Friday, December 29, 2006

Mammal in the Shadows

A balmy evening had me out on the deck yesterday, waiting for the charcoal to ignite. I heard a rustling in the leaves along the stairway and caught a brief glimpse of a shrew. Primarily carnivorous, shrews hunt for worms and insects in the leaf litter and are seldom seen. They may be active day or night but are usually encountered at dusk. Their home is an underground cavity, lined with plant debris; it is here that the female raises her four litters each year.

The earliest mammals were thought to have been shrew-like creatures which appeared in the Triassic Period, some 200 million years ago. As the mega-continent of Pangea split, eutherians (placental mammals) dominated on the northern continents while marsupials spread across Gondwanaland (proto Africa-South America-Antarctica-Australia). Dinosaurs would rule the earth for the next 130 million years until a massive asteroid strike changed the climate, altered the flora, triggered a mass extinction and ushered in the era of birds and mammals.