Ammonite and inoceramid bivalve extinction patterns in Cretaceous/Tertiary boundary sections of the Biscay region (southwestern France, northern Spain)
Abstract
Cretaceous/Tertiary boundary sections located in the Biscay region of southwestern France and northern Spain are among the most complete of all known land-based sequences across this boundary. New collections of ammonites and inoceramid bivalves from five localities show quite distinct extinction patterns for these two groups of characteristic Cretaceous molluscs: from eight to ten ammonite species extend into the latest Cretaceous, and possibly to the boundary. In contrast, inoceramid bivalve diversity gradually diminished from a minimum of six species in the early Maastrichtian to zero at the beginning of the late Maastrichtian, when they were replaced by the cryptic pteriomorph Tenuipteria.</em> Extinction of typical inoceramids well before the end of the Maastrichtian is supported by data from other regions, indicating that it was a global rather than local phenomenon.
- Publication:
-
Geology
- Pub Date:
- December 1991
- DOI:
- 10.1130/0091-7613(1991)019<1181:AAIBEP>2.3.CO;2
- Bibcode:
- 1991Geo....19.1181W