Cryptospore assemblages from Upper Ordovician (Katian–Hirnantian) strata of Anticosti Island, Québec, Canada, and Estonia: Palaeophytogeographic and palaeoclimatic implications

Rich palynological assemblages have been recovered from deposits of Hirnantian age in Anticosti Island (Québec, Canada), and in borehole Valga-10 in southern Estonia. The assemblages are well preserved, and include acritarchs, chitinozoans, and cryptospores. The age of the deposits is well constrained by means of palynomorphs (acritarchs and chitinozoans) as well as sequence stratigraphic and chemostratigraphic correlations. Cryptospore assemblages from the two localities are similar and are also broadly comparable to the few known coeval assemblages described elsewhere. They include 11 genera and 20 species, and testify to the presence of an extended and diverse flora during Hirnantian times in Laurentia and, for the first time, also in Baltica.The present findings contribute to an improved knowledge of origin and early development of vegetative cover. The recovery of diverse and abundant cryptospores in Hirnantian deposits may be related to increased input of land-derived sediment during the global sea-level fall linked to the Late Ordovician glaciation, but it also demonstrates that the early land plants may have tolerated a wide range of climatic conditions.

Research highlights
► Diverse cryptospore assemblages are reported from the Late Ordovician of Estonia (Baltica) and Québec (Laurentia).
► Existence of bryophyte-like vegetative cover is demonstrated for the first time in the Late Ordovician of Baltica.
► Biodiversity of early land plants increased through the Late Ordovician glaciation.
► Moderate phytogeographical differentiation characterizes Late Ordovician continental domains separated by wide oceans.