字幕表 動画を再生する 英語字幕をプリント Good morning, John! My name is Dr. Lawrence Turtleman. Hank graciously handed the reins over to me for the last day of Pizzamas, which is a huge honor. I really loved watching Pizzamas over the last couple of weeks. The haul videos, the reunions, the almond orchards, the reviews, but me, Dr. Turtleman, I'm here to talk to you today about taxonomical oddities. See, all organisms on Earth are related to each other. We can trace that the way that scientists did for hundreds of years using the morphology of organisms, and we can also trace it using genetics. Like it's easy to see how a tiger and a lion are related to each other, and it's easy to see how a wolf and a fox would be related to each other. But you can also kind of tell that a lion and a wolf are more related to each other than they would be to, say, I don't know, like a sheep or a turtle man. And if we look into the fossil record, we can find the common ancestor of dogs and cats: it's the miacid, a sort of weird proto-carnivore bear-dog-cat thing. Now when we learned about organisms and their relationship to each other in school, we learned about it through the lens of taxonomy. Every category in taxonomy, going all the way from domain down to species, is called a taxon. And every taxon is built to contain multiple taxa. So in the order carnivora we have all kinds of families: We have the canids and the felids, we also have the ursids and the pinnipeds and the mustelids, and each of those families there are multiple genera, and in each of those genuses there are a bunch of different species. But in these weird taxonomical islands that I want to talk to you about today, you might find yourself with an order that only has one family in it that only has one genus in it that only has one species in it. That'd be like having only one carnivore currently existing on the planet! Is this a thing that could even happen?! As far as I can tell, this is only the case for two terrestrial vertebrates; we have: order tubelidentata containing just the one species, the aardvark— —aardvarks are extremely successful and roam all across Africa but nevertheless, all of their ancestors have gone extinct.—and we have order opisthocomiformes, which contains just the one species, the hoatzin. The hoatzin is a South American bird that's really weird, which you can tell, by looking at it. Look, look at that thing. But I do also want to talk about two runners-up here: a non-terrestrial vertebrate that has two species in its order, the coelacanthiformes. We once thought that the coelacanths had been extinct for sixty-six million years, until we found one in 1938, and then we later found another species. And finally, we also have order rhynchocephalia, which contains the two species of tuatara. Now we very nearly lived in a world with only one species of tuatara, but a second species was found, living on only one island off the coast of New Zealand. Tuatara, of course, do look a lot like modern lizards, but in fact, their last shared ancestor with the modern lizards and snakes was over a hundred and fifty million years ago. And you might be asking, "Hey, Dr. Turtleman, if they're so different from lizards and snakes, give me an example of one of those differences." Well, tuatara like to bite and chew on stuff, but instead of using teeth to do that, they just grow their bones up through their gums! Now you might think that I'm done here that I've told you all of the weirdest taxonomic islands. But the species that really takes the cake here is not an animal alone in its order! It's a plant, alone in its division. The ginkgo tree shares a kingdom, which is the second largest of all of the taxa, with all plants, and then after that… it is all on its own, the only species in its division. And remarkably, now that you humans have come to enjoy them so much, they've been planted all over the world and spread out from their original location in Asia. The ginkgo trees have been welcomed into the Anthropocene, a lovely species stretching back through time, alone on one of the most isolated of taxonomic islands. Hank: Ah. Thank you Dr. Turtleman, that was, that was a lovely presentation. Turtleman: You're very welcome, Hank! It was a, it was a true honor. Hank: You're great. And thank you to everyone for hanging out this Pizzamas. It's been a great time. I can't believe that it's already over. Now is also your last time if you want to get this year's Pizzamas stuff. We make it for two weeks and then never again, so if you go to dftba.com/pizzamas or click on the end screen here, you can get some of that stuff. Thanks for joining us this Pizzamas, it's been a really good time, and John I will see you—like normal—on Tuesday.