xenarthra – Nix Illustration

Spectember 2023 #05: Shiny Mammal

Someone who identified themself only as “Hanna” requested a “mammal that’s shiny and iridescent like some insects and spiders”:

A shaded sketch of a speculative semiaquatic hairy armadillo. It has a wide armor carapace with a green-blue-purple iridescent sheen, a pig-like snout, wide paddle-like hands and feet, and a short tail.

Lustrophractus hannae is a relative of modern hairy armadillos that has adapted for a semiaquatic lifestyle.

About 40cm long (~16″), its unusually shiny carapace originally evolved thanks to its ancestors’ burrowing habits. Much like golden moles and some snakes, these armadillos’ scutes and hairs developed microridges that reduced friction and repelled dirt particles, with the side effect of becoming strikingly iridescent – and, conveniently, also rather water repellent, enabling Lustrophractus’ lineage to take up aquatic omnivorous foraging habits.

The iridescence also serves a defensive function, using a bright flash of color to startle and confuse predators.

Island Weirdness #47 — Megalocnus rodens

Just 21km south of the Bahamas (13 miles), Cuba is the biggest island in the Caribbean and has a complex geological history. It originated as part of a volcanic island arc in the Late Cretaceous and during its existence in the Cenozoic it was colonized by a richer variety of mammals than the Bahamas ever had, including rodents, the enigmatic solenodons and nesophontes, and ground sloths.

The Caribbean ground sloths were all part of the megalonychid lineage — which eventually reached North America and produced giants — and they arrived on Cuba by the early Miocene, about 20 million years ago.

Megalocnus rodens lived during the Late Pleistocene and Holocene, between about 125,000 and 5000 years ago. It had unusually rodent-like front teeth, and while it was dwarfed compared to its mainland relatives it was actually one of the largest of the Cuban ground sloths — close to the size of a modern black bear, about 80cm tall at the shoulder (2’5″).

Subfossil remains show that Megalocnus survived well into the Holocene, and there’s been speculation that it may even have still been around in the highland forests as late as the time of European colonization in the 1500s.

However, radiocarbon dating of remains has given no dates younger than about 5000-4000 years ago, about 1000 years after the earliest arrival of humans in Cuba.

Eons Roundup

This year I’ve been lucky enough to have some of my work featured in several PBS Eons videos – and I even recently got the opportunity to do some custom images for them! Since I didn’t show any of these off at the time, here they are now:

The basal temnospondyl amphibian Iberospondylus, from “When Giant Amphibians Reigned”
https://www.youtube.com/watch?v=rGthtRZl8B0

The flying paleognath bird Lithornis, from “When Birds Stopped Flying”
https://www.youtube.com/watch?v=M3h05ajJw0o

The ground sloth Nematherium, from “How Sloths Went From the Seas to the Trees”
https://www.youtube.com/watch?v=pt9tBtQoAHo

Happy new year, everybody!

Peltephilus

Peltephilus ferox, an armadillo from the Early Miocene of Argentina (~17-16 mya) that was similar in size to a large dog, probably around 1.5m long (5′). It had less solid armor than its modern relatives, with its bony osteoderms being arranged more like chain mail, loosely connected to each other and slightly overlapping, creating a much more flexible body covering.

Its most unusual features were the horns on its snout, convergently resembling the later horned gophers of North America. But unlike other mammals Peltephilus‘ horns were actually modified plates of its face armor, enlarged pointed osteoderms that were only connected to its skull by soft tissue membranes – meaning that after death they tended to fall off, and the exact number and position of them is still a little uncertain.

Its unusually broad snout and large teeth were originally interpreted as evidence of it being an active carnivore, but more recent studies of its anatomy have suggested that it was much more likely to have been a herbivorous or omnivorous digger, mainly feeding on underground plant matter like roots and tubers.