Crows Foot Shark Tooth / Extinct Mackerel Shark Tooth
Anomotodon cf. sheppeyensis or similar lamniform tooth • Body fossil; vertebrate dental remain (Elasmobranchii)
Geological Period
Cretaceous (Late Cretaceous) to Paleogene (Eocene)
Estimated Age
Approximately 50 to 80 million years
Preservation Type
Mineral replacement (permineralization) with phosphate and potentially iron-rich minerals giving it a dark, near-black coloration.
Condition Assessment
Fair to Good; the crown is mostly intact with visible ornamentation, but the root structure shows significant wear or breakage, and the edges are slightly rounded from water transport.
Taxonomic Classification
Phylum: Chordata, Class: Chondrichthyes, Order: Lamniformes, Family: Mitsukurinidae (likely), Genus: Anomotodon aff.
Morphological Description
A small, slender fossil tooth characterized by a narrow, tapering central cusp and distinct vertical striations/costae at the base of the crown. The 'crows foot' appearance is created by the flaring of these basal striations or small accessory cusplets. The root appears bifurcated but partially worn.
Rock Matrix
None present (isolated specimen); likely originated from a marine phosphate bed or glauconitic sand common in coastal deposits.
Formation & Location
Commonly found in the London Clay (UK), Nanjemoy Formation (USA, Maryland/Virginia), or phosphate mines in Morocco (Khouribga basin).
Size & Dimensions
Approximately 10-15mm in length; this is within the typical small-to-average size range for juvenile lamniform or goblin-type shark teeth.
Value & Rarity
Estimated Market Value
$5.00 - $15.00 USD
Auction Estimate
$10.00 - $25.00 USD (typically sold in larger study lots rather than individually)
Rarity Assessment
Common; such teeth are frequently found in classic shark tooth localities and phosphate deposits worldwide.
Scientific Significance
Provides data on the biodiversity of Mesozoic/Cenozoic marine apex predators and the evolution of specialized feeding mechanisms in lamniform sharks (related to modern Goblin sharks).
Preparation Recommendations
Requires minimal intervention. Clean with soft brush and distilled water if necessary. Store in a padded gem jar or membrane box to protect the fragile tip from impact.
Notable Features
The most striking feature is the heavy basal ribbing/striation, which helps distinguish it from more common smooth-crowned shark species like Carcharias.