A new species of alvarezsaurid from China

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A new genus of alvarezsaurid has been described from Late Jurassic age remains from the Shishugou Formation in western China. The new genus has been given the name Shishugounykus inexpectatus ("Unexpected Shishugou claw"), with the genus name originating from the Shishugou Formation, where the genus was found, and the Greek word "nykus," meaning "claw," and the species name originating from the Latin word "inexpectatus," meaning "unexpected," in reference to the unexpected discovery of a new genus of alvarezsaurid from the Shishougou Formation, which has already produced remains of two other Jurassic alvarezsaurids, Haplocheirus and Aorun, with this new species suggesting an even higher diversity of this group of theropods in this formation than previously known. Along with the other two alvarezsaurids in the Shishugou Formation, the new genus is one of the only known Jurassic alvarezsaurids in the world. Like its contemporaries, Shishougounykus shows early development of the highly modified forelimb with a single claw typical of more advanced alvarezsaurids, although it possesses a number of manual features that are more typically seen in typical coelurosaurian theropods. This suggests that the earliest alvarezsaurids were variable in size and other important morphological features, especially in features of the forelimbs. Here is an image of the skeletal reconstruction and known remains of the new genus, a chart showing the evolution of the alvarezsaurid forelimb with the addition of new data from the new genus, and a link to the paper describing the new genus.




Paper (open access!): https://www.nature.com/articles/s41598-019-48148-7

[Halichoeres]

It has pretty well-developed hands! Nice to have the picture of the alvarezsaurids' evolution filled in just a little bit.