#fossilfriday A rare example of a well-preserved gill raker of a basking shark (Cetorhinus maximus), ~6myo, from the Purisima Formation of Santa Cruz, CA - typically broken up into tiny bits. Used for filter feeding, basking shark rakers are uniquely formed from enameloid dermal denticles. 🦈🦖🧪

#whalewednesday A skull of a narwhal at the @nhm-london.bsky.social with a cutaway view of the unerupted right tusk. The left tusk is typically the only one to erupt - but rare double tuskers do occur with an erupted right tusk. Narwhal tusks evolved for sexual display/combat.

New #watercolor: an agatized fossil nautilus (Aturia angustata) from the Cenozoic rocks of the Pacific Northwest. These little gems are highly prized by fossil collectors along the Oregon and Washington coastlines. 3x4", watercolor & gouache, ~4 hours. 🐡🦖🦑 #sciart #paleontology #fossils

#caturday Orion

#fossilfriday An articulated skeleton of a porpoise (Phocoenidae) from the upper Miocene Capistrano Formation of Orange County, CA.

#throwbackthursday The Eocene-Oligocene transition resulted in a decrease in body size (and tooth size) when the first dolphins evolved from ancestral basilosaurid whales. Here's Agorophius, an early dolphin, only 8 million years younger than Dorudon, a basilosaurid archaeocete. #whaleontology 🐋🦖🧪

#whalewednesday A beautiful molar of the extinct toothed baleen whale Coronodon from the Oligocene (~30 myo) of South Carolina - very similar to the teeth of ancestral basilosaurid whales from a few million years prior. 🦖🐋🧪

Tufa towers and the salty shallows at Mono Lake, California

Incredible views of Mono Lake yesterday on our road trip up hwy 395 from socal to Tahoe. I've never seen it so flat and mirror-like! Also, yes, that island - Paoha Island - is a small volcano in the middle.

#fossilfriday A row of extinct big cat skulls on display earlier this year at the @nhm.org "Cats" exhibit, starting with La Brea specimens of Panthera atrox and Smilodon fatalis, with Homotherium (I think) and some smaller skulls (Puma, Lynx, Miracinonyx?)

#throwbackthursday The spectacular lower molars of an archaeocete whale we discovered and excavated in 2020-2021 in South Carolina - ~38-40 myo Tupelo Bay Limestone, Harleyville, SC. Basilosauridae, probably Chrysocetus or Dorudon. @tetrameryx.bsky.social's small hand for scale. 🐬🦖🧪

Got some spectacular photos of a swellshark (Cephaloscyllium ventriosum) at the Birch Aquarium - you can clearly see all the teeth and make out the dermal denticles, which make it look like its skin is encrusted with little glassy jewels. 🦑

#molluskmonday Fossil slipper snails (Grandicrepidula princeps) deposited by, and then eroded out, by the might Pacific ocean. Pliocene Purisima Formation, northern California. 🦑🦀🦖

A nice little marine firework - a painted anemone, Urticina grebnelyi, photographed at the Birch Aquarium here in San Diego 🦑🦀

Pelicans at La Jolla last month. #birding

#fossilfriday Last summer @tetrameryx and I made a pitstop on the way to Lake Tahoe and checked out the massive, 2 m long skull of the gigantic early ichthyosaur Cymbospondylus youngorum, which was on exhibit at the Nevada Museum of Art in Reno. Nevada is truly the land of giant ichthyosaurs!

#throwbackthursday A Cretaceous echinoid, Hardouinia mortonis, just waiting to be picked up on Holden Beach, NC, four years ago. A botched beach renourishment project accidentally delivered thousands of tons of fossilifeorus Cretaceous sediment onto the barrier island.

#whalewednesday A couple of weeks ago I visited my old friend the blue whale at the UC Santa Cruz Seymour Discovery Center. It's been partially taken down as the skeleton is currently under desperately needed restoration. 🐬

I'm especially skeptical about Pisco Fm. because these whales just sit out on the desert for years and in some places have been exhaustively surveyed with field IDs. Mysticete fauna seems to be entirely dominated by cetotheriids, balaenopterids, and Miocaperea. Figure from Ochoa et al.:

#toothtuesday A 31 million year old molar of a tiny toothed baleen whale (likely Fucaia buelli) emerges from a concretion after a few days in an acid bath. Specimen from the Makah Formation of Washington, made available for study by Jim Goedert. 🐬🦖

#molluskmonday I recently visited a new (to me) Purisima Formation exposure that didn't have much in the way of vertebrates, but was chock full of giant slipper snails, Grandicrepidula princeps - I must have seen thousands. I've never seen so many before in my life. 🦖🦑

Recently discovered this secrete tidefall on the northern California coast 😌

14/ The Amblyoccipita includes all odontocetes with a rounded skull vertex - it's pointed in Xenorophidae, a 'primitive' feature. The Stegoceti are all with a 'roofed over' temporal fossa and a wide, expanded intertemporal region - these are two key features to evolve in stem odontocetes.

13/ Lastly, we also named two odontocete "megaclades" - the Amblyoccipita, all odontocetes excluding the Xenorophidae, and the Stegoceti, which excludes the Xenorophidae and the Simocetidae. These clades reappear in virtually all phylogenetic analyses of early cetacans.

12/ We also examined body size trends in Neoceti. Early dolphins like Xenorophus are much smaller than your average basilosaurid - and so dolphins have a bit of an immediate size decrease, also seen in toothed mysticetes - a result of abundant food after the Oligocene climate revolution?

11/ We found that polydonty evolved early - a couple of additional tooth positions show up in early odontocetes, and within the "Stegoceti" (keep reading), the tooth count increases again, and extreme polydonty evolves even before the modern crown clade evolves.

10/ We also did a few analyses of early dolphin evolution. Odontocetes seem to have a nearly instantaneous decrease in tooth size relative to ancestral archaeocete whales:

9/ We also had a virtually complete skeleton of Xenorophus sloanii, which we used to look at vertebral patterning. Turns out that Xenorophus swam much like a basilosaurid archaeocete whale - probably slowly, and inefficiently. It would have been about three meters long

8/ These deep pits also mean that the teeth don't actually contact each other, so all tooth-tooth wear is from earlier stages of growth! In some specimens, the tips of the crowns are essentially unworn - protected by these deep pits.

7/ The teeth of old adult Xenorophus sank into very, very deep embrasure pits in the jaws - and were in-line with each other, unlike archaeocete whales where the uppers sit on the outside of the lowers. Despite having archaic teeth, they fit together more like modern toothed whales.