Fascinating Fossils of Florissant

Fossil Vertebrates

Topic Overview
Over 1,700 species of fossil organisms have been found at Florissant - things like plants, insects, spiders, and pollen. Although less common, there are also some examples of fossil vertebrates. Vertebrate fossils from Florissant include over thirty species of fossil mammals, fish, and birds.

Where are the dinosaur fossils?
Fossils from Florissant lived during the late Eocene epoch, about 34 million years ago. The age of the dinosaurs ended with their extinction at the end of the Cretaceous time period 66 million years ago, about 32 million years previously. While this time gap means that no non-avian dinosaurs are found at Florissant, there are some avian descendants (birds). After the extinction of dinosaurs, another group diversified to fill the ecological role that dinosaurs had held-- mammals.

Finding fossil vertebrates

Many mammals from Florissant have been identified by a single element such as a tooth or a single vertebra. Teeth and other bones are sturdy enough to stay intact after the rest of the body decays, and may last long enough to be fossilized. [learn more about fossilization here]. Delicate fish bones and scales as well as bird feathers are preserved in the fine layers of paper shale that form in the ancient Florissant lake.

This is a detailed fish fossil found between layers of paper-thin shale..   

Fossil mammals 
Most mammal fossils from the Florissant Formation are from the lower mudstone unit [learn more about the geology of the Florissant Formation here]. These fossils include elements of larger mammals such as early horses, brontotheres and oreodonts. Horses from the Eocene have three toes on each foot and stood only about three feet high. Brontotheres were the largest animal that lived at Florissant in the Eocene. Though belonging to0 an extinct group, brontotheres resemble a rhinoceros. One marsupial mammal has been found from Florissant- an opossum. Explore the links below to learn more about the mammals of Eocene Florissant. 
Fossil Examples: 
        Scientific Classification                                                    Common Name
          Didelphidae-------------------------------------------------> opossums
          Lipotyphla--------------------------------------------------> extinct family
          Eulipotyphla------------------------------------------------> hedgehogs, shrews, moles              
          Rodentia ---------------------------------------------------> rodents                             
          Lagomorpha -----------------------------------------------> hares and rabbits                    
          Artiodactyla------------------------------------------------> even-toed hoofed mammals                    
          Perissodactyla----------------------------------------------> odd-toed hoofed mammals      

Final All Mammals
Artist reconstruction of a 1.) mole, 2.) rabbit, 3.) unknown rodent, and 4.) shrew from Florissant. 

Life on Earth is unique at any point in time as new life forms evolve and older ones become extinct.Because of this, unique groups of organisms represent unique periods in time. The fossils are what scientists use as the clock for identifying the increments of geologic time. Divisions in geologic time are often marked by the first or last occurence of a fossil in the fossil record. The extinction of brontotheres, for example, is one marker for the end of the Eocene. Fossil evidence for brontotheres has been found at Florissant, which helps scientists know that the age of the fossil beds is not younger than the Eocene. 

Fossil Fish
Fossil fish are found in much the same way as fossil plants- by splitting the paper shales formed by the ancient lake. [Click here to learn more about fossil plants.] Fossil fish are the most abundant vertebrate fossils found at Florissant. Fish are unique because it is common to find a complete fish fossil. Bowfins, suckers, catfish, and perches have all been discovered from the shale at Florissant. Most of the fish preserved at Florissant were bottom-dwellers, feeding along the bottom of the ancient lake. Try searching for "fish" using the Browse tab of this website to see some beautiful specimens. 

Fossil Birds
Fossil birds are relatively rare at Florissant, but at least half a dozen have been found. In some of the examples found, beautifully delicate feathers can still be seen. Aves (birds) are often difficult to identify past their class, but shorebirds, rollers, cuckoos, passerine birds have all been identified by scientists.

click here to explore our collection of birds. 
Undescribed shorebird discovered in 1997 by the owner of privately-owned Florissant Fossil Quarry. Undescribed shorebird discovered in 1997 by the owner of privately-owned Florissant Fossil Quarry.