Skip to content Skip to navigation

Article: Variability in the Ordovician acritarch Dicrodiacrodium

Publication: Palaeontology
Volume: 39
Part: 2
Publication Date: June 1996
Page(s): 389 405
Author(s): Thomas Servais, Rainer Brocke and Olda Fatka
Addition Information

How to Cite

SERVAIS, T., BROCKE, R., FATKA, O. 1996. Variability in the Ordovician acritarch DicrodiacrodiumPalaeontology39, 2, 389–405.

Online Version Hosted By

The Palaeontological Association (Free Access)


Species of the Ordovician acritarch genus Dicrodiacrodium, with a single apical process, are evaluated critically, based on a review of published literature and new studies on material from Belgium, Bohemia, China, Germany, and Morocco. Investigations of large populations of such species show a wide variability between specimens. Biometric studies, including measurements on type area material, show that the subdivision into varieties and even into species is not justified. There is a complete gradation between all of the prescribed taxa. which are impossible to distinguish. Therefore, all specimens with a single apical process are classified as a single taxon. Dicrodiacrodium ancoriforme emend, nov. D. ancoriforme is very easy to recognize and of great biostratigraphical and palaeogeographical importance. Its First Appearance Datum (FAD) is in the Arenig Undulograptus sinodentatus/Didymograptus nexus graptolite Zone in South China (approximately equivalent to the British Arenig Isograptus gibberulus Biozone). Palaeobiogeographically, it is typical of the cold to temperate Gondwanan and peri-Gondwanan ('Mediterranean') Palaeoprovince.
PalAss Go! URL: | Twitter: Share on Twitter | Facebook: Share on Facebook | Google+: Share on Google+