Scale Tree Bark (Lepidodendron Bark)
Lepidodendron cf. aculeatum • Plant body fossil (compression/impression)
Geological Period
Carboniferous (Pennsylvanian subperiod)
Estimated Age
298 to 358 million years
Preservation Type
Compression and carbonization; the organic material has been converted into a thin carbon film while the physical structure is preserved as a topographical impression in the sediment.
Condition Assessment
Good; the diagnostic leaf cushion patterns are clearly visible, though the specimen is fragmented and lacks high-contrast detail or significant dimensionality (relief).
Taxonomic Classification
Kingdom: Plantae, Division: Lycopodiophyta, Class: Isoetopsida, Order: Lepidodendrales, Family: Lepidodendraceae, Genus: Lepidodendron
Morphological Description
The specimen displays characteristic diamond-shaped or rhombic leaf scars arranged in a spiral phyllotactic pattern. Each leaf cushion (pulvinus) shows subtle central markings representing the vascular bundle (leaf scar) and small parichnos scars for gas exchange. The vertical alignment is straight, indicating it originated from a primary trunk section.
Rock Matrix
Silty gray shale/mudstone with iron oxide staining (limonite) on the surface surfaces.
Formation & Location
Potentially the Mazon Creek Formation (Illinois, USA), various Coal Measures in the United Kingdom, or the Joggins Formation (Nova Scotia, Canada).
Size & Dimensions
The visible segment is approximately 5-8 cm in width; leaf cushions are roughly 1-1.5 cm high, consistent with medium-sized branches or young trunks of the Lepidodendron genus.
Value & Rarity
Estimated Market Value
$25 - $60 USD
Auction Estimate
$40 - $80 USD
Rarity Assessment
Common; Lepidodendron is a prolific fossil genus in Carboniferous coal-bearing strata worldwide, though well-defined tactile patterns are favored by collectors.
Scientific Significance
Provides evidence of the 'Coal Forest' ecosystems of the Paleozoic. These giant lycopods were major contributors to global biomass and the formation of terrestrial coal deposits, reflecting a period of high atmospheric oxygen and tropical swamp conditions.
Preparation Recommendations
Dry mechanical cleaning with a soft brush to remove loose matrix. No chemical consolidants are necessary unless the shale is flaky. Store in a low-humidity environment to prevent shale delamination.
Notable Features
Distinctive 'snake-skin' appearance caused by the detachment of leaves during the tree's growth; the specimen shows clear imbrication of the scales typical of the genus's outer cortical layer.