My apologies if this is the wrong subreddit - this seemed like the right place, but I'll be happy to take the question elsewhere.
Why is the extinction of the dodo so famous, as opposed to, say, the extinction of the carrier pigeon? The latter was actually a much more significant feat, both in the impact the species had on human life and the environment, and in terms of the sizes of the populations involved. So why have more people heard of the dodo than the carrier pigeon? Is it because the dodo itself was such an oddity, or for other reasons?
The dodo was limited to one small island in the Indian Ocean. It essentially demonstrated how birds and other animals will evolve to suit their surroundings. The dodo was enormous and a great source of food, but it had no natural predators on Mauritius. A turkey, by comparison, has a lot of predators, so it learns habits to protect itself. The dodo was beyond easy to hunt - it literally walked up to people out of curiosity. Trade ships were able to load up on dodo meat as they traveled around Africa. It was irresistible.
I think the passenger pigeon is less famous mostly because it closely resembles the common pigeon we see every day. It was also hunted to extinction, but it had more instinctive defenses against predators.
The dodo was one of the first cases of documented extinction of an animal which had existed contemporaneous with modern, "civilized" humanity. It wasn't some old creature from eons before we were around, some relic of a previous age. It was something that we had seen and, uh, killed.
Why does this matter? Consider how radical the notion of "extinction" was to European natural theology of the 18th and early 19th centuries. The general belief, among scientific men as well as lay, was that every creature on the Earth was a product of God, put here for the service of man, and that God was responsible for the bounty of natural abundance. The idea that man could be responsible for destroying an entire species — so that it was irrevocably gone — does not fit well into this model. The dodo was documentable, because it was not mythical (they had good records and body parts preserved), but its range was incredibly small, meaning that you literally could say, "there aren't any hiding somewhere that we can't see them — they're gone."
Elizabeth Kolbert's writings in the New Yorker on the history of extinction as a concept are excellent, as is her book The Sixth Extinction. The dodo was one of many things that pointed towards a new, more modern view of ecology, history, and biology — a world much more fragile, integrated, old, and malleable than the more static, Biblical model seemed to allow for.