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62-616: Eoabelisaurus ( / ˈ i oʊ ə ˌ b ɛ l ɪ ˈ s ɔː r ə s / ) is a genus of abelisauroid theropod dinosaur from the Lower Jurassic Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Argentina , South America . The generic name combines a Greek ἠώς, ( eos ), "dawn", with the name Abelisaurus , in reference to the fact it represents an early relative of the latter. Only one species

124-763: A ceratosaurid, an abelisauroid or its sister taxon outside abelisaurids. Indeterminate remains are also known from the Jurassic period of Madagascar and Tanzania . Abelisaurid remains are mainly known in the southern continents, which once made up the supercontinent of Gondwana . When first described in 1985, only Carnotaurus and Abelisaurus were known, both from the Late Cretaceous of South America . Abelisaurids were then located in Late Cretaceous India ( Indosuchus and Rajasaurus ) and Madagascar ( Majungasaurus ), which were closely connected for much of

186-407: 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

248-643: 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

310-621: 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,

372-618: A noasaurid or an abelisaurid. With the description of Skorpiovenator in 2008, Canale et al. published another phylogenetic analysis focusing on the South American abelisaurids. In their results, they found that all South American forms, including Ilokelesia (except Abelisaurus ), grouped together as a subclade of carnotaurines, which they named the Brachyrostra . In the same year Matthew T. Carrano and Scott D. Sampson published new large phylogenetic analysis of ceratosaurian. With

434-409: 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

496-427: 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. ;

558-455: 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

620-436: Is about half the length of metacarpal II and considerably more slender. The arm also bears a stout phalanx that is slightly longer than the metacarpal. The non-terminal manual phalanges are about as long as wide and lack any constriction between the articular ends, and manual unguals are reduced. It is these reduced limb proportions that demonstrate Eoabelisaurus was indeed a primitive abelisaurid. The exact number of vertebrae

682-849: Is adopted. Ekrixinatosaurus was also published in 2004, so it was not included in Sereno's analysis. However, an independent analysis, performed by Jorge Calvo and colleagues, shows it to be an abelisaurid. Some scientists include Xenotarsosaurus from Argentina and Compsosuchus from India as basal abelisaurids, while others consider them to be outside the Abelisauroidea. The French Genusaurus and Tarascosaurus have also been called abelisaurids but both are fragmentary and may be more basal ceratosaurians, though Tortosa et al. (2014) considered both to be distinct abelisaurids. Subsequent phylogenetic analyses recover Xenotarsosaurus and Tarascosaurus as an abelisaurid, but Genusaurus as either

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744-666: Is currently recognized, E. mefi ; the specific name honours the MEF, the Museo Paleontológico "Egidio Feruglio" , where discoverer Diego Pol is active. It is characterized by reduced forelimb proportions that show primitive characteristics of the Abelisauridae family. In 2009, Argentinian paleontologist Diego Pol discovered the skeleton of a theropod near the village of Cerro Cóndor in Chubut Province . The remains were found in

806-529: Is derived from the Greek suffix -ιδαι ( - idai ) meaning 'descendants'. Abelisauridae is a family in rank-based Linnaean taxonomy , within the infraorder Ceratosauria and the superfamily Abelisauroidea , which also contains the family Noasauridae . It has had several definitions in phylogenetic taxonomy . It was originally defined as a node-based taxon including Abelisaurus , Carnotaurus , their common ancestor, and all of its descendants. Later, it

868-596: 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

930-447: Is not notably thickened and no cranial ornamentation is present. Both humeri from the known material are poorly preserved, but show primitive characters. The articular head is slightly rounded, but not a globular shape that is commonly seen in noasaurids and abelisaurids . The radius and ulna are short and the ulna has a large olecranon process. The manus is very foreshortened, retains four digits, and has short metacarpals. Metacarpal I

992-460: 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,

1054-474: 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

1116-413: Is unknown due to several gaps in the holotype's spine, but its cervical vertebrae are short and have two pneumatic foramina on either side of the centra. The length of vertebral centra remains constant over the preserved portion of the tail, but middle and posterior caudals are considerably lower. Eoabelisaurus was assigned to the basalmost position in Abelisauridae by its describers. It would, then, be

1178-558: The Aalenian - Bajocian , roughly 170 million years old, yet a recent advanced zircon datation constrained its age to the Middle-Late Toarcian (179-178 million years). It consists of a nearly complete skeleton with skull, of a subadult or adult individual. The posterior half of the skeleton was found in articulation and the anterior dorsal and cervical vertebrae and forelimbs were found partially disarticulated prior to burial. The skull

1240-621: 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

1302-799: 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;

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1364-458: The Jurassic period based on fossil records, and some genera survived until the end of the Mesozoic era, around 66  million years ago . Like most theropods, abelisaurids were carnivorous bipeds . They were characterized by stocky hind limbs and extensive ornamentation of the skull bones, with grooves and pits. In many abelisaurids, such as Carnotaurus , the forelimbs are vestigial ,

1426-473: The astragalus and calcaneum (upper ankle bones) fused to each other and to the tibia , forming a tibiotarsus. The tibia was shorter than the femur , giving the hind limb stocky proportions. Three functional digits were on the foot (the second, third, and fourth), while the first digit, or hallux , did not contact the ground. Although skull proportions varied, abelisaurid skulls were generally very tall and very short in length. In Carnotaurus , for example,

1488-419: 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 ,

1550-404: 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,

1612-487: The Cretaceous. It was thought that the absence of abelisaurids from continental Africa indicated that the group evolved after the separation of Africa from Gondwana, around 100 million years ago . However, the discovery of Rugops and other abelisaurid material from the middle of the Cretaceous in northern Africa disproved this hypothesis. Mid-Cretaceous abelisaurids are now known from South America as well, showing that

1674-623: The Jugo Loco locality that is placed in a series of fine beds of mudstone, marlstone, and limestone in the Cañadón Asfalto Formation . In 2012, based on these remains, the type species Eoabelisaurus mefi was named and described by Pol and his German colleague Oliver Rauhut. Before discovery, the oldest known abelisaurids were represented only by fragmentary remains from the late Early Cretaceous of South America and Africa and older records of abelisauroids in general were questionable. With

1736-665: The ancient southern supercontinent of Gondwana , and today their fossil remains are found on the modern continents of Africa and South America , as well as on the Indian subcontinent and the island of Madagascar . Isolated teeth were found in the Late Jurassic of Portugal, and the Late Cretaceous genera Tarascosaurus , Arcovenator and Caletodraco have been described in France . Abelisaurids possibly first appeared during

1798-442: 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

1860-753: The basic position within Ceratosauridae , noting that the topology of this genus is still problematic. The following cladogram demonstrates the relationships of Eoabelisaurus according to latter publication. Spinostropheus Elaphrosaurus [REDACTED] Limusaurus [REDACTED] Deltadromeus Laevisuchus Noasaurus Velocisaurus Masiakasaurus [REDACTED] Berberosaurus Eoabelisaurus [REDACTED] Genyodectes Ceratosaurus [REDACTED] Chenanisaurus Rugops Abelisaurus Ilokelesia [REDACTED] Arcovenator [REDACTED] Indosaurus Genus The composition of

1922-466: The discovery of Eoabelisaurus , the temporal range of the clade was extended for more than 40  million years into the Toarcian . The existence of a derived ceratosaur at that time indicated a rapid diversification of ceratosaurs during that time period, as all the major ceratosaurian lineages (ceratosaurids, noasaurids, and abelisaurids) had already been established. It was a bipedal carnivore that

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1984-460: The evolution towards vestigial fore limbs in the group was because of a genetic defect; the loss of function in HOXA11 and HOXD11 , two genes that regulate the fore limbs' development. Abelisaurids are typically regarded as a Cretaceous period group. The earliest possible abelisaurid taxon is Eoabelisaurus mefi from the Jurassic period of Argentina, though other researchers either consider it as

2046-442: The eye socket, to form a ridge or brow above the eye. Sculpturing is seen on many of the skull bones, in the form of long grooves, pits, and protrusions. Like other ceratosaurs , the frontal bones of the skull roof were fused together. Carnotaurines commonly had bony projections from the skull. Carnotaurus had two pronounced horns, projecting outward above the eyes, while its close relative Aucasaurus had smaller projections in

2108-469: The first or fourth digits, only one on the second digit and two on the third digit. These two external fingers were extremely short and immobile. Manual claws were very small in Eoabelisaurus , and totally absent in carnotaurines. More primitive relatives such as Noasaurus and Ceratosaurus had longer, mobile arms with fingers and claws. Paleobiologist Alexander O. Vargas suggested a major reason for

2170-446: 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

2232-727: 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,

2294-536: The group existed prior to the breakup of Gondwana. In 2014, the description of Arcovenator escotae from southern France provided the first indisputable evidence of the presence of Abelisaurids in Europe . Arcovenator presents strong similarities with the Madagascan Majungasaurus and Indian abelisaurids, but not with the South American forms. Arcovenator , Majungasaurus , and Indian forms are united in

2356-628: 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,

2418-505: The length of the upper arm ( humerus ) in Carnotaurus and 33% in Aucasaurus . The entire arm was held straight, and the elbow joint was immobile. As is typical for ceratosaurs, the abelisaurid hand had four basic digits, but any similarity ends there. No wrist bones existed, with the four palm bones ( metacarpals ) attaching directly to the forearm. No phalanges (finger bones) were on

2480-404: The level of the skull roof. Possibly, this rugose brow ridge supported a keratinous or scaly structure for displays. Data for the abelisaurid fore limbs are known from Eoabelisaurus and the carnotaurines Aucasaurus , Carnotaurus , and Majungasaurus . All had small fore limbs, which seem to have been vestigial. The bones of the forearm ( radius and ulna ) were extremely short, only 25% of

2542-466: 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. Abelisauridae This is an accepted version of this page Abelisauridae (meaning "Abel's lizards") is a family (or clade ) of ceratosaurian theropod dinosaurs . Abelisaurids thrived during the Cretaceous period , on

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2604-403: 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

2666-565: The most advanced abelisaurids (such as Carnotaurus and Aucasaurus ), making establishment of defining features of the skeleton for the family as a whole more difficult. However, most are known from at least some skull bones, so known shared features come mainly from the skull. Many abelisaurid skull features are shared with carcharodontosaurids . These shared features, along with the fact that abelisaurids seem to have replaced carcharodontosaurids in South America, have led to suggestions that

2728-428: 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

2790-465: The new clade Majungasaurinae . Paleontologists Jose Bonaparte and Fernando Novas coined the name Abelisauridae in 1985 when they described the eponymous Abelisaurus . The name is formed from the family name of Roberto Abel, who discovered Abelisaurus , and from the Greek word σαυρος ( sauros ) meaning lizard. The very common suffix -idae is usually applied to zoological family names and

2852-1023: The oldest abelisaurid species known by forty (40) million years. The describers indicated that in the cladistic analysis a difference of only a single trait would have resulted in a position lower in the evolutionary tree, basal in the Abelisauroidea . The following cladogram follows their analysis. Berberosaurus Deltadromeus Spinostropheus Limusaurus [REDACTED] Elaphrosaurus [REDACTED] Ceratosaurus [REDACTED] Genyodectes Laevisuchus Masiakasaurus [REDACTED] Noasaurus Velocisaurus Eoabelisaurus [REDACTED] Rugops Abelisaurus Majungasaurus [REDACTED] Indosaurus Rajasaurus [REDACTED] Ilokelesia [REDACTED] Ekrixinatosaurus [REDACTED] Skorpiovenator [REDACTED] Carnotaurus [REDACTED] Aucasaurus [REDACTED] In 2018, Rafael Delcourt placed Eoabelisaurus at

2914-526: 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

2976-424: The same area. Majungasaurus and Rajasaurus had a single bony horn or dome, projecting upwards from the skull. These projections, like the horns of many modern animals, might have been displayed for species recognition or intimidation. In Arcovenator , the dorsal margin of the postorbital (and probably also the lacrimal) is thickened dorsolaterally, forming a strong and rugose bony brow ridge rising above

3038-466: 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

3100-408: 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

3162-576: The skull is shorter, and bony crests grow above the eyes. Most of the known abelisaurids would have been between 5 and 9 m (17 to 30 ft) in length, from snout to tip of tail, with a new and as yet unnamed specimen from northwestern Turkana in Kenya, Africa reaching a possible length of 11–12 m (36 to 39 ft). Before becoming well known, fragmentary abelisaurid remains were occasionally misidentified as possible South American tyrannosaurids . Abelisaurid hind limbs were more typical of ceratosaurs, with

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3224-541: The skull was nearly as tall as it was long. The premaxilla in abelisaurids was very tall, so the front of the snout was blunt, not tapered as seen in many other theropods. Two skull bones, the lacrimal and postorbital bones, projected into the eye socket from the front and back, nearly dividing it into two compartments. The eye would have been located in the upper compartment, which was tilted slightly outwards in Carnotaurus , perhaps providing some degree of binocular vision . The lacrimal and postorbital also met above

3286-497: 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,

3348-412: 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

3410-403: 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

3472-973: The two groups were related. However, no cladistic analysis has ever found such a relationship, and aside from the skull, abelisaurids and carcharodontosaurids are very different, more similar to ceratosaurs and allosauroids , respectively. Below is a cladogram generated by Tortosa et al. (2014) in the description of Arcovenator and creation of a new subfamily Majungasaurinae. Kryptops Rugops Genusaurus MCF-PVPH-237 abelisaurid Xenotarsosaurus Tarascosaurus La Boucharde abelisaurid Pourcieux abelisaurid Arcovenator [REDACTED] Majungasaurus [REDACTED] Indosaurus Rahiolisaurus Rajasaurus [REDACTED] Ilokelesia [REDACTED] Ekrixinatosaurus [REDACTED] Skorpiovenator [REDACTED] Abelisaurus Aucasaurus [REDACTED] Pycnonemosaurus Quilmesaurus [REDACTED] Carnotaurus [REDACTED] Ilokelesia

3534-566: 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

3596-429: 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

3658-507: Was discovered slightly separated from the vertebral column. The skull and anterior presacrals were also exposed at the time of discovery and had been partially been destroyed by erosion. From the material known of the snout, only a small fragment of the right maxilla has been recovered and shows that the interdental plates are fused, but not striated. The known posterior part of the skull is high, with an oval orbit and an enlarged infratemporal fenestra, similar to other ceratosaurs . The skull roof

3720-420: Was estimated to have reached 6–6.5 metres (19.7–21.3 ft) in length, although a comprehensive analysis of abelisaur size conducted in 2016 yielded a size estimate of 5.8 metres (19 ft). It is estimated to have weighed up to 730–800 kilograms (1,610–1,760 lb). The holotype specimen, MPEF PV 3990 , was uncovered in a layer of the Cañadón Asfalto Formation , a lacustrine deposit dating originally from

3782-480: Was originally described as a sister group to the Abelisauroidea. However, Sereno tentatively places it closer to Abelisaurus than to noasaurids, a result which agrees with several other recent analyses. If a stem-based definition is used, Ilokelesia and Rugops are therefore basal abelisaurids. However, as they are more basal than Abelisaurus , they are outside of the Abelisauridae if the node-based definition

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3844-601: Was redefined as a stem-based taxon, including all animals more closely related to Abelisaurus (or the more complete Carnotaurus ) than to Noasaurus . The node-based definition would not include animals such as Rugops or Ilokelesia , which are thought to be more basal than Abelisaurus and would be included by a stem-based definition. Within the Abelisauridae is the subgroup Carnotaurinae , and among carnotaurines, Aucasaurus and Carnotaurus are united in Carnotaurini . Complete skeletons have been described only for

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