Alvarezsauridae Bonaparte, 1991

Xu, Xing, Upchurch, Paul, Ma, Qingyu, Pittman, Michael, Choiniere, Jonah, Sullivan, Corwin, Hone, David W. E., Tan, Qingwei, Tan, Lin, Xiao, Dong & Han, Fenglu, 2013, Osteology of the Late Cretaceous alvarezsauroid Linhenykus monodactylus from China and comments on alvarezsauroid biogeography, Acta Palaeontologica Polonica 58 (1), pp. 25-46 : 26

Alvarezsauridae Bonaparte, 1991

Parvicursorinae Karhu and Rautian, 1996

Remarks.—The Parvicursorinae were originally proposed by Karhu and Rautian (1996), but a phylogenetic taxonomic definition for the clade was first proposed by Choiniere et al. (2010), which is a node−based definition ( Choiniere et al. 2010). Linhenykus and other recently reported parvicursorines such as Albertonykus ( Longrich and Currie 2009) and Xixianykus ( Xu et al. 2010) are morphologically very similar to members of this node−based Parvicursorinae, but they are excluded from the node−based clade based on the recovered alvarezsauroid phylogeny. We believe that it is not necessary to establish a new clade and the most informative option is to treat Parvicursorinae as a stem−based taxon, allowing for the inclusion of Linhenykus and other taxa ( Xu et al. 2011a, b). Thus, we define Parvicursorinae as the most inclusive clade including Parvicursor remotus but not Patagonykus puertai

Revised Parvicursorinae diagnosis.—Dorsal vertebrae opisthocoelous and without hyposphene−hypantrum articulations, dorsal parapophyses elevated to level of diapophyses, dorsal infradiapophyseal fossae hypertrophied, posterior sacral vertebrae with hypertrophied ventral keels, anterior caudal vertebrae with anteriorly displaced transverse processes, metacarpal II that is mediolaterally wider than proximodistally long and dorsoventrally shallow, bears two articular facets on the proximal surface, and lacks collateral ligamental fossae, manual ungual II with ventral axial groove and without flexor tubercle, tibial distal end with lateral malleolus anteroposteriorly expanded, astragalar ascending process L−shaped, and specialized arctometatarsalian condition with metatarsal III shorter than metatarsals II and IV. Other possible parvicursorine synapomorphies include: posterior dorsal vertebrae with small and posterodorsally oriented neural spines; biconvex vertebra near posterior end of dorsal series; keeled and boatlike sternum with median groove along midline; manual phalanx II−2 longer than II−1; supracetabular crest of ilium more prominent anteriorly than posteriorly; metatarsus longer than femur; metatarsals II and IV subequal in length; and pedal digit III more slender than digits II and IV.