Ecpagloxylon mathiesenii gen. nov. et sp. nov., a Jurassic wood from Greenland with several primitive angiosperm features

摘要

Fossil wood specimens from the late Early–early Middle Jurassic of Jameson Land, Eastern Greenland, have several unexpected features: tracheids of irregular size and shape, thinly pitted ray cell walls, heterogeneous rays, partially scalariform radial pitting, both areolate and simple pits, and pitted elements associated with rays. These characters diverge markedly from those typical of Jurassic wood, which usually conform to those of modern conifers. Although this combination of features is not encountered in any extant angiosperm, each has been documented in one or several extant homoxylous angiosperms, particularly Amborella, Trochodendron, and Tetracentron. As these wood specimens are not found in connection with any reproductive part, it is impossible to confidently assign them to the angiosperms. If a Jurassic angiosperm did exist, however, it might well have had a similar wood. This material is an early bench-mark in the evolution that led from homoxylous conifer-like wood to that of the angiosperms. Its particular biogeography (Arctic) could renew the discussion about the area of origin of the angiosperms.