Welcome Guest [Log In] [Register]
Welcome to Carnivora. We hope you enjoy your visit.


You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile and voting in polls. Registration is simple, fast, and completely free.


Join our community!


If you're already a member please log in to your account to access all of our features:

Username:   Password:
Add Reply
Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs; A. Hassler et al. Proceedings of the Royal Society B: Biological Sciences (2018). DOI: 10.1098/rspb.2018.0197
Topic Started: Apr 12 2018, 04:31 PM (59 Views)
Taipan
Member Avatar
Administrator

The dinosaur menu, as revealed by calcium

April 11, 2018, CNRS

Posted Image
Teeth from the Gadoufaoua deposit (Niger). The scale bar represents 2 cm. From left to right: teeth of a giant crocodile, Sarcosuchus imperator, a spinosaurid, a non-spinosaurid theropod (abelisaurid or carcharodontosaurid), a pterosaur, a hadrosaurid (a herbivorous dinosaur), a pycnodont (fish), and a small crocodylomorph. Credit: Auguste Hassler / LGL-TPE / CNRS-ENS de Lyon-Université Lyon 1

By studying calcium in fossil remains in deposits in Morocco and Niger, researchers have been able to reconstruct the food chains of the past, thus explaining how so many predators could coexist in the dinosaurs' time. This study, conducted by the Laboratoire de géologie de Lyon: Terre, planètes et environnement (CNRS/ENS de Lyon/Claude Bernard Lyon 1 University), in partnership with the Centre for Research on Palaeobiodiversity and Palaeoenvironments (CNRS/French National Museum of Natural History/Sorbonne University), is published on April 11, 2018 in the Proceedings of the Royal Society of London B.

A hundred million years ago, in North Africa, terrestrial ecosystems were dominated by large predators—giant theropod dinosaurs, large crocodiles—with comparatively few herbivores. How were so many carnivores able to coexist?

To understand this, French researchers have studied fossils in the Gadoufaoua deposits in Niger (dating from 120 million years ago) and the Kem Kem Beds in Morocco (dating from 100 million years ago). These two sites are characterized by an overabundance of predators compared to the herbivorous dinosaurs found in the locality. More specifically, the researchers measured the proportions of different calcium isotopes in the fossilized remains (tooth enamel and fish scales).

Among vertebrates, calcium is almost exclusively derived from food. By comparing the isotopic composition of potential prey (fish, herbivores) with that of the carnivores' teeth, it is thus possible to retrace the diet of those carnivores.

The data obtained show similar food preferences at the two deposits: some large carnivorous dinosaurs (abelisaurids and carcharodontosaurids) preferred to hunt terrestrial prey such as herbivorous dinosaurs, while others (the spinosaurids) were piscivorous (fish-eating). The giant crocodile-like Sarcosuchus had a diet somewhere in between, made up of both terrestrial and aquatic prey. Thus, the different predators avoided competition by subtly sharing food resources.

Some exceptional fossils, presenting traces of feeding marks and stomach content, had already provided clues about the diet of dinosaurs. Yet such evidence remains rare. The advantage of the calcium isotope method is that it produces a global panorama of feeding habits at the ecosystem scale. It thus opens avenues for further study of the food chains of the past.

This study received support from the Labex Institut des origines de Lyon, the Institut national des sciences de l'Univers, part of the CNRS (through the Diunis project), and the Jurassic Foundation.

https://phys.org/news/2018-04-dinosaur-menu-revealed-calcium.html




Journal Reference:
A. Hassler et al. Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs, Proceedings of the Royal Society B: Biological Sciences (2018). DOI: 10.1098/rspb.2018.0197

Abstract
Large predators are overabundant in mid-Cretaceous continental dinosaur assemblages of North Africa. Such unbalanced ecosystem structure involves, among predatory dinosaurs, typical abelisaurid or carcharodontosaurid theropods co-occurring with long-snouted spinosaurids of debated ecology. Here, we report calcium (Ca) isotope values from tooth enamel (expressed as δ44/42Ca) to investigate resource partitioning in mid-Cretaceous assemblages from Niger (Gadoufaoua) and Morocco (Kem Kem Beds). In both assemblages, spinosaurids display a distinct isotopic signature, the most negative in our dataset. This distinct taxonomic clustering in Ca isotope values observed between spinosaurids and other predators provides unambiguous evidence for niche partitioning at the top of the trophic chains: spinosaurids foraged on aquatic environments while abelisaurid and carcharodontosaurid theropods relied almost exclusively on terrestrial resources.

http://rspb.royalsocietypublishing.org/content/285/1876/20180197
Offline Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
« Previous Topic · Dinosaur News · Next Topic »
Add Reply

Find this theme on Forum2Forum.net & ZNR exclusively.