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Information about Crocodylomorph

Crocodylomorpha
Fossil range: Late Triassic - Recent
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Protosuchus, an early crocodylomorph

Protosuchus, an early crocodylomorph
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Sauropsida
Infraclass:Archosauromorpha
(unranked)Crurotarsi
Superorder:Crocodylomorpha
Hay, 1930
Orders


see text


The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.

Evolutionary history

When their extinct species and stem group are examined, the crocodylian lineage (clade Crurotarsi) proves to have been a very diverse and adaptive group of reptiles. Not only are an ancient group of animals, at least as old as the dinosaurs, they also evolved into a great variety of forms. The earliest forms, the Sphenosuchians, evolved during the Late Triassic, and were highly gracile terrestrial forms built like greyhounds. Several terrestrial species during the Cretaceous evolved herbivory, such as Simosuchus clarki and Chimaerasuchus paradoxus. During the Jurassic and the Cretaceous marine forms in the family Metriorhynchidae such as Metriorhynchus evolved forelimbs that were paddle-like and had a tail similar to modern fish. Dakosaurus andiniensis a closely related species to Metriorhynchus had a skull that was adapted to eat large marine reptiles.

During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were supplanted during the early Jurassic by various aquatic and marine forms. The Later Jurassic, Cretaceous, and Tertiary saw a wide diversity of terrestrial and semi-aquatic lineages. "Modern" crocodilians do not appear until the Late Cretaceous.

Phylogenetic definition

The Crocodylomorpha are defined phylogenetically by Sereno 2005 as "The most inclusive clade containing Crocodylus niloticus (Laurenti 1768) but not Poposaurus gracilis Mehl 1915, Gracilisuchus stipanicicorum Romer 1972, Prestosuchus chiniquensis Huene 1942, Aetosaurus ferratus Fraas 1877."

This a stem-based definition and therefore includes all taxa closer to extant crocodilians than to other crurotarsan clades.

Taxonomy and phylogeny

Historically, all known living and extinct crocodiles were indiscriminately lumped into the order Crocodilia. But it is now known that this is erroneous, based on the uniqueness of the crocodilian morphology. Thus, the order Crocodilia is nowadays restricted to the living species and close extinct relatives such as Mekosuchus.

The old Crocodilia was subdivided into the suborders: Mesosuchia is a paraphyletic group as it does not include eusuchians (which nest within Mesosuchia). Mesoeucrocodylia was the name given to the clade that contains mesosuchians and eusuchians (Whetstone and Whybrow, 1983).

Phylogeny

Mikko's Phylogeny Archive provided this detailed cladogram, after Clark (1994), Ortega et al. (2000), and Turner & Calvo (2005):

CrocodyliformesEopneumatosuchus?Microchampsa `-+-?ArtzosuchusProtosuchia `--+--Shartegosuchidae `--Mesoeucrocodylia?Hsisosuchus `--+-?Gobiosuchidae `--+-?SimosuchusZiphosuchia `--+-?Uruguaysuchus `--+--Araripesuchus `--+--Peirosauridae `--+--Trematochampsidae `--Neosuchia?ElosuchidaePeirosauridae `--+--ComahuesuchusItasuchusAtoposauridae `--+--+--Eutretauranosuchus | `--+-?+--Dyrosauridae | | `--+--Sarcosuchus | | `--Terminonaris | `--+--Pholidosauridae | `--+--Thalattosuchia | `--+--Pelagosuchus | `--+--Teleosauridae | `--Metriorhynchidae `--+--Goniopholididae `--+--Bernissartia `--+--GilchristosuchusRugosuchus?Paralligatoridae `--EusuchiaHylaeochampsa `--+--Allodaposuchus `--Crocodilia

The previous definitions of Crocodilia and Eusuchia do not accurately resemble the evolution of the group. The only order-level taxon that is currently considered valid is Crocodilia in the present definition. Prehistoric crocodiles are represented by many taxa, but since few major groups of the ancient forms are recognizable, a decision where to delimit new order-level clades is not yet possible. (Benson & Clark, 1988).

References

External links

The Late Triassic (also known as Upper Triassic, or Keuper) is the third and final of three epochs of the Triassic period. It spans the time between 228 ± 2 Ma and 199.6 ± 0.6 Ma (million years ago).
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Protosuchus

Species
  • P. richardsoni (type)
  • P. haughtoni
  • P. micmac


Protosuchus was a genus of carnivorous crocodylomorph from the Early Jurassic.
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Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Chordata
Bateson, 1885

Typical Classes

See below

Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates.
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Sauropsida*
Goodrich, 1916

Subclasses
  • Anapsida
  • Diapsida
Synonyms
  • Reptilia Laurenti, 1768
Reptiles are tetrapods and amniotes, animals whose embryos are surrounded by an amniotic membrane, and members of the class
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Archosauromorpha
von Huene, 1946

Orders

See text
Archosauromorpha (Greek for "ruling lizard forms") is an Infraclass of diapsid reptiles that first appeared during the late Permian and became more common during the Triassic.
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Crurotarsi
Sereno & Arcucci, 1990

Orders
  • Phytosauria
  • Aetosauria
  • Rauisuchia*
  • Crocodilia


The Crurotarsi ("cross-ankles") are a group of archosaurs created as a node-based clade by Paul Sereno in 1991 to supplant the old term
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Oliver Perry Hay (22 May, 1846 – 2 November, 1930) was an American professor and paleontologist. In 1912, Hay was appointed as a research associate at the Carnegie Institute, and was given office space at the United States National Museum.
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order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). The superorder is a rank between class and order. Exact details of formal nomenclature depend on the Nomenclature Code which applies.
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Archosauria
Cope, 1869

Clades
  • Crurotarsi
  • Aetosauria
  • Crocodilia (crocodiles)
  • Phytosauria

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Crocodilia
Owen, 1842

black: range of Crocodilia


Families
  • Gavialidae
  • Alligatoridae
  • Crocodylidae


Crocodilia
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In palaeontology, a stem group is a systematic grouping that is required to accommodate fossils in the classification of organisms. A stem group lies basally to a crown group, consisting of its most closely related living relatives.
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Crurotarsi
Sereno & Arcucci, 1990

Orders
  • Phytosauria
  • Aetosauria
  • Rauisuchia*
  • Crocodilia


The Crurotarsi ("cross-ankles") are a group of archosaurs created as a node-based clade by Paul Sereno in 1991 to supplant the old term
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Dinosauria *
Owen, 1842

Orders & Suborders
  • Ornithischia
  • Cerapoda
  • Thyreophora
  • Saurischia

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Sphenosuchia

Families
  • Sphenosuchidae


Sphenosuchia is the name of a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Middle Jurassic.
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The Triassic is a geologic period that extends from about 251 to 199 Ma (million years ago). As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events.
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Gracile can refer to:
  • grace
  • gracile nucleus
  • gracile fasciculus

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The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i.e. from 145.5 ± 4.0 million years ago (Ma)) to the beginning of the Paleocene epoch of the Tertiary Period (about 65.5 ± 0.3 Ma).
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Simosuchus

Binomial name
Simosuchus clarki

Simosuchus clarki ("Clark's Pug-nosed Crocodile") was a small crocodylomorph from the Early Cretaceous of Madagascar.
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Chimaerasuchus

Species: C. paradoxus

Chimaerasuchus paradoxus ("Paradoxical Chimera Crocodile") was a Chinese crocodylian from the early Cretaceous.
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The Jurassic Period is a major unit of the geologic timescale that extends from about 199.6 ± 0.6 Ma (million years ago) to 145.4 ± 4.0 Ma, the end of the Triassic to the beginning of the Cretaceous.
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Metriorhynchidae
Fitzinger, 1843

Metriorhynchids were a group of aquatic crocodilians that lived in seas of the Jurassic and Cretaceous periods.
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D. andiniensis

Binomial name
Dakosaurus andiniensis
(Gasparini et al., 2006)

Nicknamed Godzilla because of its short skull, Dakosaurus andiniensis
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The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' (making the modern era the 'Tertiary').
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phylogenetics (Greek: phyle = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e.g., species, populations).
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This article has been tagged since July 2007.
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C. niloticus

Binomial name
Crocodylus niloticus
(Laurenti, 1768)

The Nile crocodile (Crocodylus niloticus
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Poposaurus

Binomial name
Poposaurus gracilis
Mehl (1915)

Poposaurus is the name given to a genus of reptile from the Late Triassic.
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