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What do you get when you cross a raptor and several types of waterbirds? It’s not a question anyone was asking, but sometimes the natural world surprises us. This week in Nature, researchers announced the discovery of Halszkaraptor escuilliei, a bizarre little dinosaur that may have thrived on land and in the water. 

The dinosaur, which is known from a partially exposed block of stone from the Late Cretaceous sandstones of Mongolia, shows a strange grab bag of traits. Its slender legs and tail are standard parts of the raptor template. But its neck and skull are long, like a swan’s; its center of gravity gave it a goose’s waddle; and short, broad forelimbs look like those of swimming birds like penguins.

“It is the first time a bird-like dinosaur shows so many semi-aquatic features,” says lead author Andrea Cau, a vertebrate paleontologist at the University of Bologna, Italy. “We suggest it was comparable to some aquatic birds of today in ecology: an opportunistic predator able to exploit both terrestrial and aquatic resources, that relied on the long neck for foraging.”

That adaptability would have come in handy in the uncertain climes of Mesozoic Mongolia. Clues in the rock of the Gobi Desert suggest that the scrub deserts were strongly seasonal, veering between humid and semi-arid conditions. The formation where Halszkaraptor was found teems with small-bodied mammals and lizards, as well as related species like Velociraptor. Halszkaraptor’s anatomy might have helped it exploit food sources other dinosaurs missed. This strategy isn't far off from those seen today: Plenty of modern birds, including seabirds, herons, and even some songbirds, are surprisingly adept at foraging on both land and water.

Halszkaraptor is part of a sprawling and varied group called the Maniraptorans, an assemblage of animals that includes birds and related dinosaurs. While superficially bird-like, it isn’t a direct ancestor; instead, it belongs to a new family at the base of the dromaeosaurs, better known for producing Velociraptor.

According to Darren Naish, a paleontologist from the University of Southampton who was not involved in the study, Halszkaraptor isn’t the first member of the raptor family suggested to dine on fish: the unenlagiine dromaeosaurids of South America had long skulls and teeth which may have aided them in snapping up aquatic game. But Halszkaraptor seems to have really committed to the bit. “It’s really a surprise,” Naish says. “It looks like some kind of toothed, short-armed pseudo-goose.”

Interesting as the specimen is, it nearly didn’t come to scientific attention at all, Cau says. The fossil, which is still partially entombed in a block of stone, was originally poached from Mongolia. It passed through several private collections before a French fossil dealer acquired it and donated it to the Royal Belgian Institute of Natural Sciences. Rather than excavating the skeleton, Cau and his colleagues used a high-resolution synchrotron radiation scanning method to examine the block. (The specimen will be returned to Mongolia once the study is completed.) The method is a good way to make sure that the fossil is genuine: fossil poachers have been known to cobble together chimeras in hopes of selling to collectors or scientists, resulting in egg on the face of all concerned. 

That’s a good reason for some elements of Halszkaraptor to be taken with a grain of salt, says Steve Brusatte, a paleontologist at University of Edinburgh who wasn’t involved in the study. While the authors have done a good job demonstrating the specimen is real, the fact that its origins are unclear means there’s always some possibility of tampering. Plus, some of the features that the authors suggest indicate a semi-aquatic lifestyle—like the long neck—are seen on other small predatory dinosaurs and living birds like the Ostrich. “[A semi-aquatic niche] is a neat idea, and one that needs to be tested further by new fossil discoveries,” Brusatte says. “If somebody finds soft tissues on one of these fossils, that could help seal the deal whether it had flippers or other signature features of semi-aquatic creatures.”

As unlikely as the dinosaur appears in the artistic reconstructions, Cau stands by it. But more data is forthcoming, he promises: The team collected six Terabytes of scan data on the fossil that await observation, comparison, and reconstruction. “This was just the first step in the study of this new group of dinosaurs," he says.