Skull of the dicynodont Placerias from the Upper Triassic of Arizona

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Andrew B. Heckert Ph.D., Professor (Creator)
Appalachian State University (ASU )
Web Site:

Abstract: We describe here a rare, incomplete but articulated skull of the dicynodont Placerias from the Blue Mesa Member of the Petrified Forest Formation in northern Arizona. This specimen comes from near the type locality of P. hesternus Lucas, 1904 in the vicinity of Ward's Terrace. Although the skull is crushed and somewhat distorted, it confirms previous reconstructions that posit the presence of a relatively short squamosal bar and dorso-ventrally robust, but relatively short, maxillary process, as opposed to the first reconstruction based on isolated bones from the Placerias quarry in east-central Arizona. With the exception of the Placerias quarry, dicynodonts in general are uncommon in the Chinle Group, but their occurrences are from strata of Otischalkian or Adamanian (late Carnian) age, and in part define a Placerias biochron of Otischalkian-Adamanian age.

Additional Information

Lucas, S.G., and Heckert, A.B., (2002) Skull of the dicynodont Placerias from the Upper Triassic of Arizona. New Mexico Museum of Natural History and Science Bulletin 21, p. 77-85. (ISSN 1524-4156) Archived in NC DOCKS with permission of the editor. The version of record is available at:
Language: English
Date: 2002

Email this document to