Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Amphibians and dinosaurs were the new large predators after the mass extinction

20.03.2014

Immediately after the biggest extinction event of all time there were once again functioning and complete food webs in the oceans of the Early Triassic. Contrary to previous assumptions there were large predators, too. Large predatory fish and amphibians, and later dinosaurs too, were the last link in the food chain. This is demonstrated in new studies by palaeontologists at the Universities of Zurich and Utah, USA.

252 million years ago the largest extinction event occurred at the end of the Permian age. It wiped out almost 90 percent of all life in water.


Fossil von Saurichthys, einem Topräuber unter den Trias-Fischen. Bild: UZH


Fossil und Lebendrekonstruktion von Askeptosaurus, eines grossen Meeresreptils der Trias-Zeit. Solche Thalattosaurier bzw. Meeres- oder Ozanechsen konnten über vier Meter lang werden. Bild: UZH

So far researchers had assumed that the ecosystems gradually recovered from this catastrophe over a long stretch of eight to nine million years and that large predators at the uppermost end of the food chain were the last to reappear.

A Swiss-American team of palaeontologists headed by Torsten Scheyer and Carlo Romano from the University of Zurich demonstrate in their new study that the food nets during the Early Triassic did not recover in stages. Large predators like, for instance, crocodile-like amphibians and later the precursors of the known plesiosaurs and ichthyosaurs went in search of prey in the oceans soon after the end of the mass extinction. 

Large predators in on the action from the very start

Apex predators – large predators at the uppermost end of the food chain – are extremely important for the health and stability of an ecosystem. They eradicate sick and weak animals and exercise constant selection pressure on the species they prey on. Hence, Scheyer and his colleagues wanted to establish whether the apex predators really were missing from the oceans after the mass extinction and how the ecosystems functioned.

The researchers looked at the global distribution of predatory marine vertebrates and their body size in the Early and Middle Triassic and came to surprising conclusions. “The apex marine predators recovered after the large extinction over a very, comparatively short period of time”, says Torsten Scheyer.

The researchers were also able to refute a second theory. Earlier it had been assumed that marine predators grew continuously larger from the Early to the Middle Triassic culminating in the apex predators.

“We now demonstrate that already in the Early Triassic large predators hunted in the seas”, adds Carlo Romano.”The length of the food chains was not shortened by the end-Permian mass extinction. Nor are there any signs of a gradual re-emergence of the classical trophic pyramids from the base to the top”, explains Hugo Bucher.

To gain greater understanding of food webs, attention had to be paid not only to the shape of the food webs but also to the dynamics, i.e. the evolutionary rates of the participating species.

New actors in old roles

The large end-Permian mass extinction led to a completely new composition of apex predators. Large predatory fish were dominant in the Permian age but they had to share this role with predatory crocodile-like amphibians after the mass extinction. Another extinction event around two million years later, the End Smithian crisis, triggered changes in the group of apex predators. From this point in time fish and for the first time reptiles like, for instance, Askeptosaurus were at the uppermost end of the food chains.

“The role of the large predators always remained the same in the ecosystems; only the actors changed over the course of time”, comments Torsten Scheyer when summing up the new results. The researchers are convinced that insight into events in the past will contribute to better understanding of the impact of today’s climate changes on ecosystems.

Literature:
Torsten M. Scheyer, Carlo Romano, Jim Jenks, Hugo Bucher. Early Triassic Marine Biotic Recovery: The Predators’ Perspective. PLOS ONE, March 19, 2014. DOI: 10.1371/journal.pone.0088987


Contact:
Dr. Torsten Scheyer
Palaeontological Institute and Museum
University of Zurich
Tel. + 41 634 23 22
Email:tscheyer@pim.uzh.ch

Dr. Carlo Romano
Palaeontological Institute and Museum
University of Zurich
Karl Schmid-Strasse 4
CH 8006 Zürich
Tel. + 41 634 23 47
Email carlo.romano@pim.uzh.ch

Weitere Informationen:

http://www.mediadesk.uzh.ch

Nathalie Huber | Universität Zürich

Further reports about: Askeptosaurus Recovery Saurichthys Triassic amphibians dinosaurs ecosystems oceans species

More articles from Earth Sciences:

nachricht NASA sees quick development of Hurricane Dora
27.06.2017 | NASA/Goddard Space Flight Center

nachricht Collapse of the European ice sheet caused chaos
27.06.2017 | CAGE - Center for Arctic Gas Hydrate, Climate and Environment

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>