Miocene (Pt 31): Terror Mice and the First Howler Monkeys

Phoberomys

As the heat of the Middle Miocene gave way to the more moderate temperatures of the Late Miocene, grasslands grew across much of the Northern Hemisphere. In South America, however, the changes were, perhaps, less significant due, in part to its more equatorial position. Nonetheless, even aside from the general worldwide cooling trend, the South American climate was changing as the Andes continued to rise, affecting weather patterns across the continent. It was also continuing to edge closer to North America, so that, towards the end of the epoch, it became possible for a few animals to make the crossing using the islands of what is now Central America as stepping stones.

Tuco-tucos on the Edge

Flamarion's tuco-tuco (C. flamarioni)

There are a great number of endangered animal species in the world, and, as of the time of writing, 644 of them are mammals. These include, of course, such dramatic and visible animals as rhinos and pandas. But they also include many smaller, less glamorous animals. For example, over 200 species of rodent are endangered worldwide, and while that's not actually very many out of the total number of rodent species that exist, it's still quite high in absolute terms.

I realise, of course, that it's unrealistic to expect the public to get as concerned about obscure rodent species as they are about, say, endangered cats. Because, you know, snow leopards. But, in the semi-random style of this blog, inspired largely by whatever I happen to have seen in the literature recently, I want to talk about the social tuco-tuco (Ctenomys sociabilis).

For those who've not heard of them, tuco-tucos are a family of burrowing rodents native to South America. They look rather like voles, but are somewhat larger, at around 20 cm (8 inches) long, if you include the tail. They're good at digging, but they don't live underground in the same sense that moles or mole-rats do, since they leave their burrows during the day to feed on things like grass seeds. In fact, they've been described as the South American equivalent of gophers, although the two groups aren't really that closely related as rodents go. One of their distinctive features is their loose, wrinkly, skin, which apparently allows them to turn round easily in their narrow burrows.