Tuesday, May 10, 2005

A living fossil

A dead possum in the street in front of the house this morning.

Possums reached Massachusetts in the mid-60s, from their more southerly habitats. The construction of Interstate 95 may have helped their migration north, providing a nice runway of ditches and culverts. I wonder how they got across the Hudson?

With the scruffy look of a Bowery bum and a reputation for stupidity, the possum is nevertheless resourceful. The first possums, after all, shared the Earth with dinosaurs.

When volcanic action at Panama connected North and South America about 3 million years ago, the possum was one of the few southern animals to successfully make the journey north, and the only marsupial to survive on the new continent. In general, the southern marsupials didn't fare well against northern placentals.

But the plucky possum adapted to changing environments and climates. It outsmarted placental mammals, including humans and their dogs. We mostly see possums today dead in the road, but they will likely outlast the automobile as well.