Key Laboratory for the Evolutionary Systematics of Vertebrates, Institute of Vertebrate, Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China.
CAS Center of Excellence in Life and Paleoenvironment, Beijing, 100044, China.
Sci Rep. 2019 Aug 13;9(1):11727. doi: 10.1038/s41598-019-48148-7.
Alvarezsaurian dinosaurs, a group of bizarre theropods with greatly shortened and modified forelimbs, are known mostly from the Cretaceous of Asia and South America. Here we report a new alvarezsaurian, Shishugounykus inexpectus gen. et sp. nov, based on a specimen recovered from the Middle-Upper Jurassic Shishugou Formation of the Junggar Basin, western China. Together with two other alvarezsaurians from this formation, i.e., Haplocheirus sollers and Aorun zhaoi, these Shishugou forms represent the only known Jurassic alvarezsaurians worldwide. Similar to the two other Shishugou alvarezsaurians, this new alvarezsaurian displays early stages in the development of the highly modified alvarezsaurian forelimb, but it possesses a number of manual features closer to the typical coelurosaurian theropod condition. Combining morphological and histological features, our analysis indicates that the earliest known alvarezsaurians are variable in size and other important morphological features, and in particular display a mosaic distribution of forelimb features.
阿尔瓦雷斯龙类恐龙是一组形态奇异的兽脚亚目恐龙，它们的前肢非常短且高度特化。这类恐龙主要发现于亚洲和南美洲的白垩纪地层中。本文报道了一件发现于中国西部准噶尔盆地中侏罗统石树沟组的新的阿尔瓦雷斯龙类恐龙，模式种为意外石树沟鸟克斯。该种与产自同一地层的两件已知的阿尔瓦雷斯龙类，即：单脊龙和赵氏敖闰龙一起代表了全世界目前已知的侏罗纪阿尔瓦雷斯龙类。与产自同一地层的另外两件阿尔瓦雷斯龙类一样，这件新的标本显示出高度特化的前肢在早期的发育阶段，但它具有一些更接近典型虚骨龙类兽脚亚目恐龙的手部特征。综合形态学和组织学特征，我们的分析表明，最早的阿尔瓦雷斯龙类在体型和其他重要的形态特征上存在差异，并且前肢特征表现出镶嵌演化的分布模式。
