Mandelloideids

Mandelloideids are a group of extinct marine mollusks that lived during the Jurassic and Cretaceous periods. They are characterized by their distinctive shell morphology, which includes a large, flat, and often asymmetrical shell with a prominent umbo (a raised point) at one end. The shell is typically composed of aragonite, a form of calcium carbonate, and can vary in size from a few centimeters to over a meter in length.

Mandelloideids are believed to have been suspension feeders, filtering plankton and small particles from the water using their siphons. Their shells were likely used for protection and buoyancy. The group is named after the type genus Mandel, which was first described by the German paleontologist Friedrich von Alberti in 1839.

Mandelloideids are found in marine deposits worldwide, with the majority of species originating from the Tethys Ocean. They are often associated with other marine invertebrates, such as ammonites and belemnites, in fossil assemblages. The group is considered to be a part of the larger clade Heteroconchia, which includes other extinct and modern mollusks with similar shell characteristics.

The study of mandelloideids provides valuable insights into the evolution of marine mollusks and the paleoecology of ancient marine environments. Their distinctive shell morphology and widespread distribution make them an important subject of research in paleontology and evolutionary biology.