Discoaster triradiatus

Edited by Lyndsey on Thu, 10/03/2011 - 12:58

Disscoaster triradiatu Tan, 1927

Description: Symmetric 3-rayed variety of D. brouweri.

Remarks: Tan's description was extremely cursory but the concept is simple. These specimens occur throughout the range of D. brouweri, somewhat more consistently than D. asymmetricus. They do not increase in abundance in the mid-Pliocene, but do at the end of the Pliocene, just prior to the extinction of D. brouweri (Backman et al 1983, Backman 1986, 1987, Chapman & Chepstow-Lusty 1997).

Original description:

Geological Time Data

Geological Time Periods:

NN21

NN9

Biblio Reference:

Young, JR. 1998. Neogene. Calcareous nannofossil biostratigraphy. :225-265.

Notes on occurrence information:

Common in upper part of NN18 (typically occurring at 1/5 to 1/2 the abundance of D. brouweri), occasional specimens NN9-21 (but rarely occurring at more than a few percent of abundance of D. brouweri)