Omastata

Omastata is a genus of extinct marine mollusks that lived during the Mesozoic era, approximately 250 to 66 million years ago. The name "Omastata" is derived from the Greek words "oma" meaning ear, and "statos" meaning standing, referring to the distinctive ear-like structures on the shells of these organisms. Omastata is classified within the subclass Ammonoidea, which includes other extinct marine mollusks known as ammonites.

The shells of Omastata are typically coiled, with a smooth or slightly ribbed surface, and can reach lengths of up to 30 centimeters. They are characterized by their distinctive ear-like structures, which are actually extensions of the siphuncle, a tube that runs through the center of the shell. These structures are thought to have been used for buoyancy control or communication.

Omastata is found in marine sedimentary rocks from the Jurassic and Cretaceous periods, primarily in Europe and North America. Fossils of Omastata are relatively common and are often used as index fossils to help determine the age of sedimentary rocks. The genus includes several species, with the most well-known being Omastata compressa and Omastata rostrata.

Omastata is an important fossil group for paleontologists, as it provides valuable information about the evolution of marine mollusks and the environments in which they lived. The study of Omastata has contributed to our understanding of the diversity and adaptations of these ancient organisms, as well as the changes in oceanic conditions over time.