More than 150 million years ago, a strange dinosaur with spiky, armored skin roamed Earth.
That dinosaur was the ankylosaur, a close relative of the more well-known stegosaurus. Ankylosaurs likely traversed diverse regions of our planet between the late Jurassic and early Cretaceous periods. However, geographically limited fossil records have prevented us from knowing this bizarre ancient creature’s true range — until now.
A study published Thursday in the journal Nature Ecology & Evolution reveals the oldest known ankylosaur in the world — and the first to be found in Africa.
The findings unearth remarkable details about the “bizarre” appearance and evolution of the ankylosaur and suggest more dinosaur discoveries could be made in Africa.
“We’ve been looking for dinosaurs for a long time in Europe, Asia, and North America, but the southern continents, and particularly parts of Africa, are much less well-explored,” lead author Susannah Maidment, a researcher at the Natural History Museum in London, tells Inverse.
How the discovery was made — Using X-ray technology, Maidment and colleagues analyzed a specimen, NHMUK PV R37412, from the Natural History Museum of London. The specimen originated from Morocco, but the museum acquired it through a fossil dealer.
The specimen contained a rib with four rows of spines that were originally fused to the skin on the animal’s back.
“No known vertebrate, living or extinct, has armor fused to its bones.”
At first, the researcher thought they might be looking at an ancient bony fish. Further examination of the skin armor revealed it was a dinosaur.
What they found — The scientists identified the specimen as an ankylosaur dating to the Middle Jurassic period 163.5-168.3 million years ago.
The researchers named the dinosaur Spicomellus afer gen. et sp. nov. — a cheeky reference to the dinosaur’s unusual spike armor and geographical origin. “Spicus” is Latin for “spikes” and “afer” refers to a resident of Africa.
“Spicomellus, therefore, represents the oldest ankylosaur identified so far,” the study team writes.
It’s also, remarkably, the first ankylosaur specimen ever found in Africa.
The paleontologists describe the ankylosaur as having “bizarre” armor that’s fused to the animal’s rib and protrudes from the surface of the skin.
It’s a type of physiology so unique that it’s never been seen in any other vertebrate.
“This is weird because animals have muscles that run across the surface of the ribs. This ankylosaur must have had a different arrangement of muscles across its back,” Maidment tells Inverse.
“No known vertebrate, living or extinct, has armor fused to its bones,” she says.
Why it matters — The classification of Spicomellus afer gen. et sp. nov as an ankylosaur is significant for two reasons:
First, the fossil’s origins in Morocco suggest ankylosaurs did roam Africa. The study’s findings reveal the enormous potential for undiscovered fossil records of ankylosaurs, as well as other dinosaurs and ancient vertebrates, in Africa.
Because of a lack of paleontological interest in this region, especially compared to Europe, scientists may be missing out on key fossil specimens from the middle Jurassic period — a little-understood time in the ankylosaur’s history.
“The Middle Jurassic of Morocco hasn’t really been examined for dinosaur fossils before,” Maidment says.
Challenges in the fossil trade complicate matters even further and make study of any fossils in this region difficult.
“The beds where this specimen came from are being excavated by local collectors who primarily sell to the commercial market, so there’s little chance for scientists to systematically study the specimens,” Maidment says.
Second: the discovery dramatically challenges our understanding of the evolution of armored dinosaurs like the ankylosaur.
“We thought that ankylosaurs must have been around in Middle Jurassic ecosystems because their sister group, the stegosaurs, are known from this time period,” Maidment says.
Previous research suggests that stegosaurus became extinct, in part, due to competition with ankylosaurs, but this new discovery upends that theory. Instead, these two armored dinosaurs likely lived side-by-side.
“Spicomellus shows us that ankylosaurs were around during the Middle Jurassic and living alongside stegosaurs,” Maidment says.
The study team argues:
“The specimen reveals an unrealized morphological diversity of armored dinosaurs during their early evolution, and implies the presence of an important but undiscovered Gondwanan fossil record.”
What’s next — The researchers wanted to do on-site research in Morocco in 2020 but had to halt their plans due to SARS-CoV-2. They hope to do more excavation work with collectors on the ground, which would help scientists study fossils that might otherwise be commercially sold.
The limited fossil record from the Middle Jurassic period in Africa has to do with the fact that there are more marine fossil specimens from Europe and North America, where sea levels were higher during this era.
“Part of the problem is that there aren’t many Middle Jurassic terrestrial sequences of rock,” Maidment says.
Fossils of armored dinosaurs from the Middle Jurassic period from Gondwana — an ancient supercontinent comprising South America, Africa, Arabia, Madagascar, India, Australia, and Antarctica — especially tend to be lacking. Maidment intends to address that inequity.
“In future work, we want to explore other poorly sampled Middle Jurassic ecosystems to find more about the enigmatic dinosaurs that lived at this time,” Maidment tells Inverse.
Abstract: Ankylosauria is a diverse clade of armoured dinosaurs whose members were important constituents of many Cretaceous faunas. Phylogenetic analyses imply that the clade diverged from its sister taxon, Stegosauria, during the late Early Jurassic, but the fossil records of both clades are sparse until the Late Jurassic (~150 million years ago). Moreover, Ankylosauria is almost entirely restricted to former Laurasian continents, with only a single valid Gondwanan taxon. Spicomellus afer gen. et sp. nov. appears to represent the earliest-known ankylosaur and the first to be named from Africa, from the Middle Jurassic (Bathonian–Callovian) of Morocco, filling an important gap in dinosaur evolution. The specimen consists of a rib with spiked dermal armour fused to its dorsal surface, an unprecedented morphology among extinct and extant vertebrates. The specimen reveals an unrealized morphological diversity of armoured dinosaurs during their early evolution, and implies the presence of an important but undiscovered Gondwanan fossil record.