How old are the angiosperms?

Abstract

Available evidence has earlier led to the inference that ancient angiosperms originated in moist tropical upland regions during Permo-Triassic time. Recent arguments, which purport to show that there was a much briefer interval between the time of origin and appearance of angiosperms in the record, and that they evolved in lowland areas, are not consistent with evidence from morphology, evolution, paleoecology, or paleoclimate.