Tag: cetancodontamorpha

Phiomicetus

Named after the canine-headed Ancient Egyptian god, Phiomicetus anubis is the first fossil cetacean to discovered, described, and named entirely by a team of Arab paleontologists.

Living during the mid-Eocene, about 43 million years ago, in a shallow sea-covered region that is now part of Egypt‘s Western Desert, Phiomicetus was an early protocetid – an amphibious foot-powered swimmer, at a transitional point in the evolution of whales from deer-like terrestrial animals to fully aquatic screaming torpedoes.

About 3m long (~10′), it had large jaw muscles and sharp teeth with wear patterns that suggest it was a raptorial hunter grabbing and snapping at prey with powerful bites. It would have probably tackled fairly big prey compared to other protocetids, hunting things like large fish, turtles, and even smaller whales in an ecological role similar to that of modern orcas.

Along with the distantly-related long-snouted Rayanistes it’s one of the earliest known whales from Africa, giving us further glimpses at a time period when early cetaceans were first dispersing out from the South Asian subcontinent via the ancient Tethys Sea.

Heliosus

Just before the 2017 solar eclipse, some unusual fossils were discovered in Southern Wyoming, USA.

Consisting of a partial jawbone and a humerus, and dating to the mid-Eocene (~47 million years ago), the remains clearly belonged to an early even-toed ungulate – but one much bigger than the rabbit-sized herbivores known from that time. This was something closer in size and build to a large modern pig, standing at least 1m tall at the shoulder (3’3″).

It turned out to belong to a member of a somewhat obscure lineage known as the helohyids, a group whose evolutionary relationships are a bit uncertain but are generally considered to be part of the whale-and-hippo lineage. These pig-like animals were large opportunistic omnivores, possibly occupying a similar ecological role to the later entelodonts, with some Late Eocene forms reaching sizes comparable to black bears.

This new helohyid was named Heliosus apophis, inspired by the eclipse, with its genus name meaning “sun pig”, and its species name referencing a sun-devouring Ancient Egyptian deity.

It was one of the earliest known large-bodied members of the group, and shows that these animals must have increased in size very rapidly during their early evolution, going from rabbit-sized to pig-sized within just a couple of million years.

Borealodon

Modern mysticete whales all have baleen plates in their mouths, but before the evolution of these specialized filter-feeding structures the early members of their lineage still had toothy jaws.

Borealodon osedax here was one of those “toothed mysticetes”, living about 30-28 million years ago during the mid-Oligocene off the coast of Washington state, USA.

Unlike modern baleen whales it was small, about the size of a modern porpoise at around 2m long (6’6″), and the wear on its multi-cusped teeth suggest it was a predator taking slicing bites of fish – possibly using suction-assisted feeding like its close relatives the aetiocetids.

Its fossilized remains are also a rare example of an ancient whale fall, with characteristic bore holes in its bones from Osedax worms.

Eons Roundup 4

Some more recent commission work for PBS Eons!

  • An illustration of an extinct entelodont, an omnivorous hoofed mammal. It has a hippo-like head and a body proportioned rather like a hyena, with high shoulders and long slender legs. It has cloven-hoofed feet and a short tail, and its body is covered in a coat of short bristly fur.
    Eoentelodon
  • An illustration of an extinct entelodont, an omnivorous hoofed mammal. It has a hippo-like head and a body proportioned rather like a hyena, with high shoulders and long slender legs. It has cloven-hoofed feet and a short tail, and its body is covered in a coat of short bristly fur.
    Brachyhyops

The entelodonts Eoentelodon and Brachyhyops, from “The Hellacious Lives of the Hell Pigs”
https://www.youtube.com/watch?v=trJpxwMGoCw

  • An illustration of an extinct ichthyosaur, an ancient marine reptile. It has a short narrow snout full of rounded teeth, large eyes, a long tapering body, four flippers, and a long tail ending in a vertical fin.
    Tholodus
  • An illustration of an extinct mosasaur, an ancient marine reptile. It has long triangular jaws full of many small sharp teeth, a long lizard-like body, four paddle-like flippers, and a long tail ending in a vertical fin.
    Pluridens

The early ichthyosaur Tholodus and the mosasaurPluridens, from “When Ichthyosaurs Led a Revolution in the Seas”
https://www.youtube.com/watch?v=V342aXQs9XY

  • An illustration of an extinct early bat in flight. It has claws on all five fingers on each wing, along with small ears and a long tail.
    Onychonycteris
  • An illustration of an extinct early bat in flight. It has claws on both its thumb and the first wing finger one each wing, along with small ears and a long tail.
    Icaronycteris

The early bats Onychonycteris and Icaronycteris, from “When Bats Took Flight”
https://www.youtube.com/watch?v=zWeYCULC0UQ

Inermorostrum

Inermorostrum xenops, a recently-named ancient cetacean!

Living about 30 million years ago in shallow coastal waters around the southeast USA, in what is now South Carolina, it was a member of one of the very earliest groups of toothed whales known as the xenorophids. Although only very distantly related to modern forms, xenorophids show evidence of being able to echolocate, suggesting the ability was probably ancestral to all toothed whales.

Estimated to have measured about 1m long (3′3″), Inermorostrum had a very short downturned snout and was completely toothless – specialized adaptations for suction feeding on small soft-bodied creatures on the seafloor.

Unusually for a toothed whale it also had proportionally large infraorbital foramina, openings in the bones of its snout for blood vessels and nerves to pass through. This suggests the presence of well-developed fleshy lips and possibly whiskers (as illustrated here), or maybe even an electroreceptive sense similar to some modern dolphins.

Ambulocetus

Ambulocetus natans, the Eocene “walking whale” – who might not actually have been able to walk at all!

A study published in 2016 suggests this early cetacean was actually fully aquatic and unable to support its own weight on land. So here’s an updated version compared to the Ambulocetus I did a couple of years ago.

Globicetus

Globicetus hiberus, a 5m long (16′4″) beaked whale from the Atlantic coast of Portugal and Spain. Its fossils can’t be easily dated since they were fished up from the seafloor, but it was probably around Early-to-Mid Miocene in age (~20-14 mya).

Its skull sported an odd bony sphere at the base of its snout, just in front of the melon, which appears to have been larger and more prominent in males than in females. Many modern beaked whales also have sexually dimorphic crests, ridges, and domes in their skulls, and these structures may function as sort of “internal antlers” – a display structure the whales can “see” via echolocation that signals their size, strength, and health to each other.

Unsolved Paleo Mysteries Month #14 – The Mystery Mega Mammal

During a 1923 expedition by the American Museum of Natural History to Inner Mongolia, China, a huge mammal skull was discovered dating to the Middle Eocene (~48-37 mya). About 83cm long (2′8″), with small low-set eyes, it was named Andrewsarchus mongoliensis in honor of expedition member Roy Chapman Andrews.

Almost a century later that one skull is still all we have. And despite this animal’s popularity among paleo-fans, we actually know very little about it.

It was originally classified as a mesonychian, leading to the many many depictions of it as a sort of “big bad wolf”. But more recent studies have placed it in the even-toed ungulates instead, with some suggestions that it might be most closely related to entelodonts, hippos, and whales.

Although it was certainly a big animal, it may not have been the giant “super predator” it’s often depicted as – its teeth aren’t particularly specialized and resemble those of entelodonts, suggesting it may have been more of an opportunistic omnivore than a dedicated carnivore.

Without more material we just don’t know for certain. So, frustratingly, the rest of Andrewsarchus’ body remains a mystery.

I’ve reconstructed it here based on one of its more obscure possible relatives: the anthracotheres, a group which may have been closely related to modern hippos. Scaling its body proportions to these animals produces rough measurements of about 1.45m tall at the shoulder (4′9″) and 3m long (9′10″), or about the same size as some of the big entelodonts or large modern bears.