Graphoceras cf concavum Calcite Steinkern Ammonite Fossil Dorset UK Jurassic Bridport Inferior Oolite Genuine Specimen COA
£ 24.00
GENUINE GRAPHOCERAS CF. CONCAVUM CALCITE STEINKERN AMMONITE FOSSILThis is a genuine Graphoceras cf. concavum calcite steinkern ammonite fossil
from the Inferior Oolite Formation, Middle Jurassic, Bajocian Stage, collected from Bridport, Dorset, UK. This carefully chosen fossil specimen is an excellent piece for collectors of British ammonites, Jurassic fossils, Dorset fossils, cephalopods, calcite-preserved fossils, and natural history display specimens.The photograph shows the actual fossil you will receive, allowing you to view the individual shape, surface preservation, colour, mineral detail, matrix, and natural character of this specimen before purchase. Full sizing details can be seen in the photo. This fossil is supplied with a Certificate of Authenticity lifetime guarantee generic card, confirming it as a genuine specimen. FOSSIL TYPE, GENUS AND SCIENTIFIC IDENTIFICATIONGraphoceras cf. concavum is an ammonite, an extinct marine cephalopod from the order Ammonitida. Ammonites were related to modern squid, cuttlefish, octopus, and nautilus, and are among the most recognisable fossils of the Jurassic Period. Their coiled shells, changing ornamentation, and rapid evolution make them highly important in palaeontology and especially useful for dating sedimentary rocks.The abbreviation “cf.” means the specimen is comparable to Graphoceras concavum. This is a useful scientific convention when a fossil strongly resembles a named species but is identified with a degree of caution, often because of preservation, natural wear, incomplete shell detail, or subtle taxonomic variation. This makes the fossil particularly interesting for collectors who appreciate properly labelled and carefully described specimens.Graphoceras is associated with the family Graphoceratidae within the order Ammonitida. Graphoceratid ammonites are important Middle Jurassic fossils and are known for their compressed, planispiral shell forms and value in biostratigraphic study. Graphoceras concavum is closely linked with the Concavum Zone, an important ammonite biozone around the Aalenian to Bajocian interval. CALCITE STEINKERN PRESERVATIONThis specimen is described as a calcite steinkern. A steinkern is an internal mould formed when sediment or minerals fill the inside of a shell after the original shell material is lost or altered. In ammonites, this can preserve the overall coiled form and internal shape of the original shell, sometimes with excellent three-dimensional character.Calcite preservation adds further geological interest. Calcite, calcium carbonate, is a common mineral in fossil-bearing limestone deposits and can form as part of the fossilisation process. A calcite steinkern may show attractive natural mineral surfaces, pale cream, grey, beige, brown, or honey-toned colour variation, and subtle crystalline texture depending on the individual specimen. These natural mineral features add character and distinguish the fossil as a genuine geological object rather than a modern cast. GEOLOGICAL AGE, FORMATION AND LOCALITYThis ammonite comes from the Inferior Oolite Formation of Bridport, Dorset, UK. The Inferior Oolite is a classic British Middle Jurassic rock unit, famous for its fossiliferous limestones and rich marine fauna. It preserves evidence of warm, shallow seas that covered parts of southern Britain during the Bajocian Stage, approximately 170 to 168 million years ago.During the Bajocian, ammonites lived in marine environments alongside belemnites, bivalves, brachiopods, gastropods, echinoids, corals, and other invertebrates. After death, ammonite shells settled onto the sea floor and could become buried within lime-rich sediment. Over millions of years, mineralisation, compaction, and chemical alteration preserved some shells as fossils, including internal moulds such as steinkerns.Bridport and the wider Dorset area are well known for Jurassic geology and fossil collecting. Fossils from this region are popular with collectors because they represent classic British marine deposits and are connected to one of the most famous fossil-bearing regions in the UK. AMMONITE MORPHOLOGY AND COLLECTING APPEALThis Graphoceras cf. concavum fossil displays the classic planispiral ammonite form, with the shell coiled in a flat spiral. Depending on preservation, the specimen may show whorl shape, compressed shell profile, traces of ornamentation, natural mineral surfaces, sedimentary contact marks, and calcite-rich fossil texture. The whorls reflect the growth stages of the ammonite as the shell expanded during life.Ammonites are highly collectible because they combine visual appeal with scientific importance. Their changing forms allow geologists to compare rock layers and understand Jurassic time in detail. A calcite steinkern example from the Inferior Oolite Formation is especially appealing as a display fossil, educational specimen, and labelled British Jurassic collectible. AUTHENTICITY AND SPECIMEN DETAILSThis is a genuine Graphoceras cf. concavum calcite steinkern ammonite fossil from the Inferior Oolite Formation, Middle Jurassic, Bajocian Stage, Bridport, Dorset, UK. It includes a Certificate of Authenticity lifetime guarantee generic card. The photo shows the actual fossil you will receive, and full sizing information can be seen in the photo.
from the Inferior Oolite Formation, Middle Jurassic, Bajocian Stage, collected from Bridport, Dorset, UK. This carefully chosen fossil specimen is an excellent piece for collectors of British ammonites, Jurassic fossils, Dorset fossils, cephalopods, calcite-preserved fossils, and natural history display specimens.The photograph shows the actual fossil you will receive, allowing you to view the individual shape, surface preservation, colour, mineral detail, matrix, and natural character of this specimen before purchase. Full sizing details can be seen in the photo. This fossil is supplied with a Certificate of Authenticity lifetime guarantee generic card, confirming it as a genuine specimen. FOSSIL TYPE, GENUS AND SCIENTIFIC IDENTIFICATIONGraphoceras cf. concavum is an ammonite, an extinct marine cephalopod from the order Ammonitida. Ammonites were related to modern squid, cuttlefish, octopus, and nautilus, and are among the most recognisable fossils of the Jurassic Period. Their coiled shells, changing ornamentation, and rapid evolution make them highly important in palaeontology and especially useful for dating sedimentary rocks.The abbreviation “cf.” means the specimen is comparable to Graphoceras concavum. This is a useful scientific convention when a fossil strongly resembles a named species but is identified with a degree of caution, often because of preservation, natural wear, incomplete shell detail, or subtle taxonomic variation. This makes the fossil particularly interesting for collectors who appreciate properly labelled and carefully described specimens.Graphoceras is associated with the family Graphoceratidae within the order Ammonitida. Graphoceratid ammonites are important Middle Jurassic fossils and are known for their compressed, planispiral shell forms and value in biostratigraphic study. Graphoceras concavum is closely linked with the Concavum Zone, an important ammonite biozone around the Aalenian to Bajocian interval. CALCITE STEINKERN PRESERVATIONThis specimen is described as a calcite steinkern. A steinkern is an internal mould formed when sediment or minerals fill the inside of a shell after the original shell material is lost or altered. In ammonites, this can preserve the overall coiled form and internal shape of the original shell, sometimes with excellent three-dimensional character.Calcite preservation adds further geological interest. Calcite, calcium carbonate, is a common mineral in fossil-bearing limestone deposits and can form as part of the fossilisation process. A calcite steinkern may show attractive natural mineral surfaces, pale cream, grey, beige, brown, or honey-toned colour variation, and subtle crystalline texture depending on the individual specimen. These natural mineral features add character and distinguish the fossil as a genuine geological object rather than a modern cast. GEOLOGICAL AGE, FORMATION AND LOCALITYThis ammonite comes from the Inferior Oolite Formation of Bridport, Dorset, UK. The Inferior Oolite is a classic British Middle Jurassic rock unit, famous for its fossiliferous limestones and rich marine fauna. It preserves evidence of warm, shallow seas that covered parts of southern Britain during the Bajocian Stage, approximately 170 to 168 million years ago.During the Bajocian, ammonites lived in marine environments alongside belemnites, bivalves, brachiopods, gastropods, echinoids, corals, and other invertebrates. After death, ammonite shells settled onto the sea floor and could become buried within lime-rich sediment. Over millions of years, mineralisation, compaction, and chemical alteration preserved some shells as fossils, including internal moulds such as steinkerns.Bridport and the wider Dorset area are well known for Jurassic geology and fossil collecting. Fossils from this region are popular with collectors because they represent classic British marine deposits and are connected to one of the most famous fossil-bearing regions in the UK. AMMONITE MORPHOLOGY AND COLLECTING APPEALThis Graphoceras cf. concavum fossil displays the classic planispiral ammonite form, with the shell coiled in a flat spiral. Depending on preservation, the specimen may show whorl shape, compressed shell profile, traces of ornamentation, natural mineral surfaces, sedimentary contact marks, and calcite-rich fossil texture. The whorls reflect the growth stages of the ammonite as the shell expanded during life.Ammonites are highly collectible because they combine visual appeal with scientific importance. Their changing forms allow geologists to compare rock layers and understand Jurassic time in detail. A calcite steinkern example from the Inferior Oolite Formation is especially appealing as a display fossil, educational specimen, and labelled British Jurassic collectible. AUTHENTICITY AND SPECIMEN DETAILSThis is a genuine Graphoceras cf. concavum calcite steinkern ammonite fossil from the Inferior Oolite Formation, Middle Jurassic, Bajocian Stage, Bridport, Dorset, UK. It includes a Certificate of Authenticity lifetime guarantee generic card. The photo shows the actual fossil you will receive, and full sizing information can be seen in the photo.
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