The Coniacian leaf flora from the northeastern part of the Bohemian Cretaceous Basin


Authors: Halamski AT, Kvaček J

Published in: Bulletin of Geosciences, volume 91, issue 2; pages: 297 - 318; Received 14 October 2015; Accepted in revised form 11 March 2016; Online 6 June 2016

Keywords: Czech Republic, fossil plants, taxonomy, palaeobotany, palaeocommunities, Cretaceous, Coniacian,

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The "Chlomek Beds" (an informal designation of the psammitic facies of the Březno Formation, north-eastern part of the Bohemian Cretaceous Basin) yielded a poorly preserved megaflora, dated as Coniacian on the basis of co-occurring inoceramid bivalves. The flora is interpreted to have grown on the West Sudetic Island, a palaeohigh of the Central European Archipelago. Ferns are diverse both in terms of specimens and of taxa: Monheimia chlomekiana, Sphenopteris dubia, "Pteridoleimma" durum, and two unnamed species of Korallipteris. Conifers are very rare: only two twigs of Geinitzia reichenbachii have been found. Angiosperms are represented by 14 dicot fossil-taxa. Two of them, Debeya (Dewalquea) sp. and Dalbergites atavius, are referable to eudicots. The remaining 12 taxa are described as dicots incertae sedis: Laurophyllum? melanophyllum, L. acuminatum, Laurophyllum sp., Apocynophyllum fractum, Ettingshausenia superstes, Ettingshausenia sp., Celastrinites engelhardtii, Salicites petzeldianus, Dryophyllum geinitzianum, “Dryandroidesquercinea, Dicotylophyllum bohemicum, and Dicotylophyllum sp. 1. In comparison with the better-preserved coeval flora of the East Sudetic Island (Idzików Beds), ferns are more diverse and conifers are less diverse. Angiosperm flora is of similar physiognomy and is interpreted as representing riparian forests dominated by laurophylls and trees with serrate leaves. Local differentiation of riparian forests is attested by mutual exclusion of two serrate-leaved species, either Dryophyllum geinitzianum (relatively common at Robeč and Jedlová, absent at Česká Lípa) or "Dryandroides" quercinea (relatively common at Česká Lípa, absent at Robeč and Jedlová).