Mounted specimen from American Museum of Natural History, and currently part of the traveling Extreme Mammals exhibit.
Reconstruction by Charles Knight
When: Eocene (~49 to 39 million years ago)
Where: North America
What:Uintatherium is one of the first large mammalian herbivores. It stood about 6 feet (~1.8 meters) high at the shoulder and was roughly 13 feet (~4 meters) long. This isn't that large for an animal today, but in the Eocene it was a giant! It lived in the lush sub-tropical forests of mid-Eocene North America, most likely eating a combination of terrestrial bushes and shrubs along with aquatic plants from lakes and marshes. Uintatherium has a nasty pair of upper canines, not what you would expect from a herbivore! It is thought that these teeth were involved in sexual display, as they appear to be much larger in males than females. Uintatherium vanishes from the fossil record in the late Eocene, at about the time the temperature of North America was falling and the vegetation was thinning out.
Uintatherium was also one of the fossils involved in the great ‘Bone Wars’ between Cope and Marsh. It was by far the largest of the fossils to come out of the Fort Bridger fossil localities in Wyoming (this fort gives its name to a land mammal age - The Bridgerian!), and thus highly prized. Cope and Marsh both applied multiple names to specimens from this region which would later prove to all belong to the same species. The name Uintatherium wasn’t even one applied by Cope OR Marsh. Joseph Leidy named this creature in 1872, just barely edging out Marsh’s names of Dinoceras and Tinoceras. So that particular battle in the bone wars was won by someone who didn’t even have much of an interesting in fighting!
Uintatherium is not thought to have any living descendants, it is possible that the Eocene Uintatherium was the last of its kin. However, the position of Uintatherium and its brethren (grouped as the Dinocerata) within the mammal family tree is highly uncertain. They are well accepted as placental mammals, but beyond that? It is highly debated, and in my opinion, nobody has really done a rigorous enough study to support any one position over another.
When: Late Eocene to Mid Oligocene (~38 to 27 million years ago)
Where: North America
What:Palaeolagus is a fossil lagomorph. Lagomorpha is an order of mammals, that contains rabbits, hares, and pikas. Within the bunny-order rabbits and hares are more closely related to either other than either is to the pikas. If you are not familiar with pikas go check out some pictures! They are really cute little guys that resemble guinea pigs more than they do rabbits, but they are most assuredly lagomorphs. Palaeolagus falls outside all living lagomorphs in their evolutionary lineage. It can be thought of as representative of the common ancestor of all living lagomorphs.
Palaeolagus lived in North America in the late Eocene, after the dense forests had left and the grasslands of the plains started to expand. This 10 inch (~25 cm) long herbivore spread throughout the continent during the Oligocene as the grasslands grew. Palaeolagus could not hop, its hind legs show none of the features that make a hopping locomotion style possible in living rabbits.This ancient bunny is known from a large amount of fossil specimens, some of which are almost complete skeletons, but most are fragmentary pieces of bone or teeth. Most of these Palaeolagus specimens likely met their end as the lunch of one of the many predators roaming the grass lands of prehistoric North America.
Mounted specimen on display at the American Museum of Natural History, NYC
Reconstruction by Jay Matternes
When: Late Paleocene to Early Eocene (~ 61 - 55 millon years ago)
Where: North America and Europe
What:Plesiadapis is a small tree-dwelling mammal that was fairly comment in the late Paleocene of North America and Europe. This ancient mammalian taxon was about the size of a house cat, and though it may look very reminiscent of a squirrel it is a member of the primate family, as part of the larger group Plesiadapiformes. The latest research has shown that Plesiadapis was actually atypical for its namesake clade; this genus tended to be much larger than the average plesiadapiform and was not as well adapted for climbing as its smaller relatives, lacking a hand specially adapted for grasping. Plesiadapis could climb trees, but it would have been an arboreal quadruped, like the living squirrels, rather than a grasping locmotion as seen in most primates today. Another features reminiscent of rodents in Plesiadapis (and this is found in most of its kin) is its enlarged front teeth and the reduction or loss of teeth between these massive incisors and the grinding cheek teeth. Plesiadapis has been reconstructed as a frugivore - meaning its diet was primarily comprised of fruit. As much of North America and Europe was covered with lush sub-tropical forests during its range, Plesiadapis would have had quite a large selection of fruits to feed on.
The placement of Plesiadapiformes has been somewhat controversial in the past decade or so. There is uniform agreement that these animals fall somewhere near the group Euarchonta within placental mammals, but exactly where has been much debated. Euarchonta contains not only primates, but also the Scandentia (tree shrews) and Dermoptera (flying lemurs). Some early studies placed plesiadapiforms closer to the dermopterans than primates, but more recent studies tend to find this clade as either the first branches to spring off the primate lineage or just outside of Euarchonta itself, as stem taxa to all three orders. One last point to make things even more confusing! The group Plesiadapiformes? It is probably not a monophyletic (natural) group in reality. It is looking more and more like that some taxa previously grouped within Plesiadapiformes fall closer to living primates than to other taxa within the group.
To sum up that confusing mess, Plesiadapiformes are very important in understanding primate evolution, as at least some members of this assemblage of taxa are the first animals on the primate lineage. As this lineage includes me and you there is a lot of study focused on this group right now! Nice to see animals that are primarily paleocene taxa finally getting some attention.
Europolemur build for @naturhistorisches_museum_mainz. Many thanks for its deep confidence in us. Never enough gratitude with them. #europolemur #lemur #mainz #messel #eocene #darwinius #urlemur #ida (at Naturhistorisches Museum Mainz) https://www.instagram.com/p/CeLsguRqMtD/?igshid=NGJjMDIxMWI=
Metamynodon’s day is spent in leisure. Wallowing, feeding, sighing. A breeze rattles the reeds and chills the spots where its hide is wet with mud, so it sinks deeper, hides from the wind in the bog, and lets the mud squish between its toes and clog its armpits and nether regions. It breaks wind, flips its tail, watches the water slosh over the mud, its reflection rolling on ripples more active than the beast itself. Life could no be better.
Two metres long and about as tall as pig, Pezosiren is a basal sirenian from Jamaica. It was found in a lagoonal or estuarine deposit, and although it was likely in the water much of the time, it was still capable of supporting itself and walking on land.
When fossils of Basilosaurus were first discovered, it was thought to have been a marine reptile, hence its name meaning King’s Lizard. It was later correctly classified as an early whale.
Fun Fact: It is known that Ambulocetus was an early ancestor of whales because its teeth, ear bones, and nostrils are similar to those of later cetaceans.
Freaky Fish! Monte Bolca is a fossil site in Italy that contains the world’s first known coral reef community. We have a full line of beachwear featuring the funky fish from the Eocene.
The next set of Animals for @huxley-paleozoo;Leptictidium auderiense,Pholidocercus hassiacus,Darwinius massilae, and Kopidodon macrognathus, all mammals from the Early-to-Middle Eocene, known from the Messel Pit of Germany.
Welcome back to the Mammal Zone™, we’re gonna be talking about a round friend named Moeritherium. It looks kind of like a hippo, kind of like a tapir, but isn’t closely related to either.
The Eocene was a very different time from now. The earth, almost done recovering from the Cretaceous extinction, was much warmer. Animals were starting to get big again, and many well-known branches of mammals started diverging, like whales and dogs. There was likely no ice at either pole, and much of the earth was covered in sprawling forests. Moeritheriumlazed around in rivers and lakes in Egypt, feeding on soft underwater plants, if its teeth are to be believed. And teeth can tell us a lot.
Moeritheriumis an early member of the order Proboscidea, which is represented today only by elephants.It most likely had a short trunk, probably used for gripping food, not for snorkeling, sadly. It had two elongated incisors in its upper jaw, which betray its cousinship with elephants. It was only a little over 2 feet tall at the shoulder, too. Isn’t it cute?
Even though it’s commonly used as an example of the first elephant, it wasn’t directly ancestral to elephants, probably belonging to a branch of proboscids that died out long ago. Even though they have a definite resemblance, Moeritherium’sshort legs and hippo-like lifestyle probably point to a group of animals that evolved in a very different direction. In fact, they lived at roughly the same time as a more likely candidate for elephant ancestry, Phiomia.
Moeritheriumwas featured in the second episode of BBC’s Walking with Beasts, where a group of them mostly just hangs out and eats. I liked Moeritheriumas a kid because I thought it looked funny. Of course, I was told that it was the precursor to elephants (until I went to Christian school and was told that nothing was the precursor to anything). No matter how closely related to elephants it is, I just think it’s neat.
Horses, the vigilant eyes of an angry God. I think most people are familiar with horses and their journey to becoming our third best friend, and Mesohippus is plucked right from the earlier acts of that transformation.
Mesohippuslived, along with many horse ancestors, in North America. It was about two feet tall. It was still far from becoming a grassland animal. Its teeth were still designed for eating twigs and fruit. But, it shows a few important steps towards modern horse anatomy. Firstly, its snout was becoming more narrow. Its brain was larger than its forebears too, and was probably very similar to a modern horse’s. It was leaner, starting to develop that aerodynamic horse skeleton.
Its legs are longer than those of of its ancestors, and it now has three toes instead of four, with only the middle toe bearing the weight of its body. Eventually, that middle toe would go on to be its only toe, the ‘fingernail’ of which becoming the hoof. The genes for extra toes still exist in horses, and sometimes they’re born with an extra toe that looks pretty similar to Mesohippus’.
This was probably around the point when horses started running as a survival tactic. Eocene North America was also home to Hyaenodonts and Nimravids, which probably ate Mesohippusif they could catch it. Not to mention various species of flightless bird (Gastornis was a herbivore, as we talked about before, but there were other flightless birds in the early Cenozoic that absolutely ate horses). Obviously, this pressure from fast predators was helpful when humans needed to go places faster.
I wasn’t sure which horse I wanted to talk about today (because for some reason, I said I’d do a horse). I went through a few. I didn’t want to do EohippusorPropalaeotherium, because I don’t think there’s anything new I could say about them. So I went forward in time a little bit and got to know Mesohippus. It’s a neat little animal, and an interesting transition between the short, chubby horses of the early Eocene and the towering, omnipotent grass annihilators we know and righteously fear today.
Bluuughhhhhhh. I forgot the clocks were going to move forward last weekend, and my schedule is completely off-kilter. But after slamming most of a big cup of coffee, I’m here to talk about a really cool whale. The Eocene was a great time to be a mammal. After taking their first shaky steps into the limelight during the Paleocene, mammals took over the world in the Eocene. Whales were among the most immediately successful groups, and Basilosaurus was one of the earliest whales fully adapted for marine life. It had a fusiform body and a powerful fluked tail, with its forelimbs adapted into flippers. They ranged in size from 15-20 meters, making them not only one of the earliest large whales, but possibly the largest animal in the Paleogene period.
It’s no secret that I love taxonomy, so let’s talk about it!
There are two species of Basilosaurus: The type species, B. cetoides and the slightly smaller B. isis. ‘Basilosaurus’ means ‘King Lizard,’ which is weird because, you know, it’s a whale. It’s called that because its discoverers thought it was some kind of sea serpent thanks to its weird body proportions. After the realization it was a whale, the name Zeuglodon was suggested as a replacement. However, since Basilosaurus was the first name given, it had priority, and Zeuglodonbecame a junior synonym. It gets wackier. Another junior synonym is Alabamornis.This means ‘bird from Alabama,’ and was given to what was thought to be a big bird’s shoulder bone in 1906, but was actually a pelvis of Basilosaurus. And on the less scientific side of things, in 1845, Dr. Albert Koch unveiled the skeleton of a giant sea serpent he called “Hydrarchos,” which would have been really cool if it wasn’t really fake. It was probably two Basilosaurusskeletons stuck together, but we don’t know for certain because it was destroyed in 1871 by the great Chicago fire.
Despite looking like a modern whale in many respects, Basilosaurus was still weird. Compared to modern predatory whales, it has a proportionally longer body and neck. Its head was smaller, with no room for a melon (the adorable name for the hearing organ toothed whales have in their foreheads). It had a smaller brain too, and probably wasn’t as social or intelligent as say, an orca. Its flippers also had a functioning elbow joint, like sea lions. It was probably best at swimming in two dimensions near the water’s surface, rather than diving.
Perhaps the strangest thing, though, is its pair of tiny hind limbs and pelvis disconnected from the vertebral column. Some whales today have tiny, vestigial hind limbs, but they’re reduced to a few useless bones hidden beneath the skin. Basilosaurus’back legs were recognizable as such, and were used for… something. Maybe holding onto each other while mating, almost certainly not for biking.
This animal was widespread throughout the Tethys sea, the ancient waterway between Gondwana and Laurasia in the Mesozoic. As Africa and Eurasia moved toward each other, it was beginning to split in the Eocene, but it still covered swaths of land in shallow, warm sea. The two species of Basilosaurus have different teeth, and probably fed on different prey. B. cetoides typically ate large fish and sharks. B. isis, though, is known to eat Dorudon, a smaller basilosaurid whale. Specimens of Dorudon have been found with bite marks in the skull, attributed to Basilosaurus, and the damage done to the skeletons around it suggest B. isis hunted by delivering a fatal wound to the head before tearing the body apart with its jaws, which sounds metal as hell.
Basilosaurus has always been a favorite mammal of mine. It has a certain elegance and beauty I’ve always admired, the first of the cetacean giants. Although I’m not a particularly religious or spiritual person, there’s something magical about seeing such a huge animal swimming in open waters. I hope I captured some that mystified feeling with this drawing. I first saw Basilosaurusin the second episode of Walking with Beasts, wherein a pregnant B. isis has to find food at the beginning of a climate crisis. WWBconstitutes a good 70% of my Cenozoic knowledge. It probably won’t be long before I’ve drawn every mammal featured in it, and I swear I’m not doing that on purpose. Mammals aren’t really my strong suit, especially not whales, but I had a lot of fun drawing this. And part of the point of this blog is to teach myself about groups I otherwise don’t really study, so I guess you could say I did a good job of that.
