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The mission of the San Mateo County Historical Association is to inspire wonder and discovery
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Object Record

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Catalog Number 2014.009.025
Description Lucinoma annulata, ringed lucine 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. Specimen is intact, with top and bottom shells still attached at ligament. Overall reddish brown hue likely indicates the presence of iron oxide. Smaller, light brown areas along the outer edges of top and bottom shells. Reddish-brown patches of loose sediment are visible throughout.
Object Name Shell, Animal
Collection 3D - Paleontology
Title Lucinoma annulata, Ringed Lucine Fossil, 1.5-.75 Ma
Date 1.5 - .75 Ma
Kingdom Animalia (Animals)
Phylum Mollusca (Molluscs)
Class Bivalvia (Bivalves)
Order Veneroida (bivalve order)
Family Lucinidae (Saltwater clams)
Genus Lucinoma
Species annulata
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 4/24/2014.
Lucinoma annulata (Common name: Ringed Lucine) are nearly symmetrically round, with a point in the center. Shells feature ridged rings, which are added annually. This species still thrives in the Bay Area.
Dimensions H-0.75 W-1.75 D-1.75 inches
Search Terms Fossils
Merced Formation
Shellfish
South San Francisco
Subjects Fossils
Marine biology
Shellfish
Shells