Saurornitholestes langstoni (Sues 1978, Evans, et al. 2014; Currie and Evans 2019; Campanian; Figs. 1, 2) enters the large reptile tree (LRT, 1870+ taxa; subset Fig. 3) basal to the bird mimics, Wulong, Sinusonasus, Hesperornithoides, Caihong, Changyuraptor, Microraptor and Sinornithosaurus.
All these taxa
are derived from Ornitholestes in the LRT (subset Fig. 3).
Not surprisingly, considering that large ‘killer claw’,
Saurornitholestes is also basal to the clades that give rise to Velociraptor and the clade of bird precursors.
Currie PJ and Evans DC 2019. Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta. The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 303(3) DOI:10.1002/ar.24241
Evans DC, Larson DW Cullen,TM and Sullivan RM 2014. “Saurornitholestes” robustus is a troodontid (Dinosauria: Theropoda): Canadian Journal of Earth Sciences, v. 51, p. 730–734.
Sues H-D 1978. A new small theropod dinosaur from the Judith River Formation (Campanian) of Alberta Canada. Zoological Journal of the Linnean Society 62: 381-400.