Aspectos de la historia de la vegetación de México con base en macrofósiles de angiospermas

The history of Mexican vegetation is mainly known through extrapolations based on its extant flora and/or paleobotanical work done in other countries. While macrofossils corroborate that in the past, as in the present, the Mexican flora had relationships with those of other areas, its study reveals that during the Cretaceous it had affinities with the boreal floras, though, some of the d escribed plants have close phylogenetic relationships with plants now growing naturally in the southern hemisphere. During the Tertiary the relationship with the boreal floras continued, suggesting that if some taxa originated in Gondwana, at least some of their genera and species could differentiate and radiate in the northern hemisphere, as suggested by some Anacardiaceae and perhaps other Leguminosae. A legume, Lysiloma, suggest that endemic taxa that characterize the extant Mexican vegetation have a long history, since they are known from Oligocene sediments. Another plant of the same family, Reinweberia, also suggest that during the Tertiary there were endemic plants that became extinct, and underscores the fact that for a long time the Mexican vegetation have had a distinct composition. The macrofossils of angiosperms suggest that only recently, perhaps no more than 10 million years ago, the vegetation types recognized today were established, although, those of the past could be similar.