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Late Cretaceous Iharkút vertebrate assemblage in Hungary



Ben Creisler
bcreisler@gmail.com

A new online paper:


Gábor Botfalvai, Attila Osi & Andrea Mindszenty (2014)
Taphonomic and palaeoecologic investigations of the Late Cretaceous
(Santonian) Iharkút vertebrate assemblage (Bakony Mts, Northwestern
Hungary).
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
DOI: 10.1016/j.palaeo.2014.09.032
http://www.sciencedirect.com/science/article/pii/S0031018214004878

Highlights

The deposits of the fossiliferous site are interpreted as an abandoned channel.
The identified isolated material represents polytypic attritional remains.
The skeletal materials represent a mass death assemblage.
Site SZ-6 represents animals that lived at the same time in ancient
fluvial system.
The investigation suggests that the ankylosaurs preferred wetland habitats.

Abstract

The Iharkút vertebrate locality, an open-pit mine in the Bakony
Mountains (western Hungary), has provided a rich and diverse
assemblage of Late Cretaceous (Santonian) continental vertebrates. The
isolated and associated remains represent 31 different taxa including
fish, amphibians, turtles, lizards, pterosaurs, crocodilians,
non-avian dinosaurs and birds. Sedimentologic investigations suggest
that the Iharkút depositional environment was represented by the
floodplain of a very low-gradient river. The 10-50 cm thick bonebed of
site SZ-6, is the most important fossiliferous layer in the open-pit
mine and analysis of this site indicates alternating energy conditions
during the bone accumulation, which resulted in fossils of different
states of preservation being deposited together. The vertebrate
assemblage of site SZ-6 includes three main different subsets with
widely different taphonomic history. The characteristics and the
preservation mode (high rate of abrasion and the spherical shape) of
the “bone pebbles” suggest that this type of the isolated bones was
more exposed to abrasion and probably the remains were transported
from farther away than the other isolated bones. The second group
includes 88% of the Iharkút collection, containing most of the
identified isolated bones and teeth, and represents polytypic
attritional remains transported and deposited by high density flow
during ephemeral flood events. Meanwhile the monospecific ankylosaur
skeletal material from Iharkút site SZ-6 may represent a mass death
assemblage because seven skeletons of Hungarosaurus were discovered
from an area of approximately 400 m2 and in many cases close to each
other in the same layer. The Iharkút vertebrate assemblage is
dominated by bones of aquatic/semi-aquatic animals, while the number
of terrestrial animal remains is subordinate. The taphonomic analysis
of the ankylosaur material from Iharkút locality further strengthens
the previously suggested hypothesis that some of the ankylosaurs
preferred wetland habitats (e.g. areas along fluvial systems) while
the other two herbivorous dinosaur groups from Iharkút (ornithopods
and ceratopsians) were probably living in distal habitats.