 |
| Qianlong shouhu Han, Yu, Zhang, Zeng, Wang, Cai, Wu, Wen, Cai, Li, Wu, Zhao & Xu, 2023 DOI: 10.1093/nsr/nwad258 |
Abstract
Our understanding of pre-Cretaceous dinosaur reproduction is hindered by a scarcity of evidence within the fossil record. Here we report three adult skeletons and five clutches of embryo-containing eggs of a new sauropodomorph from the Lower Jurassic of southwestern China, displaying several significant reproductive features that are either unknown or unlike other early-diverging sauropodomorphs, such as relatively large eggs with a relatively thick calcareous shell formed by prominent mammillary cones, synchronous hatching, and a transitional prehatching posture between the crocodilians and living birds. Most significantly, these Early Jurassic fossils provide strong evidence for the earliest known leathery eggs. Our comprehensive quantitative analyses demonstrate that the first dinosaur eggs were probably leathery, elliptical and relatively small, but with relatively long eggshell units, and that along the line to living birds, the most significant change in reptilian egg morphology occurred early in theropod evolution rather than near the origin of Aves.
dinosaur, Sauropodomorph, Jurassic, embryo, egg evolution, reproductive behaviour
 |
| Skeletal morphology of Qianlong shouhu. Skeletal silhouettes of the adult (a) and embryo (b) showing preserved bones (in grey) and standing postures. The skull photograph (c) and line-drawing (d) in right lateral view, maxillary teeth in right lateral view (e), and right pes in posterior view (f) of GZPM VN001 (adult). The skull normal image (g) and transparency image (h) showing cheek teeth in left lateral view |
Systematic paleontology
Dinosauria Owen, 1842
Saurischia Seeley, 1887
Sauropodomorpha von Huene, 1932
Qianlong shouhu gen. et sp. nov.
Etymology: The genus name is derived from Mandarin Chinese Qian (an alternative name for Guizhou Province where the fossils were collected) + long (‘dragon’); the species name shouhu means ‘guarding’ in Chinese, referring to the associated preservation of adult skeletal fossils and embryo-containing egg fossils.
Holotype: GZPM VN001 is a partial and semi-articulated skeleton (Fig. 1), though the partial skull and mandible are preserved 30 m western to the postcranial skeleton (Supplementary Fig. S1). It is probably an adult individual given the closed neurocentral sutures of all preserved vertebrae.
Locality and horizon: The locality and horizon are Zhuanpo, Pingba District, Anshun City, Guizhou Province, southwestern China and the Lower Jurassic Zhenzhuchong Member (possibly in Sinemurian), Ziliujing Formation.
Diagnosis: Qianlong differs from other sauropodomorphs in the following character states (autapomorphies marked by *): a shallow concavity at the base of the premaxilla nasal process; relatively straight teeth with labiolingually asymmetrical crowns and without denticles; jaw articulation lower than dentary dorsal margin; a short retroarticular process; a very small external mandibular fenestra; well-developed nutritive foramina on the maxillary and dentary, the width of Metacarpal I being greater than its length; Metatarsal V with a strongly expanded proximal end that is four times the mediolateral width of the distal end and with a small bulge on the lateral margin * (Fig. 1 and Supplementary Fig. S2).
Fenglu Han, Yilun Yu, Shukang Zhang, Rong Zeng, Xinjin Wang, Huiyang Cai, Tianzhuang Wu, Yingfeng Wen, Sifu Cai, Chun Li, Rui Wu, Qi Zhao and Xing Xu. 2023. Exceptional early Jurassic Fossils with Leathery Eggs shed light on Dinosaur Reproductive Biology. National Science Review, nwad258. DOI: 10.1093/nsr/nwad258
