Scale Tree Bark (Lepidodendron)
Lepidodendron cf. aculeatum • Body fossil (compression/mold); Plant (Lycopsid)
Geological Period
Carboniferous (Pennsylvanian sub-period)
Estimated Age
298 to 323 million years
Preservation Type
Carbonization and external mold. The organic material of the bark has been replaced by minerals or compressed into a thin carbon film, leaving a detailed three-dimensional impression of the surface texture.
Condition Assessment
Good. While the specimen is a fragment, it shows high-fidelity preservation of the diagnostic leaf cushions across a large surface area with minimal weathering on the primary face.
Taxonomic Classification
Kingdom: Plantae, Phylum: Lycopodiophyta, Class: Isoetopsida, Order: Lepidodendrales, Family: Lepidodendraceae, Genus: Lepidodendron
Morphological Description
The specimen displays a characteristic 'alligator skin' pattern composed of closely packed, rhomboidal/diamond-shaped leaf scars (cushions). Each scar represents the point where a leaf was originally attached. In some areas, the central leaf scar attachment point (leaf trace) is visible within the rhombic cushions.
Rock Matrix
Micaceous sandstone and siltstone. The grey-green to tan coloration is typical of iron-rich clastic sediments found in the Ouachita and Ozark regions.
Formation & Location
Likely from the Bloyd Formation or Atoka Formation in the Arkansas River Valley / Ozark Plateaus region of Arkansas, USA.
Size & Dimensions
Approximately 45-55 cm in length (based on scale). This represents a significant section of a trunk or large branch from a tree that could grow up to 30-50 meters in height.
Value & Rarity
Estimated Market Value
$150 - $350 USD
Auction Estimate
$200 - $450 USD
Rarity Assessment
Uncommon for this size and quality. While Lepidodendron fragments are common in coal-bearing regions, a large, well-defined plaque of this size is desirable for display.
Scientific Significance
Provides evidence of the 'Coal Forests' that dominated the tropics during the Pennsylvanian. These trees are significant drivers of the massive coal deposits found globally and represent an extinct lineage of giant club mosses.
Preparation Recommendations
Dry mechanical cleaning with a soft brush to remove dust. A light application of a thin archival consolidant (like Paraloid B-72) could enhance the contrast and stabilize the surface. Store in a low-humidity environment to prevent shale delamination.
Notable Features
The large surface area illustrates the consistent geometric growth pattern of the tree. The transition from fine detail to slightly obscured areas suggests varying pressure during the burial and fossilization process.
Notes
Arkansas