Which of the following was probably an important factor in bringing about the Cambrian explosion? (A) the movement of animals onto land (B) an increase in the concentration of atmospheric nitrogen (C) the emergence of predator-prey relationships (D) the origin of bilaterian animals

Video transcript

Hi everyone. Let's look at our next problem. It says the origin of bilaterally in animals is one of the significant events of the and we have choices of Cambrian extinction, mass extinction, Cambrian explosion population explosion. So let's just um briefly look at this by libertarian animals. Um If we don't recall, that's uh animals with bilateral symmetry. So let's look at our answer choices. Well, first of all we're thinking of a significant event of something, we're saying the origin of bilateral animals. Well when we look at our answers to of the choices involve an extinction, the Cambrian extinction or just in general mass extinction. Well we don't expect the origin of an animal to be part of an extinction. So we can pretty safely you might have um an extinction followed by um the origins of new species but it wouldn't be an event of that. So we're gonna go ahead and eliminate choice A. And B. Which involve extinction extinction of species. So we have our choices of Cambrian explosion or population explosion. Um Well population explosion is very generic term. Um Probably not our answer. So let's focus in on choice C Cambrian explosion. And that Cambrian explosion was indeed a sort of biological big bang. It's sometimes described as in which you had a very rapid development of many different species, including all major animal fila during that explosion um which of course resulted in the appearance of animals with bilateral symmetry. So the Cambrian explosion did have as one of the significant offense the origin of all the animal filler. So choice C. Is correct and we can go ahead and eliminate the generic term population explosion on Choice D, which refers to a population exploding an amount. Whereas we're talking about um the Cambrian explosion explosion of the number of species, including specifically the one we're talking about in this problem. See you in the next video.