Trilobite (Partial Impression)
Redlichia cf. rex or aff. chinensis • Body fossil (impression/mold); Invertebrate arthropod
Geological Period
Lower to Middle Cambrian
Estimated Age
505 to 520 million years
Preservation Type
Compression and external mold preservation with significant iron oxide (limonite/hematite) replacement and staining.
Condition Assessment
Fair; the specimen is highly weathered, fragmented, and lacks clear articulation of the distal pygidium and genal spines.
Taxonomic Classification
Phylum: Arthropoda; Class: Trilobita; Order: Redlichiida; Family: Redlichiidae
Morphological Description
The specimen exhibits a partial cephalon and likely early thoracic segments. Visible features include a faintly raised glabella and indications of a pleural lobe. The surface shows fine granulation characteristic of the exoskeleton being pressed into fine-grained sediment.
Rock Matrix
Ferruginous shale or micaceous siltstone, heavily weathered with a reddish-brown iron-rich patina.
Formation & Location
Likely the Emu Bay Shale (Australia) or the Chengjiang Biota/Maotianshan Shales (Yunnan Province, China).
Size & Dimensions
Approximately 4-6 cm in length; consistent with mid-sized Redlichiid trilobite fragments.
Value & Rarity
Estimated Market Value
$25 - $60 USD
Auction Estimate
$40 - $80 USD
Rarity Assessment
Common; while the taxa is scientifically significant, partial impressions in weathered matrix are frequently found in Cambrian deposits.
Scientific Significance
Trilobites from this period are crucial for understanding the Cambrian Explosion and the early radiation of complex arthropods. This specific type represents early ocean floor scavenging species.
Preparation Recommendations
No further mechanical preparation is advised as the matrix is brittle. Should be stored in a dry, low-humidity environment to prevent further oxidation of the iron minerals. Can be stabilized with a very dilute solution of Paraloid B-72 if flaking occurs.
Notable Features
Distinctive deep reddish-orange coloration due to high iron content in the host rock; the impression allows for visibility of the dorsal suture lines despite the lack of original calcified shell.