Dinosaur extinction didn’t cause the rise of present-day mammals, claim researchers

Ten-year study shows that current mammals evolved ten million years after the dinosaurs were wiped out<em> - News Release</em>

A joint news release from Imperial College London, the Zoological Society of London and the Natural Environment Research Council

Strictly under embargo for
1800 hours BST
Wednesday 28 March 2007

A new, complete 'tree of life' tracing the history of all 4,500 mammals on Earth shows that they did not diversify as a result of the death of the dinosaurs, says new research published in Nature today.

The study was undertaken in the UK by scientists at Imperial College London and the Zoological Society of London (ZSL). It contradicts the previously accepted theory that the Mass Extinction Event (MEE) that wiped out the dinosaurs 65 million years ago prompted the rapid rise of the mammals we see on the earth today.

The multinational research team has been working for over a decade to compile the tree of life from existing fossil records and new molecular analyses. They show that many of the genetic 'ancestors' of the mammals we see around us today existed 85 million years ago, and survived the meteor impact that is thought to have killed the dinosaurs. However, throughout the Cretaceous epoch, when dinosaurs walked the earth, these mammal species were relatively few in number, and were prevented from diversifying and evolving in ecosystems dominated by dinosaurs.

The tree of life shows that after the MEE, certain mammals did experience a rapid period of diversification and evolution. However, most of these groups have since either died out completely, such as Andrewsarchus (an aggressive wolf-like cow), or declined in diversity, such as the group containing sloths and armadillos.

The researchers believe that our 'ancestors', and those of all other mammals on earth now, began to radiate around the time of a sudden increase in the temperature of the planet – ten million years after the death of the dinosaurs.

Professor Andy Purvis   from Imperial College London's Division of Biology explains: "Our research has shown that for the first 10 or 15 million years after the dinosaurs were wiped out, present day mammals kept a very low profile, while these other types of mammals were running the show. It looks like a later bout of 'global warming' may have kick-started today’s diversity – not the death of the dinosaurs.

"This discovery rewrites our understanding of how we came to evolve on this planet, and the study as a whole gives a much clearer picture than ever before as to our place in nature."

Dr Kate Jones from the Zoological Society of London adds: "Not only does this research show that the extinction of the dinosaurs did not cause the evolution of modern-day mammals, it also provides us with a wealth of other information. Vitally, scientists will be able to use the research to look into the future and identify species that will be at risk of extinction. The benefit to global conservation will be incalculable."

The study was supported by the UK Natural Environment Research Council (NERC), the National Center for Ecological Analysis and Synthesis (NCEAS), the German Federal Ministry of Education and Research (BMBF), the German Research Association (DFG) Heisenberg, the Leverhulme Trust, the National Science Foundation (NSF), the Earth Institute at Columbia University, and the Cyberinfrastructure for Phylogenetic Research (CIPRES).

-Ends-

For more information please contact:

Danielle Reeves, Imperial College London press office
Tel: +44 (0)20 7594 2198
Mob: +44 (0) 7803 886248
Email: Danielle.reeves@imperial.ac.uk

Alice Henchley, Zoological Society of London press office
Tel: +44 (0)20 7449 6361
Mob: +44 (0) 7790 301596
Email: Alice.henchley@zsl.co.uk

Marion O'Sullivan, Natural Environment Research Council press office
Tel: +44 (0) 1793 411727
Mob: +44 (0) 7917 086369
Email: pressoffice@nerc.ac.uk

Notes to Editors:

1. 'The delayed rise of present-day mammals', Nature, 29 March 2007.

Olaf R. P. Bininda-Emonds (1), Marcel Cardillo (2), Kate Jones (4), Ross D. E. MacPhee (5), Robin M. D. Beck (6), Richard Grenyer (7), Samantha A. Price (8), Rutger A, Vos (9), John L. Gittleman (10) and Andy Purvis (2,3).

(1) Lehrstuhl fu¨r Tierzucht, Technical University of Munich, 85354 Freising-Weihenstephan, Germany.
(2) Division of Biology, and (3) NERC Centre for Population Biology, Imperial College London, Silwood Park campus, Ascot SL5 7PY, UK.
(4) Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK.
(5) Division of Vertebrate Zoology, American Museum of Natural History, New York, New York 10024, USA
(6) School of Biological, Earth and Environmental Sciences, University of New SouthWales, Sydney, New South Wales 2052, Australia.
(7) Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK
(8) National Evolutionary Synthesis Center (NESCent), Durham, North Carolina 27705, USA
(9) Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
(10) Institute of Ecology, University of Georgia, Athens, Georgia 30602, USA

2. About Imperial College London

Rated as the world's ninth best university in the 2006 Times Higher Education Supplement University Rankings, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 11,500 students and 6,000 staff of the highest international quality.

Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.

With 62 Fellows of the Royal Society among our current academic staff and distinguished past members of the College including 14 Nobel Laureates and two Fields Medallists, Imperial's contribution to society has been immense. Inventions and innovations include the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of our research for the benefit of all continues today with current focuses including interdisciplinary collaborations to tackle climate change and mathematical modelling to predict and control the spread of infectious diseases.

The College's 100 years of living science will be celebrated throughout 2007 with a range of events to mark the Centenary of the signing of Imperial's founding charter on 8 July 1907.

Website: www.imperial.ac.uk

3. About the Zoological Society of London

The Institute of Zoology (IoZ) is the research division of the Zoological Society of London. It is a government-funded research institute specialising in scientific issues relevant to the conservation of animal species and their habitats. Since 2000 , IoZ has been affiliated with the University of Cambridge, a partnership based on a shared interest in researching scientific issues that underpin decisions affecting biodiversity conservation.

Founded in 1826, the Zoological Society of London (ZSL) is an international scientific, conservation and educational charity: our key role is the conservation of animals and their habitats. ZSL runs ZSL London Zoo and ZSL Whipsnade Zoo, carries out scientific research in the Institute of Zoology and is actively involved in field conservation in other countries worldwide.

Website: www.zsl.org 

4. About the Natural Environment Research Council

The Natural Environment Research Council funds world-class science, in universities and its own research centres, that increases knowledge and understanding of the natural world. It is tackling the 21st century's major environmental issues such as climate change, biodiversity and natural hazards. It leads in providing independent research and training in the environmental sciences.

Website: www.nerc.ac.uk