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Epipophyses are bony projections of the
cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
found in
archosauromorphs Archosauromorpha ( Greek for "ruling lizard forms") is a clade of diapsid reptiles containing all reptiles more closely related to archosaurs (such as crocodilians and dinosaurs, including birds) rather than lepidosaurs (such as tuataras, l ...
, particularly
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s (including some basal
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s). These paired
processes A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management *Business process, activities that produce a specific se ...
sit above the postzygapophyses on the rear of the vertebral neural arch. Their morphology is variable and ranges from small, simple, hill-like elevations to large, complex, winglike projections. Epipophyses provided large attachment areas for several neck muscles; large epipophyses are therefore indicative of a strong neck musculature. The presence of epipophyses is a synapomorphy (distinguishing feature) of the group Dinosauria. Epipophyses were present in the basal-most dinosaurs, but absent in the closest relatives of the group, such as '' Marasuchus'' and ''
Silesaurus ''Silesaurus'' is a genus of silesaurid dinosauriform from the Late Triassic, of what is now Poland. Discovery Fossilized remains of ''Silesaurus'' have been found in the Keuper Claystone in Krasiejów near Opole, Silesia, Poland, which is a ...
''. They were typical for most dinosaur lineages; however, they became lost in several derived theropod lineages in the wake of an increasingly S-shaped curvature of the neck. Several scientific papers have observed that epipophyses were present in various non-dinosaur archosauromorphs. These include several pseudosuchians (''
Batrachotomus ''Batrachotomus'' is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of the Middle Triassic period, around 242 to 237 million years ago. ''Batrachotomus'' was descr ...
'', '' Revueltosaurus, Xilousuchus, Effigia, Hesperosuchus''), basal avemetatarsalians ( aphanosaurs) non-archosaur archosauriforms (''
Vancleavea ''Vancleavea'' is a genus of extinct, armoured, non- archosaurian archosauriforms from the Late Triassic of western North America. The type and only known species is ''V. campi'', named by Robert Long & Phillip A Murry in 1995. At that time, t ...
'', '' Halazhaisuchus''), rhynchosaurs, several tanystropheids, and allokotosaurs. Sauropod-oriented paleontologist Mike Taylor has informally suggested that epipophyses were also present in the vertebrae of certain
pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 ...
s.


References

{{cite book , editor=Philip J. Currie , editor2=Kevin Padian , first=Philip J. , last=Currie , chapter=Theropoda , title=Encyclopedia of dinosaurs , publisher=Acad. Press , isbn=978-0-12-226810-6 , year=1997, page=734 Dinosaur anatomy