Over 20 years ago, a unique fossil was unearthed in the Henan Province of China: a dinosaur embryo surrounded by a nest of eggs. Since then, the little petrified creature has travelled across the world and even earned the affectionate nickname "Baby Louie". But one big question has remained all this time – who were Louie's parents?

The eggs in Louie's nest are huge. At over 40 centimetres (16in) long and weighing five kilograms (11lbs), they're some of the largest dinosaur eggs ever discovered. But just like ancient trackways, it can be very difficult to connect prehistoric eggs with the species that produced them. Now, an international team of researchers has cracked a part of the riddle.

"For many years, it was a mystery as to what kind of dinosaur laid these enormous eggs and nests," says Darla Zelenitsky of the University of Calgary. "Thanks to this fossil, we now know that these eggs were laid by a gigantic oviraptorosaur, a dinosaur that would have looked a lot like an overgrown cassowary."

Baby Louie was found outside of an egg, probably forced out shortly before hatching. This illustration also shows how it would have curled up inside as it developed. Image: Zhao Chuang

Baby Louie finally has a species name: Beibeilong sinensis, or "baby dragon from China". The fossil is only 38 centimetres (15in) from snout to rear (the tail is missing, along with parts of the legs), but based on the size of the eggs, the researchers suspect that the parents would have reached sizes similar to the famous Gigantoraptor: eight metres (26ft) long and weighing at least a couple of tons! Beibeilong adults would have been some of the biggest two-legged dinosaurs around in China 90 million years ago.

Oviraptorosaurs were bipedal and covered in feathers, with toothless beaked mouths and often showy crests on their heads – the comparison with a cassowary is quite accurate. But Beibeilong and Gigantoraptor are odd ducks (so to speak), as most known members of this group are around the size of a Velociraptor.

However, our picture of these dinosaurs' diversity may be lacking. Giant eggs just like Baby Louie's have been found in several countries across Asia and North America, indicating that Beibeilong and closely related feathery behemoths were much more widespread than their fossil record implies.

The fossil of Baby Louie the Beibeilong embryo sitting among its nest of eggs, which are dark grey in colour. Image: Darla Zelenitsky.

Baby Louie's identification also coincides with its return home. After the discovery of the fossil in the early 1990s, the little dino and its nest of eggs, like so many others, were sold to private collectors in the US. It took an estimated 700 hours of meticulous excavation from encasing rocks, but the eggs and embryo were finally revealed (and featured in a 1996 National Geographic article). In 2001, the fossil made its way to the Indianapolis Children's Museum to go on display.

But although palaeontologists yearned to study Baby Louie up close, legal issues hampered research for decades – this dinosaur should never have been removed from its home country.

"The eggs and embryo gained worldwide fame," says University of Alberta's Phil Currie, "but it was impossible to describe them in a scientific journal – and to name the new species – until the fossils were repatriated to China." Now Louie is back home in the Henan Province, in the Henan Geological Museum.

Identifying a new dinosaur is always exciting, but we may need to find adult Beibeilong before we can say much more about this species. "Embryos, juveniles and hatchlings [of oviraptorosaur dinosaurs] are either not known or poorly known," says Steve Jasinski of the University of Pennsylvania, who wasn't involved in this research. "It is difficult to compare babies of one species with adults of another."

While Jasinski does agree that Beibeilong looks to be an oviraptorosaur, he thinks there may be surprises in store. "I think the diagnosis and definition of the species will change when an adult is found." 

Until then, there is one other thing we know about this species: its nesting habits.

Artist’s reconstruction of full-grown Beibeilong, incubating its giant eggs under its warm feathery body. Image: Zhao Chunag

Baby Louie was fossilised along with more than half a dozen other eggs, but based on other nests of this egg type, the researchers infer that the full clutch would have included over 20 eggs laid out in concentric rings up to three metres (10ft) across.

Based on other fossils, we know that smaller oviraptorosaurs sat in the centre of their nest rings, covering the eggs with their feathered bodies much like brooding birds do today.

Given its similar nest structure, could Beibeilong have been among the world's biggest brooders? Zelenitsky thinks so. "It would have been a sight to behold with a three ton animal like this sitting on its nest of eggs."


 The new study on Beibeilong was published in the journal Nature Communications by a team of researchers from China, Canada, Slovakia and the US.