Friday, December 1, 2017

[Paleontology • 2017] Hamipterus tianshanensis • Egg Accumulation with 3D Embryos provides insight into the Life History of A Pterosaur

Hamipterus tianshanensis 

Wang, Kellner, Jiang, et al. 2017
reconstruction by Zhao Chuang.  DOI: 10.1126/science.aan2329

Fossil eggs and embryos that provide unique information about the reproduction and early growth of vertebrates are exceedingly rare, particularly for pterosaurs. Here we report on hundreds of three-dimensional (3D) eggs of the species Hamipterus tianshanensis from a Lower Cretaceous site in China, 16 of which contain embryonic remains. Computed tomography scanning, osteohistology, and micropreparation reveal that some bones lack extensive ossification in potentially late-term embryos, suggesting that hatchlings might have been flightless and less precocious than previously assumed. The geological context, including at least four levels with embryos and eggs, indicates that this deposit was formed by a rare combination of events, with storms acting on a nesting ground. This discovery supports colonial nesting behavior and potential nesting site fidelity in the Pterosauria.



The reconstruction image made by Zhao Chuang shows the species Hamipterus tianshanensis according to the discoveries in a desert in Hami, northwest China's Xinjiang Uygur Autonomous Region. Over 200 three-dimensionally preserved eggs of pterosaurs have been unearthed in China, providing new insight into the life history of the rulers of the skies in the age of dinosaurs.  

Xiaolin Wang, Alexander W. A. Kellner, Shunxing Jiang, Xin Cheng, Qiang Wang, Yingxia Ma, Yahefujiang Paidoula, Taissa Rodrigues, He Chen, Juliana M. Sayão, Ning Li, Jialiang Zhang, Renan A. M. Bantim, Xi Meng, Xinjun Zhang, Rui Qiu and Zhonghe Zhou. 2017. Egg Accumulation with 3D Embryos provides insight into the Life History of A Pterosaur. Science. 358(6367); 1197-1201.  DOI: 10.1126/science.aan2329

Even more like birds
Ecological convergence between pterosaurs and birds is often invoked, but to what degree the two groups share behavior is debated. Wang et al. describe a site with more than 100 fossilized pterosaur eggs that reveals that hatchling pterosaurs were likely not as precocial as previously thought. Furthermore, the overlaying of multiple clutches suggests that the pterosaurs may have exhibited breeding site fidelity, similar to rookery-breeding seabirds. Thus, the similarity between these two groups goes beyond wings.

Over 200 fossilized eggs found in China reveal how pterosaurs breed

Hundreds of pterosaur eggs reveal early life insights via @physorg_com
Hundreds of Pterosaur Eggs Found in Record-Breaking Fossil Haul via @NatGeo
Ancient flying reptiles cared for their young, fossil trove suggests

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