German paleontologists have discovered a 247-million-year-old fossil of a reptile with a bizarre row of plumes sprouting from its back. The elaborate display is a paradox of evolution. The plumes bear some similarities to feathers, even though the newly discovered reptile was not closely related to birds.
Stephan Spiekman, a paleontologist at the Stuttgart State Museum of Natural History in Germany and an author of the new study, said that the discovery could change how scientists think about the origin of feathers. In birds, a complex network of genes is enlisted to sprout feathers from their skin. Part of the network might have already evolved in early reptiles more than 300 million years ago.
If that’s true, Spiekman said, it would mean that other ancient reptiles might have sprouted strange ornaments of their own that are waiting to be discovered.
“I hope this will broaden our perspective,” Spiekman said. “And then who knows what we’ll find?”
In their study, which was published Wednesday in the journal Nature, Spiekman and his colleagues named the reptile Mirasaura grauvogeli. In Latin, Mirasaura means “wonderful reptile.” And grauvogeli honors Louis Grauvogel, the French paleontologist who dug up the fossil in 1939.
Grauvogel was a wealthy factory owner with training in biology. He spent much of his free time looking for fossils in the quarries of northeastern France, and by the time he died in 1987, he had built up a huge private collection of animal and plant remains. His daughter, Lea Grauvogel-Stamm, herself an accomplished paleontologist, donated the fossils to the Stuttgart Museum in 2019.
When Grauvogel first uncovered Mirasaura in 1939, he could see only the animal’s crest exposed in a rock. He speculated that he had found the fin of a fish.
Eighty years later, when the Stuttgart scientists began inspecting Grauvogel’s collection, they noticed that his supposed fish fin was actually connected to a reptile bone at one end. The rest of the bone was hidden in the rock.
The researchers picked away at the rock and discovered the rest of Mirasaura’s skeleton. A further inspection of Grauvogel’s fossil collection revealed more crests, along with a second skeleton.
Looking at Mirasaura, Spiekman was immediately reminded of one of the most mysterious reptile fossils ever found, a 220-million-year-old creature called Longisquama insignis.
Discovered in Central Asia in 1969, Longisquama’s fossil preserved impressions of long, flat projections extending from its back. Its discoverers speculated that these were elongated scales that had fanned out to either side of Longisquama’s body. The reptile used them like parachutes, they claimed, slowing its fall as it jumped from trees.
In 2000, a team of American researchers offered a controversial new theory: Longisquama’s parachute scales were actually feathers, and Longisquama might be an ancient relative to today’s birds.
That view eventually fell out of favor, as paleontologists subsequently discovered many dinosaurs with feathers dating to 160 million years ago. Some of these structures were almost as complex as bird feathers; others were simple wires. It is now clear that birds are living dinosaurs.
Longisquama drifted into a scientific limbo: No one could say what kind of reptile it was, and the nature of its plumes remained anyone’s guess. “The consensus became, ‘We really don’t know what Longisquama is – it’s a weird reptile,’” Spiekman said.
With the discovery of Mirasaura, Longisquama gains a cousin. And even though Mirasaura lived almost 30 million years earlier than Longisquama, its fossils were in far better shape. Spiekman and his colleagues could study its crest in microscopic detail and inspect its exquisitely preserved skull.
Their analysis shows that Mirasaura and Longisquama belonged to an extinct lineage of reptiles that specialized in living in trees. That lineage is only distantly related to birds and dinosaurs, having split off on its own more than 300 million years ago.
Based on that finding, the scientists argue that the plumes of Mirasaura and Longisquama evolved from ordinary reptile skin. Birdlike dinosaurs independently evolved feathers.
A close inspection of Mirasaura’s crest supported that conclusion, revealing some fundamental differences from feathers. Feathers are made of branching fibers, for example, while Mirasaura sported stiff sheets that grew from a central ridge.
But Spiekman and his colleagues also concluded that Mirasaura’s crest bore some important similarities to feathers. Feathers gain some of their color from microscopic sacs of pigment called melanosomes. Mirasaura’s crest also contains melanosomes, and they have the same shape as feather melanosomes.
The shape of Mirasaura’s plumes also suggests to Spiekman that they grew in a featherlike way, developing from a ring of cells that rose up from the skin before fanning out.
If the researchers are right, then the common ancestor of Mirasaura and birds must have already carried some of the genetic instructions for building featherlike growths. Only some reptiles went on to use those instructions to that end.
As for how Mirasaura used its crest, Spiekman discounts the idea of parachuting from the trees. The new fossils clearly show that the crest stood straight up on the animal’s back – a position not conducive to slowing a fall.
“And that, for us, only really leaves some sort of display as a potential option,” Spiekman said. One possibility is that Mirasaura used its crest to show off, akin to how male anole lizards attract mates with a colorful flap of skin under their jaw.
These ideas are likely to set off a new round of debates. Richard Prum, an ornithologist at Yale University who was not involved in the new research, questioned whether Mirasaura’s crest had much in common with feathers. “I think that’s a real mistake,” he said.
He also held out the possibility that the crest was not a sheet of dead cells but, perhaps, a sheet of living tissue with blood coursing through it. “Thermal regulation becomes a prospect – absorbing the sun so they can get lots of energy to run around quicker,” Prum speculated.
Whatever Mirasaura’s strange anatomy turns out to have been, Prum agreed that the find highlights the underappreciated versatility of reptile skin.
“It’s a fascinating thing,” he said.
This article originally appeared in The New York Times.
