Category: science illustration

Inticetus

While most modern toothed whales have jaws full of teeth that are all the same simple pointed shape – an adaptation for better holding onto slippery prey – their ancient ancestors had teeth much more like other mammals, with differentiated incisors, canines, and molars.

In-between them were whales like Inticetus vertizi, which lived off the coast of southwestern Peru during the Early Miocene, about 18 million years ago.

At over 3.5m long (11′6″) it was one of the larger known toothed whales around at the time, but it wasn’t the direct ancestor of any living whales. Instead it was more of an evolutionary “cousin” to them, part of an older offshoot lineage that lived alongside the early members of modern toothed whale groups.

Inticetus had a long and unusually wide-based snout, somewhat croc-like in appearance, with sharp pointed teeth at the front and multi-lobed cheek teeth further back. A lack of obvious wear on its back teeth suggests it wasn’t using them to chew up its food, and it may have had a fairly specialized diet – possibly using those back teeth to sieve small prey out of the water in a similar manner to modern lobodontine seals.

An close-up view of Inticetus' jaws, showing the differences in tooth shape from front to back.
Closeup of Inticetus‘ jaws

Inticetus-like teeth have also been found in Miocene-aged deposits in the eastern USA, the Atlantic coast of France, and southeast Italy, indicating that this ancient whale lineage was quite widespread.

Diademodon

Modern mammals are the only surviving members of a much larger evolutionary group known as the synapsids – which back in the Permian period were the dominant land vertebrates.

But much like all other life on Earth at the time, the synapsids were absolutely devastated in the “Great Dying” mass extinction at the end of the Permian, 252 million years ago. Only three lineages survived into the Triassic: the dicynodonts (who briefly took over the world), the therocephalians (who went extinct not long afterwards), and the cynodonts (who eventually gave rise to early mammals).

Diademodon tetragonus here lived right in the wake of the extinction during the Early and Middle Triassic, about 251-242 million years ago. Around 2m long (6′6″), it was one of the largest known cynodonts, and it must have been a fairly successful species since it ranged across a large chunk of Pangaea, known from modern southern Africa, South America and Antarctica.

It had pig-like cheekbones and enormous jaw muscles, along with sharp incisors and canine teeth at the front of its jaws and grinding molars at the back. This arrangement suggests that much like modern pigs it may have been an opportunistic omnivore, occasionally snacking on smaller animals and carrion – although an isotope analysis of its teeth indicates the vast majority of its diet was probably still vegetation in shady damp environments.

Voay

Did you know some crocodiles have “horns”?

Formed from the corners of the squamosal bone at the back of their skulls, just above their ears, these structures are seen in living crocs like the Cuban crocodile and the Siamese crocodile, as well as some fossil species.

But perhaps the most impressively-horned croc was Voay robustus here.

Voay lived on the island of Madagascar during the Late Pleistocene and Holocene, between about 100,000 and 2,000 years ago. At about 5m long (16′5″) it was similar in size and build to a large male Nile crocodile – but despite this resemblance its closest living relative is actually the much smaller dwarf crocodile.

It had a fairly short and deep snout and chunky limbs, adaptations associated with a more terrestrial lifestyle that suggest it was specialized for hunting its prey on land rather than just at the water’s edge.

Much like modern horned crocodiles its particularly prominent horns were probably used for territorial displays, and may have been a sexually dimorphic feature with big mature males having the largest examples.

Voay’s disappearance just a couple of thousand years ago may have been the result of the arrival of human settlers on the island, either from being directly hunted or due to the large native species it preyed on also going extinct around the same time.

Sclerothorax

Sclerothorax hypselonotus was a temnospondyl amphibian that lived in Germany during the Early Triassic, around 251-247 million years ago.

Measuring about 1.2m long (3′11″), it had some unusual features for a temnospondyl – a very rectangular skull with a wide blunt snout, and elongated spines on its vertebrae that gave its body a sort of “hump-backed” shape.

It was part of a lineage of temnospondyls called capitosaurs, which mostly occupied the same sort of aquatic predator niche as modern crocodiles – but unlike its close relatives Sclerothorax’s well-developed spine and limbs suggest it spent much more time walking around on land.

(And while there was another temnospondyl known to have similar extended vertebrae – the sail-backed Platyhystrix – the two weren’t actually closely related to each other.)

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!

Glowing Dinosaurs

Many modern birds are capable of seeing into the ultraviolet regions of the electromagnetic spectrum, and some of their non-avian dinosaur ancestors might have had the same sort of vision. And much like their living relatives, that means various parts of their bodies and plumage may also have been UV-reflective and UV-fluorescent.

So here’s a Velociraptor with some speculative UV coloration – although this is just what it would look like to human eyes under a blacklight. What it would actually look like to a creature that can see extra colors is impossible to depict on a screen designed for trichromatic vision!

Panzhousaurus

Panzhousaurus rotundirostris, a sauropterygian marine reptile from the mid-Triassic of southwestern China (~245 mya), living just a few million years after the devastating Permian-Triassic mass extinction. This small marine reptile was only about 40cm long (1′4″) and is known from a single near-complete skeleton.

Although it was a distant evolutionary cousin to plesiosaurs (and even more distantly to modern turtles), it was actually most closely related to an early sauropterygian lineage known as the pachypleurosaurs – a group of small lizard-like aquatic reptiles with tiny heads, long necks, and paddle-like limbs.

It had an unusually short and rounded-off snout compared to its relatives, and since it would have lived alongside many other diverse marine reptiles it was probably specialized for a slightly different ecological niche.

Nanodobenus

Nanodobenus arandai, a pinniped from the mid-to late Miocene (~16-9 mya) of Baja California Sur, Mexico. Although it would have looked very similar to a sea lion, it was actually an early member of the walrus lineage that lacked the specialized long tusks that characterize its modern relatives.

At just 1.65m long (5′5″) it was only about half the size of living walruses, making it the smallest member of the group ever discovered and leading to it being given the nickname “smallrus”.

It probably occupied a similar sort of fish-eating ecological niche as true sea lions – which eventually replaced it in the region after its extinction – and since it lived alongside several other larger species of walrus it may have become dwarfed to avoid direct competition with them.

Conflicto

Conflicto antarcticus, a recently-named waterfowl bird from the earliest Palaeocene of Antarctica (~65-64 mya).

Standing around 50cm tall (1′8″), it had a slender body, long legs, a long neck, and a narrow goose-like beak. It also had an unusual pair of bony bumps on its skull which may have supported some sort of small crest superficially similar to the knob on the head of the modern magpie goose.

Temperatures in Antarctica at the time were much warmer than today, and the area where its fossils were found would have been a temperate estuary or river delta. It was probably an omnivorous wading bird, feeding on vegetation, small fish, and invertebrates in shallow freshwater.

Although it somewhat resembled a presbyornithid it was actually part of an even earlier branch of the waterfowl evolutionary tree – so its ancestors must have originated much further back in the Late Cretaceous – and their similar body shapes hint that the common ancestor of all waterfowl may also have been a rather leggy bird. Conflicto’s closest known relative might actually be the similarly-aged Anatalavis (which was previously though to be a primitive magpie-goose) from North America and Europe, suggesting that its lineage was quite widespread and already taking advantage of vacant niches in the immediate wake of the Cretaceous-Paleogene mass extinction.

Eons Roundup 2

  • California Channel Island pygmy mammoth (Mammuthus exilis) and Columbian mammoth (Mammuthus columbi)

And speaking of island elephants, I recently illustrated some for PBS Eons’ episode on the California Channel Island pygmy mammoths:

https://www.youtube.com/watch?v=dXwoKEDtdlM