Oligocène
Intervalle géologique9 image(s) · 1 Actualités
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Shetwemys, Plastral remains of the podocnemidid turtle S. fajumensis (Erymnochelyini). (a–b) NHMUK R3435, anterior plastral lobe, in ventral (a) and dorsal (b) views. (c–d) NHMUK R8441, plaster cast of the specimen CGM C8509, anterior plastral lobe, in ventral (c) and dorsal (d) views. (e–f) AMNH 5093, articulated epiplastra and entoplastron, in ventral (e) and dorsal (f) views. (g–h) SMNS 11233/6, anterior plastral lobe, in ventral (g) and dorsal (h) views. (i–j) NHMUK R3103, partial anterior plastral lobe, in ventral (i) and dorsal (j) views. (k–l) SMNS 11233/5, right hypoplastron, in ventral (k) and dorsal (l) views. (m–n) SMNS 11233/3, articulated left hypoplastron and xiphiplastron, in dorsal (m) and ventral (n) views, and detail of the outer ornamental pattern (o). Gebel Quatrani Formation, Fayum depression, Egypt, Lower Oligocene (Rupelian)
Shetwemys, Shell remains of the podocnemidid turtle S. fajumensis (Erymnochelyini). (a–c) SMNS 11233/2, partial carapace, in dorsal (a), ventral (b), and left lateral (c) views. (d) Ventral view of the anterior lobe the holotype of the species, currently lost, based on the fig. 2C in plate 8 of Andrews (1903). (e–g) SMNS 12647, plastron, in ventral (e), dorsal (f), and left lateral (g) views. (g’) corresponds to an enlarged photograph of the posterior plastral lobe, in left lateral view, in which the thickness in the regions close to the hypo-xiphiplastral suture (in blue), between the pelvic scars (in green), and at the level of the anal notch (in red), have been represented by arrows (h–i), SMNS 12646, plastron, in ventral (h) and dorsal (i) views. Gebel Quatrani Formation, Fayum depression, Egypt, Lower Oligocene (Rupelian)
Shetwemys, Shell remains of the podocnemidid turtle S. fajumensis (Erymnochelyini). (a–f) AMNH 5087, carapace and partial plastron, in dorsal (a), ventral (b), anterior (c), posterior (d), left lateral (e), and right lateral (f) views. (g–h) SMNS 11233/1, partial carapace, in dorsal (g) and ventral (h) views. Gebel Quatrani Formation, Fayum depression, Egypt, Lower Oligocene (Rupelian)
Crommium angustatum Grateloup, 1827 fossil snail shell (apical view) from the Oligocene of France. (42 mm across at its widest) Of all the molluscs, the gastropods (snails) have made the most ecological adaptations. They can be found in almost all fundamental environments: marine, freshwater, terrestrial. Most gastropods live in the ocean, and have a single, asymmetrically coiled, external shell of calcium carbonate (CaCO3 - usually aragonite). The hard calcareous shell is the most easily fossilized part of the gastropod. The soft parts of a snail (the “slug” portion) include a well developed head having eyes, tentacles, and a mouth, and a well developed, strong, muscular foot used principally for locomotion. The shell is carried upright on the snail’s back, or is partially dragged behind. When threatened by a predator, many snails can retract their soft parts into the shell’s interior for protection. Many fossil snails in the Paleozoic rock record are often not well preserved, or are preserved as internal molds. The original aragonite of many gastropod shells is not stable on geologic time scales, and often recrystallizes or dissolves completely away. Fossil snail shells in Mesozoic and Cenozoic rocks are usually better preserved. Classification: Animalia, Mollusca, Gastropoda, Naticoidea, Ampullinidae Age: Rupelian Stage (Stampian Stage), Lower Oligocene Locality: Gaas, Landes Department, Aquitaine, southwestern France
Crommium angustatum Grateloup, 1827 fossil snail shell (apical view) from the Oligocene of France. (42 mm across at its widest) Of all the molluscs, the gastropods (snails) have made the most ecological adaptations. They can be found in almost all fundamental environments: marine, freshwater, terrestrial. Most gastropods live in the ocean, and have a single, asymmetrically coiled, external shell of calcium carbonate (CaCO3 - usually aragonite). The hard calcareous shell is the most easily fossilized part of the gastropod. The soft parts of a snail (the “slug” portion) include a well developed head having eyes, tentacles, and a mouth, and a well developed, strong, muscular foot used principally for locomotion. The shell is carried upright on the snail’s back, or is partially dragged behind. When threatened by a predator, many snails can retract their soft parts into the shell’s interior for protection. Many fossil snails in the Paleozoic rock record are often not well preserved, or are preserved as internal molds. The original aragonite of many gastropod shells is not stable on geologic time scales, and often recrystallizes or dissolves completely away. Fossil snail shells in Mesozoic and Cenozoic rocks are usually better preserved. Classification: Animalia, Mollusca, Gastropoda, Naticoidea, Ampullinidae Age: Rupelian Stage (Stampian Stage), Lower Oligocene Locality: Gaas, Landes Department, Aquitaine, southwestern France
Crommium angustatum Grateloup, 1827 fossil snail shell (abapertural view) from the Oligocene of France. (57 mm tall) Of all the molluscs, the gastropods (snails) have made the most ecological adaptations. They can be found in almost all fundamental environments: marine, freshwater, terrestrial. Most gastropods live in the ocean, and have a single, asymmetrically coiled, external shell of calcium carbonate (CaCO3 - usually aragonite). The hard calcareous shell is the most easily fossilized part of the gastropod. The soft parts of a snail (the “slug” portion) include a well developed head having eyes, tentacles, and a mouth, and a well developed, strong, muscular foot used principally for locomotion. The shell is carried upright on the snail’s back, or is partially dragged behind. When threatened by a predator, many snails can retract their soft parts into the shell’s interior for protection. Many fossil snails in the Paleozoic rock record are often not well preserved, or are preserved as internal molds. The original aragonite of many gastropod shells is not stable on geologic time scales, and often recrystallizes or dissolves completely away. Fossil snail shells in Mesozoic and Cenozoic rocks are usually better preserved. Classification: Animalia, Mollusca, Gastropoda, Naticoidea, Ampullinidae Age: Rupelian Stage (Stampian Stage), Lower Oligocene Locality: Gaas, Landes Department, Aquitaine, southwestern France
“Sternberger Kuchen” (“Sternberg cake”), a large late Pleistocene glaciofluvial pebble of a highly fossiliferous, shallow marine sandstone of the North German Paleogene (Sülstorf beds, formerly known as “Sternberg rock”, Chattian, Oligocene, about 25 million years old). The fossil content is mainly made up of mollusks (pelecypods, gastropods, scaphopods). Provenance: Sternberg, Mecklenburg-Vorpommern, Northeast Germany.
