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Re: Age of La Colonia



This is very helpful. I'm curious about what Carnotaurus' age will do to the evolutionary lineage of Abelisaurs. Something never made sense to me about the massive corrocoids and tiny arms. They seemed so specialized in comparison to other Abelisaurs that occured at a later age. It hard not to make the same comparisons to the reduced arms of Late Cretaceous Tyrannosaurs.
Please forgive my improper or pedestrian use of terminology, I've been out of practice!
David Krentz
On Feb 19, 2005, at 8:36 AM, Flia. Soto-Nuñez wrote:


Is the La Colonia Formation of Argentina Albian/Aptian of Maastrichtian?

Taken from http://dml.cmnh.org/2003Sep/msg00120.html (see references therein):

The Bayo Overo Member [of Cerro Barcino Formation] has yielded the sauropod
Chubutisaurus (Del Corro, 1975), an undescribed sauropod, and several
theropod teeth ( Rich et al., 2000). Though frequently cited as being
derived from the Aptian?Albian (e.g. Weishampel, 1990; Bonaparte, 1996;
Novas, 1997) Chubutisaurus is thus most probably of Late Cretaceous age
(Page et al., 1999; Rich et al., 2000). Likewise, the abelisaurid
Carnotaurus, originally thought to be from the Albian of the Cerro Barcino
(=Gorro Frigio) Formation (Bonaparte, 1985; Bonaparte et al., 1990), is now
known to have come from the La Colonia Formation, which, according to new
palynological evidence, is Maastrichtian in age (A. Archangelsky, pers.
comm. 2001). Likewise, the abelisaurid Carnotaurus, originally thought to be
from the Albian of the Cerro Barcino (=Gorro Frigio) Formation (Bonaparte,
1985; Bonaparte et al., 1990), is now known to have come from the La Colonia
Formation, which, according to new palynological evidence, is Maastrichtian
in age (A. Archangelsky, pers. comm. 2001).


Hope this helps.

Matías Soto


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