naphtha stones are jawed vertebrates and represent that large evolutionary step with the of the development of jaws. Now, naphtha stones include fish, amphibians, reptiles and mammals. Though the early Matha stones were basically just jawed fish. Now common features amongst Matha stones include jaws, larger four brains and paired appendages. So if you think about us, for example, we don't just have one arm. We have to paired arms. Likewise, for example, you know Ah, lot of fish. You see this shark right here? They don't have just one fin on one side. They have to Finn's one on each side, those air paired appendages. Now, an interesting thing that we'll see in some of these organisms is called the lateral line system, which is a sensory system that detects movements and vibrations in the water. You can see it highlighted here in this shark in red, and you can also see a real photograph of a fish here where it has, uh, the lateral line system has been highlighted and, it appears, is all these white dots along the fishes face here. Now, as you could imagine, that's probably pretty useful for an organism that lives in water especially a predator. So living relatives of early Nath systems are the cartilaginous fish or Kendrick The INS. That's the jargon. E name cartilaginous Fish is just fine. These are organisms like sharks raise skates and what are called Kim eras, which are thes little kind of cute fish. You see right here. The defining feature for these organisms is that they have a cartilaginous skeleton, meaning a skeleton made of cartilage. And they have those paired Finns, which are again kind of hard to see in these pictures because there are profile shots. But, you know, you got the idea. This Finn right here has a pair or a partner, rather, that's on the other side of this fish that we can't see. So it should be noted that sharks actually use internal fertilization and includes species that air over Paris, vivid Paris and vivid Paris. Remember, that means, uh, they lay eggs or they keep their eggs internally and, uh, the young hatch from the eggs and leave the mother right at birth. Or they give birth to live young, right, vivid Paris. If you don't remember those terms, could go back and check out our earlier videos on animals where we covered them. Uh, also should be noticed that skates are over Paris, meaning they lay eggs and raise our vivid Paris meaning they give birth thio live organisms. And you've probably seen if you've been to a beach before, you might have seen something like this washed up on the shore. Those are actually uhh could Rick Thean eggs. And you can see this is this one is all dried out here in this image, but you can see in the image behind me Nice little shark egg with the shark developing inside there. All right with that, let's actually flip the page and talk about some other vertebrates.