Keichousaurus
Keichousaurus hui • Body fossil; Vertebrate (Small aquatic Sauropterygian)
Geological Period
Middle Triassic (Ladinian stage)
Estimated Age
242 to 237 million years ago
Preservation Type
Carbonization and permineralization on a bedding plane with high relief contrast between the bone and matrix.
Condition Assessment
Very Good; the specimen shows exceptional articulation of the phalanges and vertebral column, though the skull details are slightly compressed.
Taxonomic Classification
Phylum: Chordata, Class: Reptilia, Superorder: Sauropterygia, Family: Keichousauridae, Genus: Keichousaurus
Morphological Description
Elongated neck with numerous cervical vertebrae; small skull with high orbits; robust humerus (broader in males); five-fingered manus and pes showing aquatic adaptation; long tail and flattened ribs typical of pachypleurosaurs.
Rock Matrix
Fine-grained, dark grey to yellowish-brown bituminous limestone/shale typical of the Huishui or Zhuganpo formations.
Formation & Location
Huishui Formation or Falang Formation, Guizhou Province, Southwest China.
Size & Dimensions
Approximately 15-25 cm in length; this specimen appears to be an adult based on the robustness of the limb bones.
Value & Rarity
Estimated Market Value
$800 - $2,500 USD
Auction Estimate
$1,200 - $3,000 USD
Rarity Assessment
Common; while highly sought after for their beauty, they are found in massive quantities in concentrated 'death beds' in China.
Scientific Significance
Crucial for understanding the evolution of marine reptiles; known for providing early evidence of ovoviviparity (giving birth to live young) in marine lepidosauromorphs.
Preparation Recommendations
Mechanical preparation via vibrating stylus is standard. Surface should be consolidated with a reversible polymer like Paraloid B-72. Avoid acids which dissolve the limestone matrix.
Notable Features
Excellent preservation of the manus (front paws), showing clear articulation of the digits. The pachyostotic (thickened) ribs are clearly visible, which served as ballast for the animal while diving.