A bizarre reptile once scurried through the Triassic treetops with an extravagant crest on its back, one made from neither scale, nor bone, nor feather.
The extinct creature’s 247-million-year-old fossils immediately stood out to paleontologists. The impressive appendage on its back looks like a frill of overlapping feathers at first glance, but it’s much older than the earliest fossilized feather, and there’s no branching to indicate a plume.
The elaborate structure also lacks bony spines, such as those seen in later dinosaurs, like Spinosaurus.
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“This had to be something new,” Stuttgart State Museum of Natural History paleontologist Stephan Spiekman told ScienceAlert.
“Prior to our discovery, complex outgrowths from the skin were restricted to mammals and birds and their closest relatives, predominantly in the form of feathers and hair.
“We now have another, different type of complex appendage, in a very early reptile.”
Long before dinosaurs evolved plumage, it appears that some early reptiles were already putting together a genetic toolkit for complex appendages.
The dorsal crests discovered by Spiekman and his colleagues are “basically novel to science”, so they don’t yet have a name for the appendage. In their study, the researchers essentially refer to them as skin outgrowths, but they aren’t actually similar to reptile skin.
Spiekman thinks the outgrowths may be made of keratin, similar to nails, hairs, scales, or claws. Confirming that suspicion will require further analysis.
Altogether, Spiekman and his colleagues studied more than 80 fossils of the outgrowths, recently donated to the State Museum of Natural History in Stuttgart, Germany.
The vast majority had lost their corresponding skeletons; only one of the fossils featured the bird-like skull of a small, ancient reptile.
The extinct animal has been named Mirasaura grauvogeli, the first part of which means ‘wonderous reptile’.
Technically, the species is a drepanosaur – a small, early reptile that lived in the trees, hunting insects with its velociraptor-like claws.
But its crest is the real stand-out feature.
“Mirasaura developed an alternative to feathers very early in Earth’s history, long before the dinosaurs, which we did not expect and which will stimulate discussion and research,” says reptile paleontologist Rainer Schoch, from the State Museum of Natural History in Stuttgart.
The exact function of the Mirasaura’s dorsal appendage is unknown, but based on the physics, it probably wasn’t used for flight or insulation. A role in visual communication, such as predator deterrence or intraspecies signaling, is more likely.
The best preserved Mirasaura fossils were found to contain traces of melanosomes, which are organelles within pigment cells.
Interestingly, their geometry is consistent with the melanosomes that color feathers, but not those found in reptile skin or mammal hair.
“Mirasaura really shows how surprising evolution can be, and how much we can still learn from palaeontology,” Spiekman told ScienceAlert.
“We already knew from genetics and developmental biology that much of the pathway to form feathers, hairs, and scales, is shared between mammals, reptiles, and birds. Now, with Mirasaura, we can say that such complex structures did indeed grow in other animals, too.”
Turns out, reptiles aren’t the scaly, simple animals we often paint them out to be. They deserve more credit.
The study was published in Nature.
