3.1" Unknown Fossil Vertebrae And Bones in Matrix Late Cretaceous Era Niobrara FM KS
Location: Niobrara Formation, Gove County, Kansas
Weight: 1.9 Ounces
Dimensions: 3.1 Inches Long, 2.6 Inches Wide, 0.9 Inches Thick
Late Cretaceous, 83 million years old
The item pictured is the one you will receive.
The Niobrara Formation in Gove County, Kansas, is a significant geological unit, primarily composed of chalk and calcareous shale, deposited during the Late Cretaceous period. This formation is renowned for its rich fossil record, providing crucial insights into the marine life and paleoenvironment of the Western Interior Seaway.
The Niobrara Formation is subdivided into two members: the Fort Hays Limestone Member and the Smoky Hill Chalk Member. The Fort Hays Limestone Member, at the base, consists of massive beds of relatively pure chalk. Overlying this is the Smoky Hill Chalk Member, which is characterized by rhythmically bedded chalk and calcareous shale, often exhibiting a yellowish-white to light gray color when fresh, weathering to a buff or tan (Kansas Geology). The thickness of the Niobrara Formation in Gove County can range from approximately 500 to 700 feet (Roadside Geology of Kansas).
The depositional environment of the Niobrara Formation was a vast, shallow epicontinental sea, the Western Interior Seaway, which bisected North America during the Late Cretaceous. The fine-grained nature of the sediments, particularly the chalk, indicates deposition in relatively deep, calm waters with low terrigenous input. The chalk itself is primarily composed of the skeletal remains of coccolithophores, microscopic marine algae, along with foraminifera and other microfossils (Encyclopedia of Paleontology).
Gove County, specifically, is a well-known locality for vertebrate fossils from the Smoky Hill Chalk Member. These fossils include a diverse array of marine reptiles such as mosasaurs (e.g., Tylosaurus, Clidastes), plesiosaurs (e.g., Elasmosaurus), and sea turtles (e.g., Archelon). Fish fossils are also abundant, with notable examples including large predatory fish like Xiphactinus and numerous smaller species. Additionally, the Niobrara Formation in Gove County has yielded significant avian fossils, including the flightless diving bird Hesperornis and the toothed flying bird Ichthyornis (Fossils of the Niobrara Chalk). Invertebrate fossils, such as ammonites, inoceramid bivalves, and crinoids, are also common, providing further evidence of the marine ecosystem.
The excellent preservation of fossils in the Niobrara Formation is attributed to the anoxic or dysoxic conditions at the seafloor, which inhibited scavenging and decomposition. The fine-grained chalk matrix also contributed to the detailed preservation of skeletal remains (Vertebrate Paleontology). The study of these fossils from Gove County has been instrumental in understanding the evolution and ecology of Late Cretaceous marine life.
