300 Million Years Ago
Ancestral Rockies by Jan Vriesen
In the Pennsylvanian period the Ancestral Rockies, Frontrangia and Uncompahgria, started to form. Rivers carried the sediments, consisting mostly of feldspar-rich gravels and sand that will be the source of red color of future rock reds, from the Ancestral Rockies and today we could see the deposits near the Red Rocks Park known as a Fountain Formation. Huge Lycophytes trees that reached up to 30 m (100 feet), ferns, and horsetails were the most common plants. Oxygen level reached 35% and it allowed invertebrates to reach enormous sizes. With more terrestrial landscape appeared in Pennsylvanian, reptiles evolved an amniotic egg which allowed to reproduce on land and explore more territories.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.
280 Million Years Ago
Sand Planet by Jan Vriesen
By the early Permian Period, all Earth’s land mass collided and formed one supercontinent, Pangaea. The climate was dry and Colorado was covered in sand dunes. Lyons Formation that was deposited during this time have fossilized tracks of protomammals, reptiles and invertebrates that roamed those dunes.
250 Million Years Ago
Slimy Shoreline by Jan Vriesen
End-Permian Mass Extinction vanished over 90% of all species on Earth. Stromatolites created by photosynthetic cyanobacteria formed layered mineral “microbial mats”.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.
150 Million Years Ago
Long-Neck Meadow by Jan Vriesen
In the Late Jurassic Period, Colorado forests were home was the largest plant-eating dinosaurs, Apatosaurus, Stegosaurus, Allosaurus, an apex predator of its time, and many more that were excavated in the world famous Morrison formation at Cleveland-Lloyd Quarry, Dinosaur National Monument, and on the west side of the Dinosaur Ridge.
100 Million Years Ago
Colorado's East Coast by Jan Vriesen
In the Cretaceous Period, about 100 MA, Colorado was a coastline of the Western Interior Seaway, a large inland sea that split the continent into Laramidia and Appalachia. The Dakota Sandstone was deposited along this coast and preserved many plants and numerous of dinosaur tracks on the Cretaceous east side of Dinosaur Ridge.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.
70 Million Years Ago
Submarine Colorado by Donna Braginetz
Around 70 MA the sea level rose and submerged the whole state of Colorado, the Rocky Mountains began to rise. Pierre Shale and Mancos Shale were deposited during this time. This formations produce marine reptiles such as pliosaurs and mosasaurs as well as ammonites, snails, clams, and many invertebrates.
66 Million Years Ago
Finally, the Rockies by Gary Staab
The Front Range of the Rocky Mountains had formed. Denver Formation was deposited during this time. This formation produce a great variety of vertebrate fossils such as Tyrannosaurus rex, Triceratops, Edmontosaurus, Pachycephalosaurus. Huge Triceratops tracks could be seen at the Dinosaur Ridge sites.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.
65 Million Years Ago
After Armageddon by Donna Braginetz
After the bolide impact 66 million years ago that vanished all non-avian dinosaurs, the life recovered within the first 300,000 years and began to diversify.
64 Million Years Ago
The First Rainforest by Jan Vriesen
By 64 million years ago, swampland had given way to a tropical rainforest in the Front Range, life emerged and Colorado was covered with tall trees and vines. An interesting mammal, wombat-looking Stylinodontine taeniodont (teeny-o-dont), was excavated from a Castle Rock Rainforest site along with enormous leaves and many plants.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.
55 Million Years Ago
Red Dirt by Jan Vriesen
In the early Eocene period, Colorado was a subtropical rainforest. Earth’s ice caps melted due to global warming temperatures and Colorado lakes were full of crocodiles. Coryphodons, a primitive hoofed pantodonts and the first group of large browsing mammals, appeared. Green River Formation was deposited during this time. Today this formation produces fossilized fish, plants, turtles, crocodiles, and insects of an exeptional quality.
37 Million Years Ago
The Rockies Explode by Jan Vriesen
Dawson Arkose, multi-colored layers of clay, formed by 37 million years ago, today could be seen at the Paint Mines Interpretive Park. During this time a great volcanic eruption took place in the Collegiate Range and covered the landscape in molten hot ash that instantly torched and consumed everything across the landscape. Titanotheres, relatives to rhinos and horses, browsed the Colorado landscape. Later in time Florissant Formation formed, it produces petrified wood and the fossilized plants and animals.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.
34 Million Years Ago
Castle Rock Floods by Jan Vriesen
At the Eocene-Oligocene transition, the climate changed from warm subtropical to a colder temperate. Castel Rock Conglomerate started to form about 34 million years ago, this area around Castle Rock experienced a major flooding during this time that cut through the rhyolite and eroded much of it.
16,000 Years Ago
Ice Age Summer by Jan Vriesen
In the latest Pleistocene Epoch during the Ice Age camels, mammoth and mastodon, horses and giant sloths lived in the grasslands of Highlands Ranch Open Space. Mount Evans, the highest peak in the Front Range of the Rocky Mountains of North America is seen behind the plain and pine forests. There were glaciers in the Rocky Mountain but not much ice in the Colorado.

This photo was taken at The Denver Museum of Nature and Science. Shared on this page under the Section 107 of the Copyright Act as a Fair Use.
The artwork the “Ancient Denvers” is made by three artists: Jan Vriesen, Donna Braginetz, and Gary Staab.