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Australian Dinosaur Stampede really a day at the beach?



From: Ben Creisler
bcreisler@gmail.com

Another paper in the new JVP:

Anthony Romilio, Ryan T. Tucker & Steven W. Salisbury (2013)
Reevaluation of the Lark Quarry dinosaur Tracksite (late
Albian–Cenomanian Winton Formation, central-western Queensland,
Australia): no longer a stampede?
Journal of Vertebrate Paleontology 33(1): 102-120
DOI:10.1080/02724634.2012.694591
http://www.tandfonline.com/doi/full/10.1080/02724634.2012.694591


The Lark Quarry dinosaur tracksite has previously been recognized as
recording the stampede of a mixed herd of dozens of small theropod and
ornithopod dinosaurs. A reexamination of trackway material reveals
that the small theropod-type tracks, previously assigned to the
ichnotaxon Skartopus, can co-occur within individual trackways of the
ornithopod-type tracks assigned to Wintonopus. Moreover, in singular
deep tracks where the overall surface outline resembles Skartopus, the
base of the track can also resemble Wintonopus. Whereas the Wintonopus
holotype may reflect the pedal anatomy of a short-toed or
subunguligrade ornithopod trackmaker, the elongate ‘toe’ impressions
typically associated with Skartopus (including the holotype) primarily
provide information on digit movement through the sediment and, in
many instances, may represent swim traces. The morphological
differences between the two ichnotaxa are therefore not taxonomically
significant and we formally propose that Skartopus australis should be
considered a junior synonym of Wintonopus latomorum. Longitudinal
depth profiles through tracks indicate that many are swim traces. The
sedimentology and lithology of Lark Quarry further indicates the site
represents a time-averaged assemblage formed in a fluvial-dominated
floodplain under variable subaqueous conditions, with the parallel
orientation of the numerous trackways formed by trackmakers under the
influence of downstream current flow. This indicates that the fluvial
environment may have been a preferred route for hydrophilic bipedal
dinosaurs. We thus do not consider the Lark Quarry dinosaur tracksite
to represent a ‘stampede.’ Instead, the tracksite may represent part
of a riverine setting, where the water was shallow, in which small
dinosaurs swam and/or waded.

===
Also dino-related in the new JVP:


Richard J. Butler, Adam M. Yates, Oliver W. M. Rauhut & Christian Foth (2013)
A pathological tail in a basal sauropodomorph dinosaur from South
Africa: evidence of traumatic amputation?
Journal of Vertebrate Paleontology 33(1): 224-228
DOI:10.1080/02724634.2012.710691
http://www.tandfonline.com/doi/full/10.1080/02724634.2012.710691

(no abstract)