Alvarezsauridae

Alvarezsaurids Temporal range: Late Cretaceous, 97–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Mounted holotype of Mononykus
Skeletal mount of Alvarezsaurus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Superfamily:	†Alvarezsauroidea
Family:	†Alvarezsauridae Bonaparte, 1991
Type species
†Alvarezsaurus calvoi Bonaparte, 1991
Subgroups
†Achillesaurus? †Alvarezsaurus †Bradycneme †Heptasteornis †Patagonykinae? †Bonapartenykus †Patagonykus †Parvicursorinae †Dzharaonyx †Jaculinykus †Khulsanurus †Kol †Nemegtonykus †Ondogurvel †Parvicursor †Qiupanykus †Trierarchuncus †Ceratonykini †Albinykus †Ceratonykus †Xixianykus †Mononykini †Albertonykus †Linhenykus †Mononykus †Shuvuuia
Synonyms
Bradycnemidae? Harrison & Walker, 1975 (in part) Parvicursoridae Karhu & Rautian, 1996 Mononykidae Chiappe et al., 1998

Alvarezsauridae is a family of small, long-legged dinosaurs. Although originally thought to represent the earliest known flightless birds, they are now thought to be an early diverging branch of maniraptoran theropods. Alvarezsaurids were highly specialized. They had tiny but stout forelimbs, with compact, bird-like hands. Their skeletons suggest that they had massive breast and arm muscles, possibly adapted for digging or tearing. They had long, tube-shaped snouts filled with tiny teeth. They have been interpreted as myrmecophagous, adapted to prey on colonial insects such as termites, with the short arms acting as effective digging instruments to break into nests.

Alvarezsaurus, the type genus of the family, was named for the historian Gregorio Álvarez.^[1]