The fossilized remains of a dinosaur perched on an egg nest, complete with embryos preserved inside, have been exhumed from China, a study reported.
The discovery – a world premiere – is an oviraptorosaur, one of a group of bird-like theropod dinosaurs that thrived 130-66 million years ago during the Cretaceous.
According to experts, the specimen in question was found in 70 million-year-old rocks excavated near the station in Ganzhou City, Jiangxi Province.
The adult oviraptorosaur was partially kept with the chicks over the clutch of at least 24 eggs, of which at least seven contain skeletal remains of the unbroken young.
Late embryo development has allowed paleontologists to rule out the possibility that the adult may have died during egg laying.
Instead, the finding suggests that oviraptorosaurs incubated their nests like their modern cousins of birds – rather than guarding their nests in the manner of a crocodile.
This was supported by oxygen isotope analyzes of the eggs, which indicated that they were incubated at high temperatures just like modern bird eggs.
One study reported that fossilized remains of a dinosaur perched on an egg nest, complete with embryos preserved inside, were unearthed from China.
The adult oviraptorosaur was partially kept with the chicks over the clutch of at least 24 eggs, of which at least seven contain skeletal remains of the unbroken young. In the picture: a photo of the fossilized specimens, on the left and in the illustration, on the right
“This type of discovery – essentially fossilized behavior – is the rarest of the dinosaurs,” said paper author and vertebrate paleontologist Matthew Lamanna of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.
“Although several adult oviraptorids have been found in the nests of their eggs before, no embryos have ever been found inside these eggs.”
“In the new specimen, the babies were almost ready to hatch, which no doubt tells us that this oviraptorid had cared for its nest for a long time.”
“This dinosaur was a caring parent who eventually gave his life while caring for his cubs,” he concluded.
Analysis of fossil embryos showed that, although all were well developed, some had reached a more mature stage than others, suggesting that if they had not been buried and fossilized, they would probably have hatched at slightly different times.
This feature – which experts call “asynchronous hatching” – appears to have evolved independently in oviraptoris dinosaurs and some modern birds, the researchers explained.
The team also found a group of pebbles preserved in the abdominal region of the adult oviraptorid, which they said were gastroliths or “stomach stones” that were allegedly swallowed to help the dinosaur digest its food.
This is the first time that verified gastroliths have been found preserved in a fossilized oviraptorid and can therefore lead to new information about their diets.
Late embryo development has allowed paleontologists to rule out the possibility that the adult may have died during egg laying. Instead, the finding suggests that oviraptorosaurs incubated their nests like their modern cousins of birds – rather than guarding their nests in the manner of a crocodile. Pictured is a cut diagram of the skeleton of an adult oviraptorosaur (with preserved bones in white) hatching its egg clutch
Fossil embryo analysis (pictured) showed that although all were well developed, some had reached a more mature stage than others, suggesting that if they had not been buried and fossilized, they would probably have hatched at slightly different times.
“It’s amazing to think about how much biological information is captured in this single fossil,” said vertebrate paleontologist Xing Xu of the Chinese Academy of Sciences in Beijing.
“We will learn from this specimen for many years to come,” he added.
The full results of the study were published in the journal Science Bulletin.
The specimen was found in 70-million-year-old rocks excavated near the railway station in Ganzhou City, Jiangxi Province.