Abstract
Giant carnivorous dinosaurs such as Tyrannosaurus rex and abelisaurids are characterized by highly reduced forelimbs that stand in contrast to their huge dimensions, massive skulls, and obligate bipedalism.1,2 Another group that follows this pattern, yet is still poorly known, is the Carcharodontosauridae: dominant predators that inhabited most continents during the Early Cretaceous3–5 and reached their largest sizes in Aptian-Cenomanian times.6–10 Despite many discoveries over the last three decades, aspects of their anatomy, especially with regard to the skull, forearm, and feet, remain poorly known. Here we report a new carcharodontosaurid, Meraxes gigas, gen. et sp. nov., based on a specimen recovered from the Upper Cretaceous Huincul Formation of northern Patagonia, Argentina. Phylogenetic analysis places Meraxes among derived Carcharodontosauridae, in a clade with other massive South American species. Meraxes preserves novel anatomical information for derived carcharodontosaurids, including an almost complete forelimb that provides evidence for convergent allometric trends in forelimb reduction among three lineages of large-bodied, megapredatory non-avian theropods, including a remarkable degree of parallelism between the latest-diverging tyrannosaurids and carcharodontosaurids. This trend, coupled with a likely lower bound on forelimb reduction, hypothesized to be about 0.4 forelimb/femur length, combined to produce this short-armed pattern in theropods. The almost complete cranium of Meraxes permits new estimates of skull length in Giganotosaurus, which is among the longest for theropods. Meraxes also provides further evidence that carchardontosaurids reached peak diversity shortly before their extinction with high rates of trait evolution in facial ornamentation possibly linked to a social signaling role.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3195-3202.e5 |
| Journal | Current Biology |
| Volume | 32 |
| Issue number | 14 |
| DOIs | |
| State | Published - Jul 25 2022 |
Bibliographical note
Funding Information:The authors would like to thank to Eduardo Ruigómez, Rodolfo Coria, Jorge Calvo, Mike Getty, Vince Schneider, and Paul Sereno for allowing the access to specimens under their care. The collection visit to the USA was possible thanks to a grant from the Jurassic Foundation (to J.I.C.). Many thanks to Dr. Stephen Brusatte and an anonymous reviewer for their useful comments on the manuscript. The program TNT is made freely available, thanks to a subsidy by the Willi Hennig Society. Field operations and research were funded by The National Geographic Society , Municipalidad de Villa El Chocón , Fundación “Félix de Azara,” The Field Museum, and Agencia I+D+i (PICT 2018-04042) . We wish to thank the participants in the fieldwork and the preparators who worked of the specimen: Rogelio Zapata, Javier Pazo, Andrés Moretti, Jonatan Aroca, Leandro Ripoll, Christian Albornoz, Mara Ripoll, Natalia Gonzalez, Frank Endress, Agustín Pérez Moreno, Ignacio Maniel, Jorge Bolomey, Mauricio Cerroni, Guillermina Giordano, Damián Amarilla, Carlos Corral, Iñaki Guaycochea, Manuel Negrón, and Matt Lewin. Thanks to Damiano Palombi for his help and discussions in the final stage of the manuscript. Mr. Pedro Lucero is thanked for his logistical help with his vehicle. We also thank the Zarza family and Luis Perouene for kindly allowing access to their property. Lynnea Jackson compiled measurement data for the phylogenetic comparative analyses. P.J.M. acknowledges funding from the US National Science Foundation FRES 1925884 .
Funding Information:
The authors would like to thank to Eduardo Ruigómez, Rodolfo Coria, Jorge Calvo, Mike Getty, Vince Schneider, and Paul Sereno for allowing the access to specimens under their care. The collection visit to the USA was possible thanks to a grant from the Jurassic Foundation (to J.I.C.). Many thanks to Dr. Stephen Brusatte and an anonymous reviewer for their useful comments on the manuscript. The program TNT is made freely available, thanks to a subsidy by the Willi Hennig Society. Field operations and research were funded by The National Geographic Society, Municipalidad de Villa El Chocón, Fundación “Félix de Azara,” The Field Museum, and Agencia I+D+i (PICT 2018-04042). We wish to thank the participants in the fieldwork and the preparators who worked of the specimen: Rogelio Zapata, Javier Pazo, Andrés Moretti, Jonatan Aroca, Leandro Ripoll, Christian Albornoz, Mara Ripoll, Natalia Gonzalez, Frank Endress, Agustín Pérez Moreno, Ignacio Maniel, Jorge Bolomey, Mauricio Cerroni, Guillermina Giordano, Damián Amarilla, Carlos Corral, Iñaki Guaycochea, Manuel Negrón, and Matt Lewin. Thanks to Damiano Palombi for his help and discussions in the final stage of the manuscript. Mr. Pedro Lucero is thanked for his logistical help with his vehicle. We also thank the Zarza family and Luis Perouene for kindly allowing access to their property. Lynnea Jackson compiled measurement data for the phylogenetic comparative analyses. P.J.M. acknowledges funding from the US National Science Foundation FRES 1925884. J.I.C. S.A. P.A.G. J.M. N.D.S. T.M.C. A.S. A.H. F.A.G. and P.J.M. designed and performed research; J.M. T.M.C. A.H. and P.J.M. contributed new reagents/analytic tools; J.I.C. J.M. T.M.C. A.H. and P.J.M. analyzed data; and J.I.C. S.A. P.A.G. J.M. N.D.S. T.M.C. A.S. A.H. F.A.G. and P.J.M. wrote the paper. The authors declare no competing interests.
Publisher Copyright:
© 2022 Elsevier Inc.
Keywords
- Carcharodontosauridae
- Cretaceous
- Dinosauria
- Patagonia
- Theropoda
- anatomy
- evolution
PubMed: MeSH publication types
- Journal Article
- Research Support, U.S. Gov't, Non-P.H.S.
