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The Object That Smashed Into Our Planet 65 Million Years Ago

By Edited Feb 23, 2016 4 6
Artwork - Impact Event
Credit: Public domain image courtesy of NASA.

An artist's depiction of a large impact event, in this case striking the ocean. Chances are that meteors and comets will strike the Earth's oceans, since 71% of the surface of the Earth is ocean.[3]

It's not true that all dinosaurs went extinct

Between 66 and 65 million years ago, the reign of all dinosaurs, with the exception of birds, came to an end in a short amount of time. The top reason for this is thought to be a large object whizzing through space, most likely a comet, which struck the Earth with devastating worldwide consequences.[1]

It’s odd that this extinction event is most famous for killing off the dinosaurs, when in fact one group survived, the avian dinosaurs, which are the ancestors of modern birds. There were other animal groups that really were entirely wiped out. Some of those that disappeared forever include ammonites, mosasaurs, and plesiosaurs in the oceans, and pterosaurs in the air.[1]

Map of Cretaceous Earth showing the impact site:

Map Showing Impact Site
Credit: Image created by me, background is from Wikipedia, by Ron Blakey, NAU Geology, CC BY-SA 3.0.

The impact occurred at a site that is now situated partially upon Mexico's Yucatan Peninsula, and partially in the Gulf of Mexico.[1]

Massive object, massive impact

The object was about six miles (ten km) in diameter, and struck Earth at tens of thousands of miles per hour at what is now the Yucatan Peninsula in Mexico, as shown above.[1] The resulting explosion was so violent, and released so much energy, that if it was measured according to the Richter scale for earthquakes, it would measure as a magnitude 12.5 earthquake.[2]

The strongest earthquake ever recorded was magnitude 9.6 in Chile, South America in 1960. According to how the Richter scale works, the calculations mean that the comet impact released about 22,000 times as much energy![2]

Tyrannosaurs went extinct

Tyrannosaurus Rex
Credit: Photo is from Wikipedia, by Connie Ma, CC BY-SA 2.0.

This is the famous fossil skeleton Sue, now located at the Field Museum of Natural History in Chicago, Illinois. Tyrannosaurus rex was one of many dinosaur species that became extinct at the end of the Mesozoic Era. This particular skelton is 40 feet (12 meters) long, and the animal probably weighed somewhere close to 15,000 lbs (6,800 kg).[6]

Devastating consequences for life on Earth

The planet’s climate was instantly altered and did not recover for hundreds of thousands of years. In total, the majority of species on the Earth went extinct. Some groups were entirely wiped out, the most major of which were mentioned above.[1]

Over billions of years, Earth has been struck by objects flying through space many times. The Earth's oceans, weather, erosion, volcanic activity, and plate tectonic processes hide a lot of the evidence, which is why we see few craters on the Earth’s land masses compared with the surface of the moon.[4]

Out of all impacts known through geological evidence, only two were larger than the one that ended the era of the dinosaurs. They occurred 1.8 billion and 2.0 billion years ago. In other words, this was the largest such impact in the last 1.8 billion years.[5]

The great extinction event that divides the Mesozoic Era from the modern Cenozoic Era allowed mammals to flourish, and for primates to evolve, and then for human beings to become the dominant species upon planet Earth.[1]

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Comments

Dec 26, 2014 11:19pm
RoseWrites
Wow, 12.5 on the Richter scale. I suppose that might have caused the Atlantic ocean to widen too? I'm kind of glad those big dinosaurs aren't around today, though. I don't think they'd like my cooking.
Dec 26, 2014 11:37pm
TanoCalvenoa
I've read plenty of articles on this topic - and it seems that there are many theories about what exactly happened. One article mentioned the possibility of acid rain falling across the Earth, killing most of what lives on land plus much of the sea life. There's a lot that remains unknown, although this impact event is certainly either the sole cause of, or a major contributor to, the major extinction event at the end of the Cretaceous Period.
Dec 27, 2014 8:11am
WinterWolf
I'm surprised that the T-rex weighed only 6,800 kg when male elephants weight 6500-7000 kg easily. And the fact that it shakes the ground (as shown in movies) shows how far the movie industry can go. And I didn't know avian dinosaurs were the ancestors of birds. Fascinating stuff!

Two questions: Is it true that chickens are the closest relatives to dinosaurs? And secondly, how excited are you for Jurassic World? :D
Dec 27, 2014 9:34am
TanoCalvenoa
Most male African elephants are not over 6,000 kg, but yeah they're close to the weight of Tyrannosaurus Rex. Amazing, isn't it? The ground-shaking is rather ridiculous - but I still love the Jurassic Park movies and will be very happy to see Jurassic World. I have to ignore the scientific inaccuracies in many movies. As far as the chickens question - I actually don't think they would be the closest relatives to dinosaurs. The most primitive birds are a group called "paleognathae" which includes large flightless birds such as rheas, emus, cassowaries, and ostriches plus a few other species.
Dec 28, 2014 7:19am
WinterWolf
I knew I could not believe 9GAG for science stuffs! They are wildly posting banners that says chickens are the closest relative to dinosaurs. But ostriches do seem more closely related to Trex. Thank you!
Dec 29, 2014 4:50pm
TanoCalvenoa
It's possible that chickens and turkeys are closer to dinosaurs than other "neognathae" species, but in line with what I said above - I doubt they would be closer to dinosaurs than paleognathae species, such as the ones that I listed.
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Bibliography

  1. "Cretaceous–Paleogene extinction event." Wikipedia. 26/12/2014 <Web >
  2. "Richter magnitude scale." Wikipedia. 26/12/2014 <Web >
  3. "Ocean." Wikipedia. 26/12/2014 <Web >
  4. "Impact crater." Wikipedia. 26/12/2014 <Web >
  5. "List of impact craters on Earth." Wikipedia. 26/12/2014 <Web >
  6. "Tyrannosaurus." Wikipedia. 26/12/2014 <Web >

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