What do fossils show about earth's history?
No one denies that the fossils were once creatures that died.
But what did they die from?
When did they die?
How fast did they die?
- 1 month ago
Fossils are mostly of creatures buried quickly in catastrophic events. Dating is almost impossible because radiometric dating is a misnomer, you cannot date anything but measuring the isotope ratio because the initial daughter isotope concentration is unknown. To presume there was no created daughter isotope is ridiculous, or that there were no environmental influences to the decay rate is ridiculous.
- Anonymous1 month ago
it gives alot of detail like whats the age
- D gLv 71 month ago
Fossils are a complete history of alot of the creatures that lived on the earth...
They show simple organisms lowest level of deposits... And they show more complex dangerous animals later on
Fossils require a specific environment to be properly preserved so that not all versions of creatures may have been fossilized
Fossils do show after the iridium line the type of creatures changed so that is why we use that as the extinction line for dinosaurs
- 1 month ago
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- Robin WLv 71 month ago
Depends on the fossils. The best ones are buried so fast that scavengers can't eat them and tear them apart. For example, the ones in the Burgess shale were buried by an underwater avalanche. Some people will tell you that rock layers are dated by the fossils found in them. They're wrong. Radiometric dating (NOT carbon dating) establishes the date of the rock layer. BTW, there are people who think that fossils are fake.
- RetiefLv 72 months ago
Some died of old age, some from predation, some from accidents or changing climate or natural disasters.
Some died 150 million years ago, some 50 million years ago.
- Anonymous2 months ago
Scientists have been wondering about the cause of extinction. A famous paleontologist even wrote a book about it, titled: Extinction: Bad Genes or Bad Luck.
Geologists notice that rocks can be dated by the plants and animals found within them, and that different layers of rocks have different types of animals. For example, the Jurassic have different animals than the Cretaceus and the Cretaceous have different types of animals than the Tertiary.
In fact, there seems to be mass extinctions that mark the end of at least some of these geological periods. The end of Jurassic saw a big drop in global temperature, for example, and lots of large dinosaurs and large pterosaurs vanished. The Cretaceous that followed gradually got warmer and by the end of the Cretaceous, dinosaurs and pterosaurs have re-evolved to be as large as those that had died at the end of the Jurassic. Unfortunately for them, a giant meteor struck the earth at the end of the Cretaceous 65 million years ago and wiped out not just large dinosaurs, but 100% of dinosaurs, 100% of pterosaurs, and 100% of enantinornithine birds, the dominant land birds of the Cretaceous.
These 2 extinction events show that mass extinctions can be caused by either abrupt and dreastic climate change or a catastrophe, such as a giant meteor striking the earth. Of course there are species going extinct within any geological periods, and these extinctions can be the result of environmental changes or because of competition. For example some of the mammals that survived the end of Cretaceous mass extinction, known as mulittuberculates, were then wiped out by mammals that evolved after the dinosaurs became extinct, the rodents. The rodents live a similar lifestyle as the mulit-tuberculates, and caused them to become extinct through competition.
Similarly, when South America collided with North America 5 million years ago, lots of mammals crossed over from North America to South America. This event is known as the Great Faunal Exchange. The result of this exchange is a mass extinction of marsupials in South America. Scientists attribute this mass extinction to competition from superior species of placental mammals. Lastly, a bunch of large mammals became extinct at the end of the last ice age, but scientists have not yet reached a consensus as to what caused it. Some people claim that humans overhunted the mammals into extinction. However, some scientists notice that there is evidence of a small comet hitting the earth in North America and raising global temperatures abruptly, while ending the last ice age. Since large mammals evolved during cold climates, a sudden rise in global temperature can cause them to suffer heat stroke, wiping them all out instantly.
In conclusion, extinction can be caused by catastrophes that make conditions too drastic for the bodies of animals to survive, or it can be caused by climate change that are more gradual and slow or it can be caused by competition between different species that have the same or similar needs. We need to collect data to figure out which cause is the most likely in each individual case.
- JeremyLv 62 months ago
"No one denies that the fossils were once creatures that died."
Well not entirely. There are some fundamentalists oddballs out there that claim fossils were created by God in place to give the appearance of an old universe, or placed by the devil to lead people astray. But, they're fringe loons, the same sort of people coming up with stories like God changes the speed of light to explain away the amount of time we know it would take for light to reach us from stars millions of light years away.
What did they die from, when and how?
That's a bit like going to a cemetery and asking when and how the people there died. There isn't a single answer. There are fossil ranging from a few thousand years old to over three billion years old.
The most common factor is would be that they likely died in a watery environment where it would be covered in mud and silt, or by some other method that the body became buried.
And, they are important because they show a history of life on the planet, a glimpse at the 99% of all species that came before us and went extinct. It helps us to understand how populations gradually evolved over many lifetimes.
- DzeLv 72 months ago
the evidence suggests they were buried in a cataclysm pretty much all at once .. animals dont fall in the mud and become fossils .. thats not how it works .. they decompose and are eaten by scavengers ... the widely referred to 'geologic column' used to date things to 'eras' is a complete farce also .. the layers were deposited by a cataclysm pretty much all at once, sometimes with petrified trees running through many layers still standing where they were ..
- 2 months ago
They give valuable information.