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How To Look At Dinosaur Tracks
A new study appearing in the May issue of The Journal of Geology provides
fascinating insight into the factors geologists must account for when
examining dinosaur tracks. The authors studied a range of larger tracks
from the family of dinosaurs that includes the T. Rex and the tridactyl,
and provide a guide for interpreting the effects of many different types
of erosion on these invaluable impressions.
"Well-preserved vertebrate tracks in the rock record can be an invaluable
source of information about foot morphology, soft tissue distribution, and
skin texture," write Jesper Miln (Geological Institute, University of
Copenhagen) and David B. Loope (Department of Geosciences, University of
Nebraska, Lincoln). "However, in most instances, the tracks are less than
perfectly preserved, and sometimes they can be barely recognizable as
tracks at all."
With this in mind, Miln and Loope sought to describe and categorize
different levels of preservation.
For example, estimating foot length from tracks can be inaccurate without
these considerations -- the more erosion that has occurred, the larger the
apparent dimensions of the track. Applications of this apparently larger
foot size derived from an undertrack may lead to calculations of higher
estimated hip length, and, as the authors point out, may also lead to
slower speed estimates.
Reference: Jesper Miln and David B. Loope, "Preservation and Erosion of
Theropod Tracks in Eolian Deposits: Examples from the Middle Jurassic
Entrada Sandstone, Utah, U.S.A." The Journal of Geology: 115, p. 375-386.