cursed sauropod – Nix Illustration

Isisaurus

Isisaurus colberti was a sauropod dinosaur that lived in what is now India and Pakistan at the end of the Cretaceous Period, about 70-66 million years ago.

It was part of the titanosaur group of sauropods and had some unusual proportions* compared to its close relatives, with elongated forelimbs and a relatively short chunky neck. Since it’s only known from a partial skeleton its full size is unknown – estimates have been made as large as 18m long (~60′) but it was probably somewhat smaller, closer to around 11m in length (36′).

(*Measurement errors in the original paper resulted in some very weird proportions, but more recent and rigorous reconstructions have made Isisaurus not quite so cursed-looking.)

Like most other titanosaurs it probably lacked the thumb claws seen in other sauropods, and it may also have had some bony osteoderm armor studding its skin.

Coprolites that may represent Isisaurus’ poop show evidence of several different fungi that grow on tree leaves in humid tropical and subtropical climates, suggesting that this sauropod was a selective browser somewhat like modern giraffes.

Atlasaurus

Sauropod dinosaurs were just generally weird animals, but there’s something… not quite right about Atlasaurus imelakei.

Named after the Atlas Mountains of Morocco where its fossil remains were discovered, Atlasaurus lived during the mid-Jurassic period, around 168-165 million years ago. While it wasn’t the strangest–looking sauropod by any means, compared to other species its body proportions still show a particularly bizarre combination of features, with a slightly bigger head, unusually short neck, and very long slender legs that made up nearly half of its 9m height (29’6″).

It’s sort of the uncanny valley of sauropods. Everything about it is just a tiny bit wrong.

A photograph of an Atlasaurus model. Its been reconstructed very skinny, which only serve to emphasize its weird proportions. — And more shrinkwrapped depictions really don’t help with that. [image source]

Its tall shoulders and sloping back resemble the body plan of brachiosaurids so closely that it was initially thought to be an early member of that group, but more recent studies suggest it may have been part of an earlier evolutionary branch of sauropods known as the turiasaurs – which would mean its brachiosaur-like shape was actually the result of convergent evolution.

But what was it doing with such weird proportions?

…We really don’t know. Other short-necked sauropods seem to have been adapted for feeding on lower vegetation only a couple of meters off the ground, but Atlasaurus’ leggy build would have made it a high browser like the brachiosaurids it was mimicking. Its long legs may also have allowed it to move faster, or given it some advantage navigating over rough terrain, but since no other sauropod ever seemed to evolve this way it must have been doing something particularly unique.

Or perhaps it was just an evolutionary fluke. Maybe part of a lineage that had started adapting to short-necked low browsing, then moved back towards the high browsing niche – and happened to end up lengthening their legs instead of their necks to get the necessary height back.

Brachytrachelopan

Aaand we’re back to normal updates with a fully working computer again!

Let’s properly start off this year’s art pieces with a particularly weird sauropod dinosaur. This is Brachytrachelopan, known from Argentina at the very end of the Jurassic (~152-145 mya).

A member of the dicraeosaurids, it was a close relative of the spiky-necked Amargasaurus and was roughly the same size at about 10m long (32′9″) – but it also had the shortest neck of any known sauropod, suggesting it was specialized for a completely different diet. It may have been a sort of “iguanodont-mimic”, adapted to a low browsing niche, since actual iguanodonts were absent from its ecosystem.

I’ve given this one a little bit of speculative bristly fuzz, because I can. While all currently known sauropod skin impressions show scales, we don’t have full-body coverage and fuzz was almost certainly present in their ancestors – and both types of integument can also exist on the same animal in the same places.

~~Also I just like the idea of sauropods with manes and beards.~~