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46-788: Morrosaurus is an extinct genus of herbivorous elasmarian dinosaur that lived in the late Cretaceous in Antarctica . The only known species is the type Morrosaurus antarcticus . In 2002, the Argentine paleontologist Fernando Novas reported the discovery of a partial skeleton of a euornithopod in Antarctica. In 2016 these remains were the basis for naming the type species Morrosaurus antarcticus , named and described by Sebastian Rozadilla, Federico Lisandro Agnolin, Fernando Emilio Novas, Alexis Rolando Aranciaga Mauro, Matthew J. Motta, Juan Manuel Lirio Marcelo, and Pablo Isasi. The genus name refers to

92-797: A fauna distinct from that of Patagonia , and each of these distinct from that of India and Madagascar; likewise, Australia, New Zealand, and Antarctic seemed connected to the exclusion of the others. This contrasted with existing recognition of links between the flora and marine invertebrate fauna between Patagonia, Antarctica, Australia, and New Zealand, termed the Weddellian Bioprovince . The recognition of Morrosaurus and Trinisaura as Antarctic elasmarians closely related to animals from South America constituted important evidence of such ties between these continents existing in dinosaurs as well. This would be bolstered by later studies producing firmer evidence of Australian ornithopods as also belonging to

138-643: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as

184-419: A later point than did, consistent with other dinosaurs. Neonatal fossils of elasmarians from Australia, which offer strong evidence of elasmarians living year round in high-latitude conditions rather than being migratory in nature, were similarly found to display growth rates very similar to those of other ornithopods such as Orodromeus . The discovery of Morrosaurus was concurrent with the first evidence of

230-621: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,

276-407: A previously hypothesized uniting clade of ornithopod dinosaurs from the continents that had comprised Gondwana . The distinction between fauna of this part of the world as compared with the northern hemisphere equivalent Laurasia had long been noted, but evidence was traditionally lacking for a biogeographic link for dinosaurs between the different Gondwanan regions. Brazil and Northern Africa shared

322-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for

368-427: A running lifestyle which would be reflected by the narrow foot with a thin fourth metatarsal which indicates a high speed running; subsequently expanded chevrons , a feature that is associated with a greater surface area for attachment of the lateral muscles of the tail, which would give good control of the movements of this; and a curved humerus which demonstrates the absence of a deltopectoral ridge and therefore that

414-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;

460-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and

506-596: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms

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552-590: Is noted as more developed in elasmarian taxa than in other ornithopods such as Hypsilophodon . In 2020 a study was conducted on the growth rate of Morrosaurus , and its relative Trinisaura , through use of histological study of thin samples from the holotype fibula and fourth metatarsal . Ornithischian dinosaurs living in polar regions in the Northern Hemisphere (such as Edmontosaurus and Pachyrhinosaurus typically show different growth rates than relatives from lower latitutes, owing to

598-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,

644-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with

690-554: The humerus and vertebrae cannot be evaluated in Morrosaurus due to their lack of preservation in the genus. The femur seems to have been rather gracile, though more stout than in Trinisaura , as was the elongate foot, with the central third metatarsal being larger than the others. A series of distinctive features characterizes the genus. Two of these are autapomorphies , completely unique traits acquired by

736-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to

782-799: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;

828-419: The nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,

874-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,

920-586: The Cretaceous. [REDACTED] [REDACTED] [REDACTED] [REDACTED] Genus The composition of a genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of

966-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of

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1012-413: The cold, southern environments they lived in, elasmarians were able to succeed in such ecosystems due to the existing possession of necessary adaptations to thrive there. Higher growth rate was noted in Morrosaurus as compared to Trinisaura , consistent with being a larger species. Additionally, it was found the animals reached their sexual maturity well before their skeletal maturity, and ceased growth at

1058-473: The condition seen in Gasparinisaura as well as Kangnasaurus , a genus with overall similar morphology and proportions to Morrosaurus . In addition, there is a unique combination of two features that by themselves are not unique features. In the femur, the lesser trochanter is positioned forward and to the outside of the greater trochanter. In the tibia, medial malleolus has a triangular shape from

1104-677: The extreme temperatures of their environments, but studies have failed to find the same signs in Antarctic animals. The study confirmed this pattern in elasmarians, with comparison with South American elasmarian Gasparinisaura finding incredibly similar histology to the Antarctic genera. All three show rapid growth with periodic interruptions, variation in growth marks, and changes in growth rate across their life cycle, growing slower as they aged. Similar growth strategies are reported in other ornithopods from much lower latitudes. This indicates that rather than adapting their growth physiology in response to

1150-422: The fellow Antarctic genus Trinisaura , only 1.5 metres (4.9 ft) in length. The fragmentary nature of the material precludes saying much about the preserved regions. It is united anatomically with other elasmarians by the strongly compressed outer front edge of the greater trochanter , lacking the distinct cleft and thick edge seen in other types of ornithopod. Other uniting traits of elasmarians seen in

1196-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this

1242-450: The front and a concave surface from the same angle. Morrosaurus was classified in the group Iguanodontia , as a basal member of Euiguanodontia. This in turn formed a clade with other ornithopods of Patagonia and Antarctica, particularly Trinisaura , Gasparinisaura , Anabisetia , Notohypsilophodon , Talenkauen and Macrogryphosaurus in a group called Elasmaria , whose members are distinguished by their adaptation to

1288-400: The front leg was not used for walking. It cannot be determined, however, if Morrosaurus itself possessed these characteristics due to their limited remains. The existence of this clade may indicate that Patagonia, Antarctica and Australia shared the same type of fauna. The exact phylogenetic relationships within this clade could not be identified, except for Gasparinisaura , which proved to be

1334-727: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,

1380-526: The group, as well as possibly Kangnasaurus from Africa. Similar biogeographic patterns have been observed in megaraptoran theropods, diamantinasaurian sauropods, and parankylosaurian ankylosaurs. These discoveries of connected endemic Gondwanan ecosystems have overturned the traditional view of the southern continents, including the fauna seen in Late Cretaceous Antarctic, acting as a refugium for animals more successful elsewhere earlier in

1426-628: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,

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1472-425: The lower end of the femur, the upper part of the tibia , the underside of the tibia, the upper half of the foot, the bottom of the midfoot and the top of the first joint of the third toe. The only known specimen, thought to represent an adult, is estimated to have belong to an individual 4.5–5 metres (15–16 ft) in length. This makes it larger and more robust in skeletal build than many of its relatives, including

1518-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus

1564-462: The most basal member of group. Cladogram based in the phylogenetic analysis of Rozadilla et al ., 2016: Hypsilophodon Thescelosaurus Gasparinisaura Morrosaurus Trinisaura Macrogryphosaurus Notohypsilophodon Talenkauen Anabisetia Parksosaurus Kangnasaurus Rhabdodontidae Tenontosaurus Dryomorpha Based on the hindlimb anatomy of Morrosaurus and other elasmarians, notably

1610-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this

1656-526: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for

1702-466: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or

1748-408: The scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in

1794-581: The site of El Morro on James Ross Island , where the remains of the species were found. The specific name refers to Antarctica. The holotype specimen MACN Pv 197 , was found in a layer of the Snow Hill Island Formation (Cape Lambe, previously assigned to the Lopez de Bertodano Formation ), dating to the Maastrichtian age. The remains consists in a right hind leg, including the top of the femur ,

1840-492: The slim metatarsus , it's thought they were very capable runners, distinguishing them from other herbivorous dinosaurs they lived alongside. Elements of relatives not preserved in Morrosaurus such as expanded chevrons and distinctive bony intercostal plates along the torso would've further aided their cursorial abilities by improving tail balance and musculature control as well as breathing efficiency. This developed tail musculature and running ability of elasmarians

1886-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,

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1932-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being

1978-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for

2024-445: The taxon. In bottom view, the greater trochanter near the top of the femur forms an S-shape, with the back edge thick across and the front edge thin, similar to the condition seen in other elasmarians Anabisetia , Notohypsilophodon , and Gasparinisaura but displayed to a more extreme extent. The fourth metatarsal bone has a prominent rearward projection that wraps around the third metatarsal, likewise similar but more developed to

2070-566: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up

2116-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in

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