Keichousaurus
Keichousaurus hui • Body fossil; Marine Reptile (Vertebrate)
Geological Period
Triassic (Middle Triassic, Ladinian stage)
Estimated Age
242 to 237 million years ago
Preservation Type
Permineralization; skeletal remains are preserved in dark carbonaceous material offering high contrast against the lighter matrix. Minimal flattening suggests high-quality burial conditions.
Condition Assessment
Very Good to Excellent. The specimen is largely articulated with a complete skull, rib cage, and limbs. The deep preparation/excavation around the bone is a common commercial aesthetic choice.
Taxonomic Classification
Phylum: Chordata, Class: Reptilia, Order: Eosauropterygia, Family: Keichousauridae, Genus: Keichousaurus
Morphological Description
Small pachypleurosaur featuring a long neck, small head, and elongated tail. Distinctive compressed ulna and humerus (broadened in males). The specimen shows 5 digits on the limbs and a well-preserved vertebral column with dorsal ribs.
Rock Matrix
Carbonaceous siltstone or marly limestone, typically gray to brownish-buff. The specimen appears prepared with a deep relief 'ditch' or trough to emphasize the skeletal structure.
Formation & Location
Huishui Formation or Guanling Formation in Guizhou Province, China.
Size & Dimensions
Approximately 15-25 cm in total length. This specimen appears to be an adult of average size for the species.
Value & Rarity
Estimated Market Value
$1,200 - $3,500 USD (depending on size, gender, and proximity to authenticity verification).
Auction Estimate
$2,000 - $4,500 USD
Rarity Assessment
Uncommon but widely available. While thousands were collected in the late 20th century, high-quality, fully articulated specimens with minimal restoration are increasingly hard to find due to export restrictions.
Scientific Significance
Keichousaurus is one of the most significant taxa for studying the evolution of marine reptiles. They are known for being ovoviviparous (giving birth to live young), providing key insights into the reproductive biology of early sauropterygians.
Preparation Recommendations
Conservation focuses on mechanical cleaning (air-abrasion). Avoid water or chemicals that may degrade the matrix. Display in a climate-controlled environment to prevent 'pyrite disease' or moisture-induced fracturing.
Notable Features
The specimen is prepared in 'high relief'—a technique where the matrix is carved away to leave the fossil standing on a pedestal. The bone color is a rich brown, suggesting iron mineralization. The articulation of the cervical vertebrae and the presence of the delicate phalanges are particularly noteworthy.