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Dune-walking dinos (not)
Check out the latest issue of the journal _Geology_
(the issue with the fantastic full-color cover-photo of the excavation
of a Mongolian ankylosaur). In their paper, Loope et al. describe
new stratigraphic evidence regarding the nature of the paleo-surface
that the Mongolian dinos were walking on. They found that the
sandy substrate at that time was a type of alluvial-fan deposit that was
eroding off of aeolian dunes. The dinosaurs trampled this
sand to such a degree that "dinoturbation" is ubiquitous throughout
the strata. Therefore, the dunes may not have been as common in the
area as was previously thought. Tracts of dune-devoid land,
separated by dune fields, were common in the area during the late Cret.
An sedimentological analogy was made with the Quaternary sand dune
fields of Nebraska, U.S.A.
Loope et al. surmise that, contra others (Currie et al??)., many
of the Mongolian dinosaurs were not buried suddenly in a dune
collapse, but rather were buried in a sudden mass-flow of sand
and water initiated from rainstorms. Many of the animals were
undoubtably carcasses, and it is also possible that some were
alive at the time of the catastrophes.
So it is possible that paleo-sand dunes played little direct role
in the burial of the fully-articulated Mongolian dinosaurs.
Loope, D. B., L. Dingus, C.C. Swisher, and C. Minjin. 1998.
Life and death in a late Cretaceous dune field, Nemegt
basin, Mongolia. _Geology_, vol. 26(1):27-30.