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The mission of the San Mateo County Historical Association is to inspire wonder and discovery
of the cultural and natural history of San Mateo County.

Object Record

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Catalog Number 2014.009.030
Description Macoma inquinata, pointed macoma (clam) fossil dating from between 1.5 million years ago to .75 million years ago commonly found at low tide in littoral (sandy and muddy bottom) or sub-littoral (open bay, muddy marine) zones. Fossil specimen is irregularly shaped, with top shell easily identifiable. Shell is oval, with a slightly rounded top. Bottom portion of specimen is sediment in which the fossil is embedded. Overall reddish tinge likely indicates the presence of iron oxide.
Object Name Shell, Animal
Collection 3D - Paleontology
Title Macoma inquinata, Pointed Macoma (clam), 1.5-.75 Ma
Date 1.5 - .75 Ma
Kingdom Animalia (Animals)
Phylum Mollusca (Molluscs)
Class Bivalvia (Bivalves)
Order Veneroida (bivalve order)
Family Tellinidae (Bivalve molluscs)
Genus Macoma
Species inquinata
Inscription Text none
Provenance Fossils taken from Merced Formation collected at Westborough Boulevard at Highway 280 in the late 1970s or early 1980s. (See Yancey 1978, Fig. 2: Artifacts taken from E Stratified Section/D-5929). Most specimens (especially clams) in this collection are not extinct and can still be found in the Bay Area.
Notes Retired Geologist Ken Lajoie identified on 4/8/2014.
Macoma inquinata (also known as Pointed Macoma Clam) still thrives in the Bay Area.
Dimensions H-1.25 W-2 D-1.25 inches
Search Terms Fossils
Merced Formation
South San Francisco
Subjects Fossils
Marine biology