Alvarezsauroidea

Alvarezsauroids Temporal range: Late Jurassic-Late Cretaceous, 160–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Skeletal mount of Patagonykus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Clade:	Maniraptora
Clade:	†Alvarezsauria Bonaparte, 1991
Superfamily:	†Alvarezsauroidea Bonaparte, 1991
Type species
†Alvarezsaurus calvoi Bonaparte, 1991
Subgroups
†Aorun? †Bannykus †Bonapartenykus †Haplocheirus? †Patagonykus †Shishugounykus? †Tugulusaurus †Xiyunykus †Alvarezsauridae

Alvarezsauroidea is a group of small maniraptoran dinosaurs. Alvarezsauroidea, Alvarezsauridae, and Alvarezsauria are named for the historian Gregorio Álvarez, not the more familiar physicist Luis Alvarez, or his son geologist Walter Alvarez who jointly proposed that the Cretaceous–Paleogene extinction event was caused by an impact event. The group was first formally proposed by Choiniere and colleagues in 2010, to contain the family Alvarezsauridae and non-alvarezsaurid alvarezsauroids, such as Haplocheirus,^[1] which is the basalmost of the Alvarezsauroidea (from the Late Jurassic, Asia). The discovery of Haplocheirus extended the stratigraphic evidence for the group Alvarezsauroidea about 63 million years further in the past. The division of Alvarezsauroidea into the Alvarezsauridae and the non-alvarezsaurid alvarezsauroids is based on differences in their morphology, especially in their hand morphology.