2024 – Nix Illustration

Spectember 2024 #05: Most Weasel

GayCoonie suggested a “future legless mustelid”:

A shaded sketch of the head of a speculative descendant of the least weasel, shown in both side view and bunched up clinging to a branch. It's a very elongated animal with no obvious limbs, having just small hooked spurs where its legs should be. It has a small weasel-like head with front-facing eyes and small ears, a long neck, a long slender chest and torso, and a thicker fatter back end with a tapering semi-prehensile tail.

Descended from an arboreal offshoot lineage of the modern least weasel, Maximagale gaycooniei is a bizarre mustelid that appears to have converged on the lifestyle of ambush-hunting tree snakes, evolving in northern latitudes where actual snakes are largely absent.

Growing to about 1m long (3’3″), it’s not truly legless but its limbs are all reduced down to tiny vestigial single-clawed spurs, which are used to help anchor its body while climbing and as claspers during mating. It moves around with a distinctive inchworm-like looping gait, alternating grasping and releasing with its front and hind spurs.

Its build is bottom-heavy, with most of its mass concentrated in its thicker back end, and its tail is semi-prehensile. It clings to trees with its body bunched up, camouflaged with cryptic coloration, and rapidly whips its long flexible front half out to snap its powerfully-muscled jaws at prey – such as insects, birds, lizards, frogs, small mammals, and pretty much anything else that comes within its reach.

It will also opportunistically raid the nest of birds and arboreal mammals.

Due to the less frequent meals its ambush-hunting tactics provide, it has a much slower metabolism than its ancestors, and it conserves energy with daily periods of torpor and longer hibernation during the colder months of winter. It has also retained its ancestor’s tendency to seasonally shrink its brain size to reduce energy requirements even more.

Spectember 2024 #04: Forest Gelada

Someone who identified themself only as Pendrew asked for a “ruminant-like Old World Monkey”:

A shaded sketch of a speculative descendant of geladas. It's a baboon-like quadrupedal monkey with front limbs longer that the hind limbs giving it a sloping back. It has a long almost horse-like snout, small high-set eyes, small ears, a rather long neck for a primate, and a short tufted tail. Its front limbs are digitigrade and have large curved claws, while its back limbs are plantigrade with smaller nail-like claws.

After much of East Africa rifted off into a separate continent, shifting climate turned the alpine grasslands of what was once the Ethiopian Highlands into into warmer subtropical forests – and the highly terrestrial grass-eating geladas that inhabited the region adapted to new sources of food.

Yedenigelada pendrewsii is a large quadrupedal herbivorous monkey, about 1.5m tall at the shoulder (~5′). It has a specialized pseudoruminant digestive system with a three-chambered stomach, similar to that of camelids, and it occupies an ecological niche convergent with the ancient chalicotheres, selectively browsing on trees and shrubs while sitting upright and using its long clawed forelimbs to pull branches within reach.

Unlike its highly social ancestors this species is mostly solitary, although during the breeding season groups of males come together in leks to compete for female attention. Displays consist of inflating large colorful throat pouches to make loud resonating calls, and flipping upper lips to bare teeth and gums.

A shaded sketch of the head of a speculative descendant of geladas, showing its upper lip flipped up to display its teeth and gums, and an inflated red throat pouch.

Spectember 2024 #03: Terrible Toucan

This concept comes from thecomiccreator, who suggested a “carnivorous/omnivorous toucan”:

A shaded sketch of a speculative descendant of toucans, shown both standing on one leg and in flight. Its a stork-like bird with a massive long serrated beak, a bald vulture-like head and ruffed neck, large broad wings with slotted flight feathers, and long legs with two forward-facing toes and two backwards-facing toes.

Descended from toco toucans inhabiting savanna grasslands, Deinotukan auctorcomicus is a large stork-like bird standing about 1.2m tall (~4′).

Unlike its mostly-frugivorous ancestors it’s primarily a scavenger, soaring on thermals with its long broad wings and following vultures towards sources of carrion. Its massive serrated beak allows it to efficiently open up tough-skinned carcasses, and with its nostrils positioned up near its eyes it can probe around inside much deeper than other scavengers while still being able to breathe.

It also opportunistically hunts live prey, especially during the breeding season while raising chicks, slowly stalking around on foot snatching up anything small enough to fit in its mouth and be swallowed whole.

Its beak contains an extensive network of blood vessels, which along with the large surface area make it an effective way of shedding excess heat in its hot tropical habitat – but when soaring at high altitudes where temperatures are near-freezing it’s also able to shunt blood flow away from its beak to conserve body heat instead.

Spectember 2024 #02: Swimming Swine

An anonymous submitter asked for a “buoyant ungulate that runs atop the sea”:

A shaded sketch of a speculative semi-aquatic descendant of feral pigs. It's a long-bodied chunky hippo-like animal with short legs, wide paddle-like hooves, and a tapir-like head with a a short trunk, small high-set eyes, and small ears.

Pontoporcus plotus is a 1.5m long (~5′) amphibious pig descended from a feral population of domestic pigs left on a small tropical island. After inadvertently wreaking havoc on much of the local ecosystem, its ancestors eventually turned to a more marine-based lifestyle foraging along beaches and in coastal waters.

Naturally highly buoyant, Pontoporcus actually floats so well that it’s mostly limited to the water’s surface, unable to dive to any significant degree. But despite this it’s a fairly good swimmer, using broad hooves with wide fleshy pads to paddle itself along in an aquatic trotting- or running-like gait.

It forages both on land and in the water, mainly eating soft vegetation and marine plants, but much like its ancestors it will also opportunistically feed on whatever smaller animals it can catch or scavenge. Its semi-prehensile trunk-like snout is used to grasp at food items, to probe and root around in soft sediment, and as a snorkel.

Its hairless skin is very susceptible to sunburn, but it secretes a thick oily red-brown substance (similar to modern hippo “blood sweat”) that acts as a natural protective sunscreen.

These pigs are accomplished island-hoppers, regularly traversing the relatively shallow seas all along their island chain – but their natural flotation and long fat bodies also make them prime targets for large aquatic predators attacking from below, so these journeys tend to involve groups of Pontoporcus “running” along the sea surface aiming for their next destination as fast as they possibly can.

Spectember 2024 #01: Sea Dog

It’s September, it’s #Spectember, and I’m still plugging away at that big ol’ pile of speculative evolution idea submissions from a few years ago.

~~I will never be free.~~

Much like last year I’m not setting a definite posting schedule for this month; it’ll just be whenever and whatever I can manage to get done.

(Also, a reminder: I’m still not currently taking new requests!)

So let’s get started with an anonymous submission that requested a “swimming piscivorous canid”:

A shaded sketch of a speculative semi-aquatic descendant of modern short-eared dogs. It has an otter-like body with a long flat tail and four webbed feet, and a wide head with a long narrow toothy snout and small close-set eyes.

Descended from the short-eared dog (a species that in modern times already has partially-webbed paws and eats a large proportion of fish in its diet), Pelagicyon salsus is a 2m long (~6’6″) semi-aquatic piscivorous canid with a stocky body, short webbed limbs, and a long flattened tail.

The back of its skull is very wide, anchoring its thick neck musculature and accommodating huge cheekbones with powerful jaw muscles, but in contrast its snout is elongated and slender – a combination of features that allows it to sweep its toothy jaws through the water to rapidly snap at fish in a similar manner to gharials.

Most other members of its lineage inhabit freshwater rivers and swamps, but Pelagicyon is an unusual marine offshoot that has developed enough salt tolerance to swim, feed, and even drink exclusively in seawater.

Eons Roundup 14

It’s been a while, but let’s catch up with some more work I’ve done for PBS Eons:

An illustration of both a fossil example and the reconstructed internal structure of the enigmatic Paleodictyon, a hexagonal network of tunnels in seafloor sediment created by an unknown organism. — *Paleodictyon nodosum*

The enigmatic Paleodictyon, from “Something Has Been Making This Mark For 500 Million Years”

An illustration of Loxolophus, an extinct mammal related to early ungulates. It somewhat resembles a modern coatimundi, with a slender snout, long legs with plantigrade feet and claw-like hooves, and a long bushy tail. It's reconstructed with a mottled and striped camouflage pattern of brown and cream fur. — *Loxolophus hyattianus*

An illustration of Arctocyon, an extinct mammal related to early ungulates. It has a dog-like head with large canine teeth, a stocky bear-like body with plantigrade legs and claw-like hooves, and a long tail. It's reconstructed with an orange-brown pelt with white stripes along its limbs. — *Loxolophus hyattianus*

The archaic ungulates Loxolophus, Arctocyon, and Eoconodon, from “How a Mass Extinction Changed Our Brains”

An illustration of Aturia, an extinct relative of modern nautiluses. It's reconstructed with an orange-brown shell patterned with zigzagging darker stripes. — *Aturia sp.*

And the nautilid Aturia, from “When Nautiloids Met Their Match”

Allenypterus

Allenypterus montanus was an unusual early coelacanth that lived during the late Carboniferous, around 324 million years ago, in a tropical bay covering what is now central Montana, USA.

Up to about 15cm long (~6″), its tapering tadpole-like body plan somewhat resembled that of modern knifefishes and featherbacks, with the top part of its tail fin highly elongated into a ribbon-like shape and the rest of its tail fins being vestigial. The distinctive humped shape of its back was also much more pronounced in larger, more mature individuals.

It was probably a fairly slow swimmer, and preserved gut contents suggest it mainly ate small soft-bodied prey.

Its closest known relative seems to have been the eel-like Holopterygius – but since around 60 million years and different continents separated them both, this suggests the existence of a whole ghost lineage of other tapering coelacanths yet to be discovered.

Schoenesmahl

Schoenesmahl dyspepsia was a lizard that lived in what is now Europe during the late Jurassic, about 150 million years ago. Around 30cm long (~1′), it had a fairly small head, elongated hind limbs, and a very long tail – proportions that suggest it was an agile animal capable of fast running.

Only one specimen is known, most notable for being preserved inside the stomach of the dinosaur Compsognathus. For a long time it was classified as an example of Bavarisaurus, but it was finally recognized as representing a distinct type of lizard in 2018, with recent studies placing it as an early member of the gecko lineage closely related to ardeosaurids and eichstaettisaurids.

Compsognathus

First discovered in the 1850s, Compsognathus longipes was the first theropod dinosaur known from a fairly complete skeleton, and also the smallest known non-avian dinosaur for over 130 years.

(A second specimen was also, briefly, the “first” aquatic non-avian dinosaur, but that’s another story.)

Living in what is now Europe during the late Jurassic, about 150 million years ago, it was a lightly built animal with long legs and a long tail, growing to around 1.2m long (~4′). Its hands seem to have had only two functional fingers, with the third being vestigial and possibly not even having a claw.

Skin impressions from about a third of the way along its tail show small bumpy scales – but since other compsognathids like Sinosauropteryx are known to have been covered in fur-like feathers, this likely means that just that particular region of Compsognathus’ body wasn’t fluffy.

Some of Compsognathus‘ diet is known for certain, since preserved gut contents show it fed on smaller vertebrates like lizards and rhynchocephalians. The remains of a lizard in the stomach of one specimen were even identified as belonging to a previously-unknown species, Schoenesmahl dyspepsia, with the dismembered nature of the skeleton suggesting Compsognathus tore its prey into bite-sized chunks in a similar manner to modern predatory birds.

Heterohyus

Apatemyids were a group of unique early placental mammals that lived during the first half of the Cenozoic, known from North America, Europe, and Asia. Due to their specialized anatomy their evolutionary relationships are rather murky (they were traditionally part of the convoluted mess that was “Insectivora”), but currently they’re thought to be a very early offshoot of the Euarchontoglires, the branch of placentals that includes modern rodents, lagomorphs, treeshrews, colugos, and primates.

Living in what is now western Europe during the mid-Eocene, around 47 million years ago, Heterohyus nanus was a small apatemyid about 30cm long (~12″) – although just over half of that length was made up of its tail.

Like other apatemyids it had a proportionally big boxy head, with large forward-pointing rodent-like incisors in its lower jaw and hooked “can-opener-shaped” incisors in its upper jaw.

Example of an apatemyid skull from the closely related American genus *Sinclairella*.
From Samuels, Joshua X. “The first records of Sinclairella (Apatemyidae) from the Pacific Northwest, USA.” PaleoBios 38.1 (2021). https://doi.org/10.5070/P9381053299

The rest of its body was rather slender, and fossils with soft tissue preservation from the Messel Pit in Germany show that it had a bushy tuft of longer fur at the end of its long tail.

But the most distinctive feature of apatemyids like Heterohyus were their fingers, with highly elongated second and third digits resembling those of modern striped possums and aye-ayes. This suggests they had a similar sort of woodpecker-like ecological role, climbing around in trees using their teeth to tear into bark and expose wood-boring insect holes, then probing around with their long fingers to extract their prey.