2. 1. Introduction
• 1.1 Dinosaurs
• 1.2 Necessities and characteristics
• 1.3 Description of period and habitat.
2. Theories
• Asteroid theory
• Vulcan theory
• Ice age theory
• Climate theory
3. Conclusion
3.
4. Type of animal:
Dinosaurs are a group of reptiles.
Dinosaurs had their heyday in the
Mesozoic Era.
5. Metabolism: cold blooded or warm
blooded?
Expectation of life: we don´t know it
Nutrition: carnivores and herbivores stay in
a relatively stable equilibrium
10. Where ?
Yucatan peninsula
What ?
Asteroid suppousdly coming from Jupiter or Mars.
Evidences:
External metals found near the dinosaurs fossils.
Consequences
Nuclear winter
11.
12. The end of the Cretaceous period
There was an increased of volcanic activity
Sulfur dioxide in the air
As a consequence a climatic change
13. Catastrophes shielded the earth suface
from sunlight.
As dinosaurs were thought to be cold
blooded, they survival was hard
Herbivores dinosaurs Low
quantity of plants Extinction of
dinosaurs
14. After previous catatrophies the world
climate became warmer by as much as 10cº
Main problems: Volcans and Sea level.
Sudden change or gradual change.
15. 1. Which were the main problems in which
the climate theory was based on?
2. Why the earth was shielded blocking the
sunlight?
3. What produced the huge clouds of sulfur
dioxide into the air ?
16. Lack of resources from the earth.
The most common theory is the asteriod theory.
Not all the living things disappear .
The main problem after the different
catastrophies was the climate change.
After the extinction of dinosaurs the living things
that survive try to evolve.
Editor's Notes
This is the greatest controversy surrounding the dinosaurs.
Dinosaurs are a group of reptiles with a set of physical features that are different from those of all other reptiles. They include extinct animals we know from fossils and the birds we see today. The extinct animals we normally think of as dinosaurs had their buen tiempo in the Mesozoic(an interval of geological time from about 252 to 66 million years ago). The word ‘dinosaur’ means ‘terrible lizard’ in Greek.
The Cretaceous–Paleogene (K–Pg) extinction event,[a] formerly known as the Cretaceous–Tertiary (K–T) extinction,[b] was a mass extinction of some three-quarters of plant and animal species on Earth
Dinosaur metabolism—was their metabolism cold-blooded or warm-blooded? This question has been debated since dinosaurs were first discovered. Did they produce so little body heat that they were only as warm as their surroundings, like other reptiles and frogs? Or, could they produce enough heat to warm their bodies well above ambient temperatures, like birds and mammals, and thus maintain a relatively constant and more active lifestyle?
Definition: Metabolism is the set of chemical processes that occurs within the cells of living organisms for the maintenance of life
Endotherms like us and birds are so-called warm-blooded animals; we keep our body temperatures constant. If we lose excess heat, metabolism increases to make up the loss. Ectothermic animals (often imprecisely labeled as “cold-blooded”) need external sources to regulate their body temperature: On a hot road, a snake can strike fast, but throw it on ice, and it’ll just chill out.
To help solve this decades-old mystery, researchers developed a new method for analyzing the metabolism of extinct animals. They found "dinosaurs do not fit comfortably into either the cold-blooded or warm-blooded camp — they genuinely explored a middle way," said lead study author John Grady, a theoretical ecologist at the University of New Mexico.
Expectation of life: if this theories of extinction wouldn't have happened the dinosaurs would have evolved and be around us at this moment.
Nutrition:
As the number of carnivores in a community increases, they eat more and more of the herbivores, decreasing the herbivore population. It then becomes harder and harder for the carnivores to find herbivores to eat, and the population of carnivores decreases. In this way, the carnivores and herbivores stay in a relatively stable equilibrium, each limiting the others population. A similar equilibrium exists between plants and plant-eaters.
Main habitat. Conifers and ferns dominated the landscape and the first flowering plants were appearing. About half of Australia was covered by shallow inland seas. Evidence for this comes from fossils found in the rocks of this region. They contain marine molluscs and large pre-historic reptiles such as ichthyosaurs and plesiosaurs. Today this area is called the Great Artesian Basin.
Climate : changes and problems that can cause different dangerous situations
When dinosaurs ruled the Earth, the climate was most likely hot and humid. There is no evidence of Ice Ages or glaciations found in rocks of this age. There is a lot of evidence of tropical species existing at this time
Interaction and adaptation: so when we talk about the problems ,caused by the different theories, that could have destroyed this interactions they would know why they were so necessary.
. Atmospheric carbon dioxide was close to present-day levels. The ice caps at the North and South Pole had melted, resulting in raised sea levels. Australia was breaking away from Antarctica and gradually moving away from the South Pole, closer to the Equator.
This is the most accepted theory.
ASTEROID IMPACT
Asteroids are planetary bodies or objects that revolve around the Sun. Most are in the asteroid belt between Mars and Jupiter. Meteorites are lumps of stony or metallic material that were parts of asteroids. They survive entering the Earth’s atmosphere and impact on the Earth’s surface. The Alvarez hypothesis suggests the mass extinction of the dinosaurs was caused by an impact of a large meteorite 6 to 12 miles (10 - 19 km) across on the earth about 65 million years ago.
What evidence do scientists have for this?
In Italy, between Rome and Florence, scientists found fossils in limestone rocks that date back to when the dinosaurs died out. Near these rocks is a layer of clay containing high levels of iridium. Iridium is a very rare metal and not common in rock samples found on Earth. However, it is common in meteorites. In 50 different sites around the world, scientists found iridium in this layer of clay.
Where could this have happened?
Some geologists have suggested the Chicxulub crater, a site along the north-east coast of Mexico’s Yucatán Peninsula as the impact zone. Some scientists believe that at the same time, another meteorite hit the earth in the Indian Ocean.
What would be the effects of this?
Some scientists have suggested that such an impact may have put the Earth into a ‘nuclear winter’. The ash and dust could have been so thick as to block out the sun’s rays, causing the temperature on the planet to plummet. Without light, plants could not make their own food. Herbivorous (plant-eating) dinosaurs and then carnivorous (meat-eating) ones would have been affected. The impact may have also produced giant tsunamis (tidal waves) and forest fires across the globe
the meteor strike produced huge quantities of sulfate particles, such as are often blown high into the atmosphere during a volcanic eruption, and these particles shielded the Earth’s surface from sunlight. The decrease in solar energy ultimately caused a long cold spell, called an ‘impact winter.
The hypothesised ice age would have killed off many of the planet’s living species into extinction, including dinosaurs.
As dinosaurs were thought to be cold blooded, it would have been hard for them to cope with such cold conditions. Therefore ,if large parts of the planet were covered in ice, then there would have been little or no plants for herbivorous dinos to eat.
This theory is mostly based in the consequences of to previous theories
Between the early to mid-Cretaceous, the world climate became warmer by as much as 10°C. Some scientists have linked this stage of global warming to a huge asteroid impact. Others have linked it to the large number of volcanic eruptions in the area that today is India and Pakistan.
The Late Cretaceous Period was a time of great change. The continents were breaking up. Volcanoes were throwing ash and gas into the atmosphere, rapidly altering the climate.
Sea levels fell in the final stage of the Cretaceous. Changes in climate would have occurred due to the disruption of wind and ocean currents. These marine changes, combined with volcanism and an extraterrestrial impact, may have caused the mass extinctions.
Sudden Change
Perhaps a dramatic change interrupted the weather patterns or destroyed the food of the dinosaurs. Factors that could cause a sudden change would be an asteroid, meteorite or comet.
Species become extinct if there are no individuals in the population with the necessary characteristics to survive in the changed environment. This is what happened to the dinosaurs and many other species that became extinct at this time.
Gradual Change
Other changes may have occurred over a longer time period. Perhaps the warm, wet climate gradually changed to a drier, cooler one. In many areas, the fossil record shows tropical vegetation was replaced by woodland plants. Once again, it is possible that the dinosaurs were not adapted to the new environment and therefore became extinct.
This could have been a reason why a lot of species died and those who were feeding on them
Not all the living things disappear the dinosaurs died out at the end of the Cretaceous period but mammals and the ancestors of modern birds survived. Mammals, frogs, turtles and crocodiles lived and survive to the present day. Perhaps they had the characteristics that suited them to the new environment. Mammals are able to maintain their body temperature. They are less dependent on environmental temperatures, unlike ‘cold-blooded’ species such as reptiles. After the extinction of the dinosaurs, mammals were free to colonise cooler areas of the world and dominate the planet. This led to the Rise of Mammals.
