Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Gradual Dinosaur Extinction and Simultaneous Ungulate Radiation in the Hell Creek Formation

Robert E. Sloan, J. Keith Rigby, Leigh M. Van Valen and Diane Gabriel
Science
New Series, Vol. 232, No. 4750 (May 2, 1986), pp. 629-633
Stable URL: http://www.jstor.org/stable/1696921
Page Count: 5
  • More info
  • Cite this Item
Gradual Dinosaur Extinction and Simultaneous Ungulate Radiation in the Hell Creek Formation
Preview not available

Abstract

Dinosaur extinction in Montana, Alberta, and Wyoming was a gradual process that began 7 million years before the end of the Cretaceous and accelerated rapidly in the final 0.3 million years of the Cretaceous, during the interval of apparent competition from rapidly evolving immigrating ungulates. This interval involves rapid reduction in both diversity and population density of dinosaurs. The last dinosaurs known are from a channel that contains teeth of Mantuan mammals, seven species of dinosaurs, and Paleocene pollen. The top of this channel is 1.3 meters above the likely position of the iridium anomaly, the Cretaceous/Tertiary boundary.

Page Thumbnails

  • Thumbnail: Page 
629
    629
  • Thumbnail: Page 
630
    630
  • Thumbnail: Page 
631
    631
  • Thumbnail: Page 
632
    632
  • Thumbnail: Page 
633
    633