Geodigest

摘要

There is something magical about the preservation of something as hopelessly fragile as a leaf in the fossil record; and as with many fossil occurrences, chance has a major role to play. Despite this, floras are preserved in finegrained fades and are of the greatest significance in understanding the development of the Earth's biota during the latter part of the Cretaceous, and the aftereffects of the end-Cretaceous extinction. New finds and data sources are always sought, so it is a positive boon to science when a completely new and unbiased collection of fossil leaves and associated macroflora, from the attractively named locality Palacio de los Loros ('Palace of the Parrots'), are identified (Ari Iglesias and six other authors, Geology, 2007, v.35, pp.947-950). The collection is a new one from South America--previously a rather neglected continent for such floras--hailing from the Palaeocene Salamanca Formation of Chubut Province, Argentina (Fig. 1). What this exceptional collection demonstrates is that there is greater diversity of macrofloral elements than is seen in equivalent facies of the same age farther north in the USA (Fig. 2)--suggesting greater floodplain plant diversity in South America around 4 million years after the end-Cretaceous event. Why? The authors cannot be sure--maybe just that they were farther away from the impact site at Chicxulub?