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| Xunmenglong yinliangis
Xing, Miyashita, Wang, Niu & Currie, 2019
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Abstract
Compsognathids — long regarded as an assemblage of ‘prototypical’ small theropods including the historically significant Compsognathus and Sinosauropteryx — have patchy distributions. The majority of definitive members of the clade come from the Upper Jurassic Solnhofen Archipelago and the Lower Cretaceous Yixian Formation. Chronologically falling between these two major compsognathid localities, a new compsognathid described in this paper, Xunmenglong yinliangis gen. et sp. nov., occurs in the Huajiyin Formation of northeastern China. Xunmenglong is distinguished from other compsognathids by one autapomorphy (pedal phalanx IV-4 longer than IV-3) and a unique combination of postcranial traits, including the disproportionately long lower legs. Nested among the Jehol and Solnhofen compsognathids in a phylogenetic analysis, Xunmenglong is an intriguing addition to the known range and diversity of the clade. The taxon is stratigraphically the lowest among Asian compsognathids, and its holotype specimen is the smallest among compsognathids (unless Scipionyx is treated as a compsognathid). Questions remain about habitat preferences and diversification patterns of compsognathids, but Xunmenglong offers two broader implications. (1) As previously proposed on the basis of the diverse enanthiornithine assemblage, the Huajiying Formation may preserve the oldest fauna of the Early Cretaceous Jehol Biota, which is distinct from the Late Jurassic Daohugou Biota and includes the Yixian Formation from which other Asian compsognathids were discovered. (2) Xunmenglong provides a useful calibration point with which to reconstruct biogeographic/stratigraphic patterns and to estimate allometric trends in the clade.
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| Figure 2. The holotype (YLSNHM-00005) of Xunmenglong yinliangis, gen. et sp. nov. (A, B) Photograph (A) and interpretive drawing (B) of the partial skeleton preserved on the main slab, YLSNHM-00005. (C, D) Photograph (C) and interpretive drawing (D) of the left hindlimb of YLSNHM-00005. |
Theropoda Marsh, 1881
Coelurosauria Huene, 1914
Compsognathidae Cope, 1871
Xunmenglong, gen. nov.
Type and only known species. Xunmenglong yinliangis, sp. nov.
Etymology. ‘Xunmeng,’ a Chinese Pinyin for being swift; ‘long’, Chinese Pinyin for dragon.
Xunmenglong yinliangis, sp. nov.
Etymology. ‘Yinliang’ after Yinliang Group, China. The Yinliang Stone Natural History Museum is operated by the philanthropic program of the founder (Liang Li), and is currently housed in the Global Stone Museum, Shuitou, Fujiang, China.
Lida Xing, Tetsuto Miyashita, Donghao Wang, Kechung Niu and Philip J. Currie. 2019. A New Compsognathid Theropod Dinosaur from the Oldest Assemblage of the Jehol Biota in the Lower Cretaceous Huajiying Formation, northeastern China. Cretaceous Research. 104285, In Press. DOI: 10.1016/j.cretres.2019.104285