Other Fossils

[Site Under Development]
Photograph of chevron folds in radiolarian chert.
Radiolarian chert is composed of layers of silica formed from the skeletons of microscopic, one-celled ocean animals called radiolarians. Golden Gate National Recreation Area, California.

NPS photo.

Introduction

Text

Bacteria

Bacteria are the most abundant of all organisms. They are ubiquitous in soil, water, and in symbiotic relationships with other organisms. Bacteria are unicellular organisms with a relatively simple cell structure, lacking a cell nucleus and organelles.

Bacteria fossils are the oldest and smallest ever found. Cyanobacteria, or “blue-green bacteria,” have been found in rocks from the Archean, 3.5 billion years ago. Cyanobacteria (along with other bacteria) also form mats and mounds known as stromatolites, which have existed on Earth from the Precambrian to the present day. Probably the most spectacular stromatolite fossils in the National Park System are those at Glacier National Park in Montana; however, as visitors make their ascent to the lower cliff dwellings at Tonto National Monument in Arizona, they may see Precambrian stromatolites in the Mescal-limestone boulders that line the trail. Valley Forge National Historical Park in Pennsylvania, Chesapeake and Ohio Canal National Historical Park in Maryland, and Grand Canyon National Park in Arizona also have stromatolites. Newly discovered stromatolite fossils at Capitol Reef National Park in Utah are challenging long-held assumptions about the paleoenvironment of the Navajo Sandstone.

Protists

Some scientists think that protists should be classified into several kingdom-level taxa because of their diversity in size, shape, life cycle, habitat, and feeding and reproductive strategy. However, here the term “protist” refers to any eukaryote that is not a plant, animal, or fungus. Most protists are unicellular, though some are multicellular or even multinucleate (many nuclei in one cell). Some live as single individuals, others as colonies. Some better known protists are dinoflagellates, foraminifera, radiolarians, diatoms, and green algae. Marine algae were very important to early evolution on Earth; the first land plants probably descended from them. Protists have a long, although in some cases patchy, fossil record stretching back to the Precambrian, with living relatives today.

Fungi

Other than being eukaryotes, fungi are a difficult group to define. Generally speaking they lack chlorophyll and are therefore unable to make food. As such, fungi digest their own food externally and absorb nutrients into their cells. In addition, they have a generally filamentous structure and reproduce via spores. Along with bacteria, fungi are the primary decomposers of dead organic matter in most terrestrial ecosystems. Many fungi have important symbiotic relationships with other organisms. Fungi are also used extensively by humans: yeasts are responsible for fermentation of beer and bread, and mushroom farming and gathering is a large industry in many countries. The kinds of fungi we eat or try to eradicate from our homes represent only a small number of the species in existence today. Some fungi can grow very large (e.g., mushrooms and puffballs). For example, the “humongous fungus” Armillaria gallica, commonly known as honey mushroom, is among the largest and oldest living organisms. Most fungi are multicellular, but some types such as yeasts are single celled. You might think that fungi are too fragile to fossilize or too difficult to identify as fossils; however, their fossil record goes back to the Precambrian.

Related Stories

Loading results...

    Featured Parks

    Related Links


    Last updated: December 11, 2024

    Tools

    • Site Index