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{{Short description|Extinct genus of dinosaurs}}
{{Italic title}}
{{Italic title}}
{{Automatic taxobox
{{Automatic taxobox
| name = ''Abelisaurus''
| name = ''Abelisaurus''
| fossil_range = [[Late Cretaceous]], {{fossilrange|80}}
| fossil_range = [[Campanian]], {{fossilrange|80}}<ref>{{cite web|url=https://www.nhm.ac.uk/discover/dino-directory/abelisaurus.html|title=Abelisaurus|language=en|access-date=2024-08-08}}</ref>
| image = Abelisaurus_skull.jpg
| image = Abelisaurus_skull.jpg
| image_caption = Reconstruction of the ''Abelisaurus'' skull with original bones of the holotype. Scale = 10 cm
| image_caption = Reconstruction of the ''Abelisaurus'' skull with original bones of the holotype. Scale = 10 cm
Line 8: Line 9:
| taxon = Abelisaurus
| taxon = Abelisaurus
| authority = Bonaparte & Novas, 1985
| authority = Bonaparte & Novas, 1985
| type_species = {{extinct}}'''''Abelisaurus comahuensis'''
| type_species = {{extinct}}'''''Abelisaurus comahuensis'''''
| type_species_authority = [[Jose Bonaparte|Bonaparte]] & [[Fernando Novas|Novas]], 1985
| type_species_authority = [[Jose Bonaparte|Bonaparte]] & [[Fernando Novas|Novas]], 1985
| synonyms = ?''[[Aucasaurus]]'' <small>Coria, Chippe and Dingus, 2002</small>
| synonyms =
*''[[Aucasaurus]] garridoi''? <small>Coria ''et al.'', 2002</small>
}}
}}


'''''Abelisaurus''''' ({{IPAc-en|ə|ˌ|b|ɛ|l|ᵻ|ˈ|s|ɔː|r|ə|s}}; "Abel's lizard") is a [[genus]] of predatory [[abelisaurid]] [[theropod]] [[dinosaur]] during the Late [[Cretaceous]] [[Period (geology)|Period]] ([[Campanian]]) of what is now [[South America]]. It was a [[biped]]al [[carnivore]] that probably reached about {{convert|7.4|m|ftin}} in length, although this is uncertain as it is known from only one partial [[skull]].
'''''Abelisaurus''''' ({{IPAc-en|ə|ˌ|b|ɛ|l|ᵻ|ˈ|s|ɔː|r|ə|s}}; "Abel's lizard") is a [[genus]] of predatory [[abelisaurid]] [[theropod]] [[dinosaur]] alive during the Late [[Cretaceous]] [[Period (geology)|Period]] ([[Campanian]]) of what is now [[South America]]. It was a [[biped]]al [[carnivore]] that probably reached about {{convert|7.4|m|ftin}} in length, although this is uncertain as it is known from only one partial [[skull]].


==Discovery and history==
==Discovery and naming==
[[File:Abelisaurus comahuensis.JPG|thumb|left|Restored skull in semi profile]]
[[File:Fm Anacleto Auca Mahuida 2.jpg|thumb|left|The [[Anacleto Formation]] where ''Abelisaurus'' remains have been found]]
Coining the [[type species]] ''Abelisaurus comahuensis'', both genus and species were named and described by [[List of Argentines|Argentine]] [[paleontologists]] [[José Bonaparte]] and [[Fernando Emilio Novas]] in 1985. The generic name recognizes Roberto Abel as the discoverer of the [[type specimen]], and also as the former director of the provincial Museum of [[Cipolletti]] in [[Argentina]], where the specimen is housed. It also incorporates the [[Ancient Greek|Greek]] σαυρος/''sauros'', meaning 'lizard'. The [[specific name (zoology)|specific name]] ''comahuensis'' honors the [[Comahue]] region of Argentina, where the fossil was found.<ref name="bonapartenovas1985">Bonaparte, J.F. & Novas, F.E. (1985). "''Abelisaurus comahuensis'', n.g., n.sp., Carnosauria del Crétacico Tardio de Patagonia". ''[[Ameghiniana]]''. '''21''': 259-265. [In Spanish]</ref>
Coining the [[type species]] ''Abelisaurus comahuensis'', both genus and species were named and described by [[List of Argentines|Argentine]] [[paleontologists]] [[José Bonaparte]] and [[Fernando Emilio Novas]] in 1985. The generic name recognizes Roberto Abel as the discoverer of the [[type specimen]], and also as the former director of the provincial Museum of [[Cipolletti]] in [[Argentina]], where the specimen is housed. It also incorporates the [[Ancient Greek|Greek]] {{lang|grc|σαυρος}} (''{{lang|grc-Latn|sauros}}''), meaning 'lizard'. The [[specific name (zoology)|specific name]] ''comahuensis'' honors the [[Comahue]] region of Argentina, where the fossil was found.<ref name=":0">{{Cite journal|last1=Bonaparte|first1=J.|last2=Novas|first2=E.E.|date=1985|title=Abelisaurus comahuensis, n.g., n.sp., Carnosauria del Crétacico Tardio de Patagonia|trans-title=Abelisaurus comahuensis, n.g., n.sp., Carnosauria from the Late Cretaceous of Patagonia|url=https://www.researchgate.net/publication/237714676|journal=Ameghiniana|volume=21|pages=259–265|via=ResearchGate}}</ref>


The [[holotype]], '''MC 11078''', was in 1983 uncovered at the "Cantera de la Pala Mécanica"-site in the Lago Pellegrini quarries exploited by Abel since 1975. This single known [[fossil]] of ''Abelisaurus'' consists of a skull, lacking the lower jaws, that is incomplete, especially on the right side. Most of the connections between the snout and the back of the skull are absent. It is also missing most of the [[palate]] (roof of the mouth). Despite the missing pieces, it could be estimated at over {{convert|85|cm|in|0}} long.<ref name="bonapartenovas1985"/>
The [[holotype]], '''MC 11098''', was in 1983 uncovered at the "Cantera de la Pala Mécanica"-site in the Lago Pellegrini quarries exploited by Abel since 1975. This single known [[fossil]] of ''Abelisaurus'' consists of a skull, lacking the lower jaws, that is incomplete, especially on the right side. Most of the connections between the snout and the back of the skull are absent. It is also missing most of the [[palate]] (roof of the mouth). Despite the missing pieces, it could be estimated at over {{convert|85|cm|in|0}} long.<ref name=":0" />
⚫
[[File:Carnotaurini sizes.png|thumb|left|Size comparison of ''Abelisaurus'' (second from left) with other carnotaurins]]
⚫
''Abelisaurus'' is one of the many dinosaurs that have been discovered in [[Patagonia]]. It was originally described as coming from the [[Allen Formation]] but subsequent research proved the remains were actually found in the older [[Anacleto Formation]] (part of the [[Neuquen group|Neuquén Group]]) of [[Rio Negro Province]], Argentina. The Anacleto is a [[geologic formation]] in South America, dating from the early [[Campanian]] stage of the [[Late Cretaceous]] Period, between 83 and 80 [[million years ago]].<ref name="leanzaetal2004">Leanza, H.A., Apesteguia, S., Novas, F.E., & de la Fuente, M.S. 2004. Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. ''Cretaceous Research'' 25(1): 61-87.</ref>


⚫
''Abelisaurus'' is one of the many dinosaurs that have been discovered in [[Patagonia]]. It was originally described as coming from the [[Allen Formation]] but subsequent research proved the remains were actually found in the older [[Anacleto Formation]] (part of the [[Neuquen group|Neuquén Group]]) of [[Rio Negro Province]], Argentina. However, locally ''Abelisaurus'' is known to have come from the Sr. Fernandez field, which is in the [[Campanian]] [[Allen Formation]], which makes its stratigraphic position unclear.<ref>{{Cite journal|last1=Gianechini|first1=Federico A.|last2=Apesteguía|first2=Sebastián|last3=Landini|first3=Walter|last4=Finotti|first4=Franco|last5=Juárez Valieri|first5=Rubén|last6=Zandonai|first6=Fabiana|date=2015-05-01|title=New abelisaurid remains from the Anacleto Formation (Upper Cretaceous), Patagonia, Argentina|url=http://www.sciencedirect.com/science/article/pii/S0195667114002201|journal=Cretaceous Research|language=en|volume=54|pages=1–16|doi=10.1016/j.cretres.2014.11.009|bibcode=2015CrRes..54....1G |issn=0195-6671|hdl=11336/37727|hdl-access=free}}</ref> The Anacleto is a [[geologic formation]] in South America, dating from the early [[Campanian]] stage of the [[Late Cretaceous]] Period, between 83 and 80 [[million years ago]].<ref>{{Cite journal|last1=Leanza|first1=H.A.|last2=Apesteguía|first2=S.|last3=Novas|first3=F.E.|last4=Fuente|first4=M.S.|date=2004|title=Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages|journal=Cretaceous Research|volume=25|issue=1|pages=61–87|doi=10.1016/j.cretres.2003.10.005|bibcode=2004CrRes..25...61L }}</ref>
⚫
In 2009, Novas suggested that ''[[Aucasaurus]] garridoi'' might be a [[junior synonym]] of ''Abelisaurus''.<ref name="Novas2009">Fernando E. Novas, 2009, ''The Age of Dinosaurs in South America'', Life of the Past, Indiana University Press, 480 pp</ref> In 2010, [[Gregory S. Paul]] renamed ''Aucasaurus'' into a ''Abelisaurus garridoi''.<ref name="Paul2010">Paul, G.S., 2010, ''The Princeton Field Guide to Dinosaurs'', Princeton University Press p. 79</ref> This has found no acceptance.

⚫
In 2009, Novas suggested that ''[[Aucasaurus]] garridoi'' might be a [[junior synonym]] of ''Abelisaurus comahuensis''.<ref name=":1">{{Cite book|last=Novas|first=F.E.|title=The Age of Dinosaurs in South America|publisher=Indiana University Press|year=2009|isbn=9780253352897|pages=281}}</ref> In 2010, [[Gregory S. Paul]] renamed ''Aucasaurus garridoi'' into ''Abelisaurus garridoi''.<ref name=":2">{{Cite book|last=Paul|first=G.S.|title=The Princeton Field Guide to Dinosaurs|publisher=Princeton University Press|year=2010|isbn=9781400836154}}</ref> This has found no acceptance.{{Citation needed|date=August 2020}}


==Description==
==Description==
⚫
[[File:Carnotaurini sizes updated.png|thumb|left|Size comparison of ''Abelisaurus'' (red) with other carnotaurins]]
[[File:Abelisaurus comahuensis jmallon.jpg|thumb|Artist's restoration]]
[[File:Abelisaurus comahuensis jmallon.jpg|thumb|right|Artist's restoration]]
As only the skull is known, it has proven difficult to provide a reliable size estimate of ''Abelisaurus''. It has transpired that abelisaurids have relatively short heads. In 2010, [[Gregory S. Paul]] estimated its body length at {{convert|10|m|ftin|spell=in}}, its weight at {{convert|3|t|0}}.<ref name="Paul2010"/> In 2016, its length was estimated to be {{convert|7.4|m|ftin}} in a comprehensive analysis of abelisaur size.<ref>{{cite journal |last1 = Grillo | first1 = O. N. | last2 = Delcourt | first2 = R. |date = 2016 | title = Allometry and body length of abelisauroid theropods: ''Pycnonemosaurus nevesi'' is the new king | url = http://www.sciencedirect.com/science/article/pii/S0195667116301902 | journal = Cretaceous Research | doi = 10.1016/j.cretres.2016.09.001}}</ref>
As only the skull is known, it has proven difficult to provide a reliable size estimate of ''Abelisaurus''. It has transpired that abelisaurids have relatively short heads. In 2010, [[Gregory S. Paul]] estimated its body length at {{convert|10|m|ftin|spell=in}}, its weight at {{convert|3|t|0}}.<ref name=":2" /> In 2012 [[Thomas R. Holtz Jr.|Thomas Holtz]] gave a possible length of 11 metres (36.3 feet).<ref>{{Cite book|last=Holtz|first=T.R.|title=Dinosaurs: The Most Complete, Up-to-date Encyclopedia for Dinosaur Lovers of All Ages|publisher=Random House|year=2012|isbn=9780375824197|pages=83}}</ref> In 2016, its length was estimated to be {{convert|7.4|m|ftin}} in a comprehensive analysis of abelisaur size.<ref>{{cite journal|last1=Grillo|first1=O.N.|last2=Delcourt|first2=R.|date=2016|title=Allometry and body length of abelisauroid theropods: ''Pycnonemosaurus nevesi'' is the new king|journal=Cretaceous Research|volume=69|pages=71–89|doi=10.1016/j.cretres.2016.09.001|bibcode=2017CrRes..69...71G }}</ref> Others authors gave a similar size at 7.2 metres (23.6 feet) and 1.65 tonnes (1.82 short tons).<ref>{{Cite book|last1=M-P.|first1=R.|title=Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos|last2=Larramendi|first2=A.|publisher=Larousse|year=2016|isbn=9788416641154|location=Barcelona, Spain|pages=257}}</ref>


Skull length was estimated at {{convert|859|mm|in|frac=4}} in 1985. The skull is relatively deep. Although there are no bony crests or horns, like those found in some other abelisaurids, such as ''[[Carnotaurus]]'', rough ridges on the snout and above the eyes might have supported some kind of crest made out of [[keratin]], which would not have become fossilized. The skull roof is thickened. There are also very large ''fenestrae'' (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight. One of these is a large triangular [[antorbital fenestra]] in the side of the snout. The eye socket behind it is rather high. It is constricted in the middle by bony projections of the [[lacrimal bone]] in the front and the [[postorbital bone]] at the rear. The eye was located above the constriction. Behind the eye socket a large triangular [[infratemporal fenestra]] is present. Its form reflects a strong forward inclination of the back of the skull.<ref name="bonapartenovas1985"/>
Skull length was estimated at {{convert|85|cm|in|frac=4}} in 1985. The skull is relatively deep. Although there are no bony crests or horns, like those found in some other abelisaurids, such as ''[[Carnotaurus]]'', rough ridges on the snout and above the eyes might have supported some kind of crest made out of [[keratin]], which would not have become fossilized. The skull roof is thickened. There are also very large ''fenestrae'' (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight. One of these is a large triangular [[antorbital fenestra]] in the side of the snout. The eye socket behind it is rather high. It is constricted in the middle by bony projections of the [[lacrimal bone]] in the front and the [[postorbital bone]] at the rear. The eye was located above the constriction. Behind the eye socket a large triangular [[infratemporal fenestra]] is present. Its form reflects a strong forward inclination of the back of the skull.<ref name=":0" />


The front snout bone, the [[praemaxilla]], bore four relatively small teeth. The [[maxilla]] behind it had at least seven, but perhaps as many as thirteen, larger teeth.<ref name="bonapartenovas1985"/>
The front snout bone, the [[praemaxilla|premaxilla]], bore four relatively small teeth. The [[maxilla]] behind it had at least seven, but perhaps as many as thirteen, larger teeth.<ref name=":0" />


==Classification==
==Classification==
Bonaparte and Novas placed ''Abelisaurus'' in the newly created [[family (biology)|family]] [[Abelisauridae]] in 1985. They thought it was a member of the [[Carnosauria]].<ref name="bonapartenovas1985"/> ''Abelisaurus'' was the first abelisaurid named.<ref name="Novas2009"/>
[[File:Fossil dinosaur tooth (possibly from Abelisaurus).jpg|thumb|187x187px|Tooth of ''[[cf.]] Abelisaurus'']]
Bonaparte and Novas placed ''Abelisaurus'' in the newly created [[family (biology)|family]] [[Abelisauridae]] in 1985. They thought it was a member of the [[Carnosauria]].<ref name=":0" /> ''Abelisaurus'' was the first abelisaurid named.<ref name=":1" />


Many other abelisaurids have since been discovered, including much more complete specimens of ''[[Aucasaurus]]'', ''Carnotaurus'' and ''[[Majungasaurus]]''. They showed that abelisaurids were not carnosaurs in the modern sense, but belonged to the [[Neoceratosauria]] instead. Some scientists place ''Abelisaurus'' as a [[Basal (phylogenetics)|basal]] abelisaurid, outside the subfamily [[Abelisauridae|Carnotaurinae]].<ref name="tykoskirowe2004">Tykoski, R.S. & Rowe, T. 2004. Ceratosauria. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.) ''The Dinosauria'' (2nd edition). Berkeley: University of California Press. Pp. 47-70.</ref><ref name="serenoetal2004">Sereno, P.C., Wilson, J.A., & Conrad, J.L. 2004. New dinosaurs link southern landmasses in the Mid-Cretaceous. ''Proceedings of the Royal Society of London: Biological Sciences'' 271: 1325-1330.</ref> Others are less certain of its position.<ref name="sampsonetal1998">Sampson, S.D., Witmer, L.M., Forster, C.A., Krause, D.A., O'Connor, P.M., Dodson, P., Ravoavy, F. 1998. Predatory dinosaur remains from Madagascar: implications for the Cretaceous biogeography of Gondwana. ''Science'' 280: 1048-1051.</ref><ref name="lammanaetal2002">Lamanna, M.C., Martinez, R.D., & Smith, J.B. 2002. A definitive abelisaurid theropod dinosaur from the early Late Cretaceous of Patagonia. ''Journal of Vertebrate Paleontology''. 22(1): 58-69.</ref> ''Abelisaurus'' shares some skull features, such as a relative elongation, with the [[carcharodontosauridae|carcharodontosaurids]], a group unrelated to other species assigned to the Abelisauridae, and, since it is known only from a skull, it has been suggested that future discoveries may show that ''Abelisaurus'' was in fact a carcharodontosaurid.<ref name="novas1997">Novas, F.E. 1997. Abelisauridae. In: Currie, P.J. & Padian, K.P. ''Encyclopedia of Dinosaurs''. San Diego: Academic Press. Pp. 1-2.</ref> However, this is thought unlikely.<ref name="lammanaetal2002"/>
Many other abelisaurids have since been discovered, including much more complete specimens of ''[[Aucasaurus]]'', ''Carnotaurus'' and ''[[Majungasaurus]]''. They showed that abelisaurids were not carnosaurs in the modern sense, but belonged to the [[Neoceratosauria]] instead. Some scientists place ''Abelisaurus'' as a [[Basal (phylogenetics)|basal]] abelisaurid, outside the subfamily [[Abelisauridae|Carnotaurinae]].<ref>{{Cite book|last1=Tykoski|first1=R.S.|title=The Dinosauria|last2=Rowe|first2=T.|publisher=University of California Press|year=2004|isbn=9780520941434|editor-last=Dodson|editor-first=P.|pages=47–70|chapter=Ceratosauria|editor2-last=Osmólska|editor2-first=H.|editor3-last=Weishamepl|editor3-first=D.B.|edition=2nd }}</ref><ref>{{Cite journal|last1=Sereno|first1=P.C.|last2=Wilson|first2=J.A.|last3=Conrad|first3=J.L.|date=2004|title=New dinosaurs link southern landmasses in the Mid-Cretaceous|journal=Proceedings of the Royal Society B: Biological Sciences|volume=271|issue=1546|pages=1325–1330|doi=10.1098/rspb.2004.2692|pmid=15306329|pmc=1691741}}</ref> Others are less certain of its position.<ref>{{Cite journal|last1=Sampson|first1=S.D.|last2=Witmer|first2=L.M.|last3=Forster|first3=C.A.|last4=Krause|first4=D.A.|last5=O'Connor|first5=P.M.|last6=Dodson|first6=P.|last7=Ravoavy|first7=F.|date=1998|title=Predatory Dinosaur Remains from Madagascar: Implications for the Cretaceous Biogeography of Gondwana|journal=Science|volume=280|issue=5366|pages=1048–1051|doi=10.1126/science.280.5366.1048|pmid=9582112|bibcode=1998Sci...280.1048S }}</ref><ref name=":3">{{Cite journal|last1=Lamanna|first1=M.C.|last2=Martínez|first2=R.D.|last3=Smith|first3=J.B.|date=2002|title=A definitive abelisaurid theropod dinosaur from the early Late Cretaceous of Patagonia|journal=Journal of Vertebrate Paleontology|volume=22|issue=1|pages=58–69|doi=10.1671/0272-4634(2002)022[0058:ADATDF]2.0.CO;2|s2cid=86153297 |issn=0272-4634}}</ref> ''Abelisaurus'' shares some skull features, such as a relative elongation, with the [[carcharodontosauridae|carcharodontosaurids]], a group unrelated to other species assigned to the Abelisauridae, and, since it is known only from a skull, it has been suggested that future discoveries may show that ''Abelisaurus'' was in fact a carcharodontosaurid.<ref>{{Cite book|last=Novas|first=F.E.|title=Encyclopedia of Dinosaurs|publisher=Academic Press|year=1997|isbn=9780080494746|editor-last=Currie|editor-first=P.J.|location=San Diego|pages=1–2|chapter=Abelisauridae|oclc=436848919|editor2-last=Padian|editor2-first=K.P.}}</ref> However, this is thought unlikely.<ref name=":3" />


==Paleobiology==
==Paleobiology==
[[File:Abelisaurus BW.jpg|thumb|Restoration of the head of ''Abelisaurus''|left]]
As the skull of ''Abelisaurus'' was relatively broad at the back, Bonaparte and Novas drew a comparison between the newly described species and the also wide-skulled [[Tyrannosauridae]]. They assumed that, just as tyrannosaurids, ''Abelisaurus'' were the [[apex predator]]s of their [[ecosystem]].<ref name="bonapartenovas1985"/>
As the skull of ''Abelisaurus'' was relatively broad at the back, Bonaparte and Novas drew a comparison between the newly described species and the also wide-skulled [[Tyrannosauridae]]. They assumed that, just as tyrannosaurids, ''Abelisaurus'' were the [[apex predator]]s of their [[ecosystem]].<ref name=":0" />


In 2010, Paul proposed that ''Abelisaurus'' hunted [[titanosauria]]n [[sauropods]].<ref name="Paul2010"/>
In 2010, Paul proposed that ''Abelisaurus'' hunted [[titanosauria]]n [[sauropods]], such as ''[[Antarctosaurus]]'', ''[[Pellegrinisaurus]]'', ''[[Barrosasaurus]]'' and ''[[Neuquensaurus]]''.<ref name=":2" />


==See also==
== See also ==
{{Portal|Dinosaurs}}
* [[Timeline of ceratosaur research]]
* [[Timeline of ceratosaur research]]


Line 50: Line 54:
{{Reflist}}
{{Reflist}}


==External links==
== External links ==
{{commons category|Abelisaurus}}
{{commons category|Abelisaurus}}
⚫
* [https://web.archive.org/web/20071209234858/http://www.nhm.ac.uk/jdsml/nature-online/dino-directory/detail.dsml?Genus=Abelisaurus ''Abelisaurus'' in the Dino Directory]


{{Ceratosauria}}
{{Theropoda|B.}}
⚫
* [http://www.nhm.ac.uk/jdsml/nature-online/dino-directory/detail.dsml?Genus=Abelisaurus ''Abelisaurus'' in the Dino Directory]

{{Taxonbar|from=Q130921}}
{{Taxonbar|from=Q130921}}


[[Category:Brachyrostrans]]
[[Category:Abelisaurids]]
⚫
[[Category:Campanian life]]
[[Category:Late Cretaceous dinosaurs of South America]]
[[Category:Late Cretaceous dinosaurs of South America]]
[[Category:Cretaceous Argentina]]
[[Category:Fossils of Argentina]]
[[Category:Anacleto Formation]]
[[Category:Fossil taxa described in 1985]]
[[Category:Fossil taxa described in 1985]]
[[Category:Taxa named by José Bonaparte]]
[[Category:Taxa named by José Bonaparte]]
[[Category:Taxa named by Fernando Novas]]
[[Category:Taxa named by Fernando Novas]]
⚫
[[Category:Anacleto Formation]]

Latest revision as of 21:52, 17 October 2024

Abelisaurus
Temporal range: Campanian, 80 Ma
↓
[1]
Reconstruction of the Abelisaurus skull with original bones of the holotype. Scale = 10 cm
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Abelisauridae
Clade: †Furileusauria
Tribe: †Carnotaurini
Genus: †Abelisaurus
Bonaparte & Novas, 1985
Type species
†Abelisaurus comahuensis
Synonyms

Abelisaurus (/əˌbɛlɪˈsɔːrəs/; "Abel's lizard") is a genus of predatory abelisaurid theropod dinosaur alive during the Late Cretaceous Period (Campanian) of what is now South America. It was a bipedal carnivore that probably reached about 7.4 metres (24 ft 3 in) in length, although this is uncertain as it is known from only one partial skull.

Discovery and naming

[edit]
The Anacleto Formation where Abelisaurus remains have been found

Coining the type species Abelisaurus comahuensis, both genus and species were named and described by Argentine paleontologists José Bonaparte and Fernando Emilio Novas in 1985. The generic name recognizes Roberto Abel as the discoverer of the type specimen, and also as the former director of the provincial Museum of Cipolletti in Argentina, where the specimen is housed. It also incorporates the Greek σαυρος (sauros), meaning 'lizard'. The specific name comahuensis honors the Comahue region of Argentina, where the fossil was found.[2]

The holotype, MC 11098, was in 1983 uncovered at the "Cantera de la Pala Mécanica"-site in the Lago Pellegrini quarries exploited by Abel since 1975. This single known fossil of Abelisaurus consists of a skull, lacking the lower jaws, that is incomplete, especially on the right side. Most of the connections between the snout and the back of the skull are absent. It is also missing most of the palate (roof of the mouth). Despite the missing pieces, it could be estimated at over 85 centimetres (33 in) long.[2]

Abelisaurus is one of the many dinosaurs that have been discovered in Patagonia. It was originally described as coming from the Allen Formation but subsequent research proved the remains were actually found in the older Anacleto Formation (part of the Neuquén Group) of Rio Negro Province, Argentina. However, locally Abelisaurus is known to have come from the Sr. Fernandez field, which is in the Campanian Allen Formation, which makes its stratigraphic position unclear.[3] The Anacleto is a geologic formation in South America, dating from the early Campanian stage of the Late Cretaceous Period, between 83 and 80 million years ago.[4]

In 2009, Novas suggested that Aucasaurus garridoi might be a junior synonym of Abelisaurus comahuensis.[5] In 2010, Gregory S. Paul renamed Aucasaurus garridoi into Abelisaurus garridoi.[6] This has found no acceptance.[citation needed]

Description

[edit]
Size comparison of Abelisaurus (red) with other carnotaurins
Artist's restoration

As only the skull is known, it has proven difficult to provide a reliable size estimate of Abelisaurus. It has transpired that abelisaurids have relatively short heads. In 2010, Gregory S. Paul estimated its body length at ten metres (32 ft 10 in), its weight at 3 tonnes (3 long tons; 3 short tons).[6] In 2012 Thomas Holtz gave a possible length of 11 metres (36.3 feet).[7] In 2016, its length was estimated to be 7.4 metres (24 ft 3 in) in a comprehensive analysis of abelisaur size.[8] Others authors gave a similar size at 7.2 metres (23.6 feet) and 1.65 tonnes (1.82 short tons).[9]

Skull length was estimated at 85 centimetres (33+1⁄2 in) in 1985. The skull is relatively deep. Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin, which would not have become fossilized. The skull roof is thickened. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight. One of these is a large triangular antorbital fenestra in the side of the snout. The eye socket behind it is rather high. It is constricted in the middle by bony projections of the lacrimal bone in the front and the postorbital bone at the rear. The eye was located above the constriction. Behind the eye socket a large triangular infratemporal fenestra is present. Its form reflects a strong forward inclination of the back of the skull.[2]

The front snout bone, the premaxilla, bore four relatively small teeth. The maxilla behind it had at least seven, but perhaps as many as thirteen, larger teeth.[2]

Classification

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Tooth of cf. Abelisaurus

Bonaparte and Novas placed Abelisaurus in the newly created family Abelisauridae in 1985. They thought it was a member of the Carnosauria.[2] Abelisaurus was the first abelisaurid named.[5]

Many other abelisaurids have since been discovered, including much more complete specimens of Aucasaurus, Carnotaurus and Majungasaurus. They showed that abelisaurids were not carnosaurs in the modern sense, but belonged to the Neoceratosauria instead. Some scientists place Abelisaurus as a basal abelisaurid, outside the subfamily Carnotaurinae.[10][11] Others are less certain of its position.[12][13] Abelisaurus shares some skull features, such as a relative elongation, with the carcharodontosaurids, a group unrelated to other species assigned to the Abelisauridae, and, since it is known only from a skull, it has been suggested that future discoveries may show that Abelisaurus was in fact a carcharodontosaurid.[14] However, this is thought unlikely.[13]

Paleobiology

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Restoration of the head of Abelisaurus

As the skull of Abelisaurus was relatively broad at the back, Bonaparte and Novas drew a comparison between the newly described species and the also wide-skulled Tyrannosauridae. They assumed that, just as tyrannosaurids, Abelisaurus were the apex predators of their ecosystem.[2]

In 2010, Paul proposed that Abelisaurus hunted titanosaurian sauropods, such as Antarctosaurus, Pellegrinisaurus, Barrosasaurus and Neuquensaurus.[6]

See also

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References

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  1. ^ "Abelisaurus". Retrieved 2024-08-08.
  2. ^ a b c d e f Bonaparte, J.; Novas, E.E. (1985). "Abelisaurus comahuensis, n.g., n.sp., Carnosauria del Crétacico Tardio de Patagonia" [Abelisaurus comahuensis, n.g., n.sp., Carnosauria from the Late Cretaceous of Patagonia]. Ameghiniana. 21: 259–265 – via ResearchGate.
  3. ^ Gianechini, Federico A.; Apesteguía, Sebastián; Landini, Walter; Finotti, Franco; Juárez Valieri, Rubén; Zandonai, Fabiana (2015-05-01). "New abelisaurid remains from the Anacleto Formation (Upper Cretaceous), Patagonia, Argentina". Cretaceous Research. 54: 1–16. Bibcode:2015CrRes..54....1G. doi:10.1016/j.cretres.2014.11.009. hdl:11336/37727. ISSN 0195-6671.
  4. ^ Leanza, H.A.; Apesteguía, S.; Novas, F.E.; Fuente, M.S. (2004). "Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages". Cretaceous Research. 25 (1): 61–87. Bibcode:2004CrRes..25...61L. doi:10.1016/j.cretres.2003.10.005.
  5. ^ a b Novas, F.E. (2009). The Age of Dinosaurs in South America. Indiana University Press. p. 281. ISBN 9780253352897.
  6. ^ a b c Paul, G.S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press. ISBN 9781400836154.
  7. ^ Holtz, T.R. (2012). Dinosaurs: The Most Complete, Up-to-date Encyclopedia for Dinosaur Lovers of All Ages. Random House. p. 83. ISBN 9780375824197.
  8. ^ Grillo, O.N.; Delcourt, R. (2016). "Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king". Cretaceous Research. 69: 71–89. Bibcode:2017CrRes..69...71G. doi:10.1016/j.cretres.2016.09.001.
  9. ^ M-P., R.; Larramendi, A. (2016). Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos. Barcelona, Spain: Larousse. p. 257. ISBN 9788416641154.
  10. ^ Tykoski, R.S.; Rowe, T. (2004). "Ceratosauria". In Dodson, P.; Osmólska, H.; Weishamepl, D.B. (eds.). The Dinosauria (2nd ed.). University of California Press. pp. 47–70. ISBN 9780520941434.
  11. ^ Sereno, P.C.; Wilson, J.A.; Conrad, J.L. (2004). "New dinosaurs link southern landmasses in the Mid-Cretaceous". Proceedings of the Royal Society B: Biological Sciences. 271 (1546): 1325–1330. doi:10.1098/rspb.2004.2692. PMC 1691741. PMID 15306329.
  12. ^ Sampson, S.D.; Witmer, L.M.; Forster, C.A.; Krause, D.A.; O'Connor, P.M.; Dodson, P.; Ravoavy, F. (1998). "Predatory Dinosaur Remains from Madagascar: Implications for the Cretaceous Biogeography of Gondwana". Science. 280 (5366): 1048–1051. Bibcode:1998Sci...280.1048S. doi:10.1126/science.280.5366.1048. PMID 9582112.
  13. ^ a b Lamanna, M.C.; Martínez, R.D.; Smith, J.B. (2002). "A definitive abelisaurid theropod dinosaur from the early Late Cretaceous of Patagonia". Journal of Vertebrate Paleontology. 22 (1): 58–69. doi:10.1671/0272-4634(2002)022[0058:ADATDF]2.0.CO;2. ISSN 0272-4634. S2CID 86153297.
  14. ^ Novas, F.E. (1997). "Abelisauridae". In Currie, P.J.; Padian, K.P. (eds.). Encyclopedia of Dinosaurs. San Diego: Academic Press. pp. 1–2. ISBN 9780080494746. OCLC 436848919.
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