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Dinosaur ichnofauna from Paraná basin (Brazil and Uruguay)
A new online paper:
H. Francischini, P.C. Dentzien–Dias, M.A. Fernandes & C.L. Schultz (2015)
Dinosaur Ichnofauna of the upper Jurassic/lower Cretaceous of the
Paraná basin (Brazil and Uruguay).
Journal of South American Earth Sciences (advance online publication)
Guará/Batoví (fluvio-aeolian) and Botucatu/Rivera (aeolian) units are compared.
Theropod and ornithopod traces are present in both units.
Botucatu paleoerg lacks sauropod traces.
Dinosaur ichnofauna of Guará/Batoví is larger than Botucatu ones.
Aridity of Botucatu paleoerg limits the dinosaur fauna in size and distribution.
Upper Jurassic and Lower Cretaceous sedimentary layers are represented
in the Brazilian Paraná Basin by the fluvio–aeolian Guará Formation
and the Botucatu Formation palaeoerg, respectively, overlapped by the
volcanic Serra Geral Formation. In Uruguay, the corresponding
sedimentary units are named Batoví and Rivera Members (both from the
Tacuarembó Formation), and the lava flows constitute the Arapey
Formation (also in Paraná Basin). Despite the lack of body fossils in
the mentioned Brazilian formations, Guará/Batoví dinosaur fauna is
composed of theropod, ornithopod and wide–gauge sauropod tracks and
isolated footprints, as well as theropod teeth. In turn, the
Botucatu/Rivera dinosaur fauna is represented by theropod and
ornithopod ichnofossils smaller than those from the underlying units.
The analysis of these dinosaur ichnological records and comparisons
with other global Mesozoic ichnofauna indicates that there is a size
reduction in dinosaur fauna in the more arid Botucatu/Rivera
environment, which is dominated by aeolian dunes. The absence of
sauropod trackways in the Botucatu Sandstone fits with the
increasingly arid conditions because it is difficult for heavy animals
to walk on sandy dunes, as well as to obtain the required amount of
food resources. This comparison between the Upper Jurassic and Lower
Cretaceous dinosaur fauna in south Brazil and Uruguay demonstrates the
influence of aridization on the size of animals occupying each