25-472: Elasmaria is a clade of ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia that contains many bipedal ornithopods that were previously considered "hypsilophodonts" . Calvo et al. (2007) coined Elasmaria to accommodate Macrogryphosaurus and Talenkauen , which they recovered as basal iguanodonts distinct from other iguanodontians in having mineralized plates on
50-559: A Macrogryphosaurus , but noted to be from an animal of similar size and anatomy, and from approximately the same geographic and stratigraphic location, though it lived at a slightly earlier time. Other indeterminate ornithopod specimens from Argentina similarly indicate animals of similar size to the taxon . M. gondwanicus received a complete osteology in 2020, a study published in Cretaceous Research by Sebastián Rozadilla, Penélope Cruzado-Caballero, Jorge O. Calvo. This described
75-525: 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
100-479: 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
125-623: 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
150-422: 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
175-429: 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 ,
200-499: 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,
225-471: 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
250-515: 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
275-489: 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
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#1733086160629300-782: The Portezuelo Formation of the Neuquén Group , its locality was later revised to be in the Sierra Barrosa Formation of the same geologic group. This unit is dated to the Coniacian age of the Late Cretaceous . Noted for bony plates on its thorax, it was identified as a large species of ornithopod. The species would be described and named Macrogryphosaurus gondwanicus in 2007, in a study authored by Jorge O. Calvo, Juan D. Porfiri, and Fernando E. Novas. Its generic name
325-499: The anatomy of the species in much more thoroughly and investigating its classification and biomechanics under a more modern lens. They considered the genus to be of importance, due to being the largest known elasmarian species, and for the completeness of its known remains, informing on the anatomy of the group. Macrogryphosaurus has been noted for its large size compared to other South American ornithopods. It has been estimated to have been around 6 metres (20 ft) in length, though
350-463: The fossil was described by Dr. Stephen F. Poropat as "amazing" in nature. Subsequent research has not referred any other specimens to the species. However, in 2016, a study was published on MAU-Pv-PH-458, a fragmentary dorsal neural arch from the Plottier Formation of northern Argentina. The bone is the northernmost record of an ornithopod in South America. It was not determined to belong to
375-451: 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
400-546: 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"
425-590: 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"
450-518: 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
475-467: The most remarked upon features of the taxon is its mineralized thoracic plates, also referred to as intercostal plates. These are a series of plates along the side of the torso, shared with a handful of other ornithischians such as Talenkauen , Thescelosaurus , and Hypsilophodon . Along with a fused, birdlike sternum, its short torso would have been rather stiff in nature. This, alongside its relatively elongate neck and coelurosaur -like tail, gave it
500-485: The only known individual may not have been fully grown. Gregory S. Paul estimated the length of this specimen at 5 m (16 ft) in length and 300 kg (660 lb) in body mass. As such, it is the largest species of South American ornithopod outside of Hadrosauridae , and the largest species of elasmarian. Approaching the size of many more derived iguanodontian ornithopods, it is, compared to these derived taxa, much more graceful and lightly built in form. One of
525-1336: The results of their own study. Gideonmantellia amosanjuanae Hypsilophodon foxii Rhabdodontomorpha Callovosaurus leedsi Elrhazosaurus nigeriensis Valdosaurus canaliculatus Eousdryosaurus nanohallucis Dysalotosaurus lettowvorbecki Dryosaurus altus Dryosaurus elderae CM 1949 Draconyx loureiroi Oblitosaurus bunnueli Camptosaurus dispar Uteodon aphanoecetes Cumnoria prestwichii Owenodon hoggii Hippodraco scutodens Ouranosaurus nigeriensis Iguanodon bernissartensis Hadrosauroidea Iyuku raathi Weewarrasaurus pobeni Kangnasaurus coetzeei Anabisetia saldiviai Diluvicursor pickeringi Notohypsilophodon comodorensis Trinisaura santamartaensis Gasparinisaura cincosaltensis Galleonosaurus dorisae Mahuidacursor lipanglef Morrosaurus antarcticus Atlascopcosaurus loadsi Qantassaurus intrepidus Fostoria dhimbangunmal Isasicursor santacrucensis Muttaburrasaurus langdoni Talenkauen santacrucensis Sektensaurus sanjuanboscoi Leaellynasaura amicagraphica Macrogryphosaurus gondwanicus [REDACTED] [REDACTED] [REDACTED] [REDACTED] Clade In biological phylogenetics ,
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#1733086160629550-997: The ribs. In 2016, a paper describing the genus Morrosaurus found Elasmaria to be far larger than its initial contents of two taxa, instead containing a variety of ornithopods from the Southern Hemisphere . In 2021, under the Phylocode , Madzia et al. (2021) formally defined Elasmaria as "the smallest clade containing Macrogryphosaurus gondwanicus and Talenkauen santacrucensis , provided that it does not include Hypsilophodon foxii , Iguanodon bernissartensis , or Thescelosaurus neglectus . Fonseca et al. (2024) redefined Elasmaria as "the largest clade containing Macrogryphosaurus gondwanicus and Talenkauen santacrucensis but not Dryosaurus altus , Hypsilophodon foxii , Iguanodon bernissartensis , and Thescelosaurus neglectus" so that it included more related taxa. The cladogram below follows their preferred reference phylogeny, taken from
575-665: 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. Macrogryphosaurus gondwanicus Macrogryphosaurus (meaning "big enigmatic lizard") is a genus of elasmarian dinosaur from the Coniacian age Upper Cretaceous Sierra Barrosa Formation ( Neuquén Group ) of Argentina in Patagonia . It
600-504: Was derived from the Greek macro , meaning large, grypho , meaning enigmatic, and saurus , meaning lizard. The specific epithet gondwanicus refers to the ancient continent of Gondwana . The holotype specimen, MUCPv-32, consists of an essentially complete set of vertebra, a number of ribs, four mineralized thoracic plates, both sides of the pectoral girdle, and a sternum. The individual is considered to have been an adult. The preservation of
625-552: Was described by Jorge Calvo and colleagues in 2007, with M. gondwanicus as the type and only species. In May 1999, during field work at Mari Menuco Lake , Argentina (sixty kilometres northwest of Neuquén ) conducted by the National University of Comahue , an articulated, nearly complete dinosaur skeleton was discovered and excavated. It was brought to the attention of the palaeontologists by young boy Rafael Moyano, who had discovered it. Originally reported to hail from
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