THEORIES FOR

THE

EXTINCTION OF

DINOSAURS

INTRODUCTION

Disappeared around 65 million years ago.

Scientists do not know yet why they did disappear

although there are

three different THEORIES:

- Asteroid collision - Enormous eruptions

- Competence with mammals

TWO VIEWS

Intrinsicgradualists

Platetectonics

Volcanism

Extrinsic

Asteroidscollisions

EARTH NATUREEXTRATERRESTRIAL NATURE

PaleontologistsAstronomers,

physicists..

ASTEROID COLLISION

- A meteorite fell in the Earth

- It was 10km wide

- It contained iridium, a metal usually found in

asteroids.

- It created a 180km wide crater (Chicxulub) in the

Yucatan Peninsula, 65 million years ago.

- A layer of rubble (remains) was created in the

atmosphere, covering the Earth.

- Luis and Walter Alvarez were the first ones that

carried out some investigations all around the world.

EFFECTS

This are the effects that

different scientists think

that happened:

Dust cloud blocked

sunlight for a year

Location where the

asteroid fell big

disasters (tsunamis,

earthquakes, volcanic

eruptions…)

DIFFERENT OPINIONS

RTVE.es - 04.03.2010

Confirmado: un meteorito provocó la extinción de los dinosaurios

Fin de la discusión: un meteorito mató a los dinosauriosJOSÉ MANUEL NIEVES / MADRID

Día 08/02/2013 - 14.28h

Público.es Si un gran meteorito provocó la extinción de los dinosaurios, ¿por qué otras especies

sobrevivieron?

JORGE MORALES (INVESTIGADOR DEL CSIC) 17/08/2011

ENORMOUS ERUPTIONS

Theory developed by Gerta Keller

EVIDENCES FOR THE TEHORY:

-Eruptions occured Clay rocks with iridium

-There were flood basalts Basalt rocks found in India

ENORMOUS ERUPTIONS

CAUSES OF THE ERUPTIONS

-Poisonous gases were expelled

-Layer of dust around the Earth

-Climate change due to the greenhouse effect

PROBLEM OF THE THEORY

There were other flood basalts with no massive

extinction.

COMPETENCE WITH MAMMALS

Extinction implies that the species that are

lost are poorly adapted to a changing set

of conditions.

-Taking into account the changing set of

conditions that may have occurred at the

end of the Cretaceous.

-Mammals and dinosaurs may have

competed for the last resources of mass

COMPETENCE WITH MAMMALS

How were dinosaurs at that time?

-Most of the vast quantity of dinosaurs was big

and slow.

-The smallest species of dinosaurs were fitter and

more agile.

What mammals could have done at that time?

-Mammals at that time would have competed with

dinosaurs for food.

- Carnivorous mammals would have stolen and

preyed on dinosaur’s eggs.

COMPETENCE WITH MAMMALS

Fossil record evidence:

-Depending on location and interpretation,

the fossil record seems to say different

things.

-It is unclear whether mammals and

dinosaurs experienced little competition or

if they regularly challenged each other for

limited resources.

AND TO END

WITH THIS

PRESENTATION

…..