Incredibly preserved dinosaur embryo found inside fossilized egg

The dinosaur, known as an oviraptorosaur (oviraptor), is part of a group of bird-like theropod dinosaurs that flourished throughout the Cretaceous Period (145 to 66 million years ago).

The adult oviraptor fossils and embryonic eggs have been dated to around 70 million years ago. This is the first time researchers have discovered a non-avian dinosaur resting on a petrified nest of eggs, which still contain the baby within!

The fossil in question is a 70-million-year-old adult oviraptorid theropod dinosaur sitting atop a nest of its petrified eggs. Multiple eggs (at least three of which contain embryos) are visible, as are the adult’s forearms, pelvis, hind limbs, and a portion of the tail. (Indiana University of Pennsylvania’s Shandong Bi)

What do scientists have to say about the discovery?

The study’s lead author, Dr. Shundong Bi of the Centre for Vertebrate Evolutionary Biology, Institute of Palaeontology, Yunnan University, China, and Department of Biology, Indiana University of Pennsylvania, USA, stated in a press release, “Dinosaurs preserved on their nests are rare, and so are fossil embryos. This is the first time a non-avian dinosaur has been found, sitting on a nest of eggs that preserve embryos, in a single spectacular specimen.”

Although scientists have spotted adult oviraptors on their nests with eggs before, this is the first time embryos have been discovered within the eggs. Study co-author Dr. Lamanna, a paleontologist from the Carnegie Museum of Natural History, USA, explains: “This kind of discovery, in essence, fossilized behavior, is the rarest of the rare in dinosaurs. Though a few adult oviraptorids have been found on nests of their eggs before, no embryos have ever been found inside those eggs.”

Dr. Xu, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, and one of the study’s authors, believes that this uncommon discovery contains a wealth of information, “It’s extraordinary to think how much biological information is captured in just this single fossil.” Dr. Xu says, “We’re going to be learning from this specimen for many years to come.”

The fossilized eggs were about to hatch!

The scientists discovered an adult oviraptor’s fragmentary skeleton with stones in its stomach. This is an example of gastroliths, “stomach stones,” which the creature had consumed to help it digest its food. It’s also the first instance of undisputed gastroliths discovered in an oviraptorid, which the scientists feel might help shed light on the dinosaurs’ nutrition.

In a brooding or protective stance, the dinosaur was discovered crouching over a nest of at least 24 fossilized eggs. This indicates that the dinosaur perished while brooding or protecting its babies.

However, when the researchers utilized oxygen isotope analysis on the eggs, they discovered that they had been incubated at high, bird-like temperatures, lending credence to the theory that the adult perished while brooding its nest.

At least seven of the fossilized eggs still had unhatched oviraptorid embryos inside them. Scientists believe that some of the eggs were on the edge of hatching based on the development of the sources. According to Dr. Lamanna, “This dinosaur was a caring parent that ultimately gave its life while nurturing its young.”