Travel Reference
In-Depth Information
2
Radiometric
Clocks
When
ammonites still lived and died and
fell
into the sandy bottom of
what is now Sucia Island, North America was a divided continent. For tens
of millions of years during the Late Cretaceous Period, a giant seaway hun-
dreds of miles wide cut the continent in two. From the arctic regions of the
far north to the Gulf of Mexico in the south, this wide yet shallow sea, called
the Western Interior Seaway, was home to an incredible bestiary of now-
extinct creatures. Archaic fish and giant marine reptiles prowled the blue
waters in search of prey; monstrous turtles sculled among the wavetops; and
giant clams were so abundant that their shells paved the muddy bottoms.
Overhead, long-winged pterosaurs and primitive birds circled above the
