Megaraptor
| Megaraptor | |
|---|---|
| |
| Reconstructed hand | |
Scientific classification
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Megaraptora |
| Family: | †Megaraptoridae |
| Genus: | †Megaraptor Novas1998 |
| Species: | †M. namunhuaiquii
|
| Binomial name | |
| †Megaraptor namunhuaiquii Novas 1998
| |
Megaraptor(lit. 'large thief') is agenusof largetheropoddinosaurthat lived in the ages of theLate Cretaceous.[2][3]Its fossils have been discovered in the PatagonianPortezuelo FormationofArgentina,South America. Initially thought to have been a giantdromaeosaur-likecoelurosaur,it was classified as aneovenatoridallosauroidin previous phylogenies, but more recent phylogeny and discoveries of relatedmegaraptorangenera has placed it as either a basaltyrannosauroidor a basalcoelurosaurwith some studies still considering it a neovenatorid.[4][5]
Description
[edit]
Megaraptorwas initially described as a giant 8 metres (26 ft) longcoelurosaur,known primarily from a single claw (about 30 cm long) that resembled the sickle-shaped foot claw ofdromaeosaurids.[2]The discovery of a complete front limb, however, showed that this giant claw actually came from the first finger of the hand. In 2010,Gregory S. Paulestimated its length at 8 metres (26 ft), its weight at 1 tonne (2,200 lb).[6]The hands were unusually elongated, bearing sickle-shaped claws even more recurved than those ofspinosaurids.[7]
Classification
[edit]The hand is quite distinct from other basaltetanurans,so it was not initially clear whetherMegaraptorwas an allosaurid, a carcharodontosaurid, a spinosauroid, or something else entirely.[3]Subsequent studies, as well as the identification of close relatives with similar large claws on the forelimbs (see below), helped identifyMegaraptoras a highly advanced and lightly built allosauroid, and a member of the familyNeovenatoridae.[8]More recent studies have proposed thatMegaraptorand its kin are actuallytyrannosauroids[9]orspinosauroids[10]as opposed toallosauroids.[9]A juvenile specimen described in 2014 has provided more evidence towardsMegaraptorbeing a primitive tyrannosauroid.[11]The discovery ofGualichoindicates thatMegaraptormay not be a tyrannosauroid, but either an allosauroid or basal coelurosaur.[12]
When first discovered and prior to publication, thespinosauridBaryonyxwas also reported to be a dromaeosaurid, and the allosauroidChilantaisauruswas reported to be a possible spinosaurid, both based on the large hand claws.
The cladogram shown below follows an analysis by Porfiriet al.,2014.[1]
In the 2022 description ofMaip,Rolandoet al.noted the presence of two distinct megaraptoran clades: a more inclusive clade, comprising all megaraptorids exceptFukuiraptorandAustralovenator,(shown below as "Clade A" ), and a more exclusive clade of larger, entirely South American megaraptorids (shown below as "Clade B" ). Like some previous analyses by other authors,Megaraptorais nested withinCoelurosauria,as the sister taxon toTyrannosauroidea.The cladogram below displays the megaraptoran results of thephylogenetic analysesby Rolandoet al(2022).[13]
| Megaraptora |
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Paleoecology
[edit]
Megaraptoris known from the LateTuronianto EarlyConiacian-datedPortezuelo Formationof Argentina. Other named dinosaurs known from the formation include thetitanosauriansauropodsFutalognkosaurus,Baalsaurus,andMalarguesaurus,and several other theropod taxa including thedromaeosauridsNeuquenraptor,Unenlagia,andPamparaptor,thealvarezsauridPatagonykus,and theabelisauridElemgasem.[14]Indeterminate remains belonging to an unnamedmegaraptorid,a possiblenoasaurid,andornithopodshave also been recovered from the formation. Fossils ofteleostfish(Leufuichthys),turtles(Portezueloemysand a species ofProchelidella),birds,andpterosaurs(Argentinadraco) are also known.
References
[edit]- ^abJuan D. Porfiri; Fernando E. Novas; Jorge O. Calvo; Federico L. Agnolín; Martín D. Ezcurra; Ignacio A. Cerda (2014). "Juvenile specimen ofMegaraptor(Dinosauria, Theropoda) sheds light about tyrannosauroid radiation ".Cretaceous Research.51:35–55.Bibcode:2014CrRes..51...35P.doi:10.1016/j.cretres.2014.04.007.hdl:11336/12129.
- ^abNovas, F.E. (1998). "Megaraptor namunhuaiquii,gen. et sp. nov., a large-clawed, Late Cretaceous theropod from Patagonia ".Journal of Vertebrate Paleontology.18(1): 4–9.Bibcode:1998JVPal..18....4N.doi:10.1080/02724634.1998.10011030.
- ^abCalvo, J. O.; Porfiri, J.D.; Veralli, C.; Novas, F.E.; Poblete, F. (2004). "Phylogenetic status ofMegaraptor namunhuaiquiiNovas based on a new specimen from Neuquén, Patagonia, Argentina ".Ameghiniana.41:565–575.
- ^Rauhut, Oliver (2019)."Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs".Sci Rep.9(1): 18826.Bibcode:2019NatSR...918826R.doi:10.1038/s41598-019-53672-7.PMC6906444.PMID31827108.
- ^"Just out | A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia @ Cretaceous Research".
- ^Paul, G.S., 2010,The Princeton Field Guide to Dinosaurs,Princeton University Press p. 99
- ^Calvo, J.O., Porfiri, J.D., González-Riga, B.J., and Kellner, A.W. (2007) "A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur".Anais da Academia Brasileira de Ciências,79(3): 529–41.[1]
- ^Benson, R.B.J.; Carrano, M.T; Brusatte, S.L. (2010). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic".Naturwissenschaften.97(1): 71–78.Bibcode:2010NW.....97...71B.doi:10.1007/s00114-009-0614-x.PMID19826771.S2CID22646156.
- ^abF. E. Novas; F. L. Agnolín; M. D. Ezcurra; J. I. Canale; J. D. Porfiri (2012)."Megaraptorans as members of an unexpected evolutionary radiation of tyrant-reptiles in Gondwana".Ameghiniana.49(Suppl): R33.
- ^Holtz, T.R. Jr. (2012).Dinosaurs: The Most Complete, Up-to-date Encyclopedia for Dinosaur Lovers of All Ages.Random House Books for Young Readers. pp.95–96.ISBN978-0-375-82419-7.
- ^Porfiri, J. D., Novas, F. E., Calvo, J. O., Agnolín, F. L., Ezcurra, M. D. & Cerda, I. A.; Novas; Calvo; Agnolín; Ezcurra; Cerda (2014). "Juvenile specimen of Megaraptor (Dinosauria, Theropoda) sheds light about tyrannosauroid radiation".Cretaceous Research.51:35–55.Bibcode:2014CrRes..51...35P.doi:10.1016/j.cretres.2014.04.007.hdl:11336/12129.
{{cite journal}}:CS1 maint: multiple names: authors list (link) - ^Apesteguía, Sebastián; Smith, Nathan D.; Juárez Valieri, Rubén; Makovicky, Peter J. (2016)."An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina".PLOS ONE.11(7): e0157793.Bibcode:2016PLoSO..1157793A.doi:10.1371/journal.pone.0157793.PMC4943716.PMID27410683.
- ^Rolando, Alexis M. A.; Motta, Matias J.; Agnolín, Federico L.; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (26 April 2022)."A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina".Scientific Reports.12(1): Article number 6318.Bibcode:2022NatSR..12.6318A.doi:10.1038/s41598-022-09272-z.PMC9042913.PMID35474310.
- ^Baiano, Mattia A.; Pol, Diego; Bellardini, Flavio; Windholz, Guillermo J.; Cerda, Ignacio A.; Garrido, Alberto C.; Coria, Rodolfo A (5 September 2022). "Elemgasem nubilus:a new brachyrostran abelisaurid (Theropoda, Ceratosauria) from the Portezuelo Formation (Upper Cretaceous) of Patagonia, Argentina ".Papers in Palaeontology.8(5): e1462.Bibcode:2022PPal....8E1462B.doi:10.1002/spp2.1462.S2CID252097368.
