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There are few studies focused on spore and pollen clumps in paleopalynological samples, and these are only reports from the Northern Hemisphere. These aggregates may be of animal or floral origin. The goal of this contribution is to provide the first detailed study of spore and pollen clumps from the Southern Hemisphere, and to discuss their possible origin, botanical affinities, and pollination modes, based on their morphological characteristics, preservation and comparison with putative living representatives. Three fern spore clumps and 18 angiosperm pollen clumps were recognized in Maastrichtian-Danian La Colonia Formation sediments that outcrop at Chubut Province, Patagonia, Argentina. Most clumps are monospecific and composed of undamaged elements but some of them have two types of spore/pollen with corroded and/or fragmented exines. These findings represent the most diverse and abundant record of fern and angiosperm clumps from the Late Cretaceous and early Paleocene so far known from South America and the Southern Hemisphere. These results are indicative of the need for comprehensive large-scale studies on pollination of modern taxa and careful processing of palynological samples to lessen the already large bias in paleopalynological interpretations. The paucity of information on clumps in the fossil record has impaired our comprehension of dispersion/pollination in deep time.
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Spores from the K–Pg boundary of the La Colonia Formation, Patagonia, Argentina
A palynological study was carried out based on 157 samples collected from four representative stratigraphic sections of the Maastrichtian-Danian deposits of the La Colonia Formation outcropping in northern Chubut Province, Patagonia, Argentina. About 240 palynomorphs were recognized. Plant communities were dominated in terms of richness by ferns and angiosperms, but algae and gymnosperms are also well-represented. In this contribution, we present the systematic study of bryophyte, lycophyte, and fern spores. Bryophytes comprise eight species (10% of spore diversity), including representatives of Marchantiophyta, Bryophyta, and Anthocerotophyta. Lycophytes encompass 15 species (20% of spore diversity) and are represented by the families Lycopodiaceae and Selaginellaceae. Ferns comprise 53 species (70% of spore diversity), including members of Anemiaceae, Dicksoniaceae, Dipteridaceae, Gleicheniaceae, Lygodiaceae, Marsileaceae, Matoniaceae, Osmundaceae, Polypodiaceae, Salviniaceae, and Schizaeaceae, among others of uncertain affinities. Four new species are erected: a lycophyte (Neoraistrickia loconiensis sp. nov.), a salvinialean (Thecaspora polygonalis sp. nov.), and two fern species of unknown affinities (Clavatosporis varians sp. nov. and Microreticulatisporites patagonicus sp. nov.). The recorded palynoflora reinforces previous environmental interpretation of the La Colonia deposits as coastal plains bathed by shallow seas and barrier island/lagoon complexes and the presence of freshwater bodies where aquatic plant communities developed. The vegetational history of the bryophytes, lycophytes, and ferns in the studied sections of the La Colonia Formation indicates the lack of a significant floristic change across the K–Pg interval at the local scale.
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- PAR ID:
- 10589911
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Review of Palaeobotany and Palynology
- Volume:
- 328
- ISSN:
- 0034-6667
- Page Range / eLocation ID:
- 105159
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.revpalbo.2024.105159
