Abstract Detail



Pteridology

De Benedetti, Facundo [1], Zamaloa, Maria Del Carmen [2], Gandolfo, Maria [3], Cuneo, Nestor [4].

Diversification of heterosporous water ferns during the Late Cretaceous of Patagonia.

Heterosporous water ferns constitute a monophyletic group that includes two extant families: Marsileaceae and Salviniaceae. Marsileaceae comprises small, rooted ferns that are usually found on the margins of ponds, lakes, and rivers; whereas Salviniaceae includes small plants that are free floating and form extensive communities on the surface of low energy freshwater environments, such as swamps, ponds, and lakes. The fossil record of water ferns goes back to the Late Jurassic, although the group seems to have diversified highly during the Late Cretaceous together with the flowering plants. Recently, several aquatic fern remains (macro and microfossils) were reported from the Upper Cretaceous La Colonia Formation, Patagonia, Argentina, and some of them are the southernmost records for the group. In the light of new discoveries, we present a review of the megaspores and microspores related to both families. Marsileaceae is represented by Molaspora lobata, M. reticulata, and Crybelosporites cf. C. pannuceus while Salviniaceae by Azolla coloniensis, Azolla sp., Paleoazolla patagonica, cf. Azollopsis coccoides, and cf. Azollopsis intermedia. The spores were recovered from massive to finely laminated sediments, probably deposited by suspension in stagnant freshwater bodies. This spore assemblage is the most diverse so far known for South America and of the Southern Hemisphere, and it is clear evidence of the marked radiation of aquatic ferns at the end-Cretaceous worldwide. 


1 - Museo Paleontológico Egidio Feruglio, Avenida Fontana 140, Trelew, U, 9100, Argentina
2 - Universidad De Buenos Aires, Ecologia, Genética Y Evolucion, Ciudad Universitaria. Pab 2. Piso 4, Buenos Aires, 1428, Argentina
3 - Cornell University, L.H. Bailey Hortorium, Section Of Plant Biology, 410 Mann Library Building, Ithaca, NY, 14853.0, United States
4 - MEF, Av. Fontana 140, Trelew-Chubut, U, 9100, Argentina

Keywords:
water ferns
Late Cretaceous
Patagonia
fossil
megaspores
microspores.

Presentation Type: Oral Paper
Number: 0003
Abstract ID:261
Candidate for Awards:Edgar T. Wherry award


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