Section Links:

History and Genealogy

HISTORY
  Big Bang
  Galaxies etc.
  The Earth
  Continents
  Ice Epochs
  Life
  Precambrian
  Paleozoic
  Mesozoic
  Cenozoic
  First People
  Europeans

GENEALOGY
  Genpics

  Database

LINKS

Paleozoic

© 1985 by Andrew J. Morris

The Paleozoic era spans less than 400 thousand years, but it was a time of incredible changes on the face of the Earth, due in large part to the evolution of more advanced lifeforms. The Paleozoic era is called the "Age of Fishes."

Early in the Paleozoic era about 500 million years ago, the sea was creeping across Colorado from west to east. Larimer County then would have been part of a vast plain, and later a sandy beach, until finally it too was submerged, a home for fishes. The land may have emerged briefly from the sea for short periods over the next 200 million years, but most of that time it ws submerged. Then, about 300 million years ago, two more mountain ranges arose in our area, known as the "Ancestral Rockies." One of these ranges spread across central Colorado, while the other was to be found in the southwestern part of the state. Once these mountains emerged the western edge of present day Larimer County was at the edge of the mountains, the central part of the county was covered with sand dunes and beaches, while the eastern edge was at or near the ancient seashore. Then these mountains too began to erode away, until Colorado was once again a vast plain. The sea covering the eastern part of the state receded or dried up, and by 225 million years ago, at the end of the Paleozoic era, Colorado was mostly desert with great sand dunes as in today's Sahara.

Because of these desert conditions there was probably not a great deal of plant or animal life in the area of Larimer County during the late Paleozoic era. Elsewhere on the planet though giant ferns and other simple plant forms firmly established themselves during this time. Insects were numerous and diverse, and small lizards were developing. The seas abound with fish, clams, and other shellfish, coral and seaweeds.

Visit our Genealogy section to find Larimer County ancestors, or see our Employment department to find a job!