Extinct taxa of exotestal seeds close to Austrobaileyales and Nymphaeales from the Early Cretaceous of Portugal
|Klíčová slova||fossil embryos, fossil seeds, Illiciaceae, Nymphaeaceae, rudimentary cotyledons, synchrotron radiation X-ray tomographic microscopy (SRXTM)|
|Citace||FRIIS, Else Marie, CRANE, Peter R. a PEDERSEN, Kaj Raunsgaard. Extinct taxa of exotestal seeds close to Austrobaileyales and Nymphaeales from the Early Cretaceous of Portugal. Fossil Imprint / Acta Musei Nationalis Pragae, Series B – Historia Naturalis. Prague: National Museum, 2018, 74(1-2), 135-158. DOI: https://doi.org/10.2478/if-2018-0010. ISSN 2533-4050 (tisk), 2533-4069 (online). Also available from: https://publikace.nm.cz/periodicals/fiamnpsbhn/74-1-2/extinct-taxa-of-exotestal-seeds-close-to-austrobaileyales-and-nymphaeales-from-the-early-cretaceous-of-portugal|
Early Cretaceous mesofossil floras from Portugal and North America include a surprising diversity of small, bitegmic angiosperm seeds with a hard exotestal seed coat. This study describes six different kinds of these seeds from three Portuguese mesofossil localities; Vale de Agua, Torres Vedras, and especially from Famalicão, which has yielded a flora exceptionally rich in exotestal seeds. All the seeds are almost smooth with a characteristic jigsaw puzzle-shaped surface pattern that is formed from the strongly undulate anticlinal walls of the sclerenchyma cells that comprise the exotesta. Several specimens have internal details preserved, including remains of a cellular nutritive tissue interpreted as endosperm, and a tiny embryo with two rudimentary cotyledons. Based on differences in details of the seed coat, and configuration of hilum and micropyle, the fossil seeds are assigned to six new genera, as six new species: Gastonispermum portugallicum gen. et sp. nov., Pazlia hilaris gen. et sp. nov., Pazliopsis reyi gen. et sp. nov., Reyispermum parvum gen. et sp. nov., Lusitanispermum choffatii gen. et sp. nov. and Silutanispermum kvacekiorum gen. et sp. nov. The characteristic exotestal cells with undulate anticlinal walls, details of the hilar and micropylar region, together with the tiny dicotyledonous embryos with rudimentary cotyledons, suggest close relationships to seeds of Nitaspermum and Tanispermum described previously from Early Cretaceous mesofossil floras from eastern North America. These exotestal seeds from Portugal and North America indicate the presence of diverse extinct early angiosperms close to the lineages that today include extant Austrobaileyales and Nymphaeales.