1 00:00:00,123 --> 00:00:02,376 In the video on the Cambrian explosion 2 00:00:02,376 --> 00:00:06,103 I talked about how suprisingly, or somewhat surprisingly 3 00:00:06,103 --> 00:00:09,373 animals were the first to colonize 4 00:00:09,373 --> 00:00:10,657 or to move on land. 5 00:00:10,657 --> 00:00:13,388 They did that before plants did. 6 00:00:13,388 --> 00:00:16,123 And someone brought up a question which I thought was a very good question. 7 00:00:16,123 --> 00:00:18,457 If they were the first, what did they eat? 8 00:00:18,457 --> 00:00:20,798 I thought it was a good question 9 00:00:20,798 --> 00:00:23,842 and it justified a video on clarifying 10 00:00:23,842 --> 00:00:26,794 exactly who was first on the land. 11 00:00:26,794 --> 00:00:30,303 So right here, this is a picture of algae on the coast 12 00:00:30,303 --> 00:00:33,103 this is kind of algal scum right here. 13 00:00:33,103 --> 00:00:36,123 So this is algae. 14 00:00:36,123 --> 00:00:37,045 And just to be clear 15 00:00:37,045 --> 00:00:39,969 sometimes cyanobacteria, which we talked about as the first 16 00:00:39,969 --> 00:00:42,537 photosynthetic organism 17 00:00:42,537 --> 00:00:45,208 Sometimes that's called blue-green algae 18 00:00:45,208 --> 00:00:46,969 but that's really bacteria. 19 00:00:46,969 --> 00:00:49,324 Algae is considered eukaryotic 20 00:00:49,324 --> 00:00:51,969 it just doesn't have the structures of modern plants. 21 00:00:51,969 --> 00:00:53,566 So this is algae right here. 22 00:00:53,566 --> 00:00:56,207 And our best estimate 23 00:00:56,207 --> 00:00:59,148 is that algae actually colonized coastal rocks 24 00:00:59,409 --> 00:01:01,790 about 1.2 billion years ago. 25 00:01:02,120 --> 00:01:05,220 1,2 Ga 26 00:01:06,364 --> 00:01:09,308 G for "Giga". 27 00:01:09,308 --> 00:01:12,254 So if you wanted the first thing that even resembled 28 00:01:12,254 --> 00:01:14,798 or was close to plants or animals 29 00:01:14,798 --> 00:01:17,332 and if you consider algae close to a plant, 30 00:01:17,332 --> 00:01:20,468 then this would be the winner of who got on land first. 31 00:01:23,198 --> 00:01:25,740 Now in the last video where I talk about animals 32 00:01:25,740 --> 00:01:28,066 colonizing the land first 33 00:01:28,066 --> 00:01:30,748 they weren't animals that only existed on land. 34 00:01:30,748 --> 00:01:34,047 They were animals that probably spent 35 00:01:34,047 --> 00:01:36,867 most of their time in the ocean collecting food or whatever 36 00:01:36,867 --> 00:01:39,507 and they would show up on land to lay eggs. 37 00:01:39,507 --> 00:01:40,636 And if you think about it, back then 38 00:01:40,636 --> 00:01:42,635 the land would have been a really good place to lay eggs 39 00:01:42,635 --> 00:01:44,637 because there wouldn't have been much else on the land. 40 00:01:44,637 --> 00:01:47,131 So you would have been protected from predators. 41 00:01:47,131 --> 00:01:50,777 So it might have been slug-like creatures like this 42 00:01:50,777 --> 00:01:54,571 Some people talk about spider-like creatures 43 00:01:54,571 --> 00:01:56,396 but it still would have been at the coast. 44 00:01:56,396 --> 00:01:59,887 And these would have been creatures that spent 45 00:01:59,887 --> 00:02:01,463 a lot of time in the ocean 46 00:02:01,463 --> 00:02:02,969 and some time on land. 47 00:02:02,969 --> 00:02:04,639 So this is what I was referring to 48 00:02:04,639 --> 00:02:10,195 as kind of animals colonizing the land before plants. 49 00:02:10,195 --> 00:02:19,502 And this would have happened about 530 million years ago. 50 00:02:19,502 --> 00:02:24,479 Now the first living organisms to fully live on the land 51 00:02:24,479 --> 00:02:26,637 their whole life is on the land 52 00:02:26,637 --> 00:02:28,547 those would be plants. 53 00:02:28,547 --> 00:02:30,934 So it depends if you think about things that 54 00:02:30,954 --> 00:02:33,569 live part of their lives on land, you'd get the animals 55 00:02:33,569 --> 00:02:36,005 things that live their whole life on land, then you'd get the plants. 56 00:02:36,005 --> 00:02:39,638 So this right here, this is what we think 57 00:02:39,638 --> 00:02:42,969 the first primitive plants would have looked like. 58 00:02:42,969 --> 00:02:46,119 And the evidence, we actually don't have fossils of the plants themselves 59 00:02:46,119 --> 00:02:48,922 we have fossils of their spores. 60 00:02:48,922 --> 00:02:53,704 But we think that these, the earliest fossils of their spores, that shows that these existed 61 00:02:53,704 --> 00:03:01,411 were about 475 million years ago. 62 00:03:07,321 --> 00:03:10,316 So 1.2 billion years ago you have the algae 63 00:03:10,316 --> 00:03:13,126 530 million years ago we have evidence 64 00:03:13,126 --> 00:03:16,389 of things kind of oozing out of the ocean and maybe laying their eggs 65 00:03:16,389 --> 00:03:20,236 475 million years ago we have evidence 66 00:03:20,236 --> 00:03:23,473 of what we would call "really" plants 67 00:03:23,473 --> 00:03:27,001 but the evidence is really the fossils of their spores. 68 00:03:27,001 --> 00:03:30,722 And then the first evidence of what you could call 69 00:03:30,722 --> 00:03:33,969 real 'animals' that have spent their entire life on the land 70 00:03:33,969 --> 00:03:40,969 the oldest fossil we have was discovered in Scotland fairly recently in 2004 71 00:03:40,969 --> 00:03:43,056 and it was... 72 00:03:43,056 --> 00:03:47,648 this is the fossil over here, it was discovered by a bus driver, Mike Newman 73 00:03:47,648 --> 00:03:54,438 it was a bus driver in Scotland, and they actually named the thing after him. 74 00:03:54,438 --> 00:03:59,834 It is called Pneumodesmus newmani, they got the Newmani from Mike Newman 75 00:03:59,834 --> 00:04:02,655 and this fossil is 428 million years old 76 00:04:02,655 --> 00:04:10,636 428 million years old 77 00:04:10,636 --> 00:04:14,846 and right now it is the oldest fossil we have of a true land animals 78 00:04:14,846 --> 00:04:16,323 if we think about true land animals 79 00:04:16,323 --> 00:04:20,902 if you think about true plant versus true land animals that spend their entire life on the land 80 00:04:20,902 --> 00:04:25,837 if you think about about things that spend part of their time on the land, 81 00:04:25,837 --> 00:04:27,870 the the animals would probably the one out 82 00:04:27,870 --> 00:04:30,904 if you view algae as plants, then plant were the one out 83 00:04:30,904 --> 00:04:33,091 so it depends where you want to draw the line. 84 00:04:33,091 --> 00:04:35,929 this first fossil, this is a real myriapode 85 00:04:35,929 --> 00:04:40,503 which just means "a lot of legs". Let me write it over here. 86 00:04:40,503 --> 00:04:43,983 Myriapods. You probably know the word "myriad" 87 00:04:43,983 --> 00:04:46,797 that means a bunch of thing or a huge amount, 88 00:04:46,797 --> 00:04:50,586 so myriapods - a huge amount of legs. 89 00:04:50,586 --> 00:04:52,908 And you might be familiar with the milipedes and centipedes, 90 00:04:52,908 --> 00:04:55,560 those are myriopods. So those first primitive myriapods 91 00:04:55,560 --> 00:04:59,459 428 million years ago, and they would have lived 92 00:04:59,459 --> 00:05:02,208 off of plants and maybe other myriapods and other slugs 93 00:05:02,208 --> 00:05:04,324 or whatever other animals they would have found, 94 00:05:04,324 --> 00:05:07,191 might have looked something like that. 95 00:05:07,191 --> 00:05:09,106 So hopefully, it gives a little bit of clarification. 96 00:05:09,106 --> 00:05:13,380 It wasn't like, you know, you had dogs sitting on the land 97 00:05:13,380 --> 00:05:14,644 and they had nothing to eat. 98 00:05:14,644 --> 00:05:19,790 It is kind of argeement what you define a plant or an animal 99 00:05:19,790 --> 00:05:21,971 and who gets the brandining rights 100 00:05:21,971 --> 00:05:23,901 for being the first on the land and it depends on 101 00:05:23,901 --> 00:05:25,892 what you consider a plant or an animal 102 00:05:25,892 --> 00:05:31,848 and whether spending part of your life on the land, 103 00:05:31,848 --> 00:05:34,008 will actually qualify.