ungulate – Nix Illustration

Aureia

Aureia rerehua was a toothed whale that lived during the late Oligocene and early Miocene, around 23-22 million years ago, in shallow coastal waters covering most of what is now Aotearoa New Zealand.

It was closely related to the waipatiids – a group traditionally classified as platanistoids (the South Asian river dolphin lineage), but more recently proposed as instead representing a separate earlier branch of the toothed whale evolutionary tree.

About 2m long (~6’6″), Aureia had distinctive tusk-like teeth that splayed outwards from its snout, interlocking when its mouth was closed. Along with a flexible neck and its fairly delicately-built skull and jaws, this suggests it was specialized for catching small prey in a “fish trap” of teeth, a unique feeding strategy for a toothed whale.

Along with different feeding specializations in other close relatives like Nihohae, Aureia shows us how multiple species of these ancient Aotearoan cetaceans were able to coexist in the same place and time by diversifying into different novel ecological niches.

Ninoziphius

Ninoziphius platyrostris was an early beaked whale that lived during the late Miocene (~6 million years ago) in warm coastal waters covering what is now southwestern Peru. Its ancestors appear to have branched off from all other beaked whales very early in the group’s history, indicating a “ghost lineage” going back to at least 17 million years ago.

About 4.4m long (~14’5″), it was less specialized for suction feeding and deep diving than modern beaked whales. Also unlike most modern species its jaws were lined with numerous interlocking teeth, with heavy wear suggesting it may have hunted close to the seafloor, where disturbed sand and grit would have regularly ended up in its mouth along with its prey and steadily ground down its teeth during its lifetime.

Males had a pair of stout tusks at the tip of their upward-curving lower jaw, with possibly a second smaller set of tusks behind them, which were probably used for fighting each other like in modern beaked whales.

Its shallow water habitat and more abrasive diet suggest Ninoziphius’ lifestyle was much more like modern dolphins than modern beaked whales, and other early beaked whales like Messapicetus similarly seem to have occupied dolphin-like ecological niches.

These dolphin-like forms disappeared around the same time that true dolphins began to diversify, possibly struggling to compete for the same food sources, while other beaked whales that had begun to specialize for deep sea diving survived and thrived. Interestingly this ecological shift seems to have happened twice, in two separate beaked whale lineages – although only one of them still survives today – with bizarre bony “internal antlers” even independently evolving in both groups.

Cadurcodon

Cadurcodon ardynensis was an odd-toed ungulate that lived in what is now Mongolia during the late Eocene, about 37-34 million years ago.

It was around 2m long (6’6″) and, despite its very tapir-like appearance and lack of horns, it was actually closer related to modern rhinoceroses – it was part of a group of early rhino-cousins known as amynodontids, which convergently evolved both hippo-like and tapir-like lifestyles.

Cadurcodon was the most tapir-like of the tapir-like amynodontids, with a short deep skull and retracted nasal bones that indicate it had a well-developed prehensile trunk. Males also had large tusks formed from their upper and lower canine teeth, which may have been used for fighting each other.

Spectember/Spectober 2023 #10: Tree Goat

An anonymous submitter asked for an “arboreal goat with grasping sloth-like claws”:

A shaded sketch of a speculative tree-climbing descendant of goats. It's a hairy sloth-like animal, clinging to a tree trunk with long chunky limbs that end in large hooked claw-like hooves. Its head is proportionally small, with fleshy giraffe-like lips, forward-facing eyes, and small stubby horns.

Cluraix cephalula is a distant descendant of feral goats in a tropical forest environment, representing a small tree-climbing offshoot of a specialized chalicothere-like lineage.

About 70cm long (~2’4″), it clambers around in the high tree canopies, with its forward-facing eyes providing good depth perception in this complex three-dimensional habitat. Its long hooked claw-hooves are used both to cling onto branches and to hook-and-pull clumps of foliage towards itself, stripping the leaves with its flexible fleshy lips.

Spectember 2023 #02: Carnivorous Ungulates

An anonymous submitter asked for a “derived carnivorous, pack-hunting agriochoerid“:

A shaded sketch of a speculative predatory early ungulate. It has a cat-like body, long and low-slung with clawed feet and a long slender tail. Its head looks like a mix between a cat and a camel, with a fleshy cleft lip, forward-facing eyes, leaf-shaped ears, and a mouth full of sharp pointy teeth. It's depicted in two poses: on the left climbing up a tree trunk, and on the right standing and baring its fangs.

Felichoerus ochlos is fairly similar-looking to its herbivorous relatives, but this cat-sized agriochoerid comes from a lineage that initially specialized in eating fleshy fruits – and then shifted towards eating actual flesh.

With its long cat-like body, forward-facing eyes, clawed digits, and flexible limbs, it’s a capable tree climber. Groups of this animal practice cooperative hunting, with one member chasing arboreal prey down to the ground for the rest to mob.

And another anon wanted to see an “obligate carnivore bovine”:

(I see what you did there. A literal carnotaurus!)

A shaded sketch of a speculative predatory bovine. It has a muscular body with humped shoulders and cloven hoofed feet, a thick neck, and a large cow-like head. Two individuals are depicted, a standing long-horned bull and a sitting short-horned cow. The cow has a chunk missing from one ear and has her mouth open to display her sharp teeth.

The bulltcher (Carnovitulus grassator) is a sheep-sized descendant of small buffalo that gradually took up more and more omnivorous diets, eventually becoming somewhat entelodont-like opportunists. This particular species has shifted over into hypercarnivory, occupying a predator niche in an ecosystem lacking other types of carnivorous mammal.

Like their ancestors they still lack upper front teeth, and instead have modified their dental pad into an almost beak-like tough keratinized structure that their sharp lower teeth can slice and self-sharpen against.

These animals live in small matriarchal herds, with bulls usually hanging around on the edges of the group to protect from threats. Bulls have larger backwards-pointing horns, used to compete with each other for mates – but the size of these structures on their skulls results in them having slightly less powerful jaw muscles than cows.

Herds hunt cooperatively, pursuing and harassing larger prey until it can be brought down and torn apart.

Perucetus

While last week’s Tutcetus was the smallest known basilosaurid whale, another recently-announced member of that group was almost the complete opposite.

Perucetus colossus was a chonker. An absolute unit of a whale.

Living during the Eocene (~38 million years ago) in shallow marine waters covering what is now the coast of Peru, this ancient whale is known from several vertebrae, ribs, and parts of its pelvis. As a result its full size is uncertain, but based on the proportions of other basilosaurids it was probably somewhere around 17-20m long (~56′-66′) – similar in length to the larger specimens of Basilosaurus.

However, it had much thicker denser bones, even more so than those of its close relative Antaecetus, suggesting that its full body mass was much higher than the rather slender Basilosaurus – and possibly heavier than even modern blue whales despite being shorter in overall length.

Perucetus’ thickened vertebrae were also fairly inflexible in most directions, indicating it was a sirenian-like slow swimmer with limited maneuverability – but it did have a surprisingly good ability to bend its body downwards. Without skull material it’s unclear what its diet was like, but it may have been a suction-feeder hoovering up seafloor prey like modern grey whales or walruses.

I’ve reconstructed it here with a speculative bristly fleshy downturned snout inspired by the weird skull of Makaracetus, an earlier whale that may have also been a walrus-like bottom-feeder.

Tutcetus

Tutcetus rayanensis was a whale that lived in warm shallow tropical seas covering what is now Egypt during the Eocene, about 41 million years ago.

It was an early member of the “basilosaurids“, a grouping made up of multiple early cetacean lineages (an “evolutionary grade“) representing some of the first fully aquatic forms. Like other members of this group it probably would have had a rather long and slender body shape – but unlike most of its relatives Tutcetus was comparatively tiny, estimated to only have been around 2.5m long (~8’2″).

The fusion of the skull bones in the one known fossil specimen indicate it was almost fully grown at the time of its death, and the pattern of tooth replacement suggests this small basilosaurid species matured very rapidly – a sort of “live fast, die young” life strategy.

Tutcetus’ small size and early demise also inspired its genus name, with “Tut” referencing the teenage Egyptian Pharaoh Tutankhamun.

Crystal Palace Field Trip Part 3: Walking With Victorian Beasts

[Previously: the Jurassic and Cretaceous]

The final section of the Crystal Palace Dinosaur trail brings us to the Cenozoic, and a selection of ancient mammals.

A photograph of the Crystal Palace palaeotheres, depicted as tapir-like animals. A smaller one on the left is in a sitting pose, while a larger one on the right is in a walking pose. — Image from 2009 by Loz Pycock (CC BY-SA 2.0)

Originally represented by three statues, there are two surviving originals of the Eocene-aged palaeotheres depicting Plagiolophus minor (the smaller sitting one) and Palaeotherium medium (the larger standing one).

The sitting palaeothere unfortunately lost its head sometime in the late 20^th century, and the image above shows it with a modern fiberglass replacement. Then around 2014/2015 the new head was knocked off again, and has not yet been reattached – partly due to a recent discovery that it wasn’t actually accurate to the sculpture’s original design. Instead there are plans to eventually restore it with a much more faithful head.

These early odd-toed ungulates were already known from near-complete skeletons in the 1850s, and are depicted here as tapir-like animals with short trunks based on the scientific opinion of the time. We now think their heads would have looked more horse-like, without trunks, but otherwise they’re not too far off modern reconstructions.

There was also something exciting nearby:

A photograph of the restored Crystal Palace Palaeotherium magnum statue. It's a chunky animal with a trunked tapir-like head, wrinkly skin, and a rhino-like body.

The recently-recreated Palaeotherium magnum!

This sculpture went missing sometime after the 1950s, and its existence was almost completely forgotten until archive images of it were discovered a few years ago. Funds were raised to create a replica as accurate to the original as possible, and in summer 2023 (just a month before the date of my visit) this larger palaeothere species finally rejoined its companions in the park.

Compared to the other palaeotheres this one is weird, though. Much chonkier, wrinkly, and with big eyes and an almost cartoonish tubular trunk. It seems to have taken a lot of anatomical inspiration from animals like rhinos and elephants, since in the mid-1800s odd-toed ungulates were grouped together with “pachyderms“.

An illustration comparing the Crystal Palace depiction of Palaeotherium magnum with a modern interpretation. The retro version is a chunky animal with a trunked tapir-like head and rhino-like body. The modern version is more horse-like, with slender legs and three-toed hoofed feet.

Nihohae

Nihohae matakoi was a dolphin that lived in the coastal waters around what is now Aotearoa New Zealand during the late Oligocene, about 25 million years ago. Part of a group known as waipatiids, it was much closer related to modern South Asian river dolphins than to modern oceanic dolphins.

Around 2m long (6’6″), it had unusually long tusk-like teeth at the front of its jaws, splaying out almost horizontally forwards and to the sides.

These teeth lay too flat to effectively interlock as a “fish trap”, and their fairly delicate structure and lack of wear marks suggests they also weren’t used for piercing large prey, sifting through gritty sediment, defending against predators, or for fighting each other. But Nihohae did have a highly flexible neck and the ability to quickly snap its jaws from side to side – although with a relatively weak bite force, suggesting it was primarily tackling small soft-bodied prey that could be easily swallowed whole.

Overall its feeding ecology seems to have been similar to modern sawfish, stunning prey such as squid with rapid slashing swipes of its jaws.

Neolicaphrium

Neolicaphrium recens here might look like some sort of early horse, but this little mammal was actually something else entirely.

Known from southern South America during the late Pleistocene to early Holocene, between about 1 million and 11,000 years ago, Neolicaphrium was the last known member of the proterotheriids, a group of South American native ungulates that were only very distantly related to horses, tapirs, and rhinos. Instead these animals evolved their remarkably horse-like body plan completely independently, adapting for high-speed running with a single weight-bearing hoof on each foot.

Neolicaphrium was a mid-sized proterotheriid, standing around 45cm tall at the shoulder (~1’6″), and unlike some of its more specialized relatives it still had two small vestigial toes on each foot along with its main hoof. Tooth microwear studies suggest it had a browsing diet, mainly feeding on soft leaves, stems, and buds in its savannah woodland habitat.

It was one of the few South American native ungulates to survive through the Great American Biotic Interchange, when the formation of the Isthmus of Panama allowed North and South American animals to disperse into each other’s native ranges. While many of its relatives had already gone extinct in the wake of the massive ecological changes this caused, Neolicaphrium seems to have been enough of a generalist to hold on, living alongside a fairly modern-looking selection of northern immigrant mammals such as deer, peccaries, tapirs, foxes, jaguars… and also actual horses.

Some of the earliest human inhabitants of South America would have seen Neolicaphirum alive before its extinction. We don’t know whether they had any direct impact on its disappearance – but since the horses it lived alongside were hunted by humans and also went extinct, it’s possible that a combination of shifting climate and hunting pressure pushed the last of the little not-horses over the edge, too.