Here's an interesting story. Apparently there has been a sighting of what is thought to be a woolly mammoth (elephant) in Siberia. This creature supposedly became extinct 4000 years ago. Here's the LINK and there is a blurry video included. Whatever is in the video has a trunk and certainly appears to be a reasonable facsimile of an elephant. Is it a woolly mammoth? Well that is a little hard to tell from the video.
The article suggests that Siberia is so large, uninhabited, and unexplored, that other such findings may occur from time to time. Who knows what other "prehistoric" creatures may exist in our oceans as well?
If someone finds a T. rex in the Amazon jungle, I'll really get excited.