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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 2014.009.042
Description Saxidomus nuttalli, California butter 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 intact, with top and bottom shells still attached at ligament. Growth lines are easily visible. Overall hue is reddish-brown, indicating the likely presence of iron oxide.
Object Name Shell, Animal
Collection 3D - Paleontology
Title Saxidomus nuttalli, California Butter Clam Fossil, 1.5-.75 Ma
Date 1.5 - .75 Ma
Kingdom Animalia (Animals)
Phylum Mollusca (Molluscs)
Class Bivalvia (Bivalves)
Order Veneroida (bivalve order)
Family Veneridae (Butterclam)
Genus Saxidomus
Species nuttalli
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.
Saxidomus nuttalli (Common name: California Butter Clam) still thrives in the Bay Area.
Dimensions H-1.375 W-3.25 D-2.25 inches
Search Terms Fossils
Merced Formation
Shellfish
South San Francisco
Subjects Fossils
Marine biology
Shellfish
Shells