Eggs in a Basket: Fossil Find Opens Up Lost World of Pterosaurs

With apologies, I have been delayed in posting several articles I published previously this year. Attempting to update now.

by Richard Conniff/Scientific American

Thanks in part to an abundance of fossil discoveries in recent decades, scientists now recognize more than 200 species of pterosaur—the winged reptiles that dominated the world’s skies for 160 million years. But almost nothing is known about how they bred or how their young developed. As recently as 2014 the available scientific evidence on those topics added up to a grand total of just three pterosaur eggs, all badly flattened.

That dramatically changes with the description in this week’s Science of a sandstone block containing at least 215 fossilized eggs of a Cretaceous era pterosaur, Hamipterus tianshanensis. Many are preserved in three dimensions, and at least 16 contain partial embryonic remains.

Paleontologists Alexander Kellner and Xiaolin Wang

A research team led by Xiaolin Wang of the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing discovered the eggs, embedded in a rock slab more than three square meters in area, at a dig in northwestern China. Analysis of sediments in the find suggests “that events of high energy such as storms passed over a nesting site” by an ancient lake, the co-authors write, causing the egg mass to float “for a short period of time, becoming concentrated and eventually buried.”

Preservation of any pterosaur fossil is exceptional, partly because their bones were so thin. Extreme scarcity is even