Cladoceramus

Cladoceramus was an extinct genus of fossil marine pteriomorphian bivalves. These ancient creatures looked a bit like the winged pearly oysters in the extant genus Pteria, but they lived long ago during a time called the Santonian stage of the Late Cretaceous. Scientists study fossils of Cladoceramus to learn more about life in the oceans millions of years ago. Even though these bivalves are no longer around today, their fossils help us understand how marine life has changed over time.

Description

Adult shells of Cladoceramus ranged from small to very large, with some being more than 1 metre (3 ft 3 in) long. Many species had special patterns on their shells, made of closely spaced lines that grew in circles. These shells also had unique shapes, including a well-defined, triangular part at the back and sometimes small "ears" at the front.

Biostratigraphic significance

The first time scientists found the species Cladoceramus undulatoplicatus, it helped them know when the Santonian stage began. This tiny sea creature appeared at the start of this time period in Earth's history.

Distribution

Fossils of this ancient sea creature have been discovered in several places. In Africa, they were found in the Matulla Formation in Egypt. In the United States, fossils have been uncovered in Forbes Shale in California, the Smoky Hill Shale and Niobrara Formation in Colorado and New Mexico, the Austin Chalk in Texas, and the Mancos Shale in Wyoming.