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GEOREF RECORD

Windows on the evolution of Picrodus (Plesiadapiformes, Primates); morphology and relationships of a species complex from the Paleocene of Alberta

Craig S. Scott and Richard C. Fox
Windows on the evolution of Picrodus (Plesiadapiformes, Primates); morphology and relationships of a species complex from the Paleocene of Alberta
Journal of Paleontology (July 2005) 79 (4): 635-657

Abstract

Since 1908, the peculiar North American primate Picrodus Douglass, 1908 (Picrodontidae; Plesiadapiformes) has been thought to contain only a single species, P. silberlingi Douglass, 1908, of late Paleocene age. However, new collections from the Paskapoo Formation, Alberta, Canada, reveal that instead a rich complex of Picrodus species lived during the Paleocene. Three of these, Picrodus calgariensis, P. canpacius, and P. lepidus, are described herein as new. Others, represented by more fragmentary specimens from Canada and the United States, are included in this paper, but are not named. P. calgariensis, from Who Nose? (late Torrejonian), Calgary, is the most primitive known species of Picrodus, having molars with little crenulation of the enamel. P. canpacius, from Cochrane 2 (earliest Tiffanian), northwest of Calgary, most resembles P. silberlingi sensu stricto, but differs in P4 structure, denser enamel crenulation, and weaker molar cusps. P. lepidus, from DW-2 (middle Tiffanian), near Red Deer, is the most advanced, having, for example, a two-rooted P4, tiny p3, and single-rooted p4. At least two of these species also occur in the United States, documented by fossils referred to P. silberlingi by previous workers. Dental evolution within Picrodus seems marked by several trends, including increase in size of i1, simplification of P4, reduction of molar cusps and crests, enlargement of the horizontal occlusal surfaces of the molars, and greater crenulation of enamel. From present knowledge, Zanycteris paleocenus Matthew, 1917 is dentally more primitive than Picrodus, Draconodus Tomida, 1982 is a valid genus, and picrodontids probably originated from "purgatoriid-grade" plesiadapiforms in earliest Paleocene time.


ISSN: 0022-3360
EISSN: 1937-2337
Coden: JPALAZ
Serial Title: Journal of Paleontology
Serial Volume: 79
Serial Issue: 4
Title: Windows on the evolution of Picrodus (Plesiadapiformes, Primates); morphology and relationships of a species complex from the Paleocene of Alberta
Affiliation: University of Alberta, Laboratory for Vertebrate Paleontology, Edmonton, AB, Canada
Pages: 635-657
Published: 20050701
Text Language: English
Publisher: Paleontological Society, Lawrence, KS, United States
References: 46
Accession Number: 2005-062461
Categories: Vertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N51°04'60" - N52°30'00", W114°04'60" - W113°45'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, The Paleontological Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200521
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