Rare iridescent baculites fossil ammonite – baculites compressus, pierre shale, maastrichtian, cretaceous, montana, usa

Description This is a rare, beautifully iridescent Baculites compressus ammonite fossil from the Maastrichtian stage of the Late Cretaceous period (~72-66 million years ago), discovered in Montana, USA. Baculites were a genus of straight-shelled ammonites, an extinct group of marine cephalopods closely related to modern squid and cuttlefish. Unlike their coiled relatives, Baculites developed an elongated, uncoiled shell, allowing for greater hydrodynamic efficiency in open marine environments. This specimen is notable for its stunning natural iridescence, caused by the preservation of the original nacreous shell layers. The shimmering colors make this fossil highly desirable among collectors and paleontology enthusiasts. Geological Information: Formation: Pierre Shale Formation Stage: Maastrichtian (~72-66 million years old) Location: Montana, USA Depositional Environment: Marine seafloor sediment within the Western Interior Seaway Fossil Characteristics: Straight-shelled ammonite with well-defined suture patterns Exceptional iridescent nacreous shell preservation Rare Late Cretaceous specimen from Montana Highly collectible fossil with both scientific and aesthetic appeal Key Features: Authentic Baculites compressus fossil ammonite Rare iridescent shell preservation From the Alice Purnell Collection 100% genuine specimen with Certificate of Authenticity Scale Rule / Cube = 1cm – Please refer to the photos for accurate sizing. All fossils are securely packaged for worldwide shipping.