Miocene (Pt 33): Killer Armadillos and Far-travelling Raccoons

Lycopsis

As the Miocene epoch drew towards its conclusion, the island continent of South America drew steadily closer to its northern counterpart. The gap would not be fully bridged by land until a few million years later at the end of the following, Pliocene, epoch but, when it did, many of the peculiar mammals of the southern continent would die out, albeit in many cases it was the subsequent Ice Ages and/or the arrival of humans that truly finished them off. One group that survived the experience, and that is still around today, is that of the armadillos.

Even so, armadillos were more diverse in the Late Miocene than they are today. Probably the most distinctive were the glyptodonts, which had solid, often domed, shells without the flexible bands seen in living armadillos. As the sweltering heat of the Middle Miocene faded towards temperatures closer to those we see today, grasslands began to extend across much of the southern part of the continent, and the glyptodonts adapted to it, switching towards an even more heavily grass-based diet than before. The resulting group of what we might loosely call "advanced glyptodonts" was the one that would later briefly cross over into the north and includes the most famous examples. In addition to certain features of their shell, they were distinguished by having teeth especially suited for chewing, with the high crowns suitable for grinding up grass and other tough vegetation.

Pliocene (Pt 14): Terror of the Marsupial Sabretooths

As I have described in previous posts, during the Pliocene, South America was nearing the end of a long period of isolation, having been separated from the other habitable continents for millions of years. In the very latest part of the Pliocene, it collided with North America, leading to the massive influx of northern animals known as the Great American Interchange. Until that time, many of the native animals were, to modern eyes, rather strange, evolutionary experiments, that, while evidently successful in their own right, could not compete with the invaders from the north, such as deer, llamas, bears, and big cats.

One of the oddities of pre-Interchange South America, though, was the absence of large placental mammalian carnivores. There were, as I have already noted, a few, since the raccoons somehow crossed the seas between the continents well before the rise of Central America. And, towards the end of the Pliocene, a few other animals narrowly beat the Interchange by island-hopping before the land bridge was completed. But, raccoons aside, none of the large mammalian carnivores we would associate with the continent today had yet arrived.