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Late Cretaceous Aquatic Plant World in Patagonia, Argentina

Ben Creisler

New in PLoS ONE and may be of interest to some. Carnotaurus comes from
the La Colonia Formation.

N. Rubén Cúneo, María A. Gandolfo, María C. Zamaloa & Elizabeth Hermsen (2014)
Late Cretaceous Aquatic Plant World in Patagonia, Argentina.
PLoS ONE 9(8): e104749.

In this contribution, we describe latest Cretaceous aquatic plant
communities from the La Colonia Formation, Patagonia, Argentina, based
on their taxonomic components and paleoecological attributes. The La
Colonia Formation is a geological unit deposited during a
Maastrichtian-Danian transgressive episode of the South Atlantic
Ocean. This event resulted in the deposition of a series of
fine-grained sediments associated with lagoon systems occurring along
irregular coastal plains in northern Patagonia. These deposits
preserved a diverse biota, including aquatic and terrestrial plants
and animals. The aquatic macrophytes can be broadly divided into two
groups: free-floating and rooted, the latter with emergent or floating
leaves. Free-floating macrophytes include ferns in Salviniaceae
(Azolla and Paleoazolla) and a monocot (Araceae). Floating microphytes
include green algae (Botryoccocus, Pediastrum and Zygnemataceae).
Among the rooted components, marsileaceous water ferns (including
Regnellidium and an extinct form) and the eudicot angiosperm Nelumbo
(Nelumbonaceae) are the dominant groups. Terrestrial plants occurring
in the vegetation surrounding the lagoons include monocots (palms and
Typhaceae), ferns with affinities to Dicksoniaceae, conifers, and
dicots. A reconstruction of the aquatic plant paleocommuniy is
provided based on the distribution of the fossils along a freshwater
horizon within the La Colonia Formation. This contribution constitutes
the first reconstruction of a Cretaceous aquatic habitat for southern
South America.