First report of silicified wood from a late Pennsylvanian intramontane basin in the Pyrenees: systematic affinities and palaeoecological implications.

Abstract

The first anatomically preserved wood specimensof an upland Carboniferous flora from the Iberian Peninsulaare reported from the Erillcastell Basin (Eastern Pyrenees,Catalonia, Spain). Two taxa are described, a calamitaceanEquisetales (Arthropitys sp.) and a Cordaitales (Dadoxylonsp.). The Arthropitys specimen has fusiform multiseriate rayscomposed of square parenchyma cells with conspicuous uniseriateor multiseriate simple pits. These pits are located nearthe transverse walls and occasionally in the tangential walls.The tracheids vary in lumen size, with scalariform-borderedpits on their radial walls and multiseriate pits in their crossfieldareas. The Dadoxylon specimen commonly has uniseriatefusiform rays. The tracheids are long, with a square shapein transverse section. Their radial walls bear araucarian pittingwith a uniseriate to triseriate arrangement. The pits arecircular with a spindle-shaped aperture. Comparison of theErillcastell specimens with coeval species from Europe indicatesthat they could belong to new species. The good preservationof the new fossil wood yields significantpalaeoenvironmental information. The lack of markedgrowth rings in both specimens and the presence of tylosesin Dadoxylon suggest that the climate in the intramontanebasins of the Pyrenees was slightly seasonal towards the endof the Carboniferous. This contrasts with the marked seasonalityof coeval lowland basins. Such upland habitats mayhave enhanced the survival of plants adapted to humid conditionsin a global context of increasing aridity.