This is a rare, beautifully iridescent Baculites compressus ammonite fossil, dating back to the Santonian stage of the Late Cretaceous period (~86-83 million years ago), discovered in South Dakota, USA. Baculites were straight-shelled ammonites, an extinct group of cephalopods closely related to modern squid and cuttlefish. Unlike coiled ammonites, Baculites developed an elongated, uncoiled shell, which likely aided in buoyancy and movement within the marine environment

This specimen features stunning natural iridescence, a result of the original aragonite shell layers reflecting light, creating an eye-catching play of colors. These fossils are highly sought after by collectors due to their aesthetic appeal and scientific importance.

Geological Information:

• Formation: Upper Cretaceous Marine Deposits
• Stage: Santonian (~86-83 million years old)
• Location: South Dakota, USA
• Depositional Environment: Shallow marine seafloor with fine sediment accumulation

Fossil Characteristics:

• Straight-shelled ammonite with well-defined suture patterns
• Exceptional iridescent nacreous shell preservation
• Rare Late Cretaceous specimen from the USA
• Highly collectible fossil with scientific and aesthetic value

Key Features:

• Authentic Baculites compressus fossil ammonite
• Rare iridescent preservation of the original shell
• From the Alice Purnell Collection
• 100% genuine specimen with Certificate of Authenticity

Scale Rule / Cube = 1cm – Please see photos for accurate sizing.

All fossils are securely packaged for worldwide shipping.