41-638: Crocodyliformes is a clade of crurotarsan archosaurs , the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudosuchians to survive the K-Pg extinction event . In 1988, James M. Clark argued that traditional names for well-known groups of animals should be restricted to their crown clades , that is, used only for natural groups comprising all living members of any given lineage and descendants of their closest common ancestor. This posed
82-525: A clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group , is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree . In the taxonomical literature, sometimes the Latin form cladus (plural cladi ) is used rather than the English form. Clades are
123-479: A "ladder", with supposedly more "advanced" organisms at the top. Taxonomists have increasingly worked to make the taxonomic system reflect evolution. When it comes to naming , this principle is not always compatible with the traditional rank-based nomenclature (in which only taxa associated with a rank can be named) because not enough ranks exist to name a long series of nested clades. For these and other reasons, phylogenetic nomenclature has been developed; it
164-431: A body length about 0.6 meters, and a flattened skull, a typical skull of crocodilian. The external skull surface is covered randomly with small pits. The orbits are huge, with a complete dorsal roof made by the paired supraorbitals. The maxilla has sharp edge, which extends forward and covers some part of the lateral notch. The ears are protected by earflaps , which prevent water inflow to the otic recess when this animal
205-623: A clade can be described based on two different reference points, crown age and stem age. The crown age of a clade refers to the age of the most recent common ancestor of all of the species in the clade. The stem age of a clade refers to the time that the ancestral lineage of the clade diverged from its sister clade. A clade's stem age is either the same as or older than its crown age. Ages of clades cannot be directly observed. They are inferred, either from stratigraphy of fossils , or from molecular clock estimates. Viruses , and particularly RNA viruses form clades. These are useful in tracking
246-407: A long scapula and a shorter coracoid . The interclavicle is hypothesized to be cartilaginous. As for the forelimb, the fossil records showed that Orthosuchus has similar humerus, but the distal and proximal expansions does not lay on the same plane as the modern crocodiles . Also, not like the living crocodiles, the ulna and radius of Orthosuchus , or other typical archosaurs , are around 88% of
287-479: A problem for the crocodilians, because the name Crocodylia , while used in various ways by various scientists, had always included not only living crocodilians but many of their extinct ancestors known only from the fossil record. Clark's solution to this issue was to restrict the name Crocodylia to the group containing modern alligators , crocodiles , and gharials , plus any extinct taxa descended from their closest common ancestor. The traditional group "Crocodylia"
328-422: A revised taxonomy based on a concept strongly resembling clades, although the term clade itself would not be coined until 1957 by his grandson, Julian Huxley . German biologist Emil Hans Willi Hennig (1913–1976) is considered to be the founder of cladistics . He proposed a classification system that represented repeated branchings of the family tree, as opposed to the previous systems, which put organisms on
369-426: A short secondary bony palate, with crocodilian featuring pterygoids . The elongated choana is located behind the secondary palate, which is made by the premaxilla and maxilla. In modern crocodiles, the choana is between the vomers and the anterior processes of pterygoids. The dentary forms the largest part of the lower jaw with some shallow pits, which indicated that the animal probably has 15-18 teeth, fewer teeth in
410-512: A simplified cladogram based on Fiorelli and Calvo (2007). Terrestrisuchus Dibothrosuchus Gobiosuchus Zaraasuchus Orthosuchus Protosuchus Hemiprotosuchus Kayenta Form Edentosuchus Mesoeucrocodylia In 2012, paleontologists Mario Bronzati, Felipe Chinaglia Montefeltro, and Max C. Langer conducted a broad phylogenetic analysis to produce supertrees of Crocodyliformes, including 184 species. The most parsimonious trees were highly resolved, meaning
451-429: A suffix added should be e.g. "dracohortian". A clade is by definition monophyletic , meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. The ancestor can be known or unknown; any and all members of a clade can be extant or extinct. The science that tries to reconstruct phylogenetic trees and thus discover clades is called phylogenetics or cladistics ,
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#1732887324787492-437: A synonym of a more inclusive Crocodylia, and thus replaced. Brochu and colleagues rejected this proposal, arguing that the crown definition of Crocodylia is the standard meaning both within and beyond the crocodyliform systematics community. While all extant crocodilians are carnivorous , the ecological roles of Mesozoic crocodyliforms were more diverse, and included omnivory and herbivory . Herbivorous forms were present from
533-499: Is also used with a similar meaning in other fields besides biology, such as historical linguistics ; see Cladistics § In disciplines other than biology . The term "clade" was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis , the evolutionary splitting of a parent species into two distinct species, a concept Huxley borrowed from Bernhard Rensch . Many commonly named groups – rodents and insects , for example – are clades because, in each case,
574-471: Is in turn included in the mammal, vertebrate and animal clades. The idea of a clade did not exist in pre- Darwinian Linnaean taxonomy , which was based by necessity only on internal or external morphological similarities between organisms. Many of the better known animal groups in Linnaeus's original Systema Naturae (mostly vertebrate groups) do represent clades. The phenomenon of convergent evolution
615-421: Is in water. Modern crocodiles also have earflaps to decrease water entry. The shape of the skull, especially the snout, is similar to an Indian gharial, Gavialis gangeticus , who prey on small fish. It is possible that Orthosuchus has the same predation, by slowly moving toward schools of small fish and swallow from the side. The aquatic environment provides plenty of food for the animal, besides small fish,
656-484: Is in water. The fossil resembles some features of a primitive crocodilian, one of them is the reduced antorbital fenestra. The quadratojugal is the backbone of the skull, which connects to the jugal and quadrate. The flattened head shape of Orthosuchus is made by the posterior quadrate contact, which is below the rear end of the squamosal. This form is a typical archosaurian characteristic that had lost in modern crocodiles, and also absent in teleosaurs . It developed
697-515: Is responsible for many cases of misleading similarities in the morphology of groups that evolved from different lineages. With the increasing realization in the first half of the 19th century that species had changed and split through the ages, classification increasingly came to be seen as branches on the evolutionary tree of life . The publication of Darwin's theory of evolution in 1859 gave this view increasing weight. In 1876 Thomas Henry Huxley , an early advocate of evolutionary theory, proposed
738-489: Is still controversial. As an example, see the full current classification of Anas platyrhynchos (the mallard duck) with 40 clades from Eukaryota down by following this Wikispecies link and clicking on "Expand". The name of a clade is conventionally a plural, where the singular refers to each member individually. A unique exception is the reptile clade Dracohors , which was made by haplology from Latin "draco" and "cohors", i.e. "the dragon cohort "; its form with
779-580: Is thought to be the longest bone. The tibia is more developed than the fibula, and they are 94% of the length of the femur. Taking all the bones into account, the forelimb is 91% the length of the hind limb. Orthosuchus has similar astragalus and calcaneum. Compared to the astragalus, the rectangular shaped calcaneum is small in size and forms a prominent tuber. The first fossil materials were collected by an expedition of South African Museum in April 1963 led by Alfred W. Crompton. The materials were collected from
820-542: Is widely accepted. A revision of Notochampsa in 2021 found it valid taxon, and phylogenetic analysis recovered it as sister to Orthosuchus , in a monophyletic Notochampsidae . The existing specimens of Orthosuchus were found in the Lower Jurassic Red Bed Formation in South Africa in 1963. It was hypothesized that Orthosuchus lived mainly on terrestrial land, but some key factors contribute to
861-468: The Lower Jurassic Red Bed Formation (= Upper Elliot Formation ) of the Stormberg , so that as soon as they found out that the fossils belongs to a new crocodilian species, they named the species Orthosuchus Stormbergi in a paper published by Nash 1968. They also found a smaller skull that also belongs to Orthosuchus Stormbergi at the same horizon but in a different place at the same site. The main part of
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#1732887324787902-487: The Lower Jurassic sediments. The crocodilian found is about 1 meter long, with flattened head and large frontals. Its more advanced transverse process indicates that it is a new crocodilian species. In 1933 Barnum Brown named it Archaeosuchus , and then changed it to Protosuchus in 1934 and form the family of Protosuchidae. The classification of Protosuchidae is debatable, however, since Orthosuchus resemble some of
943-412: The animal could also feed on lake invertebrates. Orthosuchus has a small salt-secreting gland, which indicates that it is not a marine animal. And because the pubis articulates with the front region of the ischium, it is believed to be a basal animal that lived in swamps and lakes. The animal is probably quadrupedal because the fore limbs are approximately 91% the length of the hind limb, which also makes
984-458: The assessment that Crocodylia as a name has never had stable contents, and that a series of clades larger than the crown group Crocodylia (including Crocodyliformes and the slightly more inclusive clade Crocodylomorpha ) was a good solution. However, in a 2008 paper, Jeremy Martin and Benton reversed the previous opinion (co-authored by Benton) that Crocodylia should be restricted to the crown group, suggesting that Crocodyliformes should be considered
1025-408: The characteristics of Protosuchidae , it is believed to be in the part of this family. Modern crocodiles are considered within the group archosaurs , which also include birds , dinosaurs , and crocodilians . However, from appearance, archosaurs resemble more of crocodiles than of birds. Orthosuchus resembles a primitive form of crocodilian by some of its traits: the fusion midline together at
1066-458: The early Jurassic to the late Cretaceous and are thought to have evolved at least three times. Tracks of a crocodyliform are known since Cretaceous, at least. Tracks representing the ichnofamily Batrachopodidae are described from the Early Cretaceous (late Aptian ) Calonda Formation ( Angola ) by Mateus et al. (2017), who name a new ichnotaxon Angolaichnus adamanticus . Below is
1107-413: The fact that it spent time mostly in water. The first notable evidence is on the palate, which was covered by soft tissue, not bone. The choanae are on the back of the palate and a valve was used to help close the glottis . These features help Orthosuchus keep breathing when submerging in the aquatic system. The ears are protected by earflaps, which prevent water inflow to the otic recess when this animal
1148-403: The far back. The teeth are equal in size and similar in shape. Orthosuchus has 24 vertebrae, and 8 of them are believed to be in the cervical region. All vertebrae appear to be amphicoelous. It does not have tall neural spine but the height of them decrease from head to tail. The vertebrae in the neck region are tightly bonded together. The ribs start at the twelfth vertebra, which supports
1189-451: The fundamental unit of cladistics , a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population , or a species ( extinct or extant ). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over
1230-546: The group consists of a common ancestor with all its descendant branches. Rodents, for example, are a branch of mammals that split off after the end of the period when the clade Dinosauria stopped being the dominant terrestrial vertebrates 66 million years ago. The original population and all its descendants are a clade. The rodent clade corresponds to the order Rodentia, and insects to the class Insecta. These clades include smaller clades, such as chipmunk or ant , each of which consists of even smaller clades. The clade "rodent"
1271-437: The ilium. The tail consists of 8 vertebrae of different size and shape. The first one is in contact with the sacral ribs, three vertebrae at the far end of the tail are tiny in size, and the other four vertebrae form the middle of the tail. The ribs form antero-ventral and postero-dorsal flanges, which are for the muscle attachments. Orthosuchus has similar pectoral girdles and pelvic girdles compare to living crocodiles, with
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1312-590: The last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic . Some of the relationships between organisms that the molecular biology arm of cladistics has revealed include that fungi are closer relatives to animals than they are to plants, archaea are now considered different from bacteria , and multicellular organisms may have evolved from archaea. The term "clade"
1353-518: The latter term coined by Ernst Mayr (1965), derived from "clade". The results of phylogenetic/cladistic analyses are tree-shaped diagrams called cladograms ; they, and all their branches, are phylogenetic hypotheses. Three methods of defining clades are featured in phylogenetic nomenclature : node-, stem-, and apomorphy-based (see Phylogenetic nomenclature§Phylogenetic definitions of clade names for detailed definitions). The relationship between clades can be described in several ways: The age of
1394-412: The length of the humerus, while the radius and ulna in modern crocodiles are the shortest elements in the forelimb. It has two non-elongated carpals, with one of the elliptical shape. Orthosuchus appeared to have 5 digits. The first digit is the shortest and the fifth digit is the weakest. Although some of the phalanges are missing, it is believed that the phalanges formula is 2, 3, 4, 5, 3, 3. The femur
1435-427: The parietal, the form of the secondary palate, the fusion of pterygoid and quadrate, the extension of coracoid, radius, and ulna, and the form of tuber on the calcaneum. Orthosuchus is closely related to Protosuchus , Notochampsa , Erythrochampsa , and probably other crocodilian families. Although Orthosuchus could be grouped into Notochampsa , more people want to keep the family Protosuchidae because it
1476-1116: The phylogenetic relationships found in the analysis were highly likely. Below is a consensus tree based off the study: Kayentasuchus walkeri Orthosuchus stormbergi Protosuchus richardsoni Hemiprotosuchus leali Kayenta Form Edentosuchus tienshanensis Zaraasuchus shepardi Las Hoyas Croc Gobiosuchus kielanae Eopneumatosuchus colberti Zosuchus davidsoni Sichuanosuchus shuhanensis Sichuanosuchus huidongensis Shantungosuchus hangjinensis Shantungosuchus chuhsiensis Shantungosuchus brachycephalus Neuquensuchus universitas Shartegosuchus asperopalatum Fruita Form ( Fruitachampsa callisoni ) Hsisosuchus dashanpuensis Hsisosuchus chungkingensis Araripesuchus wegeneri Araripesuchus tsangatsangana Araripesuchus buitreraensis Araripesuchus patagonicus Araripesuchus gomesii Uruguaysuchus terrai Uruguaysuchus aznarezi Libycosuchus brevirostris Simosuchus clarki Malawisuchus mwakasyungutiensis Clade In biological phylogenetics ,
1517-562: The skull and the law jaw was well preserved, but some of the phalanges, ribs, and one side of the pelvic girdle with its hind limb were missing. Since the specimens had some distortions, major issues were fix at the site before it was X-rayed. In 1931, a new primitive form of crocodilian was found in the Dinosaur Canyon Beds of northern Arizona, United States. The beds are at the top of the Upper Triassic Formation and below
1558-605: The spread of viral infections . HIV , for example, has clades called subtypes, which vary in geographical prevalence. HIV subtype (clade) B, for example is predominant in Europe, the Americas and Japan, whereas subtype A is more common in east Africa. Orthosuchus stormbergi Orthosuchus (meaning "straight crocodile") is an extinct genus of crocodyliform that lived during the Early Jurassic , about 196 million years ago. It
1599-469: The walking on land easier. Unlike modern crocodiles , Orthosuchus does not creep on its belly; it probably walks at a high position with its femur vertical to the ground. According to Parrish, primitive crocodylomorphs did not have a crawling stance because it was more used to the terrestrial environment. However, Orthosuchus may not be a good swimmer, since it has amphicoelous vertebrae, whereas modern crocodiles have procoelous vertebrae, which increase
1640-526: Was first discovered in 1963 in the Red Beds Formation in the Qacha's Nek Province of Lesotho , southern Africa. The characteristics showed on its postcranial skeleton and the skull indicated that it is a crocodyliform. The finding is significant since some of the characteristics found on this specimen were believed to be absent until Jurassic . Orthosuchus has a body proportion similar to lizards, with
1681-453: Was replaced by the name Crocodyliformes, defined to include many of the extinct families that the new definition left out. Clark did not initially provide an exact definition for Crocodyliformes; but, in 2001, Paul Sereno and colleagues defined it as the clade including Protosuchus richardsoni and the Nile crocodile , plus all descendants of their common ancestor. Christopher Brochu agreed with