Yaklamnidae

Yaklamnidae is a taxonomic family of fossil mollusks within the class Bivalvia. It is known from well-preserved shell fossils found in marine sedimentary rocks of the Mesozoic era. The family is characterized by an elongated, equivalved shell with a moderately convex profile and a distinctive hinge line. Ornamentation is variable, often showing radial ribbing or concentric growth lines; the byssal notch can be present in some species. The soft-tissue anatomy remains unknown.

The taxonomy and phylogeny of Yaklamnidae are debated; while widely treated as a valid family, its exact placement within Bivalvia differs among analyses, with suggestions ranging from basal heterodonta to early luciniforms. The family comprises several described genera, but material is fragmentary, and few species are well diagnosed.

Fossils have been recovered from formations in Asia, Europe, and North America. The temporal range extends from the late Triassic to early Cretaceous, with the best-preserved specimens from the Jurassic. Most members are interpreted as shallow-marine, sessile or byssally attached filter feeders along coasts and continental shelves.

Significance: Yaklamnidae contributes to understanding early diversification of bivalves and paleobiogeographic patterns during the Mesozoic.