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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 2014.009.044
Description Macoma nasuta, bent-nosed 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 comprised of white clams with blue-gray growth rings and other shell fragments embedded in grayish sandy soil. Clam shells are cracked and have striations running across their surfaces. These striations likely resulted from tectonic movement along the juniper Serra Fault. Underside surface is predominantly shell fragments embedded throughout.
Object Name Shell, Animal
Collection 3D - Paleontology
Title Macoma nasuta, Bent-nosed 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 Tellinidae (Bivalve molluscs)
Genus Macoma
Species nasuta
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 nasuta (Common name: Bent Nose Clam) still thrives in the Bay Area.
Dimensions H-1.25 W-6 D-5 inches
Search Terms Fossils
Merced Formation
South San Francisco
Subjects Fossils
Marine biology