Tag: ungulate

Kubanochoerus

Pigs were once unicorns.

Kubanochoerus gigas lived about 15-7 million years ago during the mid-to-late Miocene, and ranged across a large portion of Eurasia with fossils known from both Georgia and China.

It was one of the largest known pig species to ever live, slightly bigger than the modern giant forest hog at about 1.2m tall at the shoulder (3′11″). But its most distinctive features were its horns, with a small pair above its eyes and a single large forward-pointing one on its forehead.

A few specimens lack the large horn, and so some paleontologists consider it to be a sexually dimorphic trait possessed only by males. But it’s currently unclear whether this was actually the case, since at least one “hornless” skull has been reported with the distinctive larger tusks also associated with male pigs – so it’s possible that the horned and hornless Kubanochoerus were actually separate species!

Island Weirdness #21 – The Malagasy Mini-Hippos

Much like elephants, hippos have frequently made their way onto islands and developed dwarfed forms. These mini-hippos are mostly known from the Mediterranean, but further south they also occurred on Madagascar.

Hippopotamus madagascariensis (also sometimes called Hexaprotodon madagascariensis or Choeropsis madagascariensis; its exact classification is uncertain) was similar in size and appearance to the modern West African pygmy hippo – which it might have been closely related to, or may have just ended up resembling through parallel evolution.

Standing under 1m tall at the shoulder (3′3″) and measuring about 1.8m long (5′11″) it lived in the forested highlands and was much more terrestrial than its larger cousins. Its eyes were further down on the sides of its head, and it was better adapted for walking and running around on land, with proportionally longer legs and a more digitigrade posture.

It also had an unusually small brain for its size – about 30% smaller than expected – which may have been an energy-saving adaptation.

Two other species of dwarf hippo have been identified on Madagascar – the similarly-sized but more aquatic Hippopotamus lemerlei in the west of the island, and the larger and poorly-known Hippopotamus laloumena in the east. It’s not clear when exactly the ancestors of these various hippos first arrived on the island, and they may even represent three independent colonization events.

The last known subfossils date to about 1000 years ago, but surprisingly accurate accounts of similar creatures in Malagasy folklore raise the possibility that small isolated populations of these hippos may have survived into more recent times. One of the most intriguing examples is the kilopilopitsofy, described as having large floppy ears and supposedly being sighted as recently as the 1970s.

Island Weirdness #14 – Hoplitomeryx

During the mid-Miocene, about 15 million years ago, a region of central and southeast Italy around Gargano and Scontrone was cut off from the mainland by rising sea levels.

For the next 7-10 million years this island (or perhaps a cluster of islands) was left isolated, and an unusual ecosystem developed known as the “Mikrotia fauna”. With the island starting off lacking large predators, small herbivorous animals like rodents, pikas, and waterfowl became huge – and then small predators like gymnures and carnivorous birds also grew to keep up with the increasing size of their prey.

One of the strangest residents of the island(s) was Hoplitomeryx, an early type of ruminant that resembled a deer or pronghorn. Nicknamed the “prongdeer”, it had a total of five horns on its head and large protruding fangs similar to some modern deer.

Multiple species of Hoplitomeryx have been identified, representing four different size classes ranging from huge down to tiny insular dwarfs. The largest is estimated to have been similarly sized to modern moose, standing around 2m tall at the shoulder (6′6″), while the smallest would have been under 50cm (1′8″).

Each of these size classes was specialized for slightly different ecological niches, eating different types of vegetation to avoid directly competing with each other for the limited amount of food on the island.

Island Weirdness #11 – Hilalia

During the mid-Eocene, about 43 million years ago, the Pontide region of modern day north-central Turkey was an island located between the Paratethys Sea to the north and the Tethys Ocean to the south.

This island had an ecosystem of native mammals unlike anything existing today, with a unique mixture of species whose ancestors had arrived over several million years via island-hopping or temporary land connections with Europe, Africa, and Asia. There were large rhino-like embrithopods, cat-sized metatherian predators, early primates, early bats, and “enigmatic” small insectivores – but the island completely lacked any of the rodents, carnivorans, creodonts, perissodactyls, or artiodactyls which were dominating the rest of Eurasia.

But one of the most surprising inhabitants of the island were the small herbivores – a genus called Hilalia that represented a type of early ungulate known as pleuraspidotheriids. Resembling deer-dogs, this group had originated in Europe during the Paleocene and had gone extinct there around 13 million years earlier than the date of the Pontide remains, making them living fossils at the time.

These survivors of an archaic lineage thrived on their isolated island refuge and there were at least four or five species of Hilalia at different sizes, suggesting they’d diversified to each occupy a slightly different niche in their ecosystem. It’s hard to accurately measure their body size from their very fragmentary remains, but they may have ranged from around 25cm to 60cm in total length (~10″- 2′).

Rayanistes

Remingtonocetids were an early branch of the whale evolutionary family tree, known from about 49-41 million years ago and splitting off somewhere between the famous “walking whale” Ambulocetus and the more oceanic protocetids. With otter-like bodies, tiny eyes, and long gharial-like snouts, they lived in near-shore shallow marine habitats and probably swam using a combination of their hind feet and tails.

They were initially found only in Pakistan and India, but then Rayanistes afer here was discovered all the way over in Egypt – suggesting that these early whales were much more widespread than previously thought, dispersing through the Tethys Sea at about the same time as their protocetid cousins.

Dating to the Middle Eocene (~45-41 mya), Rayanistes was probably about 2.5m long (8′2”). It had powerful hindlimb musculature that would have given it a very strong kicking swimming stroke, but it probably couldn’t actually support its own weight on land since its femur wasn’t very well anchored into its pelvis.

Diplacodon gigan

Diplacodon gigan, a brontothere from the Early Eocene of Wyoming, USA (~46-42 mya). Standing around 2.1m tall at the shoulder (~7′) it was named after the kaiju Gigan for its relatively large size – not quite as big as some later brontotheres, but still about 20% larger than other known species of Diplacodon.

It had a pair of blunt bony projections on its snout which would have been covered with skin in life, similar to the ossicones of modern giraffids, with males having larger “horns” than females.

Despite looking very similar to rhinos, brontotheres were actually much more closely related to horses, with the resemblance being a result of convergent evolution for the same sort of big-tanky-herbivore ecological niche.

Eucladoceros

Eucladoceros dicranios, a deer from the Pliocene and Pleistocene of Europe (~3.5-1 mya). Close in size to a modern moose, standing about 1.8m tall at the shoulder (5′10″), the males of this species had a set of particularly large antlers – measuring up to 1.7 meters across (5′6″) and bristling with at least twelve prongs each – giving it the nickname of “bush-antlered deer”.

The more famous “Irish elk” (Megaloceros giganteus) would later develop even bigger antlers, but Eucladoceros was the earliest known deer to evolve this sort of extremely elaborate headgear.

Orcinus citoniensis

Despite commonly being called “killer whales” modern orcas are actually the largest living members of the oceanic dolphin family. Their ancestors are thought to have diverged from other dolphins between 10 and 5 million years ago – and surprisingly their closest relatives are the much smaller snubfin dolphins found in Australasia.

Living during the Pliocene (5-2 mya) in the Mediterranean, Orcinus citoniensis was an early member of the orca lineage, and was probably a transitional form between their early dolphin ancestors and the modern Orcinus orca.

It was half the size of modern orcas, at about 4m long (~13′). While it had a higher tooth count than its living relatives its teeth were also proportionally smaller, suggesting it wasn’t specialized for tackling large prey and probably fed mainly on fish and squid.

Phenacodus

Phenacodus primaevus, a mammal from the Late Paleocene to Middle Eocene of North America and Europe (~60-48 mya). About 1.5m long (5′), it’s thought to have been one of the earliest known odd-toed ungulates, walking on its middle three hoofed toes.

Its teeth were adapted for a diet of mostly plant matter, although it may also have been opportunistically omnivorous.

Another species in the same genus, Phenacodus intermedius, had a skull structure that suggests it might have had a muscular prehensile upper lip – or perhaps even a short tapir-like proboscis.

Waharoa

Waharoa ruwhenua, a whale from the Late Oligocene of New Zealand (~27-25 mya). Part of an early branch of the baleen whale lineage, it’s known from partial remains of an adult and a couple of juveniles and would have reached a full size of about 6m long (19′8″).

It had an unusually long flattened snout, with its nostrils further forward than modern whales, and only had baleen in the back half of its mouth – an interesting comparison to the intermixed teeth-and-baleen of some other early mysticetes. It’s not clear whether it had any vestigial teeth in the front of its jaws, although a single possible tooth has been found associated with its close relative Tokarahia.

The rather delicate nature of Waharoa’s jawbones suggests it wasn’t capable of rapid lunges at swarms of its small prey, instead probably using slow-cruising surface skim-feeding similar to modern right whales.