Why did the Dinosaurs go Extinct?
Click Here to learn about the mass extinction event 66 million years ago and the evidence for what ended the age of the dinosaurs.
The Evidence for the Asteroid Impact Hypothesis:
Impact Crater
This 150-kilometer-wide crater lies just off the Yucatan peninsula. Scientists calculate that it was blasted into Earth by a 10-kilometer-wide asteroid or comet traveling 30 kilometers per second -- 150 times faster than a jet airliner.
Scientists have concluded that the impact that created this crater occurred 65 million years ago. The date corresponds perfectly to the date of the dinosaur extinction.
Rare Metal
The metal iridium, which is similar to platinum, is very rare on Earth's surface but is more common in asteroids and in molten rock deep within the planet.
Scientists have discovered levels of iridium 30 times greater than average in the Cretaceous/Tertiary (KT) boundary, the layer of sedimentary rock laid down at the time of the dinosaur extinction.
Melted Rock
These pieces of once-molten rock, called impact ejecta, are evidence of an explosion powerful enough to instantly melt bedrock and propel it more than a hundred miles from its origin.
Ranging in size from large chunks to tiny beads, impact ejecta are common at or near the Cretaceous/Tertiary (KT) boundary, the geological layer that defines the dinosaur extinction.
Fractured Crystals
These crystals, often called "shocked quartz," show a distinctive pattern of fracturing caused by high-energy impacts or explosions.
Some scientists maintain that the fracture pattern in these quartz crystals could only have been caused by a massive asteroid or comet impact. The pattern is prevalent in quartz found at or near the Cretaceous/Tertiary (KT) boundary, the geological layer deposited at the time of the extinction.
Fossil Record
A gradual decline in the number of dinosaur species would likely mirror an equally gradual cause of their ultimate extinction. Conversely, a sudden "now you see them, now you don't" end to the dinosaurs implies a catastrophic cause. Depending on location and interpretation, the fossil record seems to say different things.
Some paleontologists see evidence in the fossil record that dinosaurs were doing quite well prior to the end of the Cretaceous -- that they were in no way declining in abundance when the impact occurred.
(source)
This 150-kilometer-wide crater lies just off the Yucatan peninsula. Scientists calculate that it was blasted into Earth by a 10-kilometer-wide asteroid or comet traveling 30 kilometers per second -- 150 times faster than a jet airliner.
Scientists have concluded that the impact that created this crater occurred 65 million years ago. The date corresponds perfectly to the date of the dinosaur extinction.
Rare Metal
The metal iridium, which is similar to platinum, is very rare on Earth's surface but is more common in asteroids and in molten rock deep within the planet.
Scientists have discovered levels of iridium 30 times greater than average in the Cretaceous/Tertiary (KT) boundary, the layer of sedimentary rock laid down at the time of the dinosaur extinction.
Melted Rock
These pieces of once-molten rock, called impact ejecta, are evidence of an explosion powerful enough to instantly melt bedrock and propel it more than a hundred miles from its origin.
Ranging in size from large chunks to tiny beads, impact ejecta are common at or near the Cretaceous/Tertiary (KT) boundary, the geological layer that defines the dinosaur extinction.
Fractured Crystals
These crystals, often called "shocked quartz," show a distinctive pattern of fracturing caused by high-energy impacts or explosions.
Some scientists maintain that the fracture pattern in these quartz crystals could only have been caused by a massive asteroid or comet impact. The pattern is prevalent in quartz found at or near the Cretaceous/Tertiary (KT) boundary, the geological layer deposited at the time of the extinction.
Fossil Record
A gradual decline in the number of dinosaur species would likely mirror an equally gradual cause of their ultimate extinction. Conversely, a sudden "now you see them, now you don't" end to the dinosaurs implies a catastrophic cause. Depending on location and interpretation, the fossil record seems to say different things.
Some paleontologists see evidence in the fossil record that dinosaurs were doing quite well prior to the end of the Cretaceous -- that they were in no way declining in abundance when the impact occurred.
(source)
What was the first dinosaur fossil ever discovered?
Way back in 1676, Robert Plot, the curator of an English museum, described and drew a thigh bone that he believed belonged to a giant man. Although that fossil disappeared without a trace, the surviving illustration suggests that it may well have been part of a "Megalosaurus." Later, in 1822, large teeth discovered in England by Mary Ann Mantell and her husband, Gideon, were thought to be the remains of a huge and extinct iguana. It wasn't until 1841 that British scientist Richard Owen came to realize that such fossils were distinct from the teeth or bones of any living creature. The ancient animals were so different, in fact, that they deserved their own name. So Owen dubbed the group "Dinosauria," which means "terrible lizards."
(source) Explore 10 Facts about Megalosaurus |
Explore Everything about Dinosaurs at the Natural History Museum
Click Here to get your fill of dinosaur facts and fun, and find out all about the reptiles that once dominated our planet.
Click Here to Search Every Dinosaur Ever Discovered A-Z
At present over 700 different species of dinosaurs have been identified and named. However palaeontologists believe that there are many more new and different dinosaur species still to be discovered.
Click Here for a List of Dinosaurs Names with Pictures
This page contains a list of dinosaur names with pictures and information. Here you can learn about the many different kinds of dinosaur that are known to have existed during the Mesozoic Era. Designed to be an ‘online dinosaur museum’, it’s a great place to start if you want to find out more about a particular dinosaur.
Explore Dinosaur Myths and Movie Misconceptions
Click Here to explore misconceptions about dinosaurs are frequently fuelled by their inaccurate (though entertaining) representations in films. Not everything you've been led to believe about dinosaurs is true.
Could Scientists Bring Dinosaurs Back to Life?
The classic concept for dinosaur resurrection starts with a DNA-filled mosquito that has been preserved in amber for millions of years. But is this a scientific possibility or strictly resigned to fiction? Click Here to find out more!
Top 10 Questions about Dinosaurs on the Internet Answered:
1. What does dinosaur mean and how are dinosaurs named? Sir Richard Owen coined the word dinosaur, meaning "fearfully great lizard," in 1842. In Greek, deinos means "fearfully great" and sauros means "lizard." Newly discovered dinosaurs are named by the discoverer or by the paleontologist who determines that it represents a new genus (or species). There are many different ways to choose a dinosaur name. Sometimes the dinosaur is given a name that describes something unusual about it's body, head, or feet. Some are named after the location where they are found, their behavior, size, or in honor of a person. The name has to be approved by the International Commission on Zoological Nomenclature.
2. What color were the dinosaurs? No one knows. Animal's skin colors are produced by organic pigments which are not preserved in the process of fossilization. The best guess about dinosaur coloration is to try to figure out how a particular dinosaur lived and extrapolate, using modern-day reptiles (and other animals) as a guide. For example, an animal that is heavily hunted may need camouflage to help it hide from predators. Or, it may be brightly colored, mimicking a poisonous species. Basically, it is impossible to know what the dinosaurs' coloration was (using today's science).
3. How and when did the dinosaurs go extinct? The dinosaurs (except the birds) went extinct 65 million years ago, probably due to the after-effects of an asteroid impact off the Yucatan Peninsula. There are a lot of theories about why this K-T (Cretaceous-Tertiary) extinction occurred, but a widely accepted theory (proposed in 1980 by physicist Luis Alvarez and his son Walter Alvarez, a geologist), is that an asteroid 4-9 miles (6-15 km) in diameter hit the Earth about 65 million years ago. The impact would have penetrated the Earth's crust, scattering dust and debris into the atmosphere, and caused huge fires, volcanic activity , tsunamis, and severe storms with acidic rain. The impact could have caused chemical changes in the Earth's atmosphere, increasing concentrations of sulfuric acid, nitric acid, and fluoride compounds. The heat from the impact's blast wave would have incinerated all the life forms in its path. The dust and debris thrust into the atmosphere would have blocked most of the sunlight for months, and lowered the temperature globally. Those organisms that could not adapt to the temperature and light changes would die out. Since plants' energy is derived from the sun, they would likely be the first to be affected by changes in climate. Many families of phytoplankton and plants would die out, and the Earth's oxygen levels may well have dramatically decreased, both on land and in the oceans, suffocating those organisms which were unable to cope with the lower oxygen levels. Major changes in the food web would result from all of these these environmental upheavals. The herbivores (plant eaters) who ate those plants would starve soon after the plants died. Then, at the top of the food chain, the carnivores (meat eaters), having lost their prey, would have to eat each other, and eventually die out. Their large carcasses must have provided smaller animals with food for quite a while. Although most dinosaurs went extinct about 65 million years ago, one branch of the dinosaurs (the dromaeosaurids) evolved into the birds.
4. How many dinosaurs were there? There are over 500 dinosaur genera (the plural of genus) that have been found, named and scientifically accepted. There are about an additional 100 genera that are dubious. These dinosaurs, usually represented by very incomplete fossils, may actually be examples of other, already named genera. There are also almost 100 newly-discovered genera whose names have not been through the formal naming process. This process is done by the ICZN (the International Committee on Zoological Nomenclature) in which it is decided that a specimen represents a new genus. Then the really tricky part has to be considered. People have only probably found only a small fraction of all the dinosaurs that ever existed. There are a lot more dinosaurs that people are finding all the time. Also, there are probably many, many types of dinosaurs that didn't fossilize at all and are lost forever. The actual number of dinosaurs genera that lived is unknown. The population numbers of the dinosaurs (that is, how many individuals of each genus existed) are also unknown.
5. What was the biggest dinosaur? The biggest dinosaurs were sauropods which ranged in size from the early Anchisaurids that were 7-10 feet (2-3 m) long to the later giants (like diplodocids, titanosaurids, and brachiosaurids) that were over 100 feet (30 m) long; they were gigantic, slow-moving, tiny-headed, cow-like plant-eaters from the late Jurassic period and the early Cretaceous period. They had very long necks which were useful for reaching wide (and tall) swatches of vegetation. The lengthy neck was counterbalanced by a massive tail.
6. Which dinosaur was the smallest? A new, crow-sized theropod, Microraptor was recently found in China. It is about 16 inches (40 cm long) and may have been an adult.
7. Were more dinosaurs plant-eaters or meat-eaters? There were many more plant-eaters! Some dinosaurs were carnivores (meat-eaters) but most were herbivores (plant-eaters). In any food chain, there have to be more organisms at the lower levels of the chain because the transfer of food energy is inefficient and much of the energy is wasted. During the Mesozoic Era (as in other times), plant diversity was greater than animal diversity.
8. How many teeth did T. rex have (and how big were they)? T. rex's had over 60 thick, conical, bone-crunching teeth that were up to 9 inches (23 cm) long. Its jaws were up to 4 feet (1.2 m) long.
9. What is the oldest dinosaur ever found? Recent prosauropods from Madagascar are the oldest, about 230 million years old. Until recently, the oldest dinosaur found was Eoraptor (from Argentina) - it is about 228 million years old.
10. Did birds evolve from the dinosaurs? Yes, they most likely did. Many recent finds of feathered dinosaurs in China, like Caudipteryx and Sinosauropteryx have bolstered this theory, which was first advanced by the biologist Thomas Huxley in the late 1800's.
(source)
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2. What color were the dinosaurs? No one knows. Animal's skin colors are produced by organic pigments which are not preserved in the process of fossilization. The best guess about dinosaur coloration is to try to figure out how a particular dinosaur lived and extrapolate, using modern-day reptiles (and other animals) as a guide. For example, an animal that is heavily hunted may need camouflage to help it hide from predators. Or, it may be brightly colored, mimicking a poisonous species. Basically, it is impossible to know what the dinosaurs' coloration was (using today's science).
3. How and when did the dinosaurs go extinct? The dinosaurs (except the birds) went extinct 65 million years ago, probably due to the after-effects of an asteroid impact off the Yucatan Peninsula. There are a lot of theories about why this K-T (Cretaceous-Tertiary) extinction occurred, but a widely accepted theory (proposed in 1980 by physicist Luis Alvarez and his son Walter Alvarez, a geologist), is that an asteroid 4-9 miles (6-15 km) in diameter hit the Earth about 65 million years ago. The impact would have penetrated the Earth's crust, scattering dust and debris into the atmosphere, and caused huge fires, volcanic activity , tsunamis, and severe storms with acidic rain. The impact could have caused chemical changes in the Earth's atmosphere, increasing concentrations of sulfuric acid, nitric acid, and fluoride compounds. The heat from the impact's blast wave would have incinerated all the life forms in its path. The dust and debris thrust into the atmosphere would have blocked most of the sunlight for months, and lowered the temperature globally. Those organisms that could not adapt to the temperature and light changes would die out. Since plants' energy is derived from the sun, they would likely be the first to be affected by changes in climate. Many families of phytoplankton and plants would die out, and the Earth's oxygen levels may well have dramatically decreased, both on land and in the oceans, suffocating those organisms which were unable to cope with the lower oxygen levels. Major changes in the food web would result from all of these these environmental upheavals. The herbivores (plant eaters) who ate those plants would starve soon after the plants died. Then, at the top of the food chain, the carnivores (meat eaters), having lost their prey, would have to eat each other, and eventually die out. Their large carcasses must have provided smaller animals with food for quite a while. Although most dinosaurs went extinct about 65 million years ago, one branch of the dinosaurs (the dromaeosaurids) evolved into the birds.
4. How many dinosaurs were there? There are over 500 dinosaur genera (the plural of genus) that have been found, named and scientifically accepted. There are about an additional 100 genera that are dubious. These dinosaurs, usually represented by very incomplete fossils, may actually be examples of other, already named genera. There are also almost 100 newly-discovered genera whose names have not been through the formal naming process. This process is done by the ICZN (the International Committee on Zoological Nomenclature) in which it is decided that a specimen represents a new genus. Then the really tricky part has to be considered. People have only probably found only a small fraction of all the dinosaurs that ever existed. There are a lot more dinosaurs that people are finding all the time. Also, there are probably many, many types of dinosaurs that didn't fossilize at all and are lost forever. The actual number of dinosaurs genera that lived is unknown. The population numbers of the dinosaurs (that is, how many individuals of each genus existed) are also unknown.
5. What was the biggest dinosaur? The biggest dinosaurs were sauropods which ranged in size from the early Anchisaurids that were 7-10 feet (2-3 m) long to the later giants (like diplodocids, titanosaurids, and brachiosaurids) that were over 100 feet (30 m) long; they were gigantic, slow-moving, tiny-headed, cow-like plant-eaters from the late Jurassic period and the early Cretaceous period. They had very long necks which were useful for reaching wide (and tall) swatches of vegetation. The lengthy neck was counterbalanced by a massive tail.
6. Which dinosaur was the smallest? A new, crow-sized theropod, Microraptor was recently found in China. It is about 16 inches (40 cm long) and may have been an adult.
7. Were more dinosaurs plant-eaters or meat-eaters? There were many more plant-eaters! Some dinosaurs were carnivores (meat-eaters) but most were herbivores (plant-eaters). In any food chain, there have to be more organisms at the lower levels of the chain because the transfer of food energy is inefficient and much of the energy is wasted. During the Mesozoic Era (as in other times), plant diversity was greater than animal diversity.
8. How many teeth did T. rex have (and how big were they)? T. rex's had over 60 thick, conical, bone-crunching teeth that were up to 9 inches (23 cm) long. Its jaws were up to 4 feet (1.2 m) long.
9. What is the oldest dinosaur ever found? Recent prosauropods from Madagascar are the oldest, about 230 million years old. Until recently, the oldest dinosaur found was Eoraptor (from Argentina) - it is about 228 million years old.
10. Did birds evolve from the dinosaurs? Yes, they most likely did. Many recent finds of feathered dinosaurs in China, like Caudipteryx and Sinosauropteryx have bolstered this theory, which was first advanced by the biologist Thomas Huxley in the late 1800's.
(source)
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- Dinosaurs are theorized to have gone extinct approximately 65 million years ago due to a large impact event that caused dramatic climate changes.