Why do Paleobotanists Believe in a Cretaceous Origin of Angiosperms?
http://www.unifiedworlds.com/cornet/Why02/why.htm

Cornet Bruce


This technical article questions the interpretation that Angiosperms first appeared in the Cretaceous Period. Although this article was written for botany and paleobotany specialists, its diagrams, links to supporting materials, and glossary are comprehensible to non-specialists as well. Educators and research scientists alike may find this site useful for finding background information concerning the evolution of Angiosperms. This article has not been peer-reviewed.

This resource is referenced here:
Subject: Biology
Resource Type: Scientific Resources:Overview/Reference Work
Focus on the Cretaceous: Paleontology
Topics: Time/Earth History, BiosphereKeyword: paleobotany