Early Middle Ordovician Evidence for Land Plants in Argentina (eastern Gondwana)

C.V. RUBINSTEIN ; P. GERRIENNE; G.S. DE LA PUENTE; R.A. ASTINI; P. STEEMANS

NEW PHYTOLOGIST

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Lancaster; Año: 2010 vol. 188 p. 365 - 369

0028-646X

·                     The advent of embryophytes (land plants) is among the most important evolutionary breakthroughs in Earth history. It irreversibly changed climates and biogeochemical processes on a global scale; it allowed all eukaryotic terrestrial life to evolve and to invade nearly all continental environments. Before this work, the earliest unequivocal embryophyte traces were late Darriwilian (late Middle Ordovician; ~463-461 million years ago [Ma]) cryptospores from Saudi Arabia and from the Czech Republic (western Gondwana). ·                     We processed Dapingian (early Middle Ordovician, ~473-471 Ma) palynological samples from Argentina (eastern Gondwana). ·                     We discovered a diverse cryptospore assemblage, including naked and envelope-enclosed monads and tetrads, representing five genera. ·                     Our discovery reinforces the earlier suggestion that embryophytes first evolved in Gondwana. It indicates that the terrestrialisation of plants might have begun in the eastern part of Gondwana. The diversity of the Dapingian assemblage implies an earlier, presumably Early Ordovician or even Cambrian, origin of embryophytes. Dapingian to Aeronian (early Silurian) cryptospore assemblages are similar, suggesting that the rate of early embryophyte evolution was extremely slow during the first 35-45 million years of their diversification. The Argentinean cryptospores predate by ~8-12 million years other cryptospore occurrences, and are currently the earliest land plants evidence.