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Loewen MA, Sertich JJW, Sampson S, O’Connor JK, Carpenter S, Sisson B, Øhlenschlæger A, Farke AA, Makovicky PJ, Longrich N, Evans DC. Lokiceratops rangiformis gen. et sp. nov. (Ceratopsidae: Centrosaurinae) from the Campanian Judith River Formation of Montana reveals rapid regional radiations and extreme endemism within centrosaurine dinosaurs. PeerJ 2024; 12:e17224. [PMID: 38912046 PMCID: PMC11193970 DOI: 10.7717/peerj.17224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 03/20/2024] [Indexed: 06/25/2024] Open
Abstract
The Late Cretaceous of western North America supported diverse dinosaur assemblages, though understanding patterns of dinosaur diversity, evolution, and extinction has been historically limited by unequal geographic and temporal sampling. In particular, the existence and extent of faunal endemism along the eastern coastal plain of Laramidia continues to generate debate, and finer scale regional patterns remain elusive. Here, we report a new centrosaurine ceratopsid, Lokiceratops rangiformis, from the lower portion of the McClelland Ferry Member of the Judith River Formation in the Kennedy Coulee region along the Canada-USA border. Dinosaurs from the same small geographic region, and from nearby, stratigraphically equivalent horizons of the lower Oldman Formation in Canada, reveal unprecedented ceratopsid richness, with four sympatric centrosaurine taxa and one chasmosaurine taxon. Phylogenetic results show that Lokiceratops, together with Albertaceratops and Medusaceratops, was part of a clade restricted to a small portion of northern Laramidia approximately 78 million years ago. This group, Albertaceratopsini, was one of multiple centrosaurine clades to undergo geographically restricted radiations, with Nasutuceratopsini restricted to the south and Centrosaurini and Pachyrostra restricted to the north. High regional endemism in centrosaurs is associated with, and may have been driven by, high speciation rates and diversity, with competition between dinosaurs limiting their geographic range. High speciation rates may in turn have been driven in part by sexual selection or latitudinally uneven climatic and floral gradients. The high endemism seen in centrosaurines and other dinosaurs implies that dinosaur diversity is underestimated and contrasts with the large geographic ranges seen in most extant mammalian megafauna.
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Affiliation(s)
- Mark A. Loewen
- Natural History Museum of Utah, Salt Lake City, UT, United States of America
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, United States of America
- Evolutionsmuseet, Knuthenborg, Maribo, Denmark
| | - Joseph J. W. Sertich
- Evolutionsmuseet, Knuthenborg, Maribo, Denmark
- Smithsonian Tropical Research Institute, Panama City, Panamá
- Department of Geosciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Scott Sampson
- California Academy of Sciences, San Francisco, California, United States of America
| | | | - Savhannah Carpenter
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, United States of America
| | - Brock Sisson
- Independent Researcher, Pleasant Grove, Utah, United States of America
| | | | - Andrew A. Farke
- Raymond M. Alf Museum of Paleontology, Claremont, California, United States of America
| | - Peter J. Makovicky
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Nick Longrich
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - David C. Evans
- Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
- Department of Ecology and Evolution, University of Toronto, Toronto, Ontario, Canada
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Dalman SG, Loewen MA, Pyron RA, Jasinski SE, Malinzak DE, Lucas SG, Fiorillo AR, Currie PJ, Longrich NR. A giant tyrannosaur from the Campanian-Maastrichtian of southern North America and the evolution of tyrannosaurid gigantism. Sci Rep 2024; 13:22124. [PMID: 38212342 PMCID: PMC10784284 DOI: 10.1038/s41598-023-47011-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 11/07/2023] [Indexed: 01/13/2024] Open
Abstract
Tyrannosaurid dinosaurs dominated as predators in the Late Cretaceous of Laurasia, culminating in the evolution of the giant Tyrannosaurus rex, both the last and largest tyrannosaurid. Where and when Tyrannosaurini (T. rex and kin) originated remains unclear. Competing hypotheses place tyrannosaurin origins in Asia, or western North America (Laramidia). We report a new tyrannosaurin, Tyrannosaurus mcraeensis, from the Campanian-Maastrichtian Hall Lake Formation of New Mexico, based on a fossil previously referred to T. rex. T. mcraeensis predates T. rex by ~ 6-7 million years, yet rivaled it in size. Phylogenetic analysis recovers T. mcraeensis as sister to T. rex and suggests Tyrannosaurini originated in southern Laramidia. Evolution of giant tyrannosaurs in southern North America, alongside giant ceratopsians, hadrosaurs, and titanosaurs suggests large-bodied dinosaurs evolved at low latitudes in North America.
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Affiliation(s)
- Sebastian G Dalman
- New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W., Albuquerque, NM, 87104, USA
| | - Mark A Loewen
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, USA
- Natural History Museum of Utah, University of Utah, Salt Lake City, UT, USA
| | - R Alexander Pyron
- Department of Biological Sciences, The George Washington University, 2023 G St. NW, Washington, DC, 20052, USA
| | - Steven E Jasinski
- Department of Environmental Science and Sustainability, Harrisburg University, 326 Market Street, Harrisburg, PA, 17101, USA
| | - D Edward Malinzak
- Pennsylvania State University, Lehigh Valley, Center Valley, PA, 18034, USA
| | - Spencer G Lucas
- New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W., Albuquerque, NM, 87104, USA
| | - Anthony R Fiorillo
- New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W., Albuquerque, NM, 87104, USA
| | - Philip J Currie
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Nicholas R Longrich
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK.
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