Month: December 2020

Guizhouichthyosaurus

In the mid-Triassic seas, covering what will one day be part of southwestern China, an ichthyosaur flails at the surface desperately trying to deal with an ambitiously large meal.

240 million years later human paleontologists will name their kind Guizhouichthyosaurus tangae, and initially assume that their narrow snout and small peg-like teeth are suited only for a diet of small soft-bodied fish and cephalopods.

In reality they eat a much wider range of prey – including other marine reptiles.

But for a 5m long (16’5″) Guizhouichthyosaurus, perhaps this particular catch is a little too much. The unlucky thalattosaur was a rather large example of a Xinpusaurus xingyiensis – nearly matching the ichthyosaur in length at around 4m long (13’2″), although much less bulky – and after biting off the head and tail the predator is still struggling to actually eat the sizeable carcass.

Even with a gravity assist from holding their prize vertically up above the water, swallowing is proving difficult and the Guizhouichthyosaurus can’t breathe around it.

They’re slowly suffocating.

They’ll eventually get it down their gullet, but by then it’ll be too late. Weak and dizzy from asphyxiation, they’ll soon sink to the sea floor and never resurface, their body settling not very far from where their prey’s severed tail fell.

Harpagofututor

Sometimes sexual dimorphism in the fossil record is hard to identify for certain – and sometimes it’s incredibly obvious.

Harpagofututor volsellorhinus here is a wonderful example of the second category. This 17cm long (~7″) cartilaginous fish was a distant relative of modern chimaeras, and lived during the Early Carboniferous about 326-318 million years ago in the shallow tropical sea that formed the Bear Gulch Limestone deposits in Montana, USA.

While all specimens show an elongated eel-like body, they come in two different forms: one with a fairly normal skull, and one with a pair of huge jointed cartilaginous appendages in front of its eyes that resemble antennae or antlers.

The presence of large claspers on the “antlered” forms indicated they were males, with the weird appendages probably being used either for display or as “grappling hooks” to hang onto females during mating.

(Modern male chimaeras also have clasping structures on their heads!)

Meanwhile a couple of non-antlered specimens preserved with unborn offspring still inside their bodies confirmed that these unadorned forms of Harpagofututor were indeed females. Some of their young were quite large and well-developed, suggesting live birth, and with multiple different fetal growth stages found within a single mother it’s also a rare example of fossilized superfetation.

Smilesaurus

Despite having a genus name that sounds more like it should belong to a cartoon dinosaur mascot for dental hygiene, Smilesaurus ferox was actually a real gorgonopsian, a predatory synapsid distantly related to modern mammals.

Living in South Africa during the Late Permian, around 259-254 million years ago, Smilesaurus was comparable to a medium-sized dog at around 1m long (3’3″). It had some of the longest sabre-like canine teeth of any known gorgonopsian, proportionally comparable to those of sabertoothed cats – and it may have hunted in a similar manner, using powerful grasping limbs to pin down struggling prey and then dispatching it with slashing bites.

…And it also turns out that when you don’t horribly shrink-wrap a gorgonopsian, you end up with something that looks rather like a bear-hippo.

(For some similarly chonky gorgonopsians, check out Tas’ @i-draws-dinosaurs reconstructions here. Bullet Man was definitely a bit of an inspiration in this.)

Leptostomia

Leptostomia begaaensis here is a recently-discovered pterosaur that lived during the mid-Cretaceous period, around 100 million years ago.

Its fossil remains were found in the Kem Kem beds of Morocco – ancient river deposits famous for yielding some of the newer specimens of the bizarre aquatic dinosaur Spinosaurus – and consist of just a couple of small pieces of jaw bones.

But those fragments are rather weird for a pterosaur.

While it’s hard to tell for certain from such meagre remains, Leptostomia might have been part of the azhdarchoid lineage, related to both the elaborately-crested tapejarids and the terrestrial-stalking giants like Quetzalcoatlus. And if it was indded an azhdarchoid it was an especially tiny one, possibly the smallest known member of the whole group. Based on the proportions of its relatives it would have stood just 30cm tall (1′) with a wingspan of 60-70cm (2′-2’4″), roughly comparable in size to a modern pigeon.

And it had an incredibly long beak that tapered to a thin delicate tip, resembling the beaks of modern probe-feeding shorebirds more than any other known pterosaur. It may have been specialized for the same sort of ecological niche, poking around in mud and shallow water for small invertebrates and snapping them up, possibly detecting its hidden prey using super-sensitive nerve endings in the tip of its beak.