Paleozoic origin of the cycads /

Bibliographic Details
Main Author:	Mamay, Sergius H., 1920- (Author)
Format:	Government Document eBook
Language:	English
Published:	Washington : United States Department of the Interior, Geological Survey, 1976.
Series:	Geological Survey professional paper ; 934.
Subjects:	From 230 to 570 million years ago Cycads, Fossil. Paleobotany > Paleozoic. Paleobotany > West (U.S.) Paleobotany. Paleozoic Geologic Period. Southwest, New.
Online Access:	https://purl.fdlp.gov/GPO/gpo89675

Description
Item Description:	Title from title screen (viewed October 6, 2014). "Megasporophylls and associated plant parts from the Upper Pennsylvanian and Lower Permian rocks of the southwestern United States are interpreted as a lineage of cycads, derived from the pteridosperms. Cycadean foliage is thought to be derived from Paleozoic taeniopterids."
Physical Description:	1 online resource (iii, 48 pages, 5 unnumbered pages of plates) : illustrations.
Bibliography:	Includes bibliographical references (pages 44-46) and index.