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“Think of a low table. Short, wide, covered in spikes and walking towards you. It’s an ankylosaurus!”
Dr. Susie Maidment describes a fabulous new fossil in her possession.
All she has is a section of rib with attached teeth. But even from that, the paleontologist can say that this is a new species of armored dinosaur and the oldest ankylosaur ever found.
What is more, it comes from Africa, Morocco, where these creatures have never been unearthed before.
It’s pretty exciting, but there is also something very strange about this ancient specimen.
The tips are fused directly to the bone, and that’s a big headache, says Dr Maidment, affiliated with the Natural History Museum (NHM) in London.
Normally, you would expect the rib bones to be covered with muscle, then skin, and the armor – made of a protein called keratin, like your fingernails – to sit on it.
But that the tips are connected directly to the bone is just strange. On the one hand, you might think that this would restrict the extension of the muscles and make it difficult for the animal to move.
“Honestly, it’s weird,” Dr Maidment told BBC News.
“We don’t see this in any other vertebrate that exists (still alive) or extinct anywhere. It is a morphology totally unprecedented in the history of life on Earth.”
Dr. Maidment’s team were so taken aback by the fossil that they wondered for a moment whether it could be a fake or not at all an ankylosaurus; maybe it was a monster fish never identified before. But with detailed analysis and further investigation, it was possible to rule out both alternatives.
Most of us are probably more familiar with Stegosaurs. These were the armored dinosaurs that had a row of towering plaques along their spines. You will see a magnificent specimen, nicknamed Sophie, if you visit the NHM.
Ankylosaurs were their evolutionary cousins. And they’ve been very successful too.
They lived throughout the Cretaceous Period, until the asteroid struck 66 million years ago to wipe out 75% of all plant and animal species on the planet.
However, when precisely the ankylosaurs first appeared, the study is still ongoing, which makes this newly reported specimen very special.
It dates from the Middle Jurassic, around 168 million years ago.
This fills in important gaps in our knowledge of dinosaur history and strongly suggests that ankylosaurs had a worldwide distribution.
“Ankylosaurs are extremely well known from the northern continents, North America and Asia in particular. But they are extremely poorly known from the southern continents,” explained Dr Maidment.
“There have been some mouthwatering remains that suggest they were there, but we haven’t had much solid evidence other than a good specimen from Australia.
“This is Africa’s first ankylosaur, and it also dates from a very, very ancient period. We long suspected that ankylosaurs must have existed in the Middle Jurassic because we have Stegosaurs from the Middle Jurassic.
“Stegosaurs and ankylosaurs are closely related to each other, so it makes sense that if stegosaurs had evolved by then, so should the ankylosaurs.”
Dr. Maidment named the new dinosaur Spicomellus after.
Spicomella meaning “necklace of spikes” and close meaning “from Africa”.
The specimen was discovered by a farmer in the Middle Atlas Mountains in Morocco, in the same location where NHM researchers previously identified the oldest Stegosaurus ever found.
Dr Maidment had briefly visited the site before Covid restrictions made follow-up searches impossible.
When things return to normal, she will return to Morocco to see if there are any other pieces of the ankylosaurus that can help shed light on its unusual physiology.
The description of the new specimen is published in the journal Nature Ecology & Evolution.
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