Meraxes: Difference between revisions
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''Meraxes'' possessed a huge head and reduced forelimbs. Similar degrees of forelimb reduction evolved independently in four lineages: Carcharodontosauridae (''Meraxes''), [[Abelisauridae]], [[Tyrannosauridae]], and [[Alvarezsauridae]], an instance of [[convergent evolution]].<ref name=Meraxes1/> |
''Meraxes'' possessed a huge head and reduced forelimbs. Similar degrees of forelimb reduction evolved independently in four lineages: Carcharodontosauridae (''Meraxes''), [[Abelisauridae]], [[Tyrannosauridae]], and [[Alvarezsauridae]], an instance of [[convergent evolution]].<ref name=Meraxes1/> |
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The holotype specimen is estimated to have been |
The holotype specimen is estimated to have been between 9.7 (32 ft) and {{Convert|11|m|ft|abbr=out}} in length and weighed at least {{convert|4.25|MT|ST}}.<ref>{{Cite web |last=Gramling |first=Carolyn |date=2022-07-07 |title=A newfound dinosaur had tiny arms before ''T. rex'' made them cool |url=https://www.sciencenews.org/article/dinosaur-short-arms-tyrannosaurus-rex-meraxes-gigas-paleontology |access-date=2022-07-07 |website=Science News |language=en-US}}</ref><ref name=Meraxes1/><ref>{{Cite web |title=https://twitter.com/petemakovicky/status/1545041248192438273 |url=https://twitter.com/petemakovicky/status/1545041248192438273 |access-date=2022-07-08 |website=Twitter |language=en}}</ref> |
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Osteohistological analysis of the holotype suggests the theropod could have been up to 53 years old when it died, making it the longest-lived non-avian theropod currently known. ''Meraxes'' was also determined to have continued growing throughout its life even after reaching maturity, and that its growth was slower than that of other theropods from different families, such as ''[[Tyrannosaurus]]'', to which it was compared. Studies of the ''Meraxes'' holotype also suggest that carchardontosaurids reached maturity between 30–40 years of age.<ref name="Cullen" /><ref>https://www.sciencedaily.com/releases/2020/11/201124190527.htm</ref> |
Osteohistological analysis of the holotype suggests the theropod could have been up to 53 years old when it died, making it the longest-lived non-avian theropod currently known. ''Meraxes'' was also determined to have continued growing throughout its life even after reaching maturity, and that its growth was slower than that of other theropods from different families, such as ''[[Tyrannosaurus]]'', to which it was compared. Studies of the ''Meraxes'' holotype also suggest that carchardontosaurids reached maturity between 30–40 years of age.<ref name="Cullen" /><ref>https://www.sciencedaily.com/releases/2020/11/201124190527.htm</ref> |
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Revision as of 00:57, 8 July 2022
 | A request that this article title be changed to Meraxes is under discussion. Please do not move this article until the discussion is closed. |
| Meraxes Temporal range: Late Cretaceous,
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Carcharodontosauridae |
| Tribe: | †Giganotosaurini |
| Genus: | †Meraxes Canale et al., 2022 |
| Type species | |
| †Meraxes gigas Canale et al., 2022
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Meraxes (named after a dragon from the novel series A Song of Ice and Fire) is a genus of carcharodontosaurid theropod dinosaur from the Late Cretaceous Huincul Formation of Argentine Patagonia. The genus contains a single species, M. gigas.[1]
Discovery and naming
The holotype of Meraxes, previously called the "Campanas carcharodontosaurid", MMCh-PV 65, was discovered in 2012.[2] Known bones include a nearly complete skull, pectoral and pelvic elements, partial forelimbs, complete hindlimbs, fragmentary ribs and cervical and dorsal vertebrae, a sacrum, and several complete caudal vertebrae. It has the most complete carcharodontosaurid skeleton known from the Southern Hemisphere.[1]
Meraxes gigas was described in 2022 by Canale et al. based on these remains. The generic name, "Meraxes", honors a dragon from the George R.R. Martin fantasy novel series, A Song of Ice and Fire. The specific name, "gigas", is derived from a Greek word meaning "giant", in reference to its large size.[1]
Description
Meraxes possessed a huge head and reduced forelimbs. Similar degrees of forelimb reduction evolved independently in four lineages: Carcharodontosauridae (Meraxes), Abelisauridae, Tyrannosauridae, and Alvarezsauridae, an instance of convergent evolution.[1]
The holotype specimen is estimated to have been between 9.7 (32 ft) and 11 metres (36 ft) in length and weighed at least 4.25 metric tons (4.68 short tons).[3][1][4]
Osteohistological analysis of the holotype suggests the theropod could have been up to 53 years old when it died, making it the longest-lived non-avian theropod currently known. Meraxes was also determined to have continued growing throughout its life even after reaching maturity, and that its growth was slower than that of other theropods from different families, such as Tyrannosaurus, to which it was compared. Studies of the Meraxes holotype also suggest that carchardontosaurids reached maturity between 30–40 years of age.[2][5]
Classification
Meraxes represents the earliest diverging member of the tribe Giganotosaurini within the Carcharodontosauridae. The cladogram below displays the results of the phylogenetic analysis by Canale et al.[1]
Paleoenvironment
Meraxes coexisted with other theropods, within the Huincul Formation, such as the paravian Overoraptor, the elaphrosaurine Huinculsaurus, multiple abelisaurs including Skorpiovenator, and fellow giant carcharodontosaurid Mapusaurus. The herbivores of the area were represented by rebbachisaurid sauropods, several iguanodonts, and the titanosaurs Argentinosaurus and Choconsaurus.
References
- ^ a b c d e f Canale, J.I.; Apesteguía, S.; Gallina, P.A.; Mitchell, J.; Smith, N.D.; Cullen, T.M.; Shinya, A.; Haluza, A.; Gianechini, F.A.; Makovicky, P.J. (7 July 2022). "New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction". Current Biology. doi:10.1016/j.cub.2022.05.057.
- ^ a b Cullen, Thomas M.; Canale, Juan I.; Apesteguía, Sebastián; Smith, Nathan D.; Hu, Dongyu; Makovicky, Peter J. (25 November 2020). "Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution". Proceedings of the Royal Society B: Biological Sciences. 287 (1939): 20202258. doi:10.1098/rspb.2020.2258. PMC 7739506. PMID 33234083. S2CID 227154091.
- ^ Gramling, Carolyn (7 July 2022). "A newfound dinosaur had tiny arms before T. rex made them cool". Science News. Retrieved 7 July 2022.
- ^ "https://twitter.com/petemakovicky/status/1545041248192438273". Twitter. Retrieved 8 July 2022.
{{cite web}}: External link in|title= - ^ https://www.sciencedaily.com/releases/2020/11/201124190527.htm
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