Fossil Plant Species

red leaf fossil with 2 pointed lobes, one smaller than other
Gyrocarpus sp., catalog number FOBU10668

NPS Photo

Fossil leaves and plants act as ancient thermometers and rain gauges, allowing scientists to study the ancient climate of Fossil Lake. It is difficult to identify fossil leaf specimens from the Fossil Butte Member (FBM) at the species level.

See some of the plant fossils that are on display in our museum exhibits.
non-lobed leaf fossil with tiny holes on edges
Gyrocarpus sp., catalog number FOBU13320

NPS Photo

Gyrocarpus sp.

Gyrocarpus sp. specimens (pictured above and to the right) demonstrate the challenge of identifying fossil plant species.
Gyrocarpus sp. produces:

  • non-lobed specimens (pictured right)
  • 2 lobed specimens (pictured above)
  • 3 lobed specimens
One species of tree can produce different looking leaves. This makes it difficult to determine if leaves are from different trees or if they are variations within a species.
Fossil of a palm frond from the Green River Formation
Palmites sp, catalog number FOBU446

NPS Photo

Palm - Palmites species

Order Arecales, Family Aracacea
Palm inflorescences (a group of flowers arranged on a stem) and palm fronds (pictured here) are common fossil specimens from the FBM.

Variation in morphology (the form and structure) of specimens indicates Fossil Lake may have been home to several palm species. No FBM palm species have been described as of yet. The abundance of large and complete palm frond specimens suggests there may have been palm trees near the shores of Fossil Lake.

There are over 2,000 living palm species, found naturally in tropical, sub-tropical, and humid environments. Palm specimens are indicators of a warm and wet environment at Fossil Lake.
2 long leaves forming v shape with small circular seed at the base
Lagocarpus lacustris, catalog number FOBU9835

NPS Photo

Winged Fruit Species - Lagokarpos lacustris

Order unknown, Family unknown
"Hare-Fruit-Of Lakes"
Lagos - Greek for "hare" (referencing rabbit-head shape of seed and wings)
Karpos - Greek for "fruit"
Lacustris - Latin for "of lakes and ponds"

L. lacustris is recognizable by its spherical shaped seed body and dual set of wings which are characterized by a V shape. The wings indicate that fruit was wind dispersed (seeds carried by wind to new growing sites). Specimen wings range in size from 3 to 9 inches. It is known from fossil deposits in Wyoming, Utah, Colorado, Oregon, and British Columbia and is found exclusively in lake deposits, indicating it was a near-shore species.

No modern fruits are known to share the specific characteristics of L. lacustris, and the Lagokarpos genus is thought to be extinct. Species of the living Gyrocarpus genus are, however, similar in form. This genus is found primarily in tropical and subtropical regions.
a banana-shaped fossil seed with a dark circle in the center
Ailanthus confucii, catalog number FOBU6708

NPS Photo

Tree of Heaven - Ailanthus confucii

Order Sapindales, Family Simaroubaceae
There are about 100 modern species in the Simaroubaceae family, found primarily in tropical and subtropical regions. The Ailanthus genus has a disputed number of living species, somewhere between 5 and 10. They are commonly known as "Trees of Heaven."

A. confucii is a winged fruit characterized by its centrally located seed. It is known from fossil deposits in North America, Asia, and Europe and is found almost exclusively in lake and pond deposits A. confucii specimens from the FBM are the oldest known representation of the Simaroubaceae family in North America, possibly the world.

The modern Ailanthus altissima, native to China, was introduced in the United States in the 1700s as a fast-growing ornamental shade tree. Due to its ability to tolerate poor soil conditions and air quality, it has become an invasive species.
leaf-like fossil with 3 off-shoots
Platycerium, catalog number FOBU11465

NPS Photo

Staghorn Fern - Platycerium species

Order Polypodiales, Family Polypodiaceae
There are almost 20 living species in Platycerium genus. They are found primarily in tropical environments of Asia, South America, New Guinea, and Africa
fossil of 2 cup like leaves with skinny roots hanging below
Salvinia preauriculata, catalog number FOBU11895

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Water Fern - Salvinia preauriculata

Order Salviniales, Family Salviniaceae
This aquatic species had 2 floating leaves and 1 root-like leaf which would hang below the water's surface.

Living members of the Salvinia genus include 15 modern species found in tropical regions of Madagascar, Africa, West Indies, Europe, Asia, North and South America. They are only found in freshwater and spread rapidly in warm water.
fossil of 2 long skinny leaves in a v shape with small clump of seeds at the base
Lygodium kaulfussi, catalog number FOBU12018

NPS Photo

Climbing Fern - Lygodium kaulfussi

Order Schizaeales, Family Lygodiaceae
Living members of the Lygodium genus include 40 modern species found primarily in the tropical regions of Asia. They do not have a fixed growing season and will continue to grow throughout their life. The growing cycle lead to their common name, "climbing fern."
Fossil of black circle with many smaller circles inside
Nelumbo, catalog number FOBU11744

NPS Photo

Lotus - Nelumbo species

Order Proteales, Family Nelumbonaceae
The modern Nelumbo genus contains 2 living species found in Asia, North America, and the Caribbean. They are aquatic plants restricted to freshwater and are characterized by large flowers and leaves.

Fossil Lake may have been home to multiple species of the Nelumbo genus. FBM specimens include:
  • lily pads (ranging from 4 - 20 inches)
  • root systems
  • characteristic seed pods (pictured here)
fossil of five petals surrounding small circular seed, crack through left side of rock
Chayena tenuis, catalog number FOBU11466

NPS Photo

Flower-Like-Fruit - Chaneya tenuis

Although resembling a flower, C. tenuis is actually a fruit. It is characterized by 5 petal-like wings. The Chaneya genus is known from fossil deposits in North America, Asia, and Europe.
leaf fossil with triangular-shaped leaf and thick stubby stem
Birthwort, catalog number FOBU11845

NPS Photo

Birthwort - species unknown

Order Piperales, Family Aristolochiaceae
Modern members of the Aristolochiaceae family include about 400 living species and are found primarily in tropical regions. They are perennial (having a lifecycle longer than 2 years) and are working herbaceous plants (grow as non-woody shrubs or vines). Also commonly known as "pipe-vines." They are primarily pollinated by flies.

The fossil plant pictured has not been described as a species.
Fossil of feather shaped leaf with circular seed at bottom
Deviacer wolfei, catalog number FOBU11716

NPS Photo

Soapberry - Deviacer wolfei

Order Sapindales, Family Sapindaceae
Living members of the Sapindaceae family includes over 1,800 modern species found in temperate to tropical regions. Modern species include maple and the tropical lychee tree.
circular seed fossil with visible horizontal veins
Catalog number FOBU13350

NPS Photo


This seed has the appearance of a walnut.


Grande, Lance. 2013. The Lost World of Fossil Lake: Snapshots from Deep Time. Chicago: The University of Chicago Press.

Jackson, David R., Art Gover, and Sarah Wurzbacher. “Tree-of-Heaven.” Penn State Extension, November 2, 2020.

Last updated: February 29, 2024

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