Pacific Paleontology

09/05/2026

09/05/2026

“New Discovery of a Pacific Mastodon from the Bay Area”

We would like to introduce you to an exciting recent Ice Age discovery from our bay area here; the giant molar of an elephant-like creature that was neither an elephant nor a mammoth! This is a single molar from the newly described mastodon species Mammut pacificus, sp. nov., the Pacific Mastodon, and it is perhaps the most spectacularly well-preserved mastodon molar We’ve ever seen found locally here in the Bay Area to date. It is the upper left third molar, erupted but not ejected, from an adult pacific mastodon. The third molar of these proboscideans erupts at around 32 years of age, and this one shows minor wear, so we might derive this fellow was in the early 40 year-old stage, or so. This is the same species that was found at Rio Del Mar Beach, Aptos, CA, a couple of years ago (https://youtu.be/2Q6VVAEz_5U?si=q9hzdRzM48Q52GBd). We had the good fortune to be involved with this discovery from the parklands of the Mid Peninsula Regional Open Space Preserve (https://www.facebook.com/midpenopenspace) from a very early stage. We were able to do a site geological assessment and advise on its eventual conservation with colleague Chrissy Garcia at the Doerr School of Sustainability, Department of Earth and Planetary Sciences, Stanford University (https://sustainability.stanford.edu/). Unlike mammoths which were grazers, the pacific mastodon was a browser, going from tree to tree in shaded riparian environments stripping leaves from trees with its prehensile trunk. In our area during the last Ice Age this mastodon would have lived alongside other browsers, such as Jefferson’s Ground Sloth and other smaller creatures, next to the creek while at the same time Harlan’s ground sloths, mammoths, camels (yes, you heard that right), pronghorn antelopes, and giant bison were grazing in the sunny open grassy fields. For further information on this discovery see this recent article from MidPen: https://tinyurl.com/5dcf32mz. Great recreations by artists Haley Grunloh & Mason Schratter .com.

08/29/2026

Good morning, Monterey Bay. This is an uncommonly accurate true natural cast of one of Santa Cruz's most iconic fossil species, Anadara trilineata, Purisima Formation rock layer, Santa Cruz, May 16, 2026, c. 3 million years ago. These rather rare reproductions form when an organism decays inside a sediment mold, and new sediment fills the empty space to create a natural perfect replica of the original shape. This particular species spent it's days living part in and part out of the sediment at the bottom of the ancient sea, filter feeding on microorganisms with its incurrent and excurrent siphons. Often, polychaete worms would take up residence by burrowing into the part of the shell that stuck out of the sediment, mooching a free meal on the water flow at the clam's siphons.

06/18/2026

The joint was jumpin' under the ocean of the ancient Monterey Bay 5-million years ago ...

05/25/2026

Some fossilized friends from the Pliocene Purisima Formation of Santa Cruz; the extinct sand dollar species Dendraster ashleyi / D. gibbsii and the crab Cancer sp.

02/07/2026

“Cliona, the Parasitic Sponge”
Some sea sponges like this Cliona are parasitic, drilling into the calcium carbonate shells of other marine creatures to set up residence, in this case the host shell of a giant princess slipper snail, Grandicrepidula princeps. What we are seeing here is the fossilized trace of the Cliona sponge’s drillings on the inside of the snail shell; a calcitic cast of the internal mesh chambers of the sponge. Like an ant mound casting, this represents the trace of the sponge’s home, a cast of it, inside the shell of the snail, a subfield of paleontology dealing with traces of ancient life called “ichnology”.