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63-581: Proterochampsa is an extinct genus of proterochampsid archosauriform from the Late Triassic ( Carnian - Norian boundary) of South America. The genus is the namesake of the family Proterochampsidae, and the broader clade Proterochampsia . Like other proterochampsids, Proterochampsa are quadruped tetrapods superficially similar in appearance to modern crocodiles , although the two groups are not closely related. Proterochampsids can be distinguished from other related archosauriformes by characters such as

126-402: A piscivorous diet and thus a semiaquatic lifestyle, but due to Proterochampsa having fewer teeth than other proterochampsids, the genus may potentially be excluded from this assumption. The compact nature of proterochampsid osteoderms has been suggested by some to be evidence of a semiaquatic lifestyle due to a higher bone mass, despite the small size and low number of osteoderms not supporting

189-557: A species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in 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 ,

252-590: A brief system of anastomosing rivers and lakes was gradually giving way to an enduring system of braided rivers. Using Hyperodapedon -defined biozones similarly to in the Ischigualasto Formation, paleontologists have suggested that P. nodosa would have also lived in a rhynchosaur-dominated environment, with rhynchosaur specimens accounting for 90% of Carnian specimens in the Santa Maria Formation. Other proterochampsian species have been found within

315-418: A dorsoventrally flattened, triangular skull with a long, narrow snout at the anterior end and that expands transversally at the posterior end, asymmetric feet, and a lack of postfrontal bones in the skull, with the nares located near the midline. Proterochampsa is additionally defined by characters of dermal sculpturing consisting of nodular protuberances on the skull, antorbital fenestrae facing dorsally, and

378-454: A large increase in bone mass overall. This is another debate that may not be relevant to Proterochampsa , as osteoderms are not present in either species within the genus. Overall, this leaves Proterochampsa in particular with few features that can be used as definitive evidence of lifestyle, and some paleontologists have called specifically for deeper analysis of lifestyle for the genus. Studies of bone histology in proterochampsids have used

441-643: 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

504-621: 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,

567-624: A more gradually narrowing snout, and a higher occiput than P. barrionuevoi . Of the two, P. nodosa is thought to have less derived features than P. barrionuevoi . All known Proterochampsa barrionuevoi specimens have been discovered in the Cancha de Bochas, La Peña, and Valle de la Luna members of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina . The Ischigualasto Formation as

630-412: A number of other synapomorphies present in the skull that distinguish the genus Proterochampsa from others, including a reduced antorbital fossa, a ventral lamina on the angular, a divergent occipital margin, and the lack of a fossa around the supratemporal fenestra. The description of a P. barrionuevoi braincase by Trotteyn and Haro in 2009 examined several additional neurocranial features specific to

693-626: A range of faunal stages during the Triassic, the portion of the Santa Maria Formation where P. nodosa has been found is specifically estimated to be near the Carnian-Norian boundary in age, supporting a similarity in age between P. barrionuevoi and P. nodosa specimens. P. nodosa has been found in the lower portion of the Highstand systems tract of the Santa Maria 2 sequence, near the boundary between

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756-409: 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

819-491: A restricted antorbital fossa on the maxilla. The genus comprises two known species: Proterochampsa barrionuevoi and Proterochampsa nodosa . P. barrionuevoi specimens have been discovered in the Ischigualasto Formation in northwestern Argentina , while P. nodosa specimens have been found in the Santa Maria supersequence in southeastern Brazil . The two species are distinct in several characters, including that P. nodosa has larger, more well-developed nodular protuberances,

882-466: A semiaquatic lifestyle despite this new discovery. A number of notable proterochampsid features either tentatively suggest a terrestrial lifestyle if compared to modern reptile taxa, such as tail morphology, or are too ambiguous to definitively suggest one kind of lifestyle over another, such as a simple secondary palate , palatal teeth, an asymmetric foot, and osteoderms. The gharial -like teeth in proterochampsids have been suggested to be indicative of

945-427: 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. ;

1008-455: 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

1071-460: A whole is well-known to paleontologists from its rich fossil record of flora and fauna, with the latter including fishes and a variety of tetrapod lineages. The record from Ischigualasto Provincial Park in the Argentinian province of San Juan has been particularly well-studied. Because of this abundant fossil record and the biodiversity it represents, the formation has been valuable in the study of

1134-596: 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

1197-500: Is divided into four geological sequences , separated from each other by short unconformities . The first two of these sequences (Pinheiros-Chiniquá and Santa Cruz sequences) lie entirely within the Santa Maria Formation, while the third (the Candelária sequence) is shared with the overlying Norian -age Caturrita Formation . The fourth and youngest sequence (the Mata sequence) is equivalent to

1260-411: Is often a clearer indicator of posture. The available postcrania of P. barrionuevoi shows 24 presacral vertebrae with the neural spines located on the posterior portions, and development of the posterior portions of the neural arches . In contrast to other proterochampsids, which have a single row of compact, rounded osteoderms along their back, with some variation in size and positioning compared to

1323-558: Is only partially present within the formation, is the Candelária Sequence (middle Carnian-latest Carnian, ~233-228 Ma). The lower portion of this sequence, coinciding with the upper part of the Santa Maria Formation, is equivalent to the Hyperodapedon Assemblage Zone.The Hyperodapedon Assemblage Zone is itself subdivided into Hyperodapedon Acme Zone (most of the zone, where the rhynchosaur Hyperodapedon

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1386-574: Is rich in Teyumbaita specimens. One P. barrionuevoi specimen was found at the Hoyada del Cerro Las Lajas site in the Teyumbaita biozone. This dating places P. barrionuevoi in an environment consisting of rhynchosaur-dominated faunas. The biostratigraphy recorded at this site also supports the ability for researchers to correlate dating to other sites within the Ischigualasto Formation and other sites outside

1449-460: 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,

1512-474: 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

1575-419: Is widely reported) and Exaeretodon Zone (restricted to about three known and sampled localities, where rhynchsaurs are almost completely absent, but the traversodontid cynodont Exaeretodon is widely reported). These subdivisions are also known as Lower and Upper Hyperodapedon Assemblage Zone, respectively. U-Pb radiometric dating of Cerro da Alemoa (the type locality of Saturnalia tupiniquim ) in

1638-621: 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

1701-799: 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;

1764-588: The Late Triassic , particularly regarding the evolution of dinosaurs and other tetrapods. The Ischigualasto Formation is Late Triassic in age, straddling the boundary between the Carnian and Norian stages. Using the U-Pb isotopic method, the Hoyada del Cerro Las Lajas site within the formation has been dated, with an upper boundary around 221.36 million years ago and a lower boundary around 230.32 million years ago. At this site, nearly all known fossils have been discovered within

1827-703: The Rhaetian -age Mata Sandstone . The oldest sequence in the formation is the Pinheiros-Chiniquá Sequence (latest Ladinian-earliest Carnian, ~237 Ma), which is biostratigraphically equivalent to the Dinodontosaurus Assemblage Zone . It is followed by the shorter Santa Cruz Sequence (early Carnian-middle Carnian, ~236 Ma), biostratigraphically equivalent to the Santacruzodon Assemblage Zone. The final sequence, which

1890-606: The Santa Maria Formation was discovered and named by Barberena in 1982, who placed the species within Proterochampsa and Proterochampsidae. In 2000, Kischlat and Schultz proposed a new genus definition for P. nodosa , instead naming the taxon Barbarenachampsa nodosa . However, this new synonym is contested because it has not been formalized, and has received inconsistent use. By 2009, aquatic or semiaquatic lifestyles had been proposed for all proterochampsids by Schultz, and

1953-512: The herrerasaurid Staurikosaurus , the basal sauropodomorphs Buriolestes and Saturnalia , and the lagerpetid Ixalerpeton . The formation is named after the city of Santa Maria in the central region of Rio Grande do Sul, where outcrops were first studied. The Santa Maria Formation makes up the majority of the Santa Maria Supersequence , which extends through the entire Late Triassic. The Santa Maria Supersequence

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2016-442: The histology of bones or osteoderms in order to infer lifestyle. From bone histology indicating compactness comparable to modern terrestrial squamates , a terrestrial lifestyle has been suggested for the proterochampsid Chanaresuchus bonapartei , and by extension, several other related proterochampsids sharing similar morphology. Notably, Proterochampsa is distinct enough from these other taxa that it could have potentially had

2079-404: 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,

2142-469: The French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or 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

2205-456: The Rosário do Sul Group, including Rhadinosuchus gracilis , Cerritosaurus binsfeldi , and Chanaresuchus bonapartei . 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

2268-425: The Santa Maria and Caturrita formations within the broader Santa Maria supersequence. Since their discovery starting in the early twentieth century, the taxa of the clade Proterochampsia have been assigned a number of different phylogenetic placements, including as relatives of early crocodiles , phytosaurs , or proterosuchids , eventually being recognized as non-archosaur archosauriformes . The first member of

2331-455: The Upper portion of the Santa Maria Formation found an estimated age of 233.23±0.73 million years ago, putting that locality 1.5 million years older than the Ischigualasto Formation and younger than Los Chañares Formation . The Santa Maria and Ischigualasto formations are approximately equal as having the earliest dinosaur localities. Most of the information below was included on a revision of

2394-442: 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

2457-505: The discovery of highly vascular and fibrolamellar bone tissue as evidence for rapid growth rates. Notably, there is variation within some species, and inconsistencies found in some studies suggest that proterochampsids may have had developmental plasticity, meaning their growth rates were variable and could respond to environmental changes. Like other proterochampsids, the two Proterochampsa species are thought to be predatory . P. nodosa lived in an environment with increasing humidity, when

2520-420: The dorsal position of the nares , which would make it easier for proterochampsids to breathe in aquatic environments, as evidence. Despite pointing out that the only character shared between proterochampsids and crocodilians was a secondary palate , Romer still used this character as supporting evidence for a potential aquatic or semiaquatic lifestyle for proterochampsids. A Proterochampsa nodosa specimen from

2583-446: 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

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2646-529: The formation where Proterochampsa specimens have been discovered. Proterochampsa nodosa specimens have all been found in the Santa Maria Supersequence within the Rosário do Sul Group in the Paraná Basin in southeastern Brazil . Similarly to the Ischigualasto Formation, the Santa Maria Formation is rich in Triassic tetrapod fossils, and well-known for this record. Although the Rosário do Sul Group represents

2709-727: 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,

2772-527: The genus Proterochampsa to be discovered was Proterochampsa barrionuevoi . In 1959, Reig described a specimen from the Ischigualasto Formation , and suggested that the species could be related to early crocodiles. When describing the same specimen in 1967, Sill supported this idea, and additionally denominated the family Proterochampsidae within the order Crocodilia to include the single known species. The first suggestion that proterochampsids had aquatic or semiaquatic lifestyles came from Romer in 1971, citing

2835-421: The group was no longer considered to be closely related to crocodiles or phytosaurs. Today, Proterochampsa and related taxa are generally considered archosauriformes, but a variety of more specific phylogenetic placements have been proposed and it remains unclear exactly where these taxa should be placed. The Proterochampsa genus was known mainly from skulls and postcrania that did not extend posteriorly past

2898-432: 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 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

2961-628: 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,

3024-559: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Santa Maria Formation The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul , Brazil . It is primarily Carnian in age ( Late Triassic ), and is notable for its fossils of cynodonts , " rauisuchian " pseudosuchians , and early dinosaurs and other dinosauromorphs , including

3087-460: The lower (and thus older) section of the Ischigualasto Formation, with most fossils estimated to age just under 228.97 million years old, placing them near the Carnian-Norian boundary. The more fossil-rich lower section of the formation can be divided into two biozones named for the rhynchosaurs most abundant within them: the lower portion is rich in Hyperodapedon specimens, and the upper portion

3150-403: 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

3213-643: The most anterior dorsal vertebrae until the description of a new P. barrionuevoi specimen by Trotteyn in 2011. This new specimen was much more complete, and included the skull, the complete vertebral series, pelvic girdle, right hindlimb, and portions of the pectoral girdle and two other limbs. This allowed for an amended and more complete definition than the original for the species. Both Proterochampsa barrionuevoi and Proterochampsa nodosa are recognizable by their distinctly triangular, dorsoventrally flattened skulls. Proterochampsa specimens have an average skull length of 50 centimeters. The skull extends laterally at

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3276-467: The most anterior dorsal vertebrae, until a more complete P. barrionuevoi specimen was described in 2011 by Trotteyn. However, a fully complete skeleton of either species has not yet been found. Proterochampsa are known to be quadrupedal, while the posture of proterochampsians as a whole is unclear due to their intermediate tarsal type that lies between crurotarsal and mesotarsal. They are an exception to many other archosauriformes , for which tarsal type

3339-428: 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

3402-435: The nodular protuberances are smaller and more sporadically positioned, while in P. nodosa , they are more organized, larger, and more well-developed. Other features that distinguish the two species include a higher occiput, a more gradually narrowing snout, and a less pronounced anterior depression on the antorbital fenestra in P. nodosa . Historically, knowledge of Proterochampsa postcrania did not extend posteriorly past

3465-454: The posterior end to form a large temporal region, then narrows more anteriorly to form a long, narrow snout that comprises around two-thirds of the skull lengthwise. The orbits , external nares , and antorbital and temporal fenestrae all face dorsally. Proterochampsids have serrated, conical, and laterally compressed marginal teeth, resembling those of modern gharials. Proterochampsa has fewer teeth than other proterochampsids. There are

3528-526: 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

3591-475: The species, including a V-shaped ridge around the basisphenoidal fossa with convex branching, and a ventrolaterally exposed semilunar depression on the parabasisphenoid. Both species within the Proterochampsa genus have prominent dermal sculpturing in the form of pits, ridges and nodular protuberances on a variety of cranial bones. This feature, which distinguishes Proterochampsa from other proterochampsids, presents distinctly in each species. In P. barrionuevoi ,

3654-497: 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,

3717-412: 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

3780-403: 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

3843-566: 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

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3906-680: The vertebrae, the genus Proterochampsa do not have osteoderms. The lifestyle of Proterochampsa and other proterochampsids has been contested, and a number of suggestions having been proposed. Many early descriptions of proterochampsids assumed aquatic or semiaquatic lifestyles similar to modern crocodiles , due to the superficial similarities shared between the two groups, including dorsoventrally flattened skulls and orbits and external nares that face dorsally. However, some more recent studies have called into question this assumption, and have proposed terrestrial/amphibious or distinctly terrestrial lifestyles for some taxa. Several of these studies use

3969-429: 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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