This is a very fuzzy, cute rodent, and no one has seen one like it since 1898. It's called a red-crested tree rat, or, more evocatively, a red-crested soft-furred spiny-rat.
This one wandered up to two volunteers at Fundacións ProAves' El Dorado Nature Reserve in Colombia earlier this month and hung around for a couple of hours, just chilling like it wasn’t supposed to be extinct or anything. ProAves is launching what it calls a "major effort" to save the species, now that we know there are some.
Red-crested tree rat reappears after 113 years, Wired Science.