Distribution of the ferns of the family Gleicheniaceae in the past

Abstract

The distribution of the family Gleicheniaceae was studied first of all according to the data concerning the findings of spores and of the fossil leaves. The ancestors of these ferns (Oligocarpia) apppeared in the Carboniferous of Europe, North America and China. During Triassic they were distributed in USA, Switzerland; in the Late Triassic of the USSR. The remnants of Gleicheniaceae were found sporadically in Jurassic beds of the East Greenland, Sweden, Italy, the USSR, India (Rajmahal series), Japan and USA. During the Early Cretaceous Gleicheniaceae got an enormous distribution throughout the earth's surface. Their abundant remnants especially their spores were found in many localities of Eurasia, North America and Australia and it is with this time that coincide the greatest polymorphism of the family. During the Late Cretaceous the remnants of these ferns mainly their spores are found in Europe, U.S.A. and the U.S.S.R. The prevalent distribution of Gleicheniaceae in Eurasia during Jurassic and Cretaceous falls on the Indian-European paleofloristic area comprising the belt of subtropical and tropical climate. With the advent of Paleogene the areal of Gleicheniaceae was greatly reduced in the Northern hemisphere and it begins to acquire a modern shape. The remnants of Gleicheniaceae of that time are presented mainly by rare findings of spores in Eurasia and North America.