Modern chickens are a lot like dinosaurs, but there’s there’s a big difference that’s’s actually a little tender.

When a chicken sits on its eggs, it uses its beak to tuck them underneath and fluffs itself out to get the entire clutch under its feathers. Placing its body weight directly on the sturdy sturdy sturdy sturdy eggs allows the bird to partake in contact incubation: If the eggs are warmed at the right temperature, little hatchlings are born.

Meanwhile, the Oviraptorosaurs did things differently. These featheheheed, bird-like dinosaurssss lived 65 million years ago and,,,, at their largest, at their largest, at their largest, at their largest, could be as heavy as a rhinoceros. These big girls took care of their clutch of eggs without crushing them into Late Cretaceous omelets. This revelation is the focus of a study published Wednesday in Biology Letters.

An international team of scientist determined that the nests of the largest oviraptorosaurs were designed a lot like an inner tube: A circle of eggs with a space in the middle for the mama dinosaur.

“Our results suggest that the smallest oviraptorosaurs probably sat directly on the eggs, whereas with increasing body size, more weight was likely carried by the central opening, reducing or eliminating the load on the eggs and still potentially allowing for some contact during incubation in giant species,” the scientists write. “This adaptation, not seen in birds, appears to remove the body size constraints of incubation behavior in giant oviraptorosaurs.”

Oviraptorosaur, dinosaur eggs
How oviraptorosaurs sat with their eggs depended on their size

To get to this conclusion, the team studied 40 fossilized oviraptosaur nests of varying sizes spread throughout Mongolia and China — some just a foot wide while others were spread 10 feet across. The scientists noticed that in the smaller nests, the fossilized eggs were clustered together while the larger nests were more donut-like: Each included space in the middle, surrounded by an inclining spiral of two to three layers of eggs.

Study co-author and University of Calgary paleontologist Darla Zelenitsky, Ph.D. told National Geographic that they’re not exactly sure why oviraptorosaurs sat with their eggs: It’s probable that they were just providing shelter, or like birds today, being near the eggs provided some semblance of necessary warmth. “Most likely this behavior of sitting on the nest evolved first in dinosaurs,” Zelenitsky explains.

But it’s also obvious that the biggest dinosaurs simply couldn’t sit directly on their eggs without crushing them, hence the elaborate design. Most oviraptorosaur fossils have been foundsitting directly on top of their ancients nests — proving that, if anything, they were dedicated moms.