In a world first, paleontologists working in northwestern China have discovered a cache of hundreds of ancient eggs laid by pterosaurs, the flying reptiles that lived alongside the dinosaurs. Some of the eggs contain the most detailed pterosaur embryos ever found.
In a world first, paleontologists working in northwestern China have discovered a cache of hundreds of ancient eggs laid by pterosaurs, the flying reptiles that lived alongside the dinosaurs. Some of the eggs contain the most detailed pterosaur embryos ever found.
THE PERFECT STORMS
The newfound eggs belong to Hamipterus tianshanensis, a previously known species of pterosaur that lived in northwestern China more than a hundred million years ago. With a maximum wingspan of 10 feet and a probable taste for fish, these animals may have resembled today’s herons, living near waters that crisscrossed inland terrain.
“The site is in the Gobi desert, and there are strong winds, a lot of sand, with few plants and animals,” says study coauthor Shunxing Jiang of the Chinese Academy of Sciences. “However, when Hamipterus lived, the environment [was] much better—we call it Pterosaur Eden.” (Find out how scientists are fighting fossil poachers in the Gobi.)
Hamipterus not only fed in this long-lost paradise, it also bred there, likely burying clutches of eggs in vegetation or on shorelines. The eggs fossilized in lake sediments disturbed by fast-moving water, a sign that storms may have flooded a nesting site and sent the eggs bobbing into a large lake, where soupy mud entombed them. The eggs didn’t wash in all at once: They’re spread out among four distinct sediment layers, suggesting that multiple floods deposited them over time.
Wang’s team suggests that an ancient nesting site may have flooded repeatedly. This would imply that, like modern birds and turtles, Hamipterus used the same nesting sites over and over. What’s more, the sheer number of eggs suggests that Hamipterus bred in large groups like some living birds.
Further studies should help flesh out even more of the details about how these winged beasts reproduced. The shells resemble living turtles’ leathery eggs, which means that Hamipterus probably buried its eggs to protect them—but where or how is unknown. What’s more, we don’t yet know how many eggs a single female Hamipterus laid or the size of its breeding groups.
Given the incomplete fossil record, it’s also possible the proposed Hamipterus growth sequence will need to be adjusted. Perhaps the largest embryos the team found weren’t quite ready to hatch, which would throw off the developmental time line. More fossils would help, and Wang’s team remains on the hunt in northwestern China.
“What’s on my wish list?” says coauthor Alexander Kellner, a paleontologist at the Federal University of Rio de Janeiro. “Number one: to find more embryos. Number two: I wish we would find eggs in situ—that means ‘not moved.’ We would learn a lot from that.”
Source: National Geography
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