At which of the following times was there n o mass...

Key Concepts

Mass Extinction

A mass extinction is a relatively brief period in the geological record during which an exceptionally large number of species die out in a geologically short period of time. These events drastically alter the planet’s biodiversity and often lead to the reorganization of ecosystems, paving the way for new species to emerge in subsequent periods.

Big Five Mass Extinctions

The Big Five mass extinctions refer to the five most significant extinction events in Earth’s history, characterized by extensive loss of biodiversity. These events are used to mark major transitions in the geologic record and include periods like the end of the Permian and the end of the Cretaceous, highlighting how drastic changes have repeatedly reshaped life on Earth.

Geologic Time Scale

The geologic time scale is a system of chronological measurement that relates stratigraphy (the layers of rock) to time. It is divided into various eons, eras, periods, and epochs, each characterized by distinct environmental conditions, evolutionary milestones, and, in some cases, catastrophic events such as mass extinctions.

Transcript

00:01 Okay, so for this question or problem, we are going to be talking about one common theme for many different time periods, and that is the end of these periods or a significant portion of these periods.

00:16 Mostly we can think about the end.

00:17 So a lot of the ends of different time periods are categorized or characterized, i should say, by having mass extinctions, which makes sense.

00:27 Because if we're looking at a distinct period of time and then most of the organisms that exist during that time go extinct, and then we have a new period of time where new organisms arise and we can characterize or categorize either one.

00:41 I guess i'm having a bit of trouble choosing which scripted term i want to use, but they both apply here.

00:49 If we're going to have new organisms that arise after an extinction, of course it makes sense to call that different time period if we have different fauna and flora that are inhabiting the world in that time, right? it makes them very distinct from one another.

01:00 So let's look at these different time periods and see which of the following time period.

01:04 Periods because not all of them are categorized by a mass extinction, but most of them are.

01:09 And only one of them from the following is not.

01:12 So let's go through them and discuss if they had a mass extinction or not.

01:17 So answer option a is the cretaceous period.

01:21 Now, this is one of the periods when we had the dinosaurs roaming around.

01:26 But it was ended by significant evidence showing that an asteroid hits the yucatan peninsula in mexico.

01:37 And sorry, i'm sure this isn't a c and this is an a for asteroid.

01:42 And this was hypothesized to eliminate all life forms greater than around 50 pounds, lots of insects, a lot of planktonian or deep sea dwelling invertebrates.

01:56 And then we can also look at the rocks between the cretaceous period and the following periods and see lots of asteroid content, right? different things that we were normally find in asteroids, they are present between these layers in the rock.

02:11 So it's very significant evidence of this occurring.

02:14 So this can't be the right answer because there was a mass extinction.

02:18 Some things up, right? now we're looking at the devonian period.

02:23 So the devonian period, we aren't looking at the same thing as the cretaceous period.

02:31 And what i mean by this is we're not looking at dinosaurs.

02:35 So not as fun potentially, but hey.

02:40 But we still have lots of stuff.

02:41 Stuff like amphibians that began to occupy the land, lots of different bugs.

02:46 So it's still fun stuff, right? so hey, when you think about dinosaurs, think about asteroids, so maybe this one is the right answer, right? it's not the right answer.

02:56 During this period, we also saw that about 75 % of species were extinct.

03:04 And the reasoning isn't as clear as maybe the cretaceous period, but i don't know i abbreviated extinct there, just put a t on the end.

03:14 But there's some uncertainty, but it's thoughts that maybe there were two large meteorites that contacted or collided with the earth, one in nevada, which is in america, and one in western australia.

03:30 So we're kind of covering those north and south poles or hemispheres a little bit.

03:35 So not correct.

03:37 Mass extinction definitely occurred.

03:39 By mass extinction, hopefully you're familiar with the term.

03:43 Otherwise, you might have been a little loss so far.

03:44 But mass extinction we're just deferring to lots of species dying out that are no longer found on the planet because there's no more members that can reproduce and by mass we're talking about at a large scale so there are lots of species that no longer exist so now let's talk about a category or interruption c which is the end of the permian period so hey per perpermian maybe that means permanent maybe we're still in the permian period right permeant permanent wrong again this is we also had a massive extinction.

04:20 And if you want to guess what happened, an asteroid or a meteorite, some large chunk of rock from outer space collided with the earth.

04:28 And what happened, what happened from this was lots of lava was released into the oceans.

04:34 What this happened was, or what happened from this is a decreased amount of o2 concentration, oxygen gas, in the water, which is significant because this can play into a lot of the metabolism of these seedwelling creatures.

04:48 And what happened as a result is this water, deep in the water, started to rise up to the surface.

04:55 And here's my little sun to try and show you that this is the surface...

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