The team called the creature Halszkaraptor escuilliei. The name’s first half, pronounced “hull-shka-raptor,” honors Halszka Osmólska, a Polish paleontologist who discovered more than a dozen Mongolian dinosaurs and has at least four species named after her. The second half honors François Escuillié, the French collector who bought the fossil, alerted Godefroit, and worked to return the poached specimen to its rightful home in Mongolia. It currently sits in Brussels and will remain there for a year or so while the team finishes studying it.

Halszkaraptor is one of the theropods—a group of mostly meat-eating dinosaurs that count Tyrannosaurus and Velociraptor among their ranks. But unlike its kin, Halszkaraptor’s odd features suggest it was a strong swimmer that perhaps chased fish underwater, much like modern cormorants do. Outside of birds, “this is the first time we see that in a dinosaur,” says Cau. (Other ancient reptiles like paddle-limbed plesiosaurs and the dolphin-esque ichthyosaurs are not actually dinosaurs.)

Like many other fish-eating specialists, Halszkaraptor had a lot of teeth in the front of its snout—more than twice the number of a typical dinosaur. “The first time I saw that, I asked my colleagues to repeat the analysis because I wasn’t convinced,” says Cau. The snout also contained branching bony chambers that would have once housed a large network of blood vessels and sensory nerves. Such features are common in modern crocodiles, giving them an exquisite sense of touch.

Halszkaraptor’s neck made up half its length from snout to hip, reminiscent of plesiosaurs, several groups of freshwater turtles, and birds like swans and herons—all of which use their long necks to catch fish. Halszkaraptor’s neck bones also had more side-to-side mobility than those of the average theropod. “That might be an adaptation to swimming, or it may indicate that the animal used rapid sweeping motions of the neck to capture some sort of small prey,” says Michael Habib, from the University of Southern California.

The arms “are the most problematic part,” says Cau, because they’re not quite like anything else. The long bones are flattened, and the fingers get progressively longer from the outside in—the opposite pattern to most theropods. They’re closest in proportion to the limbs of swimming birds like puffins, murres, and penguins. But they’re not flippers. “I prefer not to say if [Halszkaraptor] used its arms propulsively,” says Cau. “We don’t have information on the shoulder girdle, which would be important to determine if it swam like a penguin.”

Despite all these adaptations for swimming, Halszkaraptor’s back half is that of a typical landlubbing theropod. It had long legs, although it wasn’t well adapted for running. It had a longish tail, although one that was too thin to effectively counterbalance the exceptionally long neck. To compensate, Halszkaraptor probably stood upright, more so than other raptors, but not quite as erect as a penguin. Cau thinks it lived in an unstable environment, with cycles of freshwater and drought. Halszkaraptor evolved to cope with both worlds.