Yellowstone Paleo Survey: Taxonomy



Nearly 150 species of fossil plants from Yellowstone have been described (exclusive of palynological specimens), including ferns, horsetail rushes, conifers and many deciduous plants such as sycamores, walnuts, oaks, chestnuts, soapberries, maples, and hickories. Seqouia is the dominant conifer. This type of assemblage reflects a warm temperature sub-tropical environment (Dorf 1980).

The first fossil plants from Yellowstone were taken from Elk Creek by the early Hayden Survey parties and submitted to Lesquereux, who believed them to be Eocene (1872).

In his report in the Hayden Survey in 1878, Holmes made the first reference to Yellowstone's fossil forests. The report identified the petrified trees located on the north slope of Amethyst Mountain opposite the mouth of Soda Butte Creek, about eight miles southeast of Junction Butte.

Knowlton identified 147 species of fossil plants from Yellowstone, 81 of them new to science, and three stages of Tertiary fossil flora. The oldest (79 species) were equivalent to the lower Eocene Fort Union flora and associated with acid breccias; the intermediate included 30 species; and the youngest (70 species) were associated with the basic rocks.

Knowlton believed the most remarkable fossil forest was on the northwest end of Specimen Ridge, where it covers several acres on a steep hillside about opposite the mouth of Slough Creek, a mile southeast of Junction Butte. It was first brought to scientific attention by E. C. Alderson of Bozeman, Montana, who showed it to Knowlton in 1887. Most of the trees project well above the surface, including hundreds of trunks from 1 to 8 feet in diameter and from 1 to 20 feet high, with the tallest more than 40 feet. Just beneath the largest known tree in Yellowstone (26.5 feet by 12 feet), which contains large roots, are two trees that are 9 feet in circumference and 20 feet high. Fossilized bark is preserved at this locality.

Most petrified wood and other plant fossils come from Eocene deposits, which occur in many northern portions of the park, including the Gallatin Range, Specimen Creek, Tower, Crescent Hill, Elk Creek, Specimen Ridge, Bison Peak, Barronett Peak, Abiathar Peak, Mount Norris, Cache Creek, and Miller Creek. Petrified wood is also found along streams in areas east of Yellowstone Lake. The most accessible fossil forest is west of Tower Falls (Soldier’s Station, Wylie Camp). Petrified wood can be seen today in the foundation of Roosevelt Lodge.

The Smithsonian Institute holds the primary research collections of paleobotanical specimens from Yellowstone. The collection includes fossil plants collected by the Hayden surveys. Erling Dorf’s paleobotanical collections were transferred from Princeton to the Smithsonian.

Late Cretaceous plant fossil in northern

Two new Late Cretaceous fossil plant locations were discovered on Mount Everts in 1997 by Bianca Cortez. Preliminary fieldwork has yielded a variety of deciduous leaves, including willow-like leaf (similar to Salix), and a fern. A single willow-like leaf was found in association with the plesiosaur remains excavated in 1997.

In 1994 fossil plants were discovered in Yellowstone during the East Entrance road construction project, which uncovered five areas preserving fossil sycamore leaves. Paleobotanists William Fritz (Georgia State University), Kirk Johnson (Denver Museum of Natural History) and Scott Wing (Smithsonian) visited the sites and fossils collected by them were put in the park museum collection.

Fossil pollen has been analyzed by Baker (1976) from various sites in the park, including Buckbean Fen and Blacktail Pond. Deglaciation was determined to be approximately 14,500 B.P. (Gennett and Baker 1986).

Fossil Invertebrates

Middle Cambrian trilobite Ogygopsis cf.
klotzi in Yellostone Museum Collection.

Fossil invertebrates are abundant in Paleozoic rocks in the park and the limestones associated with the Madison Group are especially fossiliferous. Numerous "type" specimens are retained in collections at the Smithsonian and the Yale Peabody Museum. However, little attention has been given fossil invertebrates since the work of Walcott, Girty, and Stanton in the late 1800s.

The diversity of fossil invertebrates reported in the park includes:

Additional surveys are needed to document the distribution and diversity of fossil invertebrates in Yellowstone, and to increase our understanding of the park’s stratigraphy and paleoecology.

Fossil Vertebrates

The lack of paleontological research has lead to the belief that fossils are rare in Yellowstone. Fossil remains of vertebrates are rare, but perhaps only because of insufficient field research. A one-day survey by a small group led by Jack Horner resulted in the discovery of a piece of turtle shell, the skeleton of a Cretaceous plesiosaur, and a dinosaur eggshell fragment. The only other fossil reptile remains known from the park are a few dinosaur bone fragments.

A cochliodont crushing tooth plate was discovered in the limestones of the Madison Group by a paleontological survey team during 1997. Cochliodonts were a primitive group of holocephalian chondrichthys fish common during the Mississippian. The Yellowstone specimen was identified by Michael Hansen and Barbara Stahl (pers. commun., 1997). According to Stahl, the crushing tooth appears similar to those identified as “Helodus.”

Other fossil fish are present in both Paleozoic and Mesozoic sediments, with phosphatized fish bones in the Permian Shedhorn Sandstone, fish scales reported in the Cretaceous Mowry Shale, and fish teeth discovered in the Cretaceous Frontier Formation.

Recommended Taxonomy Projects

• Complete a thorough literature review and record all fossil taxa identified from the park.

• Inventory all Yellowstone fossil collections in the park museum and outside repositories.

• Identify any "type" fossil specimens from the park.

• Produce a paleo-taxa list of all known park fossil specimens.

• Create a paleo-taxa database including all known park fossils and associated data.

Petrified stumps in Lamar Valley.
No paleontological surveys for fossil vertebrates have been reported for Yellowstone’s Tertiary rocks. The extensive exposures of Wapiti and Wiggins formations that occur in the Absaroka Range are rich in fossil vertebrates outside of the park, but these units are somewhat isolated. These units exposed in the Hoodoo Basin area are recommended for systematic fossil surveys.

A possible Pleistocene horse, Equus nebraskensis, was reported by Lewis in 1939 and has been assigned the catalog number YPM-PU 14673 (Malcolm McKenna, pers. commun., 1996).

There is a possible Bison occidentalis skull from the park. Bison have become smaller as the species has evolved, with Bison bison antiquus the largest, Bison occidentalis intermediate, and Bison bison bison the most recent and smallest. Hawken’s Bison occidentalis was discovered in northeast Wyoming and dated to 6470 B.P. There are various other reports of Bison from the park including: McCartney’s Cave and Stephenson’s Island (Wayne Hamilton, pers. commun., 1996).

The most significant collection of fossil vertebrates are the Holocene subfossil mammals recovered from Lamar Cave (Barnosky 1994).

Trace Fossils

Tillman (1893) provided the first report of trace fossils in the park. Evidence of channeling and burrowing of worms or other insects occur in some petrified tree bark. Deiss (1936) reports Cruziana trace fossils in the Wolsey Shale.