Fossil forelimb reveals new species with claws designed for takeout meals
This dinosaur had a penchant for stealing eggs.
New analysis of a fossilized forelimb and claw approximately 67 million years old suggests that a rare group of small Mongolian dinosaurs may have evolved to fly and eat eggs. The “remarkable” appendage was distinctive enough to classify its owner as a new genus and species, Manipulonyx reshetovireport the researchers on December 23 in the Proceedings of the Zoological Institute of the Russian Academy of Sciences.
“It’s a spectacular arm,” says Denver Fowler, a paleontologist at the Badlands Dinosaur Museum in Dickinson, North Dakota, who was not involved in the study. “The fact that this is the most complete arm of these already bizarre dinosaurs is exceptional; their arms were even stranger than we thought.”
The arm and claw were discovered in 1979 in the Nemegt Formation in Mongolia’s Gobi Desert, alongside several fragments of legs, vertebrae and pelvis. The bones represent a member of a family of feathered dinosaurs called alvarezsaurids, which ranged in size from 50 centimeters to 2 meters long and had shrunken arms and long legs. The specimen, which likely came from a 50 cm long species, languished in Russian museum archives until recently, when new preparations slowly revealed its previously unseen features.
“Manipulonyx had a large first finger and two tiny second and third fingers, but it appears to have spikes on its hands,” which is unprecedented for carnivorous dinosaurs, says Michael Pittman, a paleobiologist at the Chinese University of Hong Kong. who reported a similarly bizarre alvarezsaurid claw in 2011.
Previous research suggested that alvarezsaurids were primarily insectivorous, using their short, strong forearms to dig and pluck termites from their mounds. But the new bone analysis lends credence to a different strategy. “Such a member would have been completely unsuitable for destroying termite mounds,” says Alexei Lopatin, a paleontologist at the Russian Academy of Sciences who studied the museum specimen. “The thin piercing claw would have broken in the process, and the fragile, residual fingers and tips would have been damaged.”
Instead of hunting for buried insects, these dinosaurs used their uniquely shaped claws and spikes to scoop up, pierce and steal eggs, grabbing them tightly before running away, Lopatin and his colleagues say.
Egg-stealing dinosaurs are not a new concept in paleontology. Oviraptoranother Gobi Desert dinosaur whose name translates to “egg thief,” was thought to subsist on a diet of stolen eggs. It was found alongside several egg fragments, which paleontologists initially interpreted as a last meal. Subsequent research determined these fragments most likely came from his own broodupsetting the initial hypothesis.
“Oviraptor I didn’t eat eggs,” Lopatin says. Manipulonyxon the other hand, “had all the adaptations to do so”.
In 2018, Chinese researchers even predicted that another species of alvarezsaurid could have eaten eggsbut until now convincing evidence to support this hypothesis was lacking, explains Lopatin.
Pittman says the egg theft hypothesis is “very interesting” and worth testing further. Fowler agrees but isn’t yet convinced it’s a better idea than digging for insects. “I don’t know if it’s very practical to crush an egg in your arms and then put it down and eat it on the ground, especially since this dinosaur family was covered in feathers,” he says. A quick meal of eggs would result in messy plumage.