Pterosaur is the first flying vertebrate and the only extinct group on the earth. The knowledge of its reproduction, development and life history is limited. Here we report on a large block of specimen gathering more than two hundred eggs, embryos and bones of Hamipterus. Sixteen eggs contain 3D embryonic remains, which was the first discovery of 3D embryos. This paper led to the hypothesis that Hamipterus might have been less precocious than advocated for pterosaurs in general. The hind limbs have developed more rapidly compared to the forelimbs and might have been functional right after the animal hatched, suggesting newborns were likely to move around but were not able to fly. No tooth was found in the embryonic development, indicating newborns probably needed some parental care. The histological thin-sections from embryos to sub-adults all show fast growth bones. This paper also advanced the gregarious behavior of Hamipterus, and proposed that the Cretaceous storms might cause the mass mortality and buried fossils very fast.
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