Comments by "Angry Kittens" (@AngryKittens) on "National Geographic" channel.

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  10. Well-preserved ones are very very rare. But new species are quite common, though they are often highly incomplete. I'm talking about species only being described from a thigh bone for instance. Or a tooth. This nodosaur really is THE best-preserved dinosaur specimen ever, surviving because it was petrified in bitumen. The closest contender to the "best preserved" title is perhaps the petrified remains of a mummified Edomontosaurus (nicknamed "Dakota") found in 1999. Even that one was only partial remains, since the dinosaur actually died and had mummified before being buried and turned into stone through mineralization. As for how many, I'm not sure about species since what constitutes a different species can be highly contentious in paleontology where you don't have DNA analysis and you're only working from very limited specimens. But in terms of genera, there are currently around 800 dinosaur genera discovered since the 1800s. Again, most of which are either quite boring or known only from incomplete remains which is why you don't hear about it every time. The number discovered each year averages at around 15 to 20, and is increasing each year due to better technology and more well-informed laymen who can alert paleontologists when they discover something, like the miners did in this example. Again, I'm talking about genera. A single genus can have multiple species. Also note that I'm talking only about non-avian dinosaurs. In other words, birds are not included. Neither are, obviously, organisms which are NOT dinosaurs. Pterosaurs, plesiosaurs, mosasaurs, etc. for example are not dinosaurs. The number goes up if you include them. And even more so for other organisms (fish, invertebrates, plants, etc.). Remember, you are talking about remains of global ecosystems through spans of hundreds of millions years. A lot have been destroyed by time and geological activity, but even then, you would expect quite a lot to still be remaining to be discovered. If you live near a cliff face for example, where the rock layers are sedimentary and old, I'm sure you've seen fossils.
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  50. +OnceUponATimeThereWasAPersonWithALongUsername.TheElongationOfThatUsernameWasPlainlyLegendary Actually, no. Cats, like most mammals (except a few exceptions like humans), are dichromats. They can not distinguish red from green. However this is because mammals lost the ability to see more colors during the course of our evolution. Our common mammalian ancestors were nocturnal and thus did not need to see colors. They thus lost cone cells (cells which allow us to distinguish colors) in favor of more rod cells (cells which allow us to see better in darkness). The end result was that they became dichromats. A condition passed on to all their descendants, regardless if they were nocturnal or not. Primates only re-evolved the ability to tell red from green very recently. A result of high evolutionary pressure as it allowed them to quickly tell fruits from leaves. This is why humans, unlike other mammals, are trichromats. We can tell red from green. However, even this does not really fully compensate for the color vision our ancestors lost. The ancestral condition of most vertebrates is TETRAchromacy. That is, aside from red, green, and blue, they can also distinguish a fourth "color" - ultraviolet. Birds, unlike mammals, never went through a bottleneck in their evolutionary history as nocturnal animals. They retained the tetrachromacy of our common vertebrate ancestors (and in some groups even added to it. Pigeons for instance have five types of photoreceptors). To put it simply, birds see better than cats. Heck, they see better than humans. In particular, eagles and other raptors, aside from being tetrachromats; also have wide-field binocular vision, and have very dense photoreceptors (five times as many as humans). This allows them to see even the tiniest mouse in a wheatfield and accurately gauge how far it is from them.
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