Trigonioidea

Trigonioidea

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Fossil of a Trigonioidea

Trigonioidea is a superfamily of bivalve mollusks that belong to the order Unionida. These bivalves are known for their distinctively ornamented shells and have a long fossil record, dating back to the Triassic period. Trigonioidea are primarily found in freshwater environments, although some species have adapted to marine habitats.

Description

Members of the Trigonioidea superfamily are characterized by their thick, robust shells, which often display complex patterns of ridges and nodules. The shells are typically triangular in shape, which is reflected in the name "Trigonioidea." The hinge of the shell is equipped with strong teeth that interlock, providing stability and protection.

Evolution and Fossil Record

Trigonioidea have a rich fossil record that provides insight into their evolutionary history. They first appeared in the Triassic period and became particularly diverse during the Jurassic and Cretaceous periods. Fossils of Trigonioidea have been found on every continent, indicating their widespread distribution in ancient times.

Habitat and Distribution

Today, Trigonioidea are primarily found in freshwater environments such as rivers and lakes. Some species have adapted to brackish or marine conditions. They are distributed across various regions, with notable populations in Australia, South America, and Asia.

Taxonomy

The superfamily Trigonioidea is divided into several families, with the most prominent being the Trigoniidae. This family includes both extinct and extant species. The taxonomy of Trigonioidea is based on shell morphology and internal anatomical features.

Related Pages

• Bivalvia
• Unionida
• Mollusca

References

• Morton, B. (1996). "The Evolution of the Bivalve Molluscs." *Paleobiology* 22(4): 425-435.
• Carter, J. G., et al. (2011). "A Synoptical Classification of the Bivalvia (Mollusca)." *Paleontological Contributions* 4: 1-47.