Fossil Cowrie

Associated Smithsonian Expert: Marguerite Toscano, Ph.D.

Paleontologist Maggie Toscano with fossil shells she collected during a visit to a quarry in Naples, Florida.

Photographed by Donald E. Hurlbert, Smithsonian Institution.

Dr. Marguerite Toscano is a research geologist specializing in ancient tropical marine environments in Florida and the Caribbean. Growing up in New York City, Maggie spent summers along Long Island beaches searching for shells and other treasures of the sea, read every field guide, and knew the scientific names of just about everything marine. During college and graduate school she developed interests in marine fossils, ancient and modern coral reefs, radiometric dating, and using fossil reefs and mangrove deposits to reconstruct paleo sea levels. A highlight of graduate school in Florida was visiting the shell quarries near Sarasota and Naples where Pliocene tropical mollusks, corals, and bones were mined. After earning her doctorate in 1996, she did research on coral bleaching at NOAA, and completed the Paleontologic Inventory of the South Florida-Caribbean Network of National Parks for the National Park Service. She joined the Smithsonian in 2000. She is currently conducting geologic and sea level research in mangrove deposits in Belize, Panama and Florida, and is working with the Smithsonian’s MarineGEO and Tennenbaum Marine Observatories Network to design and install state of the art sea level monitoring stations at Smithsonian field stations.

Meet our associated expert

This image was obtained from the Smithsonian Institution. The image or its contents may be protected by international copyright laws.

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Detailed geologic time scale.
From the Geologic Society of America, used with permission

About Golden Gate Quarry

About 3 to 3.35 million years ago, when sea level was several meters higher than it is today, southern Florida was submerged by a shallow tropical sea with reefs and wetlands that were home to numerous mollusks, corals, fish, mammals, and birds. Although the shell, coral, and mollusk remains are fossils and are scientifically valuable to paleontologists and geologists, there is such a large supply of them that they can be used for other purposes. The Golden Gate Quarry uses the fossil shells and coral from this ancient environment in concrete mix in the foundations of buildings and for roads and highways in the area. Take a look when you walk down the roadways in Florida and try to find the same types of fossils from the quarry as part of the road itself.

Piles of fossils from an ancient shallow sea in Florida, ready to be used as aggregate in construction. Location: Golden Gate Quarry, Naples, FL.
Photographed by Donald E. Hurlbert, Smithsonian Institution

How People Build with Fossils from Golden Gate Quarry

It is surprising to most people that fossils are actually used to build roads and buildings. The fossils from the Golden Gate Quarry may be mixed with rocks and used as "fill" beneath roads and highways. They may also be mixed in the asphalt and be seen at the road surface. Rock and fossils from this ancient reef may also be used in producing cement, the glue of concrete. The concrete used to make curbs and gutters will contain these materials, and if you look closely, you can find shells and corals mixed in these products.

Related Resources
Drawing of fossil Miocene snail (Echphora gardnerae ) from Calvert Cliffs, Maryland
Photo by Mary Parrish, Smithsonian, National Museum of Natural History

About Gastropods (Class Gastropoda): Paleobiology

During their long history on Earth (about 500 million years), gastropods have evolved various ways to feed. Flat snails (e.g., Maclurites) likely lived like clams, sitting in one place and eating small food suspended in the water. They were common in the Paleozoic, but are now extremely rare. Most gastropods actively find detritus or algae to eat, scraping food off rocks or other surfaces using a special mouthpart (the radula). Other gastropods are carnivores: shells with holes in them are evidence of gastropods using their radula to drill a hole and eat the animal inside. The earliest gastropods were detritivores, but carnivory has evolved independently several times (convergent evolution). During the shift from herbivory to carnivory, the teeth on gastropod's radulas were lost or modified for use as predatory tools. Early gastropods lived in the sea, but by the Carboniferous (360 - 299 million years ago) some freshwater gastropods invaded land. During the transition to land, gastropod shells either remained rather thick (in dry climates) or were reduced or even lost altogether (in humid climates).