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 & Zhonghe Zhou (2017)
Egg accumulation with 3D embryos provides insight into the life history of a pterosaur.
ScienceÂ 358(6367): 1197-1201
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 (see the Perspective by Deeming). 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.
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.
D. Charles Deeming (2017)
How pterosaurs bred.
ScienceÂ 358(6367): 1124-1125
Ninety years have passed since Roy Chapman Andrews returned from his exploration of Mongolia with tales of fossilized dinosaur eggs. Fossils interpreted as dinosaur eggs had been described before, but Chapman's crew had found fossils that could only be interpreted as clutches of eggs. Recent fossil evidence of dinosaur reproduction has confirmed that all dinosaurs laid eggs, whereas other Mesozoic groups, such as the aquatic ichthyosaurs, evolved live birth. However, the reproductive biology of a key group of extinct Mesozoic species, the flying pterosaurs (see the image), has remained elusive. On page 1197 of this issue, Wang et al. report the largest accumulation of Hamipterus pterosaur eggs found to date. The work is a crucial advance in understanding pterosaur reproduction.