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A redescription of Lophorhothon atopus (Ornithopoda, Dinosauria) from the Late Cretaceous of Alabama based on new material

Terry A. Gates and James P. Lamb
A redescription of Lophorhothon atopus (Ornithopoda, Dinosauria) from the Late Cretaceous of Alabama based on new material (in New Mesozoic research inspired by the life and work of Dale A. Russell, Jordan C. Mallon (editor), Philip J. Currie (editor) and Kathlyn M. Stewart (editor))
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (September 2021) 58 (9): 918-935

Abstract

Diagnostic dinosaur fossils of the southeastern United States are rare discoveries, and even more precious are those fossils that preserve a large portion of a skeleton. Sixty years ago, the dinosaur Lophorhothon atopus was described from Upper Cretaceous sediments of Alabama. It then represented the oldest, most complete, dinosaur in the southeastern United States. Based on a reexamination of the holotype material and a new specimen collected from the same beds, we provide a new diagnosis of this taxon. In particular, the solid nasal crest has several autapomorphies including caudally projecting frontal processes that are oval in cross section, meaning that they did not coalesce at the midline. Other autapomorphies are found on the prefrontal and squamosal. Combining the two Lophorhothon specimens provides nearly the entire skeleton for phylogenetic analysis, which we find as a hadrosauromorph just outside of Hadrosauridae. The original diagnosis of this taxon included the frontonasal fontanelle as a distinguishing character, but comparing the many examples of frontonasal openings across hadrosauromorph taxa shows that in at least a few species, such as Lophorhothon, the structures should be considered a frontonasal fenestra instead of a fontanelle. Additionally, the notion that dinosaurs from the East Coast of the United States represent primitive relicts is an idea that originated before many of the European and Asian hadrosauromorphs known today had been discovered. With new dating and phylogenetic information, it appears that Appalachian dinosaurs are on par evolutionarily with most of the global community and the term "relict fauna" should be abandoned.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 58
Serial Issue: 9
Title: A redescription of Lophorhothon atopus (Ornithopoda, Dinosauria) from the Late Cretaceous of Alabama based on new material
Title: New Mesozoic research inspired by the life and work of Dale A. Russell
Author(s): Gates, Terry A.Lamb, James P.
Author(s): Mallon, Jordan C.editor
Author(s): Currie, Philip J.editor
Author(s): Stewart, Kathlyn M.editor
Affiliation: North Carolina State University, Department of Biological Sciences, Raleigh, NC, United States
Affiliation: Canadian Museum of Nature, Beaty Centre for Species Discovery, Ottawa, ON, Canada
Pages: 918-935
Published: 202109
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 77
Accession Number: 2021-066049
Categories: Vertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
N32°23'60" - N32°36'00", W87°40'60" - W87°10'60"
Secondary Affiliation: University of Western Alabama, USA, United States
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2021, American Geosciences Institute. Reference includes data from Canadian Science Publishing, NRC Research Press, Ottawa, ON, Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202121
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