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Tyrannosaurus and other tyrannosaurid teeth from Mexico



From: Ben Creisler
bcreisler@gmail.com

A new paper. (It's legit, despite the date today....)

Claudia Inés Serrano-Brañas,  Esperanza Torres-Rodríguea, Paola
Carolina Reyes Luna, Ixchel González & Carlos González-León (2014)
Tyrannosaurid teeth from the Lomas Coloradas Formation, Cabullona
Group (Upper Cretaceous) Sonora, México.
Cretaceous Research 49: 163-171
http://dx.doi.org/10.1016/j.cretres.2014.02.018
http://www.sciencedirect.com/science/article/pii/S0195667114000366

The Lomas Coloradas Formation (Cabullona Group, Upper Cretaceous) in
the state of Sonora, Mexico, has yielded a great diversity of
continental vertebrates, especially dinosaurs. In this study we
describe, analyze and illustrate six theropod teeth (ERNO specimens)
that were found isolated and surface collected. Identification of the
specimens is based upon the methodology provided by Smith (2005),
Smith et al. (2007) and Smith et al. (2005). The results showed that
the ERNO teeth are comparable to those of tyrannosaurid dinosaurs and
some of them probably correspond to a new taxon. Their referral to the
Tyrannosauridae family is supported by the presence of semi-conical,
laterally compressed crowns with an ovoid cross-sectional base;
slightly offset carinae with chisel-shaped denticles that are wider
labio-lingually than longer proximo-distally; and the presence of
enamel wrinkles at the base of some denticles on the labial surface.
These wrinkles are not prominent adjacent to the serrations but they
take the form of high relief deep enamel bands across the labial and
lingual crown faces. Statistical principal component analysis (PCA)
and discriminant function analysis (DFA) corroborated the
taxonomically assignation of these teeth into this family.
Particularly, the DFA analysis yielded very interesting results. This
analysis classified ERNO 8549, 8550, 8551 and 8552 specimens as
belonging to Tyrannosaurus, so they represent the most southern record
of this genus in Western North America. Finally, the misclassification
of ERNO 005 and ERNO 006 specimens remains puzzling. It probably was
the result of the presence of juvenile individuals.

Highlights
*
Six unknown isolated theropod teeth were collected in the state of
Sonora, Mexico.
*
Morphological and statistical analyses assigned the specimens to the
Tyrannosauridae.
*
The discriminant function analysis classified four of the six teeth as
Tyrannosaurus.
*
These specimens represent the most southern record of this genus in
North America.