Page 59 - The Restless Earth Fossils

5 Fossils

was “up.” Walcott found bits and pieces of the major predator
of the day, a floating nightmare with tentacles and rotary teeth
called Anomalocaris, whose appearance (and identity) also did not
become clear until much later.

the Mesozoic: dinosaurs rule, MaMMals
squeaK, and FloWers start a revolution
Primitive mammals and dinosaurs evolved relatively early in the
Mesozoic. The first birds, descendants of small, active, theropod
dinosaurs, evolved sometime in the Jurassic. Flowering plants first
appeared in the Late Cretaceous and out-competed other seed
plants for dominance after an end-Cretaceous disaster.

important Fossil sites
Thousands of small, early dinosaurs died at what is now called
Ghost Ranch, New Mexico, a site that reveals a glimpse of life as
it was there more than 200 million years ago. Fine-grained lime-
stones in Germany continue to produce highly detailed fossils of
plants and animals from marine and land habitats. Limestones
from Araripe Basin, Brazil yield fossil plants and insects, some
amazing fish fossils, and, most recently, crocodiles, turtles, dino-
saurs, and spectacular pterosaurs (flying reptiles). But much
of what we know about dinosaurs has come from the great
American West.

dinosaurs of the Morrison Formation
Dinosaurs roamed vast stretches of what is now the North
American West 150 million years ago. Much of the land on
which they lived has since turned to rock. Layers of rock that
are recognized as being similar over large areas are called for-
mations. An Upper Jurassic formation called the Morrison
Formation covers an area of 0.6 million square miles (1.5 mil-
lion square km), bounded by central New Mexico in the south

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