Rare Nautilus Nautiloid Fossil Upper Greensand Formation Devon UK Cretaceous Cenomanian Marine Cephalopod from Wilmington

Description Rare Nautilus Nautiloid Fossil from the Upper Cretaceous of Devon This rare fossil nautiloid identified as Nautilus sp. originates from the Upper Greensand Formation near Wilmington, Devon, United Kingdom. Preserved within Upper Cretaceous marine sediments dating to the Cenomanian stage, approximately 100–94 million years ago, this remarkable fossil represents an ancient member of one of the most enduring cephalopod lineages in Earth’s history. The fossil shown in the photographs is the exact specimen you will receive. It has been carefully chosen as an interesting and well-preserved example of a Cretaceous nautiloid fossil. Please refer to the photographs for the full sizing and proportions of the specimen. This genuine fossil includes a Certificate of Authenticity lifetime guarantee generic card confirming its authenticity as a natural fossil specimen. About Nautilus – A Living Lineage from Ancient Oceans The genus Nautilus belongs to the order Nautilida, a group of marine cephalopods that have existed for hundreds of millions of years. Nautiloids are closely related to ammonites and modern cephalopods such as squid and octopus, but they possess an external chambered shell that has remained remarkably similar in structure since ancient times. Unlike ammonites, which became extinct at the end of the Cretaceous period, nautiloids survived the mass extinction event and still exist today in the modern oceans. Fossil nautiloids from the Cretaceous therefore represent an important evolutionary link between ancient cephalopod faunas and their modern relatives. During the Cenomanian stage of the Late Cretaceous, nautiloids lived alongside a diverse array of marine organisms including ammonites, bivalves, marine reptiles, and numerous fish species. Shell Structure and Morphology Nautiloids are distinguished by their smooth, tightly coiled planispiral shells divided internally into a series of chambers separated by curved septa. The living animal occupied the outermost chamber while the inner chambers were sealed off and used to regulate buoyancy. These chambers were connected by a tube known as the siphuncle, which allowed the animal to adjust the balance of gas and liquid inside the shell. This buoyancy control system enabled nautiloids to move vertically through the water column while searching for food. The shell of Nautilus typically displays gentle curvature with relatively smooth outer surfaces compared to the more heavily ornamented shells of ammonites. The internal chambers and septa structure are key identifying features of nautiloid fossils and reflect their highly efficient hydrostatic shell design. Geological Setting – Upper Greensand Formation The Upper Greensand Formation is an important Upper Cretaceous geological unit widely exposed in southern England, particularly in Devon, Dorset, and surrounding regions. The formation consists primarily of glauconitic sandstones and marls deposited in a shallow marine environment during the Cenomanian stage. The distinctive greenish colour of the rock results from the presence of the mineral glauconite, which forms in slow sedimentation conditions on the seafloor. These sediments accumulated in warm shallow seas that covered much of southern Britain during the Late Cretaceous. The formation is known for preserving a wide range of marine fossils including ammonites, nautiloids, bivalves, echinoids, and fish remains. Fossils from the Upper Greensand provide valuable information about marine life during the early stages of the Late Cretaceous period. Cretaceous Marine Ecosystem During the Cenomanian stage, the region that is now Devon lay beneath a warm epicontinental sea connected to the vast Tethyan Ocean. These seas supported diverse marine ecosystems populated by cephalopods, crustaceans, fish, and marine reptiles such as plesiosaurs and mosasaurs. Nautiloids were opportunistic predators and scavengers, feeding on small marine organisms including crustaceans and fish. Their chambered shells provided excellent buoyancy control, allowing them to inhabit various depths within the marine environment. The presence of nautiloid fossils in Upper Greensand deposits reflects the rich biodiversity of these Cretaceous seas and the complex food webs that existed within them. Authenticity and Collectability • Rare fossil nautiloid identified as Nautilus sp. • Upper Greensand Formation, Upper Cretaceous • Cenomanian stage, approximately 100–94 million years old • Collected from Wilmington, Devon, United Kingdom • The fossil shown in the photographs is the exact specimen you will receive • Includes a Certificate of Authenticity lifetime guarantee generic card Cretaceous nautiloid fossils from the Upper Greensand of Devon are sought after by collectors due to their geological significance and relative rarity compared to ammonites. This Nautilus specimen represents a fascinating piece of ancient marine history and a superb addition to any fossil collection, geological display, or natural history study.