Maniraptora

Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Dromaeosauridae, Troodontidae, Oviraptorosauria, and Therizinosauria. Ornitholestes and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period (see Eshanosaurus), and survive today as living birds.

Maniraptorans Temporal range: Middle Jurassic–Present, 165–0 Ma[1] PreꞒ Ꞓ O S D C P T J K Pg N Possible Early Jurassic record[2]
Collage of six maniraptorans. From top left to right: the Zamyn Khondt oviraptorid, Sinornithosaurus, the Prince Creek troodontid, Patagonykus, a short-tailed albatross, and Nothronychus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Clade:	Maniraptoriformes
Clade:	Maniraptora Gauthier, 1986
Subgroups
†Fukuivenator †Juravenator? †Migmanychion †Ornitholestes? †Unquillosaurus †Yaverlandia †Alvarezsauroidea †Therizinosauria Pennaraptora Foth, Tischlinger & Rauhut, 2014 †Oviraptorosauria †Scansoriopterygidae Paraves
Synonyms
Metornithes Perle et al., 1993

Description

Microraptor specimen with feather impressions

Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a half-moon shaped (semi-lunate) bone in the wrist (carpus). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characteristics relating to specific details of the skeleton. Unlike most other saurischian dinosaurs, which have pubic bones that point forward, several groups of maniraptorans have an ornithischian-like backwards-pointing hip bone. A backward-pointing hip characterizes the therizinosaurs, dromaeosaurids, avialans, and some primitive troodontids. The fact that the backward-pointing hip is present in so many diverse maniraptoran groups has led most scientists to conclude that the "primitive" forward-pointing hip seen in advanced troodontids and oviraptorosaurs is an evolutionary reversal, and that these groups evolved from ancestors with backward-pointing hips.^[3]