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Fossils Of Ancient Plants & Animals

Archeocyathida: An Extinct Reef Building Animal

Petrified Wood, Leaf Imprints & Plants In Amber

Plants that flourished on earth millions of years ago are perfectly preserved as fossils. In petrified wood, the tissue of ancient trees is completely replaced by minerals, converting trunks and branches into stone. In some cases, the cell structure is so perfectly preserved that it resembles microscopic stem sections of modern plants. In some fossil beds of sedimentary strata, imprints of leaves and seed cones are so perfectly preserved that minute details are visible through modern microscopes. And of course amber (nature's transparent tomb) preserves ancient life so perfectly that DNA fragments within the cells can actually be extracted and sequenced.

  • Plants Of Jurassic Park
  • Petrified Forest National Park
    The Infamous Dawn Redwood
    Ancient Horsetails (Equisetum)


  • Living Fossils At Palomar College
  • Leaves And Fruit Of Ginkgo biloba
    The Petrified Trunk Of Ginkgo beckii
    Cell Structure Of Petrified Ginkgo beckii
    Maidenhair Trees During The Fall & Winter
    Ginkgo Petrified Forest State Park In Washington


  • Stromatolites: Ancient Cyanobacteria
  • Stromatolites In Glacier National Park
    Living Stromatolites In Anza-Borrego Desert


  • Amber: Nature's Transparent Tomb

  • Petrified Wood In Anza-Borrego Desert

  • Petrified Wood In Northern Arizona

  • Petrified Redwood In Yellowstone National Park

  • Petrified Redwoods In California's Coast Ranges

  • Archeocyathida: Extinct Reef Building Animal

  • Fossil Echinoderms: Sand Dollar & Sea Biscuit

  • A 250 Million-Year-Old Scale Tree (Lycophyta)

  • A 270 Million-Year-Old Extinct Tree Fern

  • Living & Fossil Trees Of The Araucariaceae

  • Jet: Carbonzed Remains Of Ancient Trees

  • A Beetle Entomed In Pleistocene Tar

  • See The Anatomy Of Palm Wood

  • Continental Drift & Geography Of Cycads
  • See Massive Cycad Cone With Large Seeds


  • See Fossil Dinosaur Poop (Coprolite) From Utah

  • See Fossil Liquidambar Fruit From Utah

  • Cycad Leaf Impression From San Diego County

  • See Petrified Fig Syconia From Montana

  • Petrified Forest National Park In Arizona

  • Petrified Wood In The Anza-Borrego Desert

    Left: Pliocene mud hills in the Carrizo Badlands of Anza-Borrego Desert State Park. Right: Petrified logs of an unknown tree, possibly a cottonwood (Populus) or willow (Salix). 4-5 million years ago this area was a vast delta plain of the ancestral Colorado River. A mixed forest of walnut (Juglans), laurel (Umbellularia), avocado (Persea), cottonwood (Populus), willow (Salix), buckeye (Aesculus), ash (Fraxinus) and palm (Sabal) once flourished here. Large herds of animals grazed in this region of grasslands and scattered forests including mastadons, llamas, horses and tapirs. Today in this parched region of barren, eroded hills and deep gullies, only the bones and petrified wood from this great fauna and flora remain.

    The remains of a petrified tree trunk in the Carrizo Badlands.

    Radial view of petrified wood showing a small knot (blue arrow) and parallel annual rings.

    Right: A petrified palm petiole, possibly from a species of Sabal. Left: Sections of palm petioles from a present-day cabbage palm (S. palmetto). The cell structure of the petrified sample, composed of scattered vascular bundles without definite annual rings indicates that is was from a palm. Its flattened rather than round cross section compares favorably with the leaf stalk or petiole of a palm. Sabal petioles do not have the spiny teeth characteristic of other palm species, and an extinct species named S. miocenica has been documented for these pliocene mud hills by Paul Remeika (Paleontology and Geology of Anza-Borrego State Park, 1995).

    Living Sabal Palms:
    The Bayleaf Palm In Belize
    Strangler Fig On Cabbage Palm
    See The Anatomy Of Palm Wood

    Reference On The Paleontology Of The Anza-Borrego Desert Region:

    Remeika, P. and R. Farley Fleming. 1995. "Cretaceous Palynoflora and Neocene Angiosperm Woods From Anza-Borrego Desert State Park, California: Implications For Pliocene Climate of the Colorado Plateau and Age of the Grand Canyon." In: Paleontology and Geology of the Western Salton Trough Detachment, Anza-Borrego Desert State Park, California (Volume I). P. Remeika and A. Sturz, Editors. San Diego Association of Geologists, San Diego, California.


    Petrified Wood Near Cameron, Arizona

    Petrified wood fragments in northern Arizona near Cameron. These are probably from the Chinle Formation dating back to the Triassic Period, approximately 200 million years ago.

    End view of one of the above wood fragments in its natural state. It was not altered (sectioned or polished). The fine grain structure shows perfectly preserved tracheids viewed in a transverse (cross section) plane. This wood predates the larger vessels characteristic of angiosperms. Photo taken with a hand held Nikon D-90 and SB 400 Flash using a 60mm Micro Nikkor AF-S F/2.8G ED Macro Lens. Camera settings: ISO 200, F22, 1/200. The high density, thick-walled tracheids and parallel rays resemble some of the images in the Online Publication by Dr. Rodney A. Savidge (2007), particularly the genera Pullisilvaxylon and Chinleoxylon (previously listed under Araucarioxylon arizonicum).

    Note: The average diameter of one tracheid cell lumen in cross section is about 30-40 µm. The resolving power of an unaided human eye with 20-20 vision is about 70 µm. Therefore, the cellular detail in above wood fragment is invisible to the naked eye.

       See A Taxonomic Problem With Araucarioxylon arizonicum   

    • Savidge, R.A. 2007. "Wood Anatomy of Late Triassic Trees in Petrified Forest National Park, Arizona, USA, in Relation to Araucarioxylon arizonicum Knowlton, 1889." Bulletin of Geosciences 82 (4): 301-328.

    Cross section of petrified wood fragment from Cameron, Arizona compared with a modern pine stem. Both stem cross sections show two spring growth periods with larger tracheids separated by a narrower summer growth band with smaller tracheids. The petrified wood dates back to the Triassic Period, approximately 220 million years ago.

       Microscopic Structure of Wood   
       Age-Dating Trees By Annual Rings   
       Microscopic Anatomy of Stems & Roots   


    Petrified Redwood In Yellowstone National Park

    Lamar River Valley with Specimen Ridge in the distance, Yellowstone National Park. This range contains well-preserved petrified trees that are still in their original upright position. The trees in the foreground are narrow-leaf cottonwood (Populus angustifolia).

    Left: An upright, petrified redwood in Yellowstone National Park. Volcanic eruptions in this region during the Eocene epoch (50 million years ago) triggered massive landslides into mountain and valley streams. The mixture of ash, water and sand buried entire forests, including redwood trees very similar to those of coastal California. Before the wood decayed, silca from the volcanic mud flow replaced the cell contents (lumens), literally creating forests of stone. Unlike other petrified woods that are completely replaced with minerals, the petrified wood of this region has lignified cell walls of the original xylem tissue that are still intact. Right: A 50 million-year-old piece of petrified wood (possibly redwood) from nearby Lamar Valley compared with a piece of recent dead wood. Both are radial sections with parallel annual rings. Can you determine which piece is petrified?


    Archeocyathida: An Extinct Reef Building Animal

    Archaeocyathids were sessile, marine organisms of shallow, tropical and subtropical waters that lived during the early Cambrian period about 550 million years ago. They were widespread in Cambrian seas throughout the world and were the first major reef-builders before the true corals (phylum Coelenterata). [Ancient colonies of cyanobacteria called stromatolites formed massive "algal reefs" over one million years ago.] The extinction of archaeocyathids by the middle Cambrian coincides with a rapid diversification of sponges. There has been considerable disagreement about their taxonomy. They are sometimes placed in the phylum Porifera (sponges), although some authorities have placed them in the extinct phylum Archeocyathida (Archaeocyatha). Cladistical analysis indicates that the Archaeocyathida is a clade within the phylum Porifera.

    An individual archeocyathid has a conical or vase-shaped skeleton of calcite similar to a pair of perforated, nested ice cream cones. The concentric inner and outer walls are separated by a space (intervallum) containing numerous partitions (septa). The concentric walls and septa are commonly observed in fossilized limestone. The abundance of archaeocyathids in limestone outcrops indicates that they grew over one another in a tangled profusion as sponges do.

    Poleta limestone from the White Mountains of Inyo County, California. Abundant fossils of archeocyathids occur in outcrops of limestone in the pinyon-juniper woodland at about 7,000 to 8,000 feet elevation. An individual archeocyathid had a conical or vase-shaped skeleton of porous calcite similar to that of a sponge (or an ice cream cone). The red arrows show remnants of conelike archeocyathids embedded in the limestone. Massive colonies of archeocyathids were major reef-builders in ancient Cambrian seas approximately 550 million years ago.

    Archaeocythids in Poleta limestone of the White Mountains (Inyo County, California).


    Trilobites: Extinct Marine Arthropods

    Trilobites are often placed in the class Trilobita within the phylum Arthropoda. They flourished during the Cambrian period about 500 million years ago. The last of the trilobites disappeared in the mass extinction at the end of the Permian, about 250 million years ago. They are a famous and well-known fossil group, possibly second only to the dinosaurs. Trilobites are subdivided into nine orders and over 15,000 species. The body is composed of three major parts, the head (cephalon), thorax, and tail (pygidium). The name trilobite is derived from their characteristic three-lobed appearance. Most trilobites were apparently bottom-dwellers that filtered mud to obtain food. Their typical size was two to eight centimeters (1-3 inches), although large trilobites up to 70 cm (27 inches) have been found.

    Elrathia kingi from 550 million-year-old Wheeler Shale near Delta Utah.


    Dinosaur Tracks In Utah

    Tracks of a small upright dinosaur in sandstone south of Zion National Park. Paleontologists believe this might be the small carnivorous dinosaur (Megapnosaurus) that walked through this Jurassic marshland area about 200 million years ago. It may have hunted in packs. Bones of this species have been found in Arizona.


    A 270 Million-Year-Old Petrified Tree Fern

    During the Carboniferous Era, approximately 300 million years ago, the earth was dominated by extensive forests of giant lycopods (division Lycophyta), horsetails (division Sphenophyta) and tree ferns (division Pterophyta). Much of the earth's coal reserves originated from massive deposits of carbonized plants from this era. Petrified trunks from Brazil reveal cellular details of an extinct tree fern (Psaronius brasiliensis) that lived about 270 million years ago, before the age of dinosaurs. The petrified stem of Psaronius does not have concentric growth rings typical of conifers and dicot angiosperms. Instead, it has a central stele composed of numerous arcs that represent the vascular bundles of xylem tissue. Surrounding the stem are the bases of leaves. In life, Psaronius probably resembled the present-day Cyathea tree ferns of New Zealand.

    A petrified trunk from the extinct tree fern Psaronius brasiliensis. The central stele region contains arc-shaped vascular bundles of xylem tissue. The stem is surrounded by leaf bases which formed the leaf crown of this fern, similar to present-day Cyathea tree ferns of New Zealand. This petrified stem has been cut and polished to make a pair of bookends.

    A well-preserved stem section from the extinct tree fern Psaronius brasiliensis. Note the central stele region containing arcs of xylem tissue (vascular bundles). The structure of this stem is quite different from the concentric growth rings of conifers and dicots, and from the scattered vascular bundles of palms.


    Sweet Gum (Liquidambar) in Utah

    Left: The fruit of sweet gum (Liquidambar styraciflua) is composed of a spherical cluster of small capsules, each capsule with a sharp-pointed style and a pericarp bearing one or two tiny winged seeds. This shade tree is native throughout the eastern and midwestern United States. It is commonly planted in southern California for its beautiful crimson foliage during the late fall. Right: A fossilized liquidambar fruit from the Cretaceous Period (70-130 million years ago) embedded in Utah sandstone.

    Capsules of sweet gum (Liquidambar styraciflua) silhouetted against a full moon in author's backyard.


    Ancient Cycad Leaf Impression From San Diego County

    A cycad leaf impression from Carlsbad, California. It was discovered in the 75 million-year-old Point Loma Formation of coastal San Diego County.

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