New Dinosaur Species Leaves Experts 'Flabbergasted'

A newly described dinosaur seems to have come with its own built-in egg-grabber. In a study published in the Proceedings of the Zoological Institute of the Russian Academy of Sciences, researchers unveil Manipulonyx reshetovi, a small Late Cretaceous dinosaur with one of the strangest forelimbs yet seen. About the size of a dog, the dinosaur had a hand dominated by a large claw, flanked by smaller digits and three bony spikes that may have helped it latch onto smooth objects—like dinosaur eggs, the New York Times reports. "I've honestly never been more flabbergasted by any dinosaur fossil," outside paleontologist Stephen Brusatte tells the outlet, noting he initially wondered if the fossil hand even belonged to a dinosaur.

The partial skeleton was first dug up in 1979 in Mongolia's Gobi Desert, a former river delta that 67 million years ago hosted a wide variety of dinosaurs. Manipulonyx (meaning "manipulating claw") belongs to the alvarezsaurids, a family of small, long-legged dinosaurs with short forearms ending in a single oversized claw and much-reduced side digits—features that once led some scientists to mistake them for flightless birds. How these animals used their peculiar arms has been debated: some researchers argue they tore into insect nests like anteaters, others that their stubby arms couldn't reach the ground and were instead suited to raiding nests.

What makes Manipulonyx stand out, lead author Alexander Averianov says, is the rare preservation of its wrist and hand. The fossil shows articulated wrist bones, tiny side fingers, and three spikes likely sheathed in keratin. One spike sat along the inner hand, another between the main claw and smaller fingers, and a third projected from the palm—an arrangement that outside researcher Michael Pittman calls "totally unexpected" for this group.

Averianov's team suggests the spikes and fingers worked together to clamp slippery eggs while the main claw split them open, perhaps during nighttime nest raids aided by good vision and hearing. Other evidence points in the same direction: another alvarezsaurid was found with oviraptorid eggshell fragments, and the original label on the Manipulonyx fossil notes nearby eggshells as well, the Times reports. Brusatte finds the egg-thief idea reasonable but says the real function could be even odder. "All I'm confident in saying is that they weren't using these arms and hands to fly or swim," he says.