INVESTIGADORES
BARREDA Viviana Dora
artículos
Título:
Fossil pollen grains of Asteraceae from the Miocene of Patagonia: Nassauviinae affinity
Autor/es:
BARREDA, V.; PALAZZESI, L.; TELLERÍA, M.C.
Revista:
REVIEW OF PALAEOBOTANY AND PALYNOLOGY
Editorial:
Elsevier
Referencias:
Año: 2008 vol. 151 p. 51 - 58
ISSN:
0034-6667
Resumen:
Fossil pollen grains with morphological features unique in the subtribe
Nassauviinae (tribe Mutisieae, Asteraceae) occur in Miocene marine deposits of
eastern Patagonia, southern South America. A new genus and two species are
proposed to assemble fossil pollen grains characterized by having a complex
bi-layered exine structure with delicate columellae, separated by an internal
tectum. Subprolate specimens with Trixis exine type (ectosexine thinner than
endosexine, straight internal tectum) are referred to Huanilipollis cabrerii.
This species is similar to pollen of recent Holocheilus, Jungia, and Proustia.
Suboblate specimens with Oxyphyllum exine type (ectosexine and endosexine
equally thick, zigzag internal tectum) are referred to Huanilipollis criscii.
This species is similar to pollen of recent Triptilion. The spore/pollen
sequences in which Nassauviinae pollen types occur suggest a wide range of
vegetation types varying from forest dominated during the Early Miocene (Chenque
Formation) to virtually xerophytic ones during the Late Miocene (Puerto Madryn
Formation). The subtribe Nassauviinae comprises 25 genera and ca. 320 species of
vines, shrubs and low trees endemic to America with a wide range of ecological
preferences; the nearest living relatives of the fossil types being mostly
confined to humid landscapes. The unusual occurrence of these groups during the
arid characterized Late Miocene time could be attributed to the complex
interplay of the mountain uplift and global circulation patterns. These forcing
factors would have created a mosaic of different habitats with both patches of
forest and dry-adapted species developing in relatively small regions. This is
the first fossil record of Nassauviinae and confirms that this subtribe of
Asteraceae was already differentiated in the Miocene.