ruled Earth, shallow seas covered much of the world's continental
lowlands. The seas were filled with life: fish, seaweed, and swimming
dinosaurs. At the end of the Cretaceous, shallow seas all over the
world dried up, leaving deserts and sand dunes where once the plesiosaurs
In this alternate
explanation of the dinosaurs' disappearance, they faded out slowly
and gradually, not suddenly. Disease played an important role, but
it was not the only factor. As you probably know, many different
kinds of dinosaurs had disappeared by the end of the Cretaceous.
Dinosaurs that had lived on the land, in the sea, and in the air
were now gone. But many other kinds of life disappeared at the same
time, including shellfish, corals, fish, flowering land plants,
and even single-celled plankton floating in the seas. Most diseases
infect only a single species or a small group of closely-related
species of plant or animal. It is hard to think of a disease that
would have affected all different kinds of dinosaurs. It is nearly
impossible to imagine a disease that would have infected life forms
as different as a T-Rex and a seaweed!
So, how could
disease cause the extinction of the dinosaurs?