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 20th 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.
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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.

Ambulator

Diprotodontids were large herbivorous marsupials distantly related to modern wombats and koalas, with some species reaching body sizes comparable to rhinos.

Ambulator keanei here was a mid-sized example, closer to bear-sized at around 1m tall at the shoulder (~3’3″). It lived in South Australia during the Pliocene, about 3.9-3.6 million years ago, at a time when the climate was becoming drier and the local habitat was shifting towards open grasslands – and so it was was one of the first diprotodontids known to have specialized its limb anatomy for more efficient long-distance walking.

A bone in its wrist was modified into a heel-like structure, and skin impressions show large cushioning fleshy pads on the undersides of its feet. Its feet were also rotated to bear weight mainly on the outside edges, similar to the condition seen in some ground sloths, and its fingers and toes appear to have been held raised up off the ground while walking.

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.

Eons Roundup 13

I haven’t posted any PBS Eons commissions here for quite a while, so let’s catch up a bit of the backlog:

The Cretaceous mammals Repenomamus robustus and Repenomamus giganticus, from “When Mammals Only Went Out At Night”
https://www.youtube.com/watch?v=JqZONKXWPfw


A carcass of the whale Borealodon, from “How Ancient Whales May Have Changed the Deep Ocean”
https://www.youtube.com/watch?v=1vb00-gcdtA


And the early vertebrates Haikouichthys and Myllokunmingia, from “Why Sour May Be The Oldest Taste”
https://www.youtube.com/watch?v=XXgd_cNZSvk

Strange Symmetries #22: The Whalerus And The Twisted Tusks

Mammalian tusks usually grow in symmetrical pairs with only minor developmental asymmetry, but a few species have evolved much more uneven arrangements.

A colored line drawing of the extinct toothed whale Odobenocetops. Its body is beluga-like but it has a face more like a walrus than a whale, with a big fleshy bristly upper lip and a pair of protruding tusks. The right side tusk is much longer than the left. It's depicted with a mottled brown and white color scheme.
Odobenocetops peruvianus

Odobenocetops peruvianus was a small toothed whale that lived during the Miocene, about 7-3 million years ago, in shallow coastal waters around what is now Peru. Around 3m long (~10′), it was a highly unusual cetacean with binocular vision, a vestigial melon, muscular lips, and a pair of tusks – features convergent with walruses that suggest it had a similar lifestyle suction-feeding on seafloor molluscs and crustaceans.

In males the right tusk was much more elongated than the left, measuring around 50cm long (~1’8″) in this species and up to 1.35m (4’5″) in the closely related Odobenocetops leptodon. Since these teeth were quite fragile they probably weren’t used for any sort of combat, and they may have instead served more of a visual display function.

And despite being closer related to modern narwhals and belugas than to other toothed whales, Odobenocetops’ long right-sided asymmetric tusks actually seem to have evolved completely independently from the iconic left-sided asymmetric spiral tusks of narwhals.

An edited meme image using screenshots of Dr. Doofenshmirtz from "Phineas and Ferb". The text reads: "If I had a nickel for every time whales evolved asymmetric tusks, I'd have two nickels. Which isn't a lot, but it's weird that it happened twice."

A colored line drawing of an extinct woolly mammoth. It's an elephant-like animal covered in a thick coat of brownish hair, with a high domed forehead, small ears, and long curving tusks. The tusks are noticeably asymmetrical, one curving more downwards than the other.
Woolly Mammoth (Mammuthus primigenius)

The woolly mammoth (Mammuthus primigenius) lived across Eurasia and North America during the last ice age, mostly from the Pleistocene about 400,000 years ago to the early Holocene about 10,000 years ago – altohugh a few relict populations survived until around 4,000 years ago in isolated areas of Alaska, Siberia, and eastern Russia.

Around 3m tall at the shoulder (~10ft), these hairy proboscideans had very long curving tusks that were used for digging out vegetation from under snow and ice, scraping bark from trees, and for fighting.

The tusks showed a lot of variation in their curvature, and were often rather asymmetrical, a condition also seen in the closely related Columbian mammoth. Like modern elephants mammoths may have also favored using one side over the other for certain tasks, which over their lifetimes could result in uneven wear exaggerating the natural asymmetry even more.

Strange Symmetries #21: Uneven Ungulates

Asymmetry is commonly seen in the headgear of modern even-toed ungulates, with natural genetic variation, developmental stress, and injuries during life sometimes causing very wonky-looking horns or antlers.

No living species have asymmetry as a standard trait, however – but some fossil ungulates did.

Ramoceros osborni was a relative of the modern pronghorn living during the mid-Miocene, about 13 million years ago, in open plain habitats of what is now the Midwest and Mountain states of the USA.

It was smaller than modern pronghorns, around 70cm tall at the shoulder (~2’4″), and males had long antler-like horns with three tines. Bizarrely, one of these horns was always at least twice the size of the other, with “left-horned” and “right-horned” individuals seeming to occur in equal numbers.

It’s not clear how this asymmetry affected combat between males. Could they only properly lock horns with “opposite-sided” rivals, or did this uneven arrangement actually prevent physical fights and restrict them more to just visual displays?


An illustration of the head of Tsaidamotherium, an extinct hoofed mammal distantly related to modern giraffe and okapi. It has a vaguely moose-like head with a bulbous fleshy snout. Its left ossicone "horn" is above its eye and very small, while the right ossicone is much larger and positioned towards the middle of its forehead, forming a wide blunt helmet-like structure like a very stubby fat unicorn horn.
Tsaidamotherium hedini

Meanwhile in China another Miocene ungulate known as Tsaidamotherium hedini also had strange headgear, with an enlarged right “horn” forming a helmet-like dome on top of its head. This species was featured here on the blog just year, so check out that post for more details about it.

Strange Symmetries #19: Wonky Whales

Toothed whales – the branch of cetaceans that includes modern dolphins, porpoises, beaked whales, and sperm whales – have surprisingly asymmetrical skulls, with some of the bones skewed to one side and just the left nostril forming their blowhole.

Some of the most obvious external manifestation of this lopsidedness can be seen in sperm whales, which have their blowhole at the front left side of their head, and in male narwhals, which usually have a single left-side tusk.

This sort of asymmetry first appeared in the skulls of early toothed whales around 30 million years ago. And since the highest amounts of wonkiness have gone on to develop in lineages that hunt in dark, cluttered, or murky waters, this suggests that the trait is somehow linked to the evolution of complex echolocation.

Some ancient members of the river dolphin lineage also had some additional unusual asymmetry, sometimes having slightly sideways-bending snouts.

Ensidelphis riveroi was one of the weirdest of these, living around the coasts of what is now Peru during the Miocene, about 19 million years ago. Around 3m long (~10′), it had a very long narrow toothy snout that curved distinctly off to the right along its length.

A sketch showing Ensidelphis' bizarre side-curving snout. A hypothetical straight snout is shown outlined in blue, while the actual curvature is overlaid in red.
Expectation vs reality

It’s not clear what the function of this bend was, or even if the only known skull actually represents the normal condition for this species. But Ensidelphis’ bendy snoot might have been used to probe around in muddy seafloor sediment or to extract prey from crevices, possibly like an underwater version of the modern wrybill.

Antaecetus

Antaecetus aithai was an early whale that lived during the late Eocene (~40 million years ago) in what is now Morocco, at a time when northern Africa was covered by a warm shallow sea.

It was part of the “basilosaurids“, some of the first fully aquatic cetaceans – traditionally considered to be a single defined group, but more recently found to be more of an “evolutionary grade” of multiple early whale lineages – and much like Basilosaurus it had elongated back vertebrae that would have given it a very long slender body shape.

Antaecetus also had a proportionally smaller head and smaller teeth than other basilosaurids, along with much denser bones and a stiffer spine that would have made it a rather slow swimmer with reduced maneuverability. It was also fairly small overall compared to most of its relatives, probably around 6m long (~20′).

It was probably a slow-moving coastal water animal somewhat like modern sirenians – except unlike manatees and dugongs it was carnivorous. Its relatively delicate teeth suggest it was feeding on soft-bodied prey like cephalodpods, and with its lack of speed it must have been some sort of ambush predator, waiting around for potential prey to come within striking range.

Unnuakomys

Towards the end of the Cretaceous, about 69 million years ago, the most diverse and numerous mammals in the northern hemisphere were the metatherians, close relatives of modern marsupials.

And Unnuakomys hutchisoni was the most northern-living of all these metatherians.

About the size of a modern mouse, around 10-15cm long (4-6″), and with teeth that suggest it was a shrew-like insectivore, this little metatherian lived in northern Alaska in what’s known as the Paaŋaqtat Province – a region with a distinctive population of endemic polar animals. At the time this area was located at an even higher latitude than it is today, around 80-85ºN, but due to a greenhouse climate it was also warmer, with no permanent ice and the average temperatures staying above freezing.

Unnuakomys was by far the most common mammal species in the Paaŋaqtat Province, represented by numerous fossil teeth and a few jaw fragments, and it also seems to have been the only metatherian living in the whole region. This may just be a preservation bias in the fossil record, but it might also indicate that Unnuakomys was uniquely specialized to endure the several months of continuous darkness each winter in its polar woodland environment, while other North American metatherians were restricted to more southerly latitudes.