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Ornithopod trackmaker identity from manus prints



From: Ben Creisler
bcreisler@gmail.com


New in PLoS ONE:

Diego Castanera, Bernat Vila, Novella L. Razzolini, Peter L.
Falkingham, José I. Canudo, Phillip L. Manning & Àngel Galobart (2013)
Manus Track Preservation Bias as a Key Factor for Assessing Trackmaker
Identity and Quadrupedalism in Basal Ornithopods.
PLoS ONE 8(1): e54177.
doi:10.1371/journal.pone.0054177
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0054177


Background

The Las Cerradicas site (Tithonian–Berriasian), Teruel, Spain,
preserves at least seventeen dinosaur trackways, some of them formerly
attributed to quadrupedal ornithopods, sauropods and theropods. The
exposure of new track evidence allows a more detailed interpretation
of the controversial tridactyl trackways as well as the modes of
locomotion and taxonomic affinities of the trackmakers.

Methodology/Principal Findings

Detailed stratigraphic analysis reveals four different levels where
footprints have been preserved in different modes. Within the
tridactyl trackways, manus tracks are mainly present in a specific
horizon relative to surface tracks. The presence of manus tracks is
interpreted as evidence of an ornithopod trackmaker. Cross-sections
produced from photogrammetric digital models show different depths of
the pes and manus, suggesting covariance in loading between the
forelimbs and the hindlimbs.

Conclusions/Significance

Several features (digital pads, length/width ratio, claw marks) of
some ornithopod pes tracks from Las Cerradicas are reminiscent of
theropod pedal morphology. This morphological convergence, combined
with the shallow nature of the manus tracks, which reduces
preservation potential, opens a new window into the interpretation of
these tridactyl tracks. Thus, trackmaker assignations during the
Jurassic–Cretaceous interval of purported theropod trackways may
potentially represent ornithopods. Moreover, the Las Cerradicas
trackways are further evidence for quadrupedalism among some basal
small- to medium-sized ornithopods from this time interval.