April 2025 – Nix Illustration

Hwiccewyrm

Hwiccewyrm trispiculum lived during the late Triassic, around 208-202 million years ago, in what is now England. It was one of the last known members of the procolophonid family, a lineage of small stocky lizard-like animals that had been widespread and abundant earlier in the Triassic.

(Traditionally procolophonids are classified as parareptiles, but some recent studies suggest this group is paraphyletic or polyphyletic, with some “parareptiles” potentially nesting within the diapsids instead.)

Measuring around 30cm long (~1′), Hwiccewyrm had wide flaring cheek bones ornamented with large spines, and like some other procolophonids it may also have had bony scute armor on its body. Its large blunt teeth suggest it was feeding on particularly tough foods such as fibrous vegetation or hard-shelled invertebrates.

Solenochilus

The distinctive pinhole eyes, leathery hood, and numerous tentacles of modern nautiluses were traditionally thought to represent the “primitive” ancestral state of early shelled cephalopods – but genetic studies have found that that nautiluses actually secondarily lost the genes for building lensed eyes, and their embryological development shows the initial formation of ten arm buds (similar to those of coeloids) with their hood appearing to be created via fusing some of the many tentacles that form later.

There’s a Cretaceous nautilidan fossil that preserves soft tissue impressions of what appear to be pinhole eyes and possibly a remnant of a hood, so we know these modern-style nautilus features were well-established by the late Mesozoic. But for much more ancient Paleozoic members of the lineage… we can potentially get more speculative.

So, here’s an example reconstructed with un-nautilus-like soft parts.

Solenochilus springeri was a nautilidan that lived during the Late Carboniferous, around 320 million years ago, in shallow tropical marine waters covering what is now Arkansas, USA.

Up to about 20cm in diameter, (~8″), its shell featured long sideways spines which may have served as a defense against predators – or possibly as a display feature since they only developed upon reaching maturity.

Mexidracon

Mexidracon longimanus was an ornithomimid dinosaur that lived during the late Cretaceous, about 72 million years ago, in what is now northern Mexico.

It was a fairly small ornithomimid at around 2.5-3m long (~8-10′), and its leg proportions suggest it was less specialized for fast running than some of its other relatives. But its most unique feature was its hands, with extremely elongated metacarpal bones – giving it palms that were longer than its upper arm!

It’s unclear what the function of these unusual limbs was. Possibly they gave Mexidracon extra reach to hook its claws onto foliage and pull it within reach of its head, in a similar manner to ground sloths, chalicotheres, and therizinosaurs.

April Fools 2025: When Pterosaurs Were Swimming Gryphons

When it was first described by Cosimo Alessandro Collini in 1784, Pterodactylus wasn’t originally interpreted as a flying reptile. The idea that species could go completely extinct wasn’t fully understood yet, so fossils were assumed to represent things that still existed somewhere in distant unexplored regions. And so, since the oceans seemed like the best place for undiscovered animals to hide, this strange little creature was initially speculated to be aquatic.

Although it was soon properly recognized as a flying animal with some surprisingly mammal-like early reconstructions, the aquatic idea persisted until at least 1830 when Johann Georg Wagler published a restoration of Pterodactylus with huge membranous paddle-like flippers. He even grouped pterosaurs together with ichthyosaurs, plesiosaurs, and monotremes in a proposed vertebrate class called “Gryphi” (literally “gryphons“) and considered them all to be transitional between birds and mammals.

Wagler’s whole classification system seems esoteric and improbable by modern standards, but it’s a fascinating look at a pre-Darwinian “chain of being” sort of mindset where all organisms were thought to exist in a fixed hierarchy with pre-set roles.