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Point Reyes National Seashore

Point Reyes National Seashore, California
by Robert W. Boessenecker

Point Reyes is perhaps best known for its significance in Renaissance-era history: Drakes Bay (on the western part of the Point Reyes peninsula) is the most likely landing site of English privateer Sir Francis Drake. After a two-year campaign pillaging towns and capturing Spanish treasure ships along the coast of South America, Drake headed north. He landed at Drakes Bay in 1579 with his last remaining ship, the Golden Hind, and stayed for a period of time to make repairs, prior to continuing with his mission to circumnavigate the earth. What had initially proved so inviting to Drake were the cliffs at Point Reyes, which apparently reminded Drake of the famed White Cliffs of Dover on the southeastern coast of England. While the cliffs at Dover are composed of the Cretaceous Upper Chalk, the cliffs at Drakes Beach are weathered deposits of the much younger Santa Margarita Sandstone, Santa Cruz Mudstone, and Purisima Formation.

These strata were sporadically visited by paleontologists and geologists and in 1977 Alan Galloway mapped these exposures as the newly named Drakes Bay Formation. The name didn't stick very long, however; in 1984, geologists Joe Clark, Earl Brabb, Gary Greene, and Donald Ross published an updated geologic study of the Point Reyes Peninsula and indicated that the "Drakes Bay Formation" was actually mappable as three different formations already named in Santa Cruz County (listed here from oldest to youngest): the Santa Margarita Sandstone, Santa Cruz Mudstone, and the Purisima Formation. Regardless, these three formations all were deposited on the continental shelf (between 100 and 500 meters water depth, given known invertebrate fossils), and range in age from late Miocene at the base (7.9 million years old at the base of the Santa Margarita, thanks to radiometric dating) to early Pliocene near the top of the Purisima Formation (based on microfossil biostratigraphy). Unlike the deposits near Santa Cruz, invertebrate fossils such as mollusks and echinoderms are relatively rare.

All three of these formations have yielded vertebrate fossils (see Barnes 1977, Repenning and Tedford 1977, Domning 1978, Zeigler et al. 1997, Boessenecker 2013), including sharks, bony fish (including the saber-toothed salmon Oncorhynchus rastrosus and giant sturgeon, Acipenser), sea birds (such as the flightless penguin-like auk Mancalla), pinnipeds (including a walrus and the fur seal Thalassoleon macnallyae), dolphins and porpoises, sperm whales, a beluga-like whale (Denebola), baleen whales (such as the dwarf right whale Balaenula, the archaic dwarf mysticetes Herpetocetus and Nannocetus, and the blue whale-like Parabalaenoptera), and sea cows (Dusisiren, Hydrodamalis).

Here is a list of the types of fossils that have been found at Point Reyes National Seashore to date.1

Eocene: carbonized plant remains, seeds, forams
Miocene: mud shrimps, crabs, echinoids, bivalves, mollusks, diatoms, forams, fish scales, whale bones, [some of the following may be Pliocene] isopods, shrimp, crabs, echinoderms, bivalves, gastropods, mollusks, wood, plants, conifer cones, diatoms, forams, radiolarians, fish (teleosts), shark teeth, marine mammals (including sea lions, dolphins, whales)
Pliocene: [some of the following may be Pleistocene] crustaceans, echinoderms, bivalves, gastropods, sponge spicules, plant remains, carbonized wood, diatoms, forams, radiolarians, feathers, bony fish, sharks, sea lions, porpoises, whales
Quaternary: charcoal, wood, pollen
Pleistocene: arthropods, bivalves, gastropods, scaphopods, plants, tree trunks, freshwater diatoms

UCMP involvement
Some of the earliest fossils collected from Point Reyes were curated at UCMP, but it wasn't until the 1960s, 1970s, and early 1980s that UCMP graduate students like Lawrence Barnes (now curator emeritus, Natural History Museum of Los Angeles), Daryl Domning (now professor of anatomy, Howard University), and Samuel McLeod (collections manager, Natural History Museum of Los Angeles) went to Point Reyes specifically to recover vertebrate fossils. Many cetacean fossils collected during these early activities figured prominently in Barnes' (1972) dissertation, and were included in a later published faunal list (Barnes 1977). Pinniped fossils, including an articulated forelimb of a walrus and a partial skeleton of a fur seal named as the new species Thalassoleon macnallyae (after Kathleen McNally of Fremont, California, who discovered the skeleton) were published by Charles Repenning and Richard Tedford (1977). Sirenian fossils were briefly listed by Domning (1978). In the early 1980s, baleen whale specimens were collected by Sam McLeod and Frank Perry (paleontologist, Santa Cruz Museum of Natural History).

More recently, UCMP graduate Nick Pyenson (curator of fossil marine mammals, Smithsonian Institution) revisited Point Reyes and discovered a partial baleen whale skull with preserved baleen impressions. A latex mold and plaster cast from the specimen at Point Reyes is curated at UCMP. Such impressions are rare but reported from elsewhere in California and from Peru; other fossilized baleen has been reported from the Purisima Formation and includes three dimensionally preserved mineralized baleen (also in UCMP collections!) from exposures near Santa Cruz.

Beginning in 2011, I began a field investigation at Point Reyes with paleontologist Richard Hilton (Sierra College, Rocklin, California) under a National Park Service permit to collect vertebrate fossils. Existing collections indicated the presence of a few marine mammals, but not quite as diverse a fauna as had already been known for the Purisima Formation in other localities such as Santa Cruz and Half Moon Bay. We went on a number of weekend trips to Point Reyes and collected everything from shark teeth to whale mandibles and walrus skulls. On some occasions we accessed some difficult to reach spots by canoe and kayak.

Lucina alcatrazis Sand dollars
Click on either image to see an enlargement. Left: Exposures of the Purisima Formation at Point Reyes. Clockwise from top, a view north across Drakes Estero, some dolphin and baleen whale bones, a view along the cliffs from the Drakes Beach visitor center, and a tooth of the fur seal Thalassoleon macnallyae protruding from a cliff. Photos by Robert Boessenecker. Right: Some fossil marine mammals in the UCMP collections. These are from the Santa Margarita Sandstone and Purisima Formation at Point Reyes. Photos by Robert Boessenecker.

In the collections
The UCMP currently houses the largest collection of fossils from Point Reyes, although other smaller collections exist at the California Academy of Sciences in San Francisco and the Sierra College Natural History Museum in Rocklin. Fossils from the Santa Margarita Sandstone include giant sturgeon bones (Acipenser), a partial walrus forelimb (Dusignathus santacruzensis), isolated teeth and a skull of a sperm whale ("Scaldicetus"), and a skeleton of a sea cow (Dusignathus). A more sparse assemblage from the Santa Cruz Mudstone includes a possible fragmentary skull and earbones of the strange dolphin Albireo and a skull of the porpoise Piscolithax (previously known from Peru and Baja California). UCMP vertebrate fossils from the Purisima Formation include shark teeth (ancestral great white shark Carcharodon hubbelli, the cow/sixgill shark Hexanchus), vertebrae and tusks of the giant saber-toothed salmon Oncorhynchus rastrosus, and the flightless penguin-like auk Mancalla. Marine mammals include several partial skeletons of the fur seal Thalassoleon macnallyae (including a new pair of jaws that Richard Hilton and I collected in fall 2011 — see photo above) and a skull of a toothless walrus (Valenictus), several earbones and partial skulls of an unidentified porpoise, and two partial skulls of the beluga-like whale Denebola. Baleen whales include a partial skull and a pair of juvenile mandibles of the dwarf whale Herpetocetus, a jaw of a minke whale-like baleen whale, earbones of other species such as the dwarf right whale Balaenula and the humpback-like "Megaptera" miocaena. A single earbone may indicate that a second sea cow, the giant sea cow (~30 foot body length) Hydrodamalis cuestae may also be present in the Purisima Formation. Further field research at Point Reyes should be able to easily expand knowledge of this fauna, and these localities will continue to be one of the most significant marine vertebrate fossil sites in Northern California.

Note: Collection of fossil material is illegal unless done under a permit from the National Park Service. If you think you have found a fossil on National Park lands, please contact a park representative.

More information
Barnes, L.G. 1972. Late Tertiary Cetacea of the Northeast Pacific Ocean. Ph.D. dissertation. University of California, Berkeley. 494 pp.

Barnes, L.G. 1977. Outline of eastern North Pacific fossil cetacean assemblages. Systematic Zoology 25:321-343. doi:10.2307/2412508
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Boessenecker, R.W. 2013. A new marine vertebrate assemblage from the late Neogene Purisima Formation in central California, part II: Pinnipeds and cetaceans. Geodiversitas 35:815-940.
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Clark, J.C., E.E. Brabb, H.G. Greene, and D.C. Ross. 1984. Geology of Point Reyes Peninsula and implications for San Gregorio Fault history. Pp. 67-86 in J.K. Crouch and S.B. Bachman (eds.), Tectonics and Sedimentation Along the California Margin. Pacific Section SEPM, Los Angeles, California.
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Domning, D.P. 1978. Sirenian evolution in the North Pacific Ocean. University of California Publications in Geological Sciences 18:1-176.

Galloway, A.J. 1977. Geology of the Point Reyes Peninsula, Marin County, California. California Division of Mines and Geology Bulletin 202:1-72.
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Repenning, C.A., and R.H. Tedford. 1977. Otarioid seals of the Neogene. US Geological Survey Professional Paper 992:1-87.
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Zeigler, C.V., G.L. Chan, and L.G. Barnes. 1997. A new Late Miocene balaenopterid whale (Cetacea: Mysticeti), Parabalaenoptera baulinensis, (new genus and species) from the Santa Cruz Mudstone, Point Reyes Peninsula, California. Proceedings of the California Academy of Sciences 50(4):115-138.
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1 Based on a paleontological inventory taken by the National Park Service (2012 data). Fossil inventories for all the NPS fossil parks can be found on The Paleontology Portal's Fossils in the National Parks" module.

Pt. Reyes "snapshot" photo by David Smith.