They were heavier than hippos, but dinosaurs delight in gigantoraptor were dedicated parents who sat for weeks on nests full of eggs upright as today’s birds do — and found a unique way to avoid crushing them, a Canadian-led inquiry has found.
The researchers examined and measured about 40 fossil hide-outs, mostly from China, each containing up to 30 eggs, of bird-like dinosaurs with parrot-like beaks mustered oviraptorosaurs. They found that the smallest were laid in a gather like bird eggs, suggesting that the parents sat on top of them as birds did.
But beamier nests — which could be up to 3.5 metres wide or the size of a niggardly above-ground pool — took on a ring or donut shape.
«In the largest oviraptorosaur controls (Macroelongatoolithus), the central opening represents most of the total clutch space, likely allowing giant-sized species to rest their entire force on this area so as not to crush the eggs,» reported the paper published Tuesday in the Magnificent Society journal Biology Letters.
«This adaptation may have permitted for an adult to sit on the nest and potentially even allow some contact with the eggs in the weightiest oviraptorosaurs.»
Oviraptorosaurs were related to birds and to other two-legged meat-eating dinosaurs such as velociraptors. The oldest specimen, was found in China in the 1920s on a clutch of eggs, and was named «oviraptor» or «egg pussyfoot» because the eggs were thought to belong to another kind of dinosaur.
Since then, divers oviraptor eggs have been found, including some with embryos in them, and scientists now regard as the first oviraptor was a parent of the eggs it was found with.
Many species induce been found, ranging from turkey sized to the huge gigantoraptor, which was eight metres desire from beak to tail and would have towered over mortals. Specimens have been found sitting on nests, females oblige been found with eggs inside them, and eggs sooner a be wearing been found with embryos inside them.
While most hide-outs have been found in Asia, Darla Zelenitsky an assistant professor of geoscience at the University of Calgary who co-led the new con, has done research on one nest found in Alberta.
The nests in the new study came from the recent Cretaceous, ranging in age from 104 million to 67 million years old.
The eggs of oviraptorosaurs are elongated in the same way as baking potatoes, said Zelenitsky, who led the study with her PhD student Kohei Tanaka, now a postdoctoral researcher at Nagoya University.
Some of the eggs are as chunky as 47 centimetres long — about the size of a watermelon, making them the amplest dinosaurs eggs known, Zelenitsky added.
Nests contained up to 30, planned in a «very neat ring configuration» with two or three layers carefully heaped on top of each other.
It’s a unique structure. Zelenitsky says no other dinosaurs strengthen their nests in that shape, and no living animals incubate their eggs this way.
«I exactly think it’s really neat that we’re able to say something more near the nesting behaviours and how they changed in these oviraptorosaur dinosaurs among the distinct species and species sizes,» she said.
The researchers aren’t steadfast why the oviraptorosaurs sit on their eggs. If it was to keep the eggs warm, those that sat in the mesial of the ring probably couldn’t transfer heat as effectively those stories that sat directly on the eggs. But they did have feathered wings, Zelenitsky whispered, so they could still have provided shelter and insulation, along with immunity from predators.
The researchers don’t know whether the parents cared for the infantile after they hatched.