|
Oppelia Mamertensis
''Oppelia'' is a haploceratoid ammonite and type genus for the Oppeliidae that lived during the Middle Jurassic. Shells of ''Oppelia'' are involute with a small to moderate size umbilicus, bluntly rounded to sharp venter, and deeply impressed dorsum. Sides are generally smooth but may be variously ribbed on the outer flanks. Similar and related genera include ''Oxycerites'' and ''Oecotraustes ''Oecotraustes'' is an extinct cephalopod genus included in the ammonid family Oppeliidae Oppeliidae are compressed to oxyconic, sculptured Haploceratoidea, either unkeeled, unicarinate, bicarinate, or tricarinate; with sutures in great varie ...''. Distribution Jurassic of Germany, Greenland, India, Italy, Madagascar, Mexico, Poland, Spain and the United Kingdom References Ammonitida genera Oppeliidae Jurassic ammonites Ammonites of Europe {{ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aptychus
An aptychus is a type of marine fossil. It is a hard anatomical structure, a sort of curved shelly plate, now understood to be part of the body of an ammonite. Paired aptychi have, on rare occasions, been found at or within the aperture of ammonite shells. The aptychus was usually composed of calcite, whereas the ammonite shell was aragonite. Aptychi can be found well-preserved as fossils, but usually quite separate from ammonite shells. This circumstance led to them being initially classified as valves of bivalves (clams), which they do somewhat resemble. Aptychi are found in rocks from the Devonian period through to those of the Cretaceous period. There are many forms of aptychus, varying in shape and in the sculpture of the inner and outer surfaces. However, because they are so rarely found in position within the ammonite shell, it is often unclear which kind of aptychus belonged to which species of ammonite. When only a single plate is present, as is sometimes the case, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
