“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 @masonschratterart.com.

 

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. Pacific Paleontology

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

 

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

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.

“Cliona, the Parasitic Marine Sponge”

 

Some sea sponges like this 5 million year old Cliona here 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's shell; a calcitic cast of the  internal mesh chambers of the sponge's drillings inside the snail's shell.  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”.  The drilling traces of the sponge can be so advanced and weakening the shell that the snail would have been more vulnerable to predators, making the interaction truly parasitic.You Tube Video: ​​https://youtu.be/bLPpwTlfiog

 

Advancements in Best Practices for Mitigation Paleontology
First update in the last 15 years to guide mitigation paleontology in California and elsewhere. This is super important for our practice and gives teeth to the foundational work of Paul Murphey, et. al. 2019, "A Foundation for Best Practices in Mitigation Paleontology". What is still needed is legislative protections and guidelines akin to what archeology has in place. Much more work is needed. https://www.paleosolutions.com/wp-content/uploads/2019/05/Murphey-et-al.-2019-Best-practices-in-mitigation-paleontology.pdf, and https://vertpaleo.org/wp-content/uploads/2025/10/SVP_Mitigation_Paleontology_Best_Practices_First_edition_October_2025.pdf

The Giant Carnivorous Sea Snail Clinopegma stantoni

The story of Clinopegma stantoni has been simmering here in Santa Cruz County for the past 116 years but is one that has been 5 million years in the making!  A little background on the name and history of this giant sea snail: Clino refers to slope and pegma is peg = pointed stick  The species is named in honor of Dr. Timothy W. Stanton, chief paleontologist. United States Geological Survey, whose work on Mesozoic faunas is well known.

The genus Clinopegma was named by Ulysses S. Grant, IV and Hoyt Rodney Gale published in 1931 in their monumental work on Pliocene and Pleistocene fossil mollusks of California.  Interestingly, here, U.S. Grant the IV, was the grandson of Ulysses S. Grant the first, president of the United States.  His grandson became a distinguished professor of paleontology at Berkeley

With regards to Clinopegma stantoni the species was named by Ralph Arnold in 1908 from the Año Nuevo park on the south side of the point in the upper member of the Purisima Fm. between Tunitas Creek and Pescadero Creek and near Ano Nuevo Creek in San Mateo County and also between New Brighton and Capitola beaches here in Santa Cruz and a couple other minor places and that’s it!

Coincidentally, Arnold also named a brand new species of Brittle Star, Amphiura sanctaecrucis that very same year of 1908 and that was discovered high up in the Santa Cruz Mountains and recently re-discovered en masse, dozens of individuals, in what’s called a brittle bed, but more on that in the movie…