Episode 164: The Pronghorn

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著作 Katherine Shaw の情報はPlayer FM及びコミュニティによって発見されました。著作権は出版社によって所持されます。そして、番組のオーディオは、その出版社のサーバから直接にストリーミングされます。Player FMで購読ボタンをタップし、更新できて、または他のポッドキャストアプリにフィードのURLを貼り付けます。
This week let's learn about the pronghorn! Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week let’s finally look at an animal I’ve wanted to cover for at least a couple of years now, the pronghorn! We’ve talked about the pronghorn before a few times, but it definitely deserves its own episode. The pronghorn is a cloven-hoofed mammal that lives in western North America, especially in open terrain where it can see any predators that might try to sneak up on it, because it has good eyesight. It stands up to about 3 ½ feet high at the shoulder, or 104 cm, and is tan or brown with black and white markings, including a black stripe down the top of the nose and a white rump and belly. Both males and females have horns, but the horns aren’t like bovid horns and they’re not like deer antlers. But they’re also not like giraffe ossicones either even though the pronghorn is most closely related to the giraffe. I’m going to quote a couple of paragraphs from one of our previous episodes where we talked about the pronghorn briefly, episode 116 about deer and antelopes and other hoofed animals. This is what I said about the pronghorn’s horns: Sure, the pronghorn looks like an antelope. It’s deer-like, runs extremely fast just like antelopes, and has short black horns. But look at those horns. It’s called a pronghorn because the horns of the males have a prong, or branch, so that the horn is shaped sort of like a Y, with the front branch of the Y shorter than the other, and the longer branch of the Y having a sort of hook at the top. Antelopes only ever have unbranched horns. But the pronghorn also isn’t a deer. Its horns are horns, not antlers, and it keeps its horns throughout its life instead of shedding them every year. Except that it kind of does shed part of the horn every year, the sheath. The inside of a horn is bone that grows from the skull, but a sheath of keratin grows over it. If you’ve ever seen an old-fashioned drinking cup made of horn, it was made of a horn sheath, usually from a bull. Most horned animals keep the sheath their whole life, which grows as the horn grows underneath, but the pronghorn male sheds the sheath of his horns every year and then grows new ones. As I mentioned a few minutes ago, although it looks like an antelope and is often referred to as an antelope, the pronghorn is most closely related to the giraffe. But it’s not very closely related to the giraffe and in fact it’s the only living member of its own family. There used to be more members of the pronghorn family, though, and some of them had really weird horns. Hayoceros was a pronghorn relative that went extinct around 300,000 years ago. It had horns that looked similar to the pronghorn’s, but it also had two more longer horns that grew behind them and pointed almost straight up with no branches. Ramoceros was much smaller than the pronghorn and had a pair of horns with several branching forks that looked a lot like antlers, although they were actual horns. Hexameryx lived around 5 million years ago and had six horns that probably looked like a pointy crown on its head, while Ilingoceros had spiral horns that were straight except at the ends, where they forked. And Stockoceros had two horns, but they divided into two at the base so from a distance it looked like it had four horns, each about the same length but sticking up like a pair of Vs. Stockoceros actually survived until only about 12,000 years ago. All these animals and others lived in North America, although obviously not all at the same time, and filled the same ecological niches that bovids fill in other parts of the world. The pronghorn eats plants, including grass, cacti, and shrubs. It can even eat plants that contain toxins that would kill or sicken other animals. It’s a ruminant that chews its cud, which is also something the giraffe does too if you remember the tallest animals episode.

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