Quote:
Originally Posted by Magin
The duck-billed platypus is the only mammal that lays eggs (I think... I'm pretty sure its the only mammal that does so, but I could be wrong)
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Not just the duck-billed platypus, but the order known as "
monotremes." You know how mammals are divided into placentals (like humans, dogs, cats, etc) and marsupials (kangaroos, wallabies, etc)? Early in the evolutionary history of mammals those weren't the only major groups. The monotremes are part of a group of mammals called Prototheria, one of the earliest groups. The problem is, most Prototheria died off and the monotremes, which include the platypus and echidna are the only surviving Prototheria and they only live in Australia and New Guinea. So despite there being three type of mammals you'll usually only hear about placentals and marsupials in the textbooks.
Speaking of the platypus, an interesting fact is what it uses that duck-bill for. It is actually a highly sensitive electro-sensor allowing it to pick up the the electric waves emitted by its prey underwater, since it usually scavenges in lakebeds where sight wouldn't help. It serves as a sixth sense.