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Sometimes I go down these Wikipedia rabbit holes, and one of the most fascinating to me is extinct animals that were not dinosaurs. Specifically, how a lot of
by dimmke 3y ago
Sometimes I go down these Wikipedia rabbit holes, and one of the most fascinating to me is extinct animals that were not dinosaurs.
Specifically, how a lot of mammal apex predators are similar to extinct versions, just like, half the size. Like the American Lion and Direwolf.
Also how this was relatively recent, as others have pointed out they think that a lot of these species went extinct around 10,000 years ago. That fits even conservative estimates of when humans had migrated to the Americas.
This is an aside, but I found it really fascinating. Alligators and crocodiles are kind of obviously in the same area from an evolutionary standpoint (they're both in the Order Crocodilia), and they're both thought to be incredibly old - 30 million+ years.
But there are only 2 species of Alligator left in the entire world. There's the American alligator which is fairly plentiful all around the Southeast United States and a slightly smaller critically endangered variant in China. There's 18 species of Crocodile, and they're in all the Americas, Australia, New Zealand, all of Asia and a huge portion of Africa. And then I learned about Caimans which I didn't even know existed before. It really goes to show how some branches can be so much more wildly successful than others.
- Tagbert 3y agoThere have been recent evidence that seems to push that 10,000 year entry of humans into the Americas out by as much as another 10K further back.
- bumby 3y agoPossibly 23k years ago https://www.usgs.gov/programs/climate-research-and-development-program/news/discovery-ancient-human-footprints-white https://www.usgs.gov/programs/climate-research-and-developme...
- dimmke 3y agoYes… but there’s so many factors at play that I don’t know enough to speculate with any hope at accuracy about (but will because it’s interesting.) These were modern humans so they had sapience and tools and some form of organization, but how widespread were they vs. the so called “megafauna” - we are talking about A LOT of species with very different biologies here that went extinct. And the timescale isn’t long enough so we know the smaller versions of some of these creatures existed at the same time. Plus, was the hunting for food or defense? If primarily for food, how was the meat preserved? Its easier to imagine a group of humans with spears taking down a lone Direwolf than a pack of giant creatures. It’s hard to reckon with humans being the primary factor in the demise of these creatures when there are still things like grizzly bears out there. I’m sure they didn’t help and in very select situations were the primary cause (such as when a very small isolated species was stuck on an island) but I just don’t know if I buy them being the primary cause of a large scale extinction of a type of organism. The earliest estimates for large scale civilizations like the Mayans were around 7000 BC. It’s hard to imagine humans having such a widespread and profound effect without that level of organization. But I’m a complete amateur on this subject, so this speculation is basically just what I find plausible with some cursory research. Clearly this is a hotly debated topic amongst scientists.
- angiosperm 3y agoThere is no possibility that this sudden extinction pulse is because of humans. People lived in the Americas for many thousands of years with hardly any effect on fauna, then suddenly, boom! And the Clovis people disappeared right at the same time.
- scythe 3y agoIf it took humans so long to get to America from Asia, it seems plausible that they were confined to the Pacific coast for a long time as well, but high rates of erosion and seismic activity could easily destroy the evidence. It's certainly counterintuitive that the first place people colonize would be the semiarid high plains of New Mexico! The easiest places to cross the American Cordillera are in southern Mexico (Chivela Pass), Nicaragua (San Juan River) and Panama. But these places are also very rainy.
- sigil 3y agoYou might enjoy the In Our Time episode on Crocodile Evolution. https://open.spotify.com/episode/2v7Dil3bVNiir5BDXxGnTe?si=oWst3_8MSLOpWCsTUlaEeg https://open.spotify.com/episode/2v7Dil3bVNiir5BDXxGnTe?si=o... There were crocs with beaks, crocs with plant-grinding molars, crocs that ran around upright on land (yikes). During Earth’s colder periods their range narrows to equatorial regions, and it expands northward & southward during warmer periods. They may rule again someday!
- dimmke 3y agoThis was incredible. It blew my mind. Thank you so much. I had no idea that crocs were basically the other side of dinosaurs.
- angiosperm 3y agoCrocs with administrative skills are a stretch, even for me.