Dino Speech
note: don't say the words in bold
INTRO - Ever since the first fossils of the dinosaurs were found, humankind has wondered, “Why did they die?” A serious question that is, for it has importance to us. If extinct animals were wiped out by some catastrophe, couldn’t the same thing happen to us? Could we be found as fossils someday and would no one know why we died? That is why we need to find out what really happened to the dinosaurs. There are over 100 theories arguing about their death, but the two hypotheses presented in my project are two of the more realistic and popular ones. I will explore both with you, and then you can hear my opinion.
BACKGROUND - Here is some background information on the death of the dinosaurs. They died about 65 million years ago (mya) during the Cretaceous Period. Around 60% of all living things on Earth died, including all of the dinosaurs and ¾ of other species. We think that nothing larger than a dog survived on land, which is why we still have several of the rodents from back then today. A main question about their extinction is if they were killed off by a catastrophe or if they weren’t evolving and faded away by perhaps a gradual environmental change.
WORLD - This is just a picture of what their world would have looked like. As you can see, it was quite different from our own.
THEORY 1 ASTRIOD - Many scientists believe that the extinction was caused by and outside source: a massive asteroid that slammed into Earth with a force estimated at 5 billion times the strength of the atom bomb dropped on Hiroshima. There is a lot of information to back up this theory.
ALVAREZs - In 1980, Luis Alvarez, a physicist, and his son Walter, a geologist, came up with a new theory. It was the K-T extinction theory (K meaning Cretaceous – T meaning Tertiary boundaries in the Earth’s layers). They were working on a geology expedition in Italy when they accidentally discovered a band of sedimentary rock that contained unusually high levels of the rare element iridium. The rock dated back 65 mya, the time the dinosaurs died out. The Alvarezes hypothesized that the iridium, which was in very even, widespread distribution, not just in Italy, was the result of a giant asteroid hitting Earth, sending smoke, dust, and iridium into the atmosphere. This smokescreen would block the sun, lowering the Earth’s temperatures, killing plants but not seeds or roots, and eventually killing the dinosaurs. The other smaller animals could survive the cold because of their fur, and could eat seeds, and that’s why they’re still around today. The pollution would eventually settle to the ground, forming the layer of iridium. This theory is also called a Nuclear Winter.
CRATER - Now all you need is a crater big enough to cause such damage. That would be the Chicxulub Crater in the Yucatan Peninsula. It is a very well preserved crater that dates back 65 mya. The asteroid would have been 100-150 miles wide, and would have weighed billions of tons. Tektites, which are rocks formed at the heat of impact, are found at the crater, and they date back 65 mya. When this asteroid hit Earth, it’s a wonder anything survived.
EFFECTS- The effects at impact would kill a large % of the dinosaurs. The first blast waves would destroy everything in it’s path. Tsunamis would occur everywhere. Then massive earthquakes would come. The power of the impact would cause global wildfires. These first effects would be fatal, but if you survived them, you’d have to face the Alvarez’s Nuclear Winter that I explained earlier.
FAULTS - There are a few faults with this theory. The death of the dinosaurs is not instantaneous, and we don’t know if Chicxulub is the actual impact site.
THEORY 2 RADIATION - The latest theory in debate comes from three scientists, Arnon Dar, Ari Laor, and Nir Shaviv. It says that cosmic radiation killed the dinosaurs. It is also known as the doom and creation theory.
SOURCE - There is no confirmed source of where the radiation comes from. Many believe that is was the collision of 2 stars, or a supernova. Others think it was a burst of solar neutrinos (which cause cancer) released by dying stars. It also could have been a super solar flare, or even a source we haven’t discovered yet. If they can figure out the source, this theory might become more intriguing.
PROS - The fossils found show signs of radiation. Also mummified dinos, fossilized dinosaur embryos, and pine cones without any signs of decay suggest radiation. An overlooked fact is that mass extinctions are followed by mass speciations. Again radiation comes to mind because radiation can split chromosomes, and through effects of recombination and DNA mutation, they would be shifted in a different order creating a new species. Also, nothing is more capable of causing genetic mutation that radiation.
DEATH - Their death would be cause by poisoning. The cosmic rays from the source would be so intense that they would destroy the ozone layer and make the planet highly radioactive. Radioactive particles can destroy an organism’s central nervous system and cause death within days. Since water is a good block against radiation, some sea creatures survived, and mud is also a good block, so small rodents could have survived.
FAULTS - There are a few faults however. First, is that there isn’t a confirmed source of the radiation, and second, there aren’t many dinosaurs found with radiation in their bones.
note: your opinion doesn't have to be the same as mine
MY OPINION - I agree with Luis and Walter’s theory. The dinosaur’s extinction was most likely cause by an asteroid or comet hitting Earth. I believe this because the information for this theory is almost flawless and it’s facts make the most sense of any other theory I’ve seen.
END - We may never know what really happened to the dinosaurs. It will probably take a time machine to learn the real truth. So this is not yet the end, but still only the beginning of our knowledge of the day the dinosaurs died.
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