Reinterpretation of Paleoazolla: a heterosporous water fern from the Late Cretaceous of Patagonia, Argentina.
Late Colonia Formation
Maastrichtian
Salviniaceae
heterospory
megaspore
microspore massulae
Journal
American journal of botany
ISSN: 1537-2197
Titre abrégé: Am J Bot
Pays: United States
ID NLM: 0370467
Informations de publication
Date de publication:
07 2020
07 2020
Historique:
received:
15
11
2019
accepted:
20
03
2020
pubmed:
1
7
2020
medline:
2
12
2020
entrez:
30
6
2020
Statut:
ppublish
Résumé
Undoubtedly, fossils are critical for understanding evolutionary transformations in deep time. Here, we reinvestigate the microspores and megaspores of Paleoazolla patagonica, a water fern found in Late Cretaceous sediments of the Chubut Province, Patagonia, Argentina, which provides novel evidence on the past history of the water fern clade. The study was based on recently collected specimens and additional observations of the original material. Most specimens analyzed herein were obtained from new palynological samples collected at the Cerro Bosta and Cañadón del Irupé localities, La Colonia Formation. Samples were mechanically disaggregated and treated with hydrofluoric and hydrochloric acid. Spores were studied using standard light microscopy and scanning electron microscopy. We also reexamined the original materials. The newly described characters of Paleoazolla include the presence of heterosporangiate sori composed of one ellipsoidal megasporangium surrounded by three to four oval microsporangia, megasporangium containing one hairy massula that encloses two trilete megaspores (rarely one or three), and microsporangia containing numerous microspore massulae with non-septate multibarbed glochidia and one trilete microspore per massula. The reinterpretation has revealed a novel set of characters for understanding the evolution of heterosporous water ferns. The presence of two megaspores in the megasporangium of Paleoazolla exposes serious gaps in the current knowledge on the evolution of monomegaspory in heterosporous water ferns, a fact that emphasizes the need of including fossils within phylogenies to elucidate patterns of character acquisition among water ferns.
Substances chimiques
Water
059QF0KO0R
Types de publication
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Langues
eng
Sous-ensembles de citation
IM
Pagination
1054-1071Informations de copyright
© 2020 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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