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OLDEST RECORD OF NOTHOFAGUS LEAVES IN NELSON ISLAND, SOUTH
SHETLAND ISLANDS, ANTARCTICA: IMPLICANCES FOR BIOGEOGRAPHY
Marcelo Leppe1, Thiers Wilberger1, María Jesus Ortuya2, Héctor Ortiz2, Joaquín Bastias3, Héctor Mansilla1& Tania Dutra4
The genus Nothofagus Blume has 35 living species that are found in
rain forests of the South Pacific (south-east Australia, Tasmania, New
Zealand, New Guinea, New Caledonia and southern South America).
The recent biogeography of the main four subgenus (Fig. 1) has been
frequently used as one of the best examples of the close relation
between continental drift and evolution. The fossil record of the
southern beech includes Oceania, South America and Antarctica
reflecting a close relation with the post-Turonian vicariant events that
We are grateful to the crew of Escudero Station and the Chilean Antarctic Institute for their logistic support for our field campaigns to this area. Financial support by the FONDECYT Project N° 1151389 “Paleogeographic
patterns v/s climate change in South America and the Antarctic Peninsula during the latest Cretaceous: a possible explanation for the origin of the Austral biota?”are gratefully acknowledged.
Figure 2: A.- In situ deposit of leaf imprints of Nothofagus, level 3 Rip Point; B.- Nothofagus sp.1 morphotype;
C.- Nothofagus sp.2 morphotype. D.- Detail of the leaf margin in Nothofagus sp.1 morphotype; E-H.- Pollen
grains of Nothofagidites from levels 3 and 4. bar= 1 cm
1.- Laboratorio de Paleobiología, Instituto Antártico Chileno-INACH, Plaza Muñoz Gamero 1055, Punta Arenas, Chile. email@example.com
2.- Departamento Ciencias de La Tierra, Universidad de Concepción, Concepción, Chile.
3.- Section of Earth and Environmental Sciences, University of Geneva, Genève, Switzerland.
4.- Programa de Pós-Graduação em Geologia, Universidade do Vale do Rio dos Sinos-UNISINOS, Brasil.
The Nothofagus leaves at Rip Point are represented by at least two
different morphotypes. The Nothofagus sp.1 type is characterized by
ovate leaves, notophyllous (8 x 5 cm) and pinnate, simple
craspedodromous venation, entering teeth centrally. Secondary veins
are delicate, varying in number from 11 to 13, one to three veins/cm,
straight, alternating along midvein, diverging from it in acute angles
(50–60°), bifurcating towards margin. Three basal ramifications of
secondary veins also diverge at acute angles. Nothofagus sp.2
morphotype are elliptical leaves with membranous and serrated
margins, mesophyllous (11 x 4,5 cm). Pinnate venation, simple
craspedodromous. Conspicuous secondary veins, varying in number
from 10 to 11, one vein/cm, straight. Secondary veins subopposite to
alternating, diverging from it at acute angles (40–50). Taphonomically
the deposit belongs to a fossil litter in lacustrine environments close to
The biology of Nothofagus support the idea that a land bridge is
needed to disperse because its anemochory and anemophily dispersal
syndromes. The asynchrony in the presence of Nothofagus leaves
could be interpreted as an evidence of land discontinuity between the
northern tip of the Antarctic Peninsula and southern South America
during an important part of the Campanian and Maastrichtian, that
prevented the dispersion of the genus from Antarctica to Patagonia.
The biogeographical barrier apparently disappeared during the Lower
Maastrichtian, permitting the colonization from Antarctica. The event
could be linked with the global record of cooling events that provoked
glacioeustacy and consequent fall in the sea levels, recorded by several
authors for Antarctica and other continents.
During the last decade, intensive paleontological studies has been
carried out in Patagonia and Antarctica producing a remarkable
collection of new fossil records and localities.
During the 2016 Chilean Antarctic Expedition, fieldwork in a
fossiliferous locality at Rip Point, Stansbury Peninsula, Nelson Island,
South Shetland Islands, Antarctica, resulted in the discovery of plant-
bearing beds containing Nothofagus-like leaf imprints, associated with
ferns and angiosperm remains.
Figure 1: Extant species and distribution of the four subgenera of Nothofagus.
The stratigraphic sequence at Rip
point is dominated by andesitic and
volcanoclastic rocks, but including
lapilli-fuff, tuff and ash fossil bearing
levels. The material here reported
belongs to the lower section with
and estimated Lower-Middle
Campanian age. The micro and
megafossils recovered includes leaf
imprints, spores and pollen grains, as
well as thin charcoal levels and
carbonized woods. Previous authors
have stablished a Middle-Upper
Campanian age (Rb-Sr 71-77 My)to
the upper section at Rip Point
through the correlation with the
closest locality of Half Three Point in