Fagopsis longifolia: an Extinct Species from Florissant

Fagopsis longifolia is one of the more common fossil plants found in the Florissant Formation. Located 35 miles west of Colorado Springs, Florissant Fossil Beds National Monument has one of the most diverse fossil deposits in the world—more than 1,700 different species have been described from this ancient lake deposit. Fagopsis, a genus that became extinct at the end of the Eocene, is thought to have been a member of the beech family (Fagaceae). Originally identified as the water elm, Planera, these fossil leaves were assigned to the genus Fagopsis.

Fagopsis longifolia is one of the most abundant fossils found in the Florissant Formation. The length of the leaves are 5 to7 cm (1.9 to 2.75 inches); and the width is from 2.5 to 3 cm (1 to 1.2 inches). Specimen FLFO3129a, Florissant Fossil Beds National Monument. Image by Russell Wood.

Fagopsis is known from just 30 other fossil specimens from the North American Eocene. Although Fagopsis longifolia is among the most abundant fossils at Florissant, this species has not been found anywhere else in the world. Fagopsis thrived along the prehistoric Florissant streams and the edges of ancient Lake Florissant, dropping its abundant leaves onto the water. Towering redwoods (Sequoia) also grew around the borders of the lake and along streams.

This brochure, featuring one of the Sequoia stumps of the Florissant fossil beds, was used to attract visitors to the fossil beds when it was a tourist attraction. Huge, petrified Sequoia trees are the largest fossils found in the monument—some have the largest diameter petrified trees known. Brochure image courtesy of the Beth Simmons collection.

Fossil plants, just like Fagopsis longifolia, provide important information about paleoclimate and the uplift history (paleoelevation) of the Rocky Mountains in the prehistoric past. Fagopsis represents plants found in a moister climate than the cool, dry climate of Florissant today. Based on characteristics of Fagopsis and other fossil plants, scientists have estimated the mean annual temperature at Florissant during the Late Eocene at approximately 10.7° to 14°C (51.2° to 57.2° F) with an estimated paleoelevation of 1,899 to 3,299 meters (6,230 to 10,500 feet) Note: there is counterevidence from non-floral studies that propose different mean annual temperatures and paleoelevations. Researchers are still working on this problem] Florissant also represents a time period just before a major cooling of the world’s climate that occurred during the end of the Eocene and at the dawn of the Oligocene .

Fossils of Fagopsis longifolia are found between layers of paper-thin lake shales in the Florissant Formation from the latest part of the Eocene (34 million years ago).  Most of the Florissant fossils are detailed compression and impression fossils of insects and plants. Image by Donald Miranda.

The conditions of ancient Lake Florissant led to exceptional fossil preservation and preserved a number of fossils—like Fagopsis longifolia—that are used by researchers as proxies or useful indicators for reconstructing ancient environments and understanding biological evolution, paleoclimate, paleoelevation, and climate change.







Dryopteris: A Fossil Fern from Florissant

Ferns are among the fossil plants found in the Florissant Fossil Beds of Colorado. Fossil plants like these ferns are records of prehistoric life—providing information about when an organism lived, where it lived, and how it lived. Fossils are vital in helping paleontologists reconstruct ancient environments and establishing the geologic history of the Earth.

Dryopteris guyotti was abundant in past geologic ages. 

Broad, flat leaves helped the fern catch more sunlight.

Florissant Fossil Beds National Monument specimen

number 3135a.  Photo by R. Wood.

The origins of ferns are not well understood, but continued study of fossil ferns may reveal more about their beginnings. The earliest recognizable ferns come from the Carboniferous (359-299 million years ago).

Ferns have large complex fronds (leaves) and are spore bearers. Some ferns are non-woody, but other ferns are woody and are called tree ferns. Ferns were common late Paleozoic plants and widespread in the Mesozoic. Today ferns are the most common and diverse spore-bearing land plants with over 10,000 species. They generally live in moist, shady areas of the forest understory.

Dryopteris, from the Greek, drus (oak) and pteris (fern) occurs in Florissant’s Eocene fossil flora as well as other Tertiary floras. Its common name—wood fern—is from the preferred woodland habitat of most Dryopteris species. Other common names include shield fern, Goldie’s fern, male fern and buckler ferns.

Today Dryopteris is a genus of about 250 species of ferns growing in the temperate Northern Hemisphere and in eastern Asia. Fronds are bipinnate (branching of leaflets at right angles to the central axis). The leaflets, or pinnules, are lobed. Fertile pinnules have round sori, which are fruit dots or reproductive bodies (Tidwell, 1998). Many of the species have solid rootstocks forming a crown with a ring of fronds.

Line drawing of Dryopteris filix.
Note round sori near top.
USDA-NRCS PLANTS Database
 Britton, N.L., and A. Brown. 1913.
An illustrated flora of the northern United States,
Canada and the British Possessions.

Off all the fossil ferns at Florissant, Dryopteris guyottii is the only species of fern described from a frond. Other ferns are known only from fossil spores. It appears that Dryopteris guyotti grew in the understory of the Eocene forest at Florissant (preferring damp and shaded environments like its modern relatives) or near ancient Lake Florissant.

A Short Note On: Fossil Spiders from Florissant

The order of Araneae (true spiders) are represented as a large and diverse group in the 34.1 million-year-old Florissant Formation. Spiders were among the earliest animals to live on land. They are thought to have evolved about 400 million years ago from primitive ancestors that emerged from water to live on land. Spiders are arachnids—not insects, however both spiders and insects belong to the largest group of animals on Earth, the arthropods.


Florissant is well-known for its fossil spiders. More than 150 specimens of spiders have been found in the Florissant shales.


This Eocene-age fossil spider is a male, based on the swelling of the pedipalps. Many fossil spiders are impressions that are barely discernable.  Toni Clare, owner of the commercial quarry north of the Florissant Fossil Beds National Monument, collected the specimen shown above in 1997. Florissant Fossil Beds National Monument specimen number 2971A. Photo: R. Wolf.

When spiders die their legs normally curl under their body. Florissant spiders, like the image of one above, have their legs extended—rather than curled up. Scientists argue that the extended legs of Florissant’s spiders suggest the waters of ancient Lake Florissant, during the latest Eocene, were warmer or more acidic than normal; the likely cause may have been from thermal vents associated with area volcanism or from ash falls.
It is difficult to assign Florissant’s fossil spiders to a genus and species based on their external features observed in the paper shales. Since microscopic characteristics cannot be seen in the fossil impressions at Florissant, an outline morphometric study, using carapace (dorsal exoskeleton) shape and leg characters, has been effective in making family placements of fossil spiders.

All spiders have two well-divided body sections: the cephalothorax (prosoma) followed by an abdomen (opisthosoma). The abdomen contains the digestive and reproductive systems and on the ventral surface near the apex are spinnerets that deliver small threads of silk.

Silk has many functions such as making intricate webs that capture prey, encasing eggs, and building elaborate nests or burrows. Spiders with a distinctive silk organ, called a cribellum, are included in a special group called the Cribellatae. The fossil spider in figure 1 has a cribellum and belongs to this group.

Spiders have eight walking legs, all attached to the cephalothorax. On the front of the cephalothorax are the mouth, fangs to bite prey with, and eyes. The first pair of appendages—the chelicerae—are used for piercing, handling prey, and injecting venom. The second pair of appendages, the pedipalps, are used for mating and are much larger in male spiders than in females.

All species of spiders are predatory—spiders that do not spin webs, such as wolf spiders and tarantulas, stalk or ambush their prey. Spiders feed by a process known as external digestion. When spiders catch an insect, they inject venom that paralyzes their prey. The spider’s venom also contains digestive enzymes. These enzymes liquefy most of its victim’s insides so the spider can feed on this mixture of nutrients.

Spiders were once a part of an ancient ecosystem at Florissant that has long since vanished; the only record of it is held in the fossil beds. Some of the spiders that lived there built elaborate webs; several built tunnel-like lairs under rocks or under the dead leaves littering the primeval forest floor, while others lived on rocks or trees. Some of the spiders ultimately turned into fossils. More exciting discoveries of these remarkable fossils will no doubt occur and add to our understanding of this prehistoric ecosystem and creatures.

Ancient Sea Urchins of Colorado Springs: Incredible Porcupines of the Sea

Just west of Garden of the Gods in Colorado Springs—about 3 kilometers from the beginning of Rampart Range Road—are the remains of fossil sea urchins found weathering out of the Glen Eyrie Formation. These fossil sea urchins are Archaeocidaris dininnii. These ancient animals reveal a span of time when Colorado Springs was under a sea and home to a large number of marine creatures.

Archaeocidaris occured in large groups since the environment included plenty of food and protection from waves and currents. Like modern sea urchins, living in groups improves spawning and provided protection. Once the first sea urchin was found at this fossil site the search was on for more. Dozens of additional specimens were collected.

Archaeocidaris had a spherical, calcareous skeleton or test made of moderately thick plates that were arranged radially in two types of double columns. The first double column, termed the ambulacrum (plural-ambulacra), had two pores in each plate for the projection of tube feet. Hydraulically powered tube feet aid in locomotion, anchoring, feeding, sensing the environment, and respiration.


The second double column, the interambulacrum, alternates with the ambulacra. Archaeocidaris had a distinctive arrangement of four columns of plates in each interambulacrum. Moveable spines were joined onto a single large tubercle on each interambulacral plate.



Polygonal interambulacral plates that form part
of the Archaeocidaris test. Spines fit on the large knobs
or tubercles in the center of the plates.Spines are
 rarely preserved as fossils.

Skin and cord-like muscle, covering the test, moved and rotated the spines in almost any direction around the tubercle. The barbed spines of Archaeocidaris provided protection from predators and allowed locomotion. 

The interambulacral plates have conspicuous bumps in
the center where the spines were once connected. 

 When a sea urchin dies, the tissue that holds the plates together decays, and the plates disassemble and scatter on the seafloor. of the Archaeocidaris dininnii fossils found at the Rampart Range Road site are represented by separate plates and spines.

Because sea urchins are generally one of the first marine organisms to show signs of stress if something is wrong with the water, the Environmental Protection Agency uses them as an indicator organism for water quality near shores and in bays. When conditions are poor, sea urchins will stop moving, their spines will droop, and they will die.





Aerial Photos Shows Outline of Ancient Lake Florissant

Just west of Pikes Peak and south of the town of Florissant, Colorado (about 40 miles west of Colorado Springs on U.S. Highway 24) lies a scenic mountain valley where a number of petrified redwood stumps dot the landscape. Beneath this beautiful setting are incredible plant and insect fossils buried in the sediments of an ancient lake. These fossils, ranging from large tree stumps to single-celled diatoms, reveal a prehistoric Colorado of long ago. Today the Florissant Fossil Beds National Monument protects these fossil resources.

About 34 million years ago, volcanic eruptions near Guffey (18 miles to the southwest) produced volcanic mudflows (water-saturated mass of ash and rock debris). These mudflows—looking and flowing like concrete—buried a lush valley and petrified the bases of huge redwood trees that grew there. These mudflows also created a dam in the valley, forming a lake about one mile wide and 12 miles long. Volcanic ash from subsequent eruptions formed fine-grained sediments at the bottom of the lake. Plants, insects, and other organisms were entombed in this material. Over millions of years these sediments were compacted into layers of shale. The delicate details of these organisms were preserved as fossils and provide a look at the life and the prehistoric ecosystem of the Florissant valley during the end of the Eocene Epoch.

The approximate area of ancient Lake Florissant is defined in this aerial photo by meadows and treeless sections. The prehistoric lake area (light gray) is seen extending through the center of the photograph and then turns west at the town of Florissant. NAPP black and white vertical aerial photo from 20,000 feet (9/29/1999). Top of the photo is north.



NAPP vertical color infrared (CIR) aerial photo of the Florissant valley from 20,000 feet (9/24/88).  Color infrared film is used to interpret natural resources such as vegetation, soil conditions, water resources, and other features.  Active vegetation appears in various shades of red and pink (intense red colors indicate vigorous and dense growth).  Water that is clean and clear appears black.  Shallow water reflects bottom sediments and appears in various shades of blue. Soil conditions (moisture levels) are revealed by the degree of the gray tone:  dry soils are light gray, moist soils are gray, and wet soils are dark gray.  Top of the photo is north.

















  





 











Topaz Crystals from the Petra Placer, Tarryall Mountains, Colorado

The Tarryall area in Park County, Colorado is known for the exceptional topaz specimens discovered there. Topaz in the Tarryall Mountains forms in cavities of various sizes in pegmatites (coarse-grained granite).

Topaz with blue tint from Tarryall area.

The Hayman Fire of 2002, the largest forest fire in Colorado's history, has been a major factor in the discovery of new topaz deposits in the Tarryalls. Frequent summer rain storms form gullies that uncover topaz-bearing pegmatites that provide new sites for collectors to work. Additionally, afternoon thunderstorms wash away gravel and reveal topaz crystals on the surface.

The Hayman Fire made topaz hunting easier.
Pilot Peak is in the background.

East of the China Wall (a prominent granite landmark in the area) Mutakat Road (Forest Road 211) winds it way near an area where a number of mineral claims are producing gem topaz. The Petra Placer is one of these claims. Rich Fretterd, a member of the Lake George Gem and Mineral Club, staked the Petra Placer in April, 2004 after discovering a number of fine topaz specimens. The name of the claim comes from the Latin word petra, meaning rock or stone. The Petra Placer is southeast of Pilot Peak (SW1/4 Ne1/4 Sec. 12 T. 11S, R72W).

A Petra Placer topaz crystal.

The specimens from the Petra Placer are remarkable for their large size and clarity. A number of topaz crystals are just below the surface in gravel deposits. Petra Placer specimens have a blocky, prismatic crystal habit. Some of the prism faces are slightly etched. Most specimens have a bluish-tinge. Anhedral (lack crystal faces) specimens are faceted into gems and euhedral (have crystal faces) specimens make their way into museums or the mineral cabinets of rock hounds.

Sifting gravel yields topaz.

As a result of the Hayman fire, the topaz crystals of the Petra Placer have been revealed. Digging in various parts of the claim continues to yield excellent specimens. The Petra Placer is now a significant Colorado topaz locality.

Clear topaz crystal from the Petra Placer



Topaz crystal perched on smoky quartz.

 



Crystal specimen with etching.





End of a good day of prospecting



© Cripple Creek Center for Earth Science Studies