.

The whiskers are of course speculative but I was going with a walrus approach. Every reconstruction of Cotylorhynchus I’ve seen looks like that one first taxidermy of a walrus where the taxidermist didn’t know they were supposed to have wrinkles and smoothed the skin out. So I made him a bit wrinkly and gave him whiskers just to drive the point home. Still looks like an awful pile of flesh but, hey, that’s Cotylorhynchus.

I wanted to draw some of the recently described dinosaurs in my Archovember style since they weren’t released when I did Archovember and I probably won’t be adding them to next year’s list but I still thought they were cool enough to make some art of them (and stickers)

First is the enantiornithine bird Falcatakely forsterae, a tiny lil bird from Cretaceous Madagascar with a big ol beak. I started off making it look like a pied crow, then realized that the skull would have only been 3 inches long, so I made it much slimmer and gave it some more “small jungle bird” type colors.

Second is Ubirajara jubatus, a small compsognathid that was (illegally) smuggled out of Brazil in 1995 and was just recently finally published. It was interesting because it had at least two long, stiff filamentous structures coming from its shoulders, similar to the Standardwing bird-of-paradise. It also had a mane of fuzzy proto-feathers running along it’s back. These features probably would normally lay flat against the animal and be puffed out only for display.

Ubirajara is also the subject of much debate, as the nature of its removal from Brazil was shady at best and, since 1990, it has remained illegal to remove any Brazilian fossils from Brazil, and to not have at least one Brazilian paleontologist on the team when assessing the fossil. The authors of the paper on Ubirajara, specifically David Martill, have scoffed at these laws and made some bordering-on-racist comments in their refusal to return the fossil.