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Vertebrate herbivory in the Mesozoic; jaws, plants, and evolutionary metrics

David B. Weishampel and David B. Norman
Vertebrate herbivory in the Mesozoic; jaws, plants, and evolutionary metrics (in Paleobiology of the dinosaurs, James O. Farlow (editor))
Special Paper - Geological Society of America (1989) 238: 87-100


Herbivory in terrestrial vertebrates dates back to at least Early Permian time. Yet herbivorous tetrapods did not greatly diversify until middle Permian and into Triassic time. All of these early herbivores are characterized by isognathy and bilateral occlusion. In the Triassic Period, these herbivores can be differentiated by several trophic-related parameters: simple dentitions (procolophonids, aetosaurs), lack of chewing teeth (dicynodonts), and complex tooth morphology (trilophosaurs, rhynchosaurs, tritylodontoids). In all cases where there is a significant degree of oral processing, masticatory movement is confined to either orthal or palinal motion of the lower jaw. The mechanics of chewing among herbivores changed markedly, beginning in the Late Triassic and extending through the Cretaceous. These animals include sphenodontids, multituberculates, prosauropods, sauropods, segnosaurs, ornithopods, stegosaurs, ankylosaurs, and pachycephalosaurs. Although retaining the primitive isognathous jaw construction and consequent bilateral occlusion, ornithopods were the first group of herbivores to develop a transverse chewing stroke (through slight rotation of the lower jaws [heterodontosaurids] or upper jaws [pleurokinesis: hypsilophodontids, iguanodontids, hadrosaurids]). Measures of diversity, speciation rates, extinction rates, and net profit or loss are used to map shifts in terrestrial floras and theropsid and sauropsid herbivore clades in the Mesozoic. Two linkages appear to exist, one from the end of Triassic and into Jurassic time, and another from the middle to the end of the Cretaceous Period. Each involves both floral restructuring and herbivore community modification.

ISSN: 0072-1077
EISSN: 2331-219X
Serial Title: Special Paper - Geological Society of America
Serial Volume: 238
Title: Vertebrate herbivory in the Mesozoic; jaws, plants, and evolutionary metrics
Title: Paleobiology of the dinosaurs
Author(s): Weishampel, David B.Norman, David B.
Author(s): Farlow, James O.editor
Affiliation: Johns Hopkins Univ., Dep. Cell Biol. and Anat., Baltimore, MD, United States
Affiliation: Indiana Univ.-Purdue Univ. at Fort Wayne, Dep. Earth and Space Sci., Fort Wayne, IN, United States
Pages: 87-100
Published: 1989
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 0-8137-2238-1
References: 129
Accession Number: 1989-073314
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: Nature Conserv. Counc., GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Bibliography of Fossil Vertebrates, Society of Vertebrate Paleontology, Berkeley, CA, United States
Update Code: 1989
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