The unearthing of the prehistoric remains of dinosaurs, while possible, often occurs in a sporadic way, and besides very few exceptions, yields relatively small and scattered amounts. For this reason, the discovery of more than 200 preserved eggs has excited the scientific community.
The eggs date back more than 120 million years and were found on the banks of a lake in northwest China in almost pristine condition. The banks were the perfect nesting site for a group of pterosaurs, and with the appearance of a powerful sandstorm, the eggs became buried. Prior to this discovery, in distant Argentina as well as in China three and five eggs, respectively, had been unearthed. The numbers, for now, are 215, though scientists believe that as many as 300 may be buried. What's even more incredible is the fully-preserved three-dimensional pterosaur embryo found, the only of its kind ever recovered.
The findings of the team were published on December 1st in an article titled “Egg accumulation with 3D embryos provides insight into the life history of a pterosaur” in Science Advances. The remains were all traced back to a single species, Hamipterus tianshanensis, whose remains the same team had also recovered in 2014.
The scientists have been able to use these remains to construct a clearer narrative about both the pterosaur as well as how the eggs came to be found at this location. They believe that several females were nesting one area, though the size variation in the eggs makes it difficult for them to identify a consistent clutch size pattern. Moreover, the team theorizes that the sandstorm created the conditions for the nests to be blown away and scattered on the lake, before sinking and becoming lodged in the sediment bed.
Shunxing Jiang, study co-author and researcher with the Chinese Academy of Sciences, discusses how the differences in the environment existing in those times played a role in preserving the eggs: “The site is in the Gobi desert, and there are strong winds, a lot of sand, with few plants and animals,” said Jiang, adding “However, when Hamipterus lived, the environment [was] much better—we call it Pterosaur Eden.”
From the embryos, the team also gathers that—given the fact that the legs were relatively more developed than the wings— most likely the pterosaurs would have needed additional support as they would not be able to fly initially after hatching.
Queen Mary University of London Researcher David Hone, though not involved directly with the study, assesses the impact of the find in the field: “We get a lot of hyperbole in paleontology, but it’s pretty phenomenal,” he said, adding, “The science is at the absolute start, but the mere raw material is game-changing, potentially.”
No doubt additional studies will need to be carried out to create a proper frame of analysis for the team, but their work is receiving the praise of the paleontological community around the globe: “We could look at the bones and see what features characterise an embryo, a hatchling, and a young individual when he’s matured,” shares Rio de Janeiro Bone-structure Expert and study co-author Juliana Sayão, adding, “This is a one-of-a-kind record for pterosaurs—for the first time, we have the whole spectrum.”