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Crocodile swim tracks from latest Cretaceous of Europe
A new online paper:
Bernat Vila, Diego Castanera, Josep Marmi, José I. Canudo and Àngel
Crocodile swim tracks from the latest Cretaceous of Europe.
Lethaia (advance online publication)
Recently discovered evidence of tracks in the continental beds of the
Late Cretaceous Tremp Formation in the southern Pyrenees (NE Iberian
Peninsula) has been identified as scratch marks made by buoyant
crocodiles. The tracks are preserved in two distinct environments and
substrates (marly limestones originating in a littoral mud flat and
fine-grained sandstones deposited in fluvial settings). Most of the
crocodylian traces are ascribed to ichnogenus Characichnos, whereas a
single plantigrade pes track is assigned to ichnogenus cf.
Crocodylopodus. The crocodylian swim traces (Characichnos ichnofacies)
found in the early and late Maastrichtian co-occur with Brontopodus
ichnofacies attributable to terrestrial tetrapods (titanosaur
sauropods, cf. Brontopodus ichnogenus; and hadrosaurid ornithopods,
Hadrosauropodus ichnogenus). Analysis of the tracks allows the
interpretation of palaeoenvironmental settings and track production.
Thus, in lagoonal environments, swim tracks of crocodylians were
produced during the rise of the water level in successive tide cycles;
in fluvial settings, the swim traces of crocodylians were produced
within the channel at the low-water stage. To date, there are no
reports of Late Cretaceous crocodylian tracks in Europe, and the
studied evidence represents the first and youngest track record of the
group in the latest part of the Cretaceous (C29r) in this continent
and probably in the world.