Saurischians Fossil range: Late Triassic - Late Cretaceous (non-avian)
Saurischian pelvic structure (left side)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Superorder: Dinosauria Order: Saurischia* Seeley, 1887
Suborders
Theropoda †Sauropodomorpha

Tyrannosaurus rex saurischian pelvis and hind limbs (left side), taken at the Oxford University Museum of Natural History. The Late Triassic (also known as Upper Triassic, or Keuper) is the third and final of three epochs of the Triassic period. Late Cretaceous (100mya - 65mya refers to the second half of the Cretaceous Period, named after the famous white Chalk cliffs of southern England Chordates ( Phylum Chordata) are a group of Animals that includes the Vertebrates together with several closely related Invertebrates Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers In Phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor but does not contain all Harry Govier Seeley ( 18 February 1839 - 8 January 1909) was a British Paleontologist who determined that Dinosaurs Theropods (ˈθɪərəpɒd theropoda /θiːˈrɒpədə/ 'beast feet' are a group of Bipedal Saurischian Dinosaurs Although they were primarily The Sauropodomorpha (sɔˌrɒpədəˈmɔrfə were a group of long-necked herbivorous Dinosaurs that eventually dropped down on all fours and became Tyrannosaurus ( or, meaning 'tyrant lizard' is a Genus of Theropod Dinosaur. The Oxford University Museum of Natural History, sometimes known simply as the Oxford University Museum, is a Museum displaying many of the University of Oxford's

Saurischia (pronounced /sɔˈrɪskiə/^[1], from the Greek sauros (σαυρος) meaning 'lizard' and ischion (ισχιον) meaning 'hip joint') is one of the two orders/branches of dinosaurs. The Ancient Greek language is the historical stage in the development of the Hellenic language family spanning the Archaic (c This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used In 1888, Harry Seeley classified dinosaurs into two great orders, based on their hip structure. Harry Govier Seeley ( 18 February 1839 - 8 January 1909) was a British Paleontologist who determined that Dinosaurs Saurischians ('lizard-hipped') are distinguished from the ornithischians ('bird-hipped') by retaining the ancestral configuration of bones in the hip. Ornithischia (ɔrnɪˈθɪskiə) or Predentata is an extinct order of beaked herbivorous Dinosaurs The name ornithischia All carnivorous dinosaurs (the theropods) are saurischians, as are one of the two great lineages of herbivorous dinosaurs, the sauropodomorphs. A carnivore (ˈkɑrnɪvɔər meaning 'meat eater' ( Latin carne meaning 'flesh' and vorare meaning 'to devour' is any animal with a diet consisting Theropods (ˈθɪərəpɒd theropoda /θiːˈrɒpədə/ 'beast feet' are a group of Bipedal Saurischian Dinosaurs Although they were primarily Herbivory is a form of Predation in which an Organism, known as a herbivore, consumes principally Autotrophs ref name=Campbell>Campbell The Sauropodomorpha (sɔˌrɒpədəˈmɔrfə were a group of long-necked herbivorous Dinosaurs that eventually dropped down on all fours and became At the end of the Cretaceous Period, all non-avian saurischians became extinct. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of In Biology and Ecology, extinction is the cessation of existence of a Species or group of taxa. This is referred to as the Cretaceous-Tertiary extinction event. The Cretaceous–Tertiary extinction event, which occurred approximately ( Ma) was a large-scale mass extinction of animal and plant species in a geologically

The saurischian lineage diverged from the ornithischians in the late Triassic Period, and retained a three-pronged pelvic structure, with the pubis pointed forward, until some advanced forms in the group Maniraptora reversed this, in parallel with the ornithischian condition. The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago For the bone in many mammals often called the penis bone see Baculum The android pubic bone is the Ventral and Anterior Maniraptora ("hand snatchers" is a Clade of Coelurosaurian Dinosaurs which includes the Birds and the dinosaurs that were more closely The ornithischians evolved a new hip structure, with the pubis rotating caudally, to become parallel with the ischium, often also with a forward-pointing process, giving a four-pronged structure. The ischium forms the lower and back part of the Hip bone ( os coxae) This hip structure is similar to that of birds, and so ornithischians are termed 'bird-hipped' dinosaurs, while the saurischians are 'lizard-hipped'. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. The true bird-hip possessed by modern birds evolved independently in the lizard-hipped theropods in the Jurassic Period, an example of convergent evolution. The Jurassic is a geologic period and system that extends from about Ma (million years ago to  Ma that is from the end of the Triassic to the beginning Convergent evolution describes the acquisition of the same biological trait in unrelated lineages

While Seeley's classification has stood the test of time, there is a minority theory, first popularized by Robert Bakker in The Dinosaur Heresies that separates the theropods into their own group and places the two great groups of herbivorous dinosaurs (the sauropodomorphs and ornithischians) together in a separate group he named the Phytodinosauria ('plant dinosaurs') (Bakker), or Ornithischiformes (Cooper). Robert T Bakker (born March 24, 1945, in Bergen County New Jersey) is an American Paleontologist who helped reshape modern theories about The Dinosaur Heresies New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction was a 1986 book published by Robert T

Taxonomy

Classification

• Order Saurischia
  • Eoraptor
  • Guaibasaurus
  • Infraorder Herrerasauria
  • Suborder Sauropodomorpha
    • Infraorder Prosauropoda
    • Infraorder Sauropoda
  • Suborder Theropoda
    • Infraorder Carnosauria
    • Infraorder Ceratosauria
    • Infraorder Deinonychosauria
    • Infraorder Ornithomimosauria
    • Infraorder Oviraptorosauria

Additionally, the genera Teyuwasu and Agnosphitys may represent early saurischians, or more primitive non-dinosaurs. Eoraptor was one of the world's earliest Dinosaurs It was a two-legged meat-eater that lived between 230 and 225  Million years ago Guaibasaurus (meaning "Guaiba lizard" was a basal Saurischian Dinosaur Genus which lived during the Triassic period Herrerasaurs are among the oldest known Dinosaurs appearing in the Fossil record about 228 million years ago (mid- Triassic) The Sauropodomorpha (sɔˌrɒpədəˈmɔrfə were a group of long-necked herbivorous Dinosaurs that eventually dropped down on all fours and became Prosauropoda (ˌproʊsɔˈrɒpədə or prosauropods (/proʊˈsɔroʊpɒd/ were a group of early Herbivorous Dinosaurs that lived during the Triassic Sauropoda (sɔˈrɒpədə or the sauropods (/ˈsɔroʊpɒd/ are a suborder or infraorder of the Saurischian ("lizard-hipped" Theropods (ˈθɪərəpɒd theropoda /θiːˈrɒpədə/ 'beast feet' are a group of Bipedal Saurischian Dinosaurs Although they were primarily Carnosauria is a group of large Predatory Dinosaurs that lived during the Jurassic and Cretaceous periods Ceratosaurs are members of a group of Theropod Dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than The Deinonychosauria ("fearsome claw lizards" were a successful Clade of theropods in the Late Jurassic and Cretaceous Periods Ornithomimosaurs (meaning ' Bird mimic lizards' or members of the Clade Ornithomimosauria are Theropod Dinosaurs like Oviraptorosaurs ("egg thief lizards" are a group of feathered Maniraptoran Dinosaurs from the Cretaceous Period of what are now Teyuwasu is a dubious Genus of Dinosaur from the Late Triassic. Agnosphitys (ˌægnoʊsˈfaɪtɪs sometimes mistakenly called Agnostiphys or Agnosphytis) is a disputed Genus of Dinosaur

Phylogeny

The following cladogram is adapted from Weishampel et al. Cladistics is the hierarchical classification of Species based on evolutionary ancestry , 2004. ^[2]

References