48-413: Row 2 ( Pseudosuchia ): Crocodylus mindorensis , Typothorax coccinarum ; Row 3 ( Avemetatarsalia ): Casuarius casuarius , Anhanguera piscator . Archosauriformes ( Greek for 'ruling lizards', and Latin for 'form') is a clade of diapsid reptiles encompassing archosaurs and some of their close relatives. It was defined by Jacques Gauthier (1994) as the clade stemming from
96-481: A monospecific family of basal archosauriforms represented by Doswellia kaltenbachi from the Late Triassic of North America. However, a 2011 cladistic analysis by Desojo, Ezcurra, & Schultz recovered the newly named Brazilian genus Archeopelta as well as the enigmatic Argentinian archosauriform Tarjadia as close relatives of Doswellia, within a monophyletic Doswelliidae. These authors defined
144-494: A branch-based clade, Pseudosuchia is the sister taxon of another branch-based clade, the Avemetatarsalia . Avemetatarsalians are bird-line archosaurs, including pterosaurs and dinosaurs (the latter including birds). A different definition was suggested by Benton and Clark, 1988: the node-based taxon including the last common ancestor of Rauisuchidae and aetosaurs and all of its descendants. Benton and Clark also named
192-841: A common origin of thermal insulation (feathers) in ornithodirans at least 250 million years ago. Erythrosuchids living in high latitudes might have benefited from some sort of insulation. If Longisquama was an archosauromorph, it could be associated with the origin of feathers. Below is a cladogram from Nesbitt (2011): Archosaurus Proterosuchus [REDACTED] Erythrosuchus [REDACTED] Vancleavea [REDACTED] Tropidosuchus Chanaresuchus [REDACTED] Euparkeria [REDACTED] Parasuchus Smilosuchus [REDACTED] Pseudopalatus Pseudosuchia [REDACTED] Avemetatarsalia [REDACTED] * Note : Phytosaurs were previously placed within Pseudosuchia, or crocodile-line archosaurs. Below
240-570: A diverse array of lifestyles during the Jurassic and Cretaceous periods, although only a single subset of crocodylomorphs, the Crocodilia, survive to the present day. Living crocodilians include crocodiles , alligators , caimans , and gavialids . The name Pseudosuchia was originally given to a group of superficially crocodile-like prehistoric reptiles from the Triassic period, but fell out of use in
288-613: A frog-like hopper by one study. They had long bodies and tails, and their front legs were shorter than their hind legs. Unlike in some other groups of archosauriforms, doswelliids retain teeth on the pterygoid , on the roof of the mouth. Although Vancleavea had a short and deep skull, most doswelliids had slender and elongated snouts, similar to other members of Proterochampsia . Advanced doswelliids possessed dorsal ribs which splay outwards (rather than downwards), making their bodies wide and low. Doswelliids were armored with multiple rows of bony scutes ( osteoderms ) on their backs. With
336-513: A group called Crocodylotarsi, which includes most taxa now considered pseudosuchians. In 1990, Paul Sereno erected the clade Crurotarsi to supplant Pseudosuchia. However, Sereno defined Crurotarsi as a node-based clade, relying on the inclusion of groups such as Phytosauria , Aetosauria, and Crocodylomorpha . It is not equivalent to Pseudosuchia, which by definition must include all crocodilian-line archosaurs. For many years, Pseudosuchia and Crurotarsi have been considered partial synonyms because
384-782: A rate similar of the fastest-growing dinosaurs. Sexual maturity in those Triassic taxa was probably reached quickly, providing advantage in a habitat with unpredictable variation from heavy rainfall to drought and high mortality. Vancleavea and Euparkeria , which show slower growth rates compared to Erythrosuchus , lived after the climatic stabilization. Early crown archosaurs possessed increased growth rates, which were retained by ornithodirans. Ornithosuchians and poposaurs are stem-crocodilians that show high growth rates similar to those of basal archosauriforms. Developmental, physiological, anatomical and palaeontological lines of evidence indicate that crocodilians evolved from endothermic ancestors. Living crocodilians are ambush predators adapted to
432-540: A semi-aquatic lifestyle that benefits from ectothermy due to the lower oxygen intake that allows longer diving time. The mixing of oxygenated and deoxygenated blood in their circulatory system is apparently an innovation that benefits ectothermic life. Earlier archosaurs likely lacked those adaptations and instead had completely separated blood as birds and mammals do. A similar process occurred in phytosaurs, which were also semi-aquatic. The similarities between pterosaur , ornithischian and coelurosaurian integument suggest
480-407: A similar definition, Crocodylotarsi, was named in 1988, possibly as a replacement for Pseudosuchia. The name Pseudosuchia, meaning "false crocodiles", has been used for over a century, and traditionally included only non-crocodilians, but when defined as a clade, Pseudosuchia came to include the group Eusuchia ("true crocodiles") as well. Crocodylotarsi may have been named to remove confusion, but as
528-410: A staggering diversity of reptiles with many different lifestyles. Early pseudosuchians were successful in the Triassic period. They included giant, quadrupedal apex predators such as Saurosuchus , Prestosuchus , and Fasolasuchus . Ornithosuchids were large scavengers, while erpetosuchids and gracilisuchids were small, light-footed predators. A few groups acquired herbivorous diets, such as
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#1732844919972576-399: A stem-based clade, it is synonymous with Pseudosuchia. Because Pseudosuchia was named first, it has precedence. A third group, Crurotarsi , traditionally included the same archosaurs as Pseudosuchia, but as a node-based clade it is not synonymous. The scope of Crurotarsi has recently been changed by the phylogenetic placement of phytosaurs. In 2011, Sterling J. Nesbitt found phytosaurs to be
624-405: A subset of the group. The clade Pseudosuchia is potentially equivalent to Crurotarsi even though the latter has a different, node-based definition: "all taxa the least inclusive clade containing Rutiodon carolinensis (Emmons, 1856), and Crocodylus niloticus (Laurenti, 1768)." However, a major 2011 study of Triassic archosaur relations proposed that Rutiodon 's group, Phytosauria ,
672-966: Is a cladogram modified from Nesbitt (2011) showing the new changes (bold terminal taxa are collapsed). † Proterosuchidae [REDACTED] † Erythrosuchus [REDACTED] † Vancleavea [REDACTED] † Proterochampsia [REDACTED] † Euparkeria [REDACTED] † Phytosauria [REDACTED] Avemetatarsalia (bird-lineage of archosaurs) [REDACTED] † Ornithosuchidae [REDACTED] † Gracilisuchus [REDACTED] † Turfanosuchus [REDACTED] † Revueltosaurus [REDACTED] † Aetosauria [REDACTED] † Ticinosuchus [REDACTED] † Poposauroidea [REDACTED] † Prestosuchus [REDACTED] † Saurosuchus [REDACTED] † Batrachotomus [REDACTED] † Fasolasuchus † Rauisuchidae [REDACTED] Crocodylomorpha [REDACTED] The following cladogram
720-400: Is a paraphyletic group, and its usage as a taxonomic category has been rejected under modern cladistic systems. The name Archosauriformes is intended as a monophyletic replacement compatible with modern taxonomy. Early archosauriforms, informally termed " proterosuchians ", were superficially crocodile-like animals with sprawling gaits, carnivorous habits, and long hooked snouts. Unlike
768-474: Is a cladogram from Sengupta et al. (2017), based on an updated version of Ezcurra (2016) that reexamined all historical members of the "Proterosuchia" (a polyphyletic historical group including proterosuchids and erythrosuchids ). The placement of fragmentary taxa that had to be removed to increase tree resolution are indicated by dashed lines (in the most derived position that they can be confidently assigned to). Taxa that are nomina dubia are indicated by
816-623: Is an extinct family of carnivorous archosauriform reptiles that lived in North America and Europe during the Middle to Late Triassic period. Long represented solely by the heavily-armored reptile Doswellia , the family's composition has expanded since 2011, although two supposed South American doswelliids ( Archeopelta and Tarjadia ) were later redescribed as erpetosuchids . Doswelliids were not true archosaurs , but they were close relatives and some studies have considered them among
864-964: Is from a slightly older study, Brusatte, Benton, Desojo and Langer (2010). Bold terminal taxa are collapsed. Several results of the study, such as the retention of a monophyletic Rauisuchia , the retention of phytosaurs within Pseudosuchia, and a close relation between aetosaurs and crocodylomorphs, replicate the results of older studies. However, the findings of Nesbitt (2011) have been more widely supported by pseudosuchian-focused analyses published since 2011. † Erythrosuchus [REDACTED] † Euparkeria [REDACTED] † Proterochampsidae [REDACTED] Avemetatarsalia [REDACTED] † Phytosauria [REDACTED] † Aetosauria [REDACTED] † Gracilisuchus [REDACTED] † Erpetosuchus [REDACTED] Crocodylomorpha [REDACTED] † Revueltosaurus [REDACTED] † Ornithosuchidae [REDACTED] Doswelliidae Doswelliidae
912-583: Is one of the two primary "daughter" clades of the Archosauria . The skull is often massively built, especially in contrast to ornithodires ; the snout is narrow and tends to be elongated, the neck is short and strong, and the limb posture ranges from a typical reptilian sprawl to an erect stance like dinosaurs ' or mammals ', although achieving it a different way. The body is often protected by two or more rows of armored plates. Many crurotarsans reached lengths of three meters or more. Pseudosuchians appeared during
960-404: Is one of two major divisions of Archosauria , including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs", in contrast to the "bird-line archosaurs" or Avemetatarsalia . Despite Pseudosuchia meaning "false crocodiles", the name is a misnomer as true crocodilians are now defined as
1008-554: The Late Permian (roughly 252 million years ago ) and persist to the present day as the two surviving archosaur groups: crocodilians and birds . Archosauriforms present several traits historically ascribed to the group Archosauria. These include serrated teeth set in deep sockets, a more active metabolism, and an antorbital fenestra (a hole in the skull in front of the eyes). Reptiles with these traits have also been termed " thecodonts " in older methods of classification. Thecodontia
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#17328449199721056-455: The last common ancestor of Proterosuchidae and Archosauria. Phil Senter (2005) defined it as the most exclusive clade containing Proterosuchus and Archosauria. Gauthier as part of the Phylonyms (2020) defined the clade as the last common ancestor and all descendants of Gallus , Alligator , and Proterosuchus . Archosauriforms are a branch of archosauromorphs which originated in
1104-572: The birds, while the crocodilians continued with little change. Today, the crocodiles , alligators , and gharials are the surviving representatives of this lineage. The Mesozoic range of cranial disparity is higher than the Triassic one, suggesting crocodylomorphs attained a high degree of diversification compared to Triassic pseudosuchians. Pseudosuchia was defined as a stem-based clade in 1985. It includes crocodiles and all archosaurs more closely related to crocodiles than to birds. A second clade with
1152-690: The bone growth rate of archosaurs, leading to the conclusion that this rate had a tendency to grow in ornithodirans and decrease in pseudosuchians. The same method also supports the existence of high resting metabolical rates similar to those of living endotherms (mammals and birds) in the Prolacerta -Archosauriformes clade that were retained by most subgroups, though decreased in Proterosuchus, Phytosauria and Crocodilia. Erythrosuchids and Euparkeria are basal archosauriforms showing signs of high growth rates and elevated metabolism, with Erythrosuchus possessing
1200-415: The bulk of their therapsid contemporaries, archosauriforms survived the catastrophic end-Permian mass extinction . The Late Permian proterosuchid Archosaurus is similar in appearance to its Early Triassic relative, Proterosuchus . Within a few million years after the beginning of the Triassic , the archosauriformes had diversified past the "proterosuchian" grade . The next major archosauriform group
1248-504: The dominant terrestrial carnivores and herbivores. As the Mesozoic progressed, the Protosuchia gave rise to more typically crocodile-like forms. While dinosaurs were the dominant animals on land, the crocodiles flourished in rivers, swamps, and the oceans, with far greater diversity than they have today. With the end-Cretaceous extinction , the dinosaurs became extinct, with the exception of
1296-466: The early Carnian Colorado City Formation . Desojo, Ezcurra, & Schultz (2011)'s analysis placed Doswellidae as the closest large monophyletic clade to Archosauria , with only the Chinese archosauriform Yonghesuchus nested closer to archosaurs. However, a phylogenetic analysis by Ezcurra (2016) recovered Doswelliidae alongside the family Proterochampsidae within the clade Proterochampsia , which
1344-399: The exception of Vancleavea , which had many different forms of smooth osteoderms, doswelliid osteoderms were characteristically covered by deep, circular pits. There is also a smooth area (an anterior articular lamina) on the front edge of each osteoderm where the preceding osteoderm overlaps. This combination of osteoderm features is also present in erpetosuchids and some aetosaurs , although
1392-424: The extinction of all the pseudosuchians with the exception of Sphenosuchia and Crocodyliformes (both Crocodylomorpha ), the latter being the ancestors of modern-day crocodiles. A study published in 2010 postulates that there is significant evidence that volcanic eruptions changed the climate, causing a mass extinction that wiped out the dinosaurs' main competitors. This allowed the dinosaurs to succeed them as
1440-435: The family as the most inclusive clade containing all archosauromorphs more closely related to Doswellia kaltenbachi than to Proterochampsa barrionuevoi , Erythrosuchus africanus , Caiman latirostris , (the broad-snouted caiman) or Passer domesticus (the house sparrow). Within the next few years, several other genera of archosauriforms were classified as Dosweliids. A second New Mexican species of Doswellia
1488-744: The first to establish the name Pseudosuchia in a phylogenetic context, using it as a branch-based taxon for all archosaurs more closely related to crocodilians than to birds. This made the name Pseudosuchia somewhat ironic because true crocodiles (i.e. members of Crocodylia) were now included in the group. Phylogenetic definitions of Pseudosuchia include "Crocodiles and all archosaurs closer to crocodiles than to birds" (Gauthier and Padian), "Extant crocodiles and all extinct archosaurs that are closer to crocodiles than they are to birds" (Gauthier, 1986), and more recently "the most inclusive clade within Archosauria that includes Crocodylia but not Aves" (Senter, 2005). As
Archosauriformes - Misplaced Pages Continue
1536-490: The heavily armored aetosaurs , and several were bipedal, such as Poposaurus and Postosuchus . The bizarre, ornithomimid -like shuvosaurids were both bipedal and herbivorous, with toothless beaks. Many of these Triassic pseudosuchian groups went extinct at or before the Triassic–Jurassic extinction event . However, one group, the crocodylomorphs , survived the major extinction. Crocodylomorphs themselves evolved
1584-528: The late Olenekian (early Triassic ); by the Ladinian (late Middle Triassic) they dominated the terrestrial carnivore niches. Their heyday was the Late Triassic, during which time their ranks included erect-limbed rauisuchians , herbivorous armored aetosaurs , the large predatory poposaurs , the small agile sphenosuchian crocodilians, and a few other assorted groups. The end-Triassic extinction caused
1632-399: The late 20th century, especially after the name Crurotarsi was established in 1990 to label the clade (evolutionary grouping) of archosaurs encompassing most reptiles previously identified as pseudosuchians. By this time, Pseudosuchia had also been defined as a clade , but it was not widely embraced until 2011. In 2011 paleontologist Sterling Nesbitt proposed that Crurotarsi, as it
1680-412: The latter clade encompasses all crocodilian-line archosaurs in most phylogenetic analyses. Sterling Nesbitt 's 2011 analysis places one crurotarsan group, Phytosauria, outside Pseudosuchia. Since the definition of Crurotarsi relies on phytosaurs, their placement outside Pseudosuchia (and thus Archosauria) means that the clade Crurotarsi includes both pseudosuchians and avemetatarsalians. Pseudosuchia
1728-489: The most derived non-archosaurian archosauriforms. They may have also been related to the Proterochampsidae , a South American family of crocodile-like archosauriforms. Doswelliids are believed to be semiaquatic carnivores similar to crocodilians in appearance, as evidenced by their short legs and eyes and nostrils which are set high on the head, though the putative member Scleromochlus has been interpreted as
1776-512: The name "false crocodiles". In mid-20th century textbooks, like Alfred Sherwood Romer 's Vertebrate Paleontology and Edwin H. Colbert 's Evolution of the Vertebrates , Pseudosuchia constitutes one of the suborders of the now-abandoned order Thecodontia . Zittel's aetosaurs were placed in their own suborder, Aetosauria. Colbert considered small lightly built archosaurs, such as Ornithosuchus and Hesperosuchus — both of which were at
1824-958: The note "dubium". Bold terminal taxa are collapsed. Allokotosauria [REDACTED] Rhynchosauria [REDACTED] Boreopricea funerea Prolacertidae [REDACTED] SAM-PK-591 " Ankistrodon indicus " (dubium) " Blomosuchus georgii " (dubium) Tasmaniosaurus triassicus Chasmatosuchus magnus Chasmatosuchus rossicus Gamosaurus lozovskii Chasmatosuchus vjushkovi Vonhuenia friedrichi Proterosuchidae [REDACTED] Eorasaurus olsoni Kalisuchus rewanensis Fugusuchus hejiapanensis Sarmatosuchus otschevi Cuyosuchus huenei Erythrosuchidae [REDACTED] Asperoris mnyama Dorosuchus neoetus Euparkeria capensis [REDACTED] Doswelliidae [REDACTED] Proterochampsidae [REDACTED] Pseudosuchia Pseudosuchia (from Greek : ψεύδος (pseudos) , "false" and Greek : σούχος (souchos) , "crocodile")
1872-419: The only members to survive into the Jurassic , were the archosaurs . Archosauria includes crocodilians, birds, and all descendants of their common ancestor . Extinct archosaurs include aetosaurs , rauisuchids (both members of the crocodilian branch), pterosaurs , and non-avian dinosaurs (both members of the avian branch). Vascular density and osteocyte density, shape and area have been used to estimate
1920-468: The osteoderms of the latter group differ in the arrangement of the pits and the fact that the anterior articular lamina is formed by a raised bar. Doswellia had at least ten rows of osteoderms, creating a flattened carapace-like armor plate on its back. Jaxtasuchus had lighter armor, with only four rows. The family was originally named by R. E. Weems in 1980 and was placed in its own suborder , Doswelliina . The Doswelliidae has long been considered
1968-422: The possession of a crocodilian-style crurotarsal ankle . Eucrocopodans include the families Euparkeriidae (small, agile reptiles), Proterochampsidae (narrow-snouted predators endemic to South America ), and Doswelliidae (heavily armored Laurasian reptiles similar to proterochampsids), as well as various other strange reptiles such as Vancleavea and Asperoris . The most successful archosauriforms, and
Archosauriformes - Misplaced Pages Continue
2016-408: The sister taxon of Archosauria, and therefore not crocodile-line archosaurs. Because phytosaurs are included in the definition of Crurotarsi, crurotarsans are not solely crocodile-line archosaurs, but also bird-line archosaurs and phytosaurs. Under this phylogeny, Crurotarsi includes phytosaurs, crocodiles, pterosaurs, and dinosaurs, while Pseudosuchia still contains only crocodile-line archosaurs. Below
2064-523: The time reconstructed as theropod dinosaur-like bipeds — to be typical pseudosuchians. These small forms were assumed to be the ancestors of all later archosaurs. The name Pseudosuchia became a wastebasket taxon into which all thecodonts that did not fit in the other three suborders could be placed. Even Sharovipteryx and Longisquama , two enigmatic Triassic reptiles that bear little resemblance to archosaurs, have been regarded as pseudosuchians. Gauthier and Padian (1985) and Gauthier (1986) became
2112-765: Was Erythrosuchidae , a family of apex predators with massive heads, the largest carnivorous reptiles up to that time. In 2016, Martin Ezcurra provided the name Eucrocopoda for the clade including all archosauriforms more crownward (closer to archosaurs) than erythrosuchids. He defined the clade all taxa more closely related to Euparkeria capensis , Proterochampa barrionuevoi , Doswellia kaltenbachi , Parasuchus hislopi , Passer domesticus (the house sparrow), or Crocodylus niloticus (the Nile crocodile) than to Proterosuchus fergusi or Erythrosuchus africanus . The name translates to "true crocodile feet", in reference to
2160-399: Was described in 2012; however, this species was subsequently transferred to the separate doswelliid genus Rugarhynchos . Two additional dosweliids were named in 2013: Jaxtasuchus salomoni based on several skeletons found in the Ladinian -age Lower Keuper of Germany, and Ankylosuchus chinlegroupensis based on fragments of four vertebrae, parts of the skull and of a limb bone from
2208-433: Was found to be the sister taxon of Archosauria . The unusual aquatic archosauriform Vancleavea was also referred to Doswelliidae in this analysis. Subsequently, Ezcurra et al. (2017) excluded Archeopelta and Tarjadia from Doswelliidae, considering them to be archosaurs of the family Erpetosuchidae instead. Litorosuchus , an aquatic archosauriform which is considered a close relative of Vancleavea , may also be
2256-404: Was not closely related to other traditional "crurotarsans", at least compared to avemetatarsalians such as pterosaurs and dinosaurs . As a result, Crurotarsi could be a much broader clade than Pseudosuchia. Other recent studies support a more traditional phylogeny. Contrary to popular belief, crocodilians differ significantly from their ancestors and distant relatives, as Pseudosuchia contains
2304-568: Was then defined, must include not only crocodilian-line archosaurs, but all other archosaurs including birds, non-avian dinosaurs , and pterosaurs . The clade Pseudosuchia as originally defined could still be used to identify crocodilian-line archosaurs, and since many recent studies support Nesbitt's findings, Pseudosuchia is again commonly used. The name Pseudosuchia was coined by Karl Alfred von Zittel in 1887–1890 to include three taxa (two aetosaurs and Dyoplax ) that were superficially crocodilian-like, but were not actually crocodilian. Hence
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