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Small Theropod Teeth Multivariate Analyses

From: Ben Creisler

New in PLoS ONE:

Derek W. Larson & Philip J. Currie (2013)
Multivariate Analyses of Small Theropod Dinosaur Teeth and
Implications for Paleoecological Turnover through Time.
PLoS ONE 8(1): e54329.

Isolated small theropod teeth are abundant in vertebrate microfossil
assemblages, and are frequently used in studies of species diversity
in ancient ecosystems. However, determining the taxonomic affinities
of these teeth is problematic due to an absence of associated
diagnostic skeletal material. Species such as Dromaeosaurus
albertensis, Richardoestesia gilmorei, and Saurornitholestes langstoni
are known from skeletal remains that have been recovered exclusively
from the Dinosaur Park Formation (Campanian). It is therefore likely
that teeth from different formations widely disparate in age or
geographic position are not referable to these species. Tooth taxa
without any associated skeletal material, such as Paronychodon
lacustris and Richardoestesia isosceles, have also been identified
from multiple localities of disparate ages throughout the Late
Cretaceous. To address this problem, a dataset of measurements of 1183
small theropod teeth (the most specimen-rich theropod tooth dataset
ever constructed) from North America ranging in age from Santonian
through Maastrichtian were analyzed using multivariate statistical
methods: canonical variate analysis, pairwise discriminant function
analysis, and multivariate analysis of variance. The results indicate
that teeth referred to the same taxon from different formations are
often quantitatively distinct. In contrast, isolated teeth found in
time equivalent formations are not quantitatively distinguishable from
each other. These results support the hypothesis that small theropod
taxa, like other dinosaurs in the Late Cretaceous, tend to be
exclusive to discrete host formations. The methods outlined have great
potential for future studies of isolated teeth worldwide, and may be
the most useful non-destructive technique known of extracting the most
data possible from isolated and fragmentary specimens. The ability to
accurately assess species diversity and turnover through time based on
isolated teeth will help illuminate patterns of evolution and
extinction in these groups and potentially others in greater detail
than has previously been thought possible without more complete
skeletal material.