Grallator Track (Theropod Footprint)
Grallator cf. tenuis • Trace fossil (Ichnofossil); Vertebrate footprint
Geological Period
Late Triassic to Early Jurassic
Estimated Age
190–210 million years
Preservation Type
Natural cast (concave epirelief or convex hyporelief) preserved in fine-grained sediment
Condition Assessment
Fair to Good; the track is partially obscured by matrix and weathered, but the tridactyl symmetry and central digit extension remain diagnostic
Taxonomic Classification
Ichnogenus: Grallator; Phylum: Chordata; Class: Reptilia; Superorder: Dinosauria; Order: Saurischia; Suborder: Theropoda
Morphological Description
Small, tridactyl (three-toed) footprint. The central digit (III) is significantly longer than the lateral digits (II and IV). The footprint shows a narrow V-shape typical of bipedal theropods, with visible impressions of the metatarsal-phalangeal pads.
Rock Matrix
Reddish-brown mudstone/siltstone (likely ferruginous sandstone or shale)
Formation & Location
Commonly found in the Newark Supergroup (East Coast USA, e.g., Passaic or Portland Formations) or the Moenave/Kayenta Formations (Southwestern USA)
Size & Dimensions
Approximately 5–8 cm in length, which falls within the typical range for Grallator-type ichnotaxa (small theropods)
Value & Rarity
Estimated Market Value
$50 - $150 USD
Auction Estimate
$75 - $200 USD
Rarity Assessment
Uncommon; while Grallator tracks are locally abundant in specific formations, quality individual specimens on manageable matrix are desirable
Scientific Significance
Provides evidence of early dinosaur distribution and behavior in fluvial or lacustrine environments; helps track the evolution of small bipedal carnivores during the Mesozoic transition
Preparation Recommendations
Low-pressure air-abrasion to clear surface debris; stabilize with a thin coat of Paraloid B-72 if the matrix is crumbly; store in a dry environment to prevent oxidation of iron minerals
Notable Features
The distinctive red 'Passaic' style matrix is a hallmark of Triassic/Jurassic rift basin deposits; the specimen shows a clear claw-tip impression on the central digit