[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Cretaceous Kem Kem Beds (Morocco) unbalanced food web with dinosaurs



Makes me wonder if carcharodontosaurs, etc. were eating spinosaurs in
a way loosely analogous to brown hyenas eating sea lions, or polar
bears eating seals . . . terrestrial predators feeding on predators of
aquatic prey.

On Sun, Apr 21, 2013 at 10:15 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> From: Ben Creisler
> bcreisler@gmail.com
>
> A new online paper:
>
>
> Läng Emilie, Boudad Larbi, Maio Laszlo, Samankassou Elias, Tabouelle
> Jérôme, Tong Haiyan & Cavin Lionel (2013)
> Unbalanced food web in a Late Cretaceous dinosaur assemblage.
> Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
> DOI: http://dx.doi.org/10.1016/j.palaeo.2013.04.011,
> http://www.sciencedirect.com/science/article/pii/S0031018213001855
>
>
> The rich assemblage of continental vertebrates from the Cenomanian Kem
> Kem Beds (Morocco) is one of the best known and most diversified for
> the mid Cretaceous period (Cenomanian). This assemblage, however,
> shows apparent ecological oddities, in particular the overabundance of
> theropod dinosaurs versus plant-eating dinosaurs. Several hypotheses
> have been proposed to explain this unbalanced ratio, including a
> peculiar ecosystem, non-systematic collecting, taphonomic factors,
> stratigraphic uncertainties and/or behavioral aspects of the dinosaur
> groups concerned. Except the comparison of proportions of taxa between
> field and shop data (McGowan and Dyke, 2009), the other hypotheses
> have not been tested so far because of the lack of accurately measured
> sections and systematically collected field data. Based on new field
> data, we test the above-mentioned hypotheses. The analysis is focused
> on the ratio of plant-eating versus carnivorous dinosaurs.
>
> This dataset confirms the unbalanced ratio; moreover, the
> stratigraphic distribution of fossils is quantitatively not
> homogeneous and consequently important to avoid time-averaging, i.e.
> the mixing of fossils of different ages together into a single unit.
> The origin of the unbalanced food web among dinosaurs is related
> neither to non-systematic collecting, nor to stratigraphic biases. The
> palaeoenvironment seems to be the only likely factor to explain the
> significantly high proportion of carnivorous versus plant-eating
> dinosaurs. Indeed, the deltaic palaeoenvironment offered unfavourable
> conditions for the setting of stable terrestrial vegetation but
> favoring aquatic life. This aquatic life formed the basic level of an
> aquatic or semi-aquatic food web, which directly fed top predators,
> such as theropods in general and spinosaurs in particular.