The origin of angiosperms is still a mystery. More than one-hundred years ago, Darwin called the origin of angiosperms an "abominable mystery". Angiosperms appear rather suddenly in the fossil record, with no obvious ancestors for a period of about 80 to 90 million years prior to their appearance. Not even fossil leaves or pollen are known from this earlier time. The truth is that we just don't have many early fossils of angiosperms, and those we do have are troublesome. Many of the early fossils show a mix of features which define modern groups, making them difficult to interpret. The implication, then, is that there was much experimentation in the early evolution of angiosperms, and only later did the features sort out into different lineages. The rapid diversification of angiosperm taxa began in the Albian, in the mid-Cretaceous, and has continued to this day. At that time, there is an almost exponential increase in angiosperm diversity, andmagnolia_blossom. there does not appear to have been any major extinctions of groups in between. Despite the large numbers of taxa that are known from rather early in this diversification, there is no indication of where the taxa are coming from. D.I. Axelrod has suggested that we do not find early angiosperm fossils because the earliest angiosperms lived in dry, upland habitats where the were unlikely to be preserved as fossils. Though this idea has long been accepted, it has not been well investigated and so remains to be tested. Although there is rapid diversification beginning in the Albian, it is not until the Cenozoic that angiosperms began to take on important ecological roles. Studies of a preserved Maastrichtian (late Cretaceous) landscape from Wyoming suggest that the high diversity of angiosperm species was confined to small populations, and that the vegetation was still largely dominated by ferns and cycads. Angiosperms found at the site were located in ephemeral habitats along streams, and were a minor component of the vegetation (Wing et al. 1993). http://tinyurl.com/33m9lz