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| Gondwanan Origins and Evolution of Megaraptoran Dinosaurs in Morrison, Scherer, O’Callaghan, Layton, Boisvert, Rolando, Durrant, Salas, Allain et Gascoigne, 2025. |
Abstract
Late Cretaceous Earth was dominated by theropods such as tyrannosauroids and megaraptorans; however, it is unclear how these clades diversified and grew to massive proportions. This study aimed to conduct a biogeographical analysis and test climate as a potential mechanism for the increase in size. We used published phylogenetic matrices with the R package BioGeoBears to test different biogeographical hypotheses for both clades. We mapped body mass (BM) and body length against known climate data to test this potential hypothesis. Continental-scale variance did not drive tyrannosauroid biogeography and instead widespread ancestral populations, sympatric speciation and localized extinctions throughout these clades constricted geographic range. Both patterns were supported by statistical analyses. This biogeographical model also indicates the ancestor of the clade Tarbosaurus and Tyrannosaurus was present in both Asia and Laramidia, and therefore the ancestor of Tyrannosaurus came from Asia. Statistical data illustrated no correlation between Mean Annual Temperature (MAT) and BM but potential climatic shifts may be associated with gigantism in derived megaraptorids and eutyrannosaurians. This biogeographical model implies megaraptorans may have had a cosmopolitan distribution prior to the splitting of Laurasia and Gondwana. Also, gigantism in these clades may be associated with climatic shifts in the Late Cretaceous.
Keywords: Biogeography, Late Cretaceous, Megaraptora, Tyrannosauroidea
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| The end Cretaceous Northern Hemisphere fauna was dominated by Tyrannosaurids (such as Tyrannosaurus rex), hadrosaurs and ceratopsian ornithischian dinosaurs. Artwork by Pedro Salas and Sergey Krasovskiy. |
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| Potential dispersal routes for megaraptorans during the Middle Jurassic–Early Cretaceous (approx. 143 Ma). ... |
Cassius Morrison, Charlie Roger Scherer, Ezekiel V. O’Callaghan, Collin Layton, Colin Boisvert, Mauro Aranciaga Rolando, Leroy Durrant, Pedro Salas, Steven J. R. Allain and Samuel J. L. Gascoigne. 2025. Rise of the King: Gondwanan Origins and Evolution of Megaraptoran Dinosaurs. R. Soc. Open Sci. 12: 242238. DOI: doi.org/10.1098/rsos.242238 [07 May 2025]
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