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tetrameryx.bsky.social
Sarah Boessenecker, MSc. 🏛️🔭
@tetrameryx.bsky.social
880 followers 490 following 190 posts
Paleontologist, fossil librarian, amateur astronomer, cat mom
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https://www.astrobin.com/users/tetrameryx/
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tetrameryx.bsky.social
Sarah Boessenecker, MSc. 🏛️🔭 @tetrameryx.bsky.social · Oct 10
This cat KNOWS he's pretty, and loves to ham it up for pictures 🖤🤍@coastalpaleo.bsky.social
Large long haired black and white cat posing for a picture next to a sliding door
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
#fossilfriday An early fossil dolphin earbone (tympanic bulla) with the middle ear sinus just completely filled with little fecal pellets, revealed by acid preparation. From the Oligocene (26 myo) Pysht Formation of Washington. More on my blog: coastalpaleo.blogspot.com/2025/11/acid...
The tympanic bulla of Iversen's simocetid after preparation and reassembly was completed. Two clusters of fecal pellets inside the tympanic bulla of an Oligocene simocetid dolphin.
November 7, 2025 at 6:03 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
I have finally gotten back to work on drafting more #fossilexplainer comics for the book - I've been feeling like illustrating key taphonomic concepts. Here's nos. 63 and 64, on preservation bias - soft v. hard tissue preservation, and preservation as it relates to environment 🐡🦖🧪 #sciart
A scientific diagram in watercolor illustrating differences in preservation from deep to shallow marine settings. Mollusk shells become increasingly disarticulated, worn, and broken, as do vertebrate bones. A scientific diagram in watercolor showing the relationship between soft v. hard tissues and preservation, using an octopus (no hard parts, only reflected as incredible but rare soft tissue specimens), a belemnoid (rare soft tissue specimens, but the guard fossilizes frequently), and a shelled ammonoid (common ammonite shells)
November 1, 2025 at 8:12 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
Apropos of recent discoveries, here's a little something I'm going to try and finish for the #2025SVP auction 🦕🧪🐡 #sciart
A work in progress watercolor painting of a dinosaur skull
November 1, 2025 at 11:59 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
But what if the male dinosaurs were subs?
denverfowler.bsky.social Denver Fowler Ph.D @denverfowler.bsky.social · 8d
A key implication is that these injuries should only be sustained by females, so this might be a way to infer the sex of dinosaurs. The inability to infer males & females in dinosaurs has frustrated scientists since study began nearly 200 years ago! (art: Troco) /9
November 4, 2025 at 8:46 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
New blog post: invertebrate fecal pellets discovered inside ~28 million year old dolphin earbones - revealed by acid preparation. Who dealt 'em? Really brings a whole new meaning to "that sounds like shit". 💩💩💩 Read it here: coastalpaleo.blogspot.com/2025/11/acid...
The tympanic bulla of Terry's baby simocetid specimen. The anterior part of the bulla fell off during acid preparation, and I took advantage of the missing part to photograph the pellets prior to reassembling it.
November 3, 2025 at 6:49 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
Fossil fur seal bones with unusual circular punctures - not from sharks, but mammals. Is this a result of predation (or infanticide) by another pinniped? Or predation by a terrestrial carnivore? Read more about the fur seal fossil record here: coastalpaleo.blogspot.com/2025/10/the-...
Two bones of fur seal pups (Thalassoleon macnallyae) with circular puncture marks. The bone surface has collapsed in, likely the result of a canine puncture.
October 28, 2025 at 5:51 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
🦖🐬🧪An incredible "fossil brain" of a fossil fur seal (Thalassoleon macnallyae) from the Pliocene Purisima Formation near Santa Cruz. This incredible specimen preserves a cranial endocast with exquisite detail. Read more about fossil fur seals on my blog: coastalpaleo.blogspot.com/2025/10/the-...
A partial fossil skull in black and white of a juvenile fur seal; the snout is missing, and the right side of the braincase has been removed, revealing an incredibly well preserved cranial endocast.
October 27, 2025 at 3:26 PM
tetrameryx.bsky.social
🔭 #astronomy #astro #astrophoto #astrophotography

C/2025 A6 (Lemmon)
This comet was discovered in January 2025 by the Mount Lemmon Survey. It's a bright comet, visible through binoculars! It'll be back around and be visible from earth again in the year 3175, so make sure to mark your calendars 😂
greenish-hued comet in a field of stars
October 24, 2025 at 7:35 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
For #fossilfriday here is the Golden Gate walrus - a partial snout and tusk of a walrus dredged from late Pleistocene sediments on the seafloor below the Golden Gate Bridge in San Francisco! This is the southernmost record of modern walrus in the eastern Pacific. On display @calacademy.bsky.social
A partial skull of a walrus in two views in a display case with some sand dollars and scallop shells. The skull consists of a greatly inflated and foreshortened rostrum with a single, ~40 cm tusk sticking out of the right tusk socket. The bone is highly weathered and a dark grayish brown.
October 24, 2025 at 3:53 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
In celebration of the 'Walrus' special on @pbs.org Nature tonight, here's a thread about the fossil record of walruses! Walruses have a surprisingly diverse fossil record, and until very recently, lived extensively on temperate and subtropical coastlines down to Florida and Baja. 1/ 🦖🐬🧪 #walrus
The skull of Valenictus sheperdi, a 5myo fossil walrus with tusks but no teeth. The skull is gray with a white background The skull of the gigantic fossil sea lion like walrus Osodobenus in side view. The skull is fractured and white with very large but short tusk-like canines An isolated, curved tusk of the Plio-Pleistocene walrus Ontocetus The skull of the fur seal sized early walrus Neotherium; it has small teeth, and a long, narrow skull.
October 22, 2025 at 5:54 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
#toothtuesday Fur seals and sea lions evolved from ancestors with double-rooted teeth - but evolved single rooted teeth over the past five million years. Shown here is the 'anagenetic' evolution of the northern fur seal, Callorhinus ursinus. Read more here: coastalpaleo.blogspot.com/2025/10/the-...
Evolution of the northern fur seal (Callorhinus) lineage over the last five million years. On the left is a series of diagrams showing the gradual fusion of the postcanine tooth roots, and on the right are photos of the actual fossils - the possibly ancestral Thalassoleon mexicanus through Callorhinus gilmorei, the early Pleistocene unnamed Callorhinus sp., and the modern Callorhinus ursinus.
October 21, 2025 at 5:17 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
New blog post, and it's a long one: all about the fossil record and evolution of "eared seals" - or, the fur seals and sea lions. I review their anatomy, current and former diversity, phylogeny, macroevolutionary patterns, and sexual dimorphism. 🦖🦑🐬🧪 #marinemammals #paleontology #evolution
The fossil record and evolution of fur seals and sea lions - the family Otariidae
A life restoration of the early fur seal Pithanotaria , hiding within a kelp forest off the California coast during the late Miocene. Artwor...
coastalpaleo.blogspot.com
October 20, 2025 at 4:23 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
And finally, my favorite sightings: I got to snorkel with a bunch of sea lion pups in their nursery at La Jolla Cove! I didn't approach them: I basically just floated there and they would do 'flybys' every couple of minutes. This one was playing with a piece of kelp! 🤿🐬🦑 #snorkeling
A sea lion pup swimming by, belly facing me, foreflippers outstretched, and letting out a ton of bubbles from its mouth; the water is a bluish turquoise and the seafloor is covered in bright green seagrass A pair of sea lion pups swimming by me, the one in front has a long piece of kelp that it is biting and pulling along; the water is a bluish turquoise and the seafloor is covered in bright green seagrass A pair of sea lion pups swimming by me, the one in front has a long piece of kelp that it is biting and pulling along; the water is a bluish turquoise and the seafloor is covered in bright green seagrass A pair of sea lion pups swimming by me, the one pulling the piece of kelp has just dropped it and is doing a loop-the-loop; the water is a bluish turquoise and the seafloor is covered in bright green seagrass
October 19, 2025 at 4:08 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
A small school of Pacific barracuda (Sphyraena argentea) - a bit smaller than the great barracuda you find in the Caribbean, and with a distinctive yellow tail; my first time seeing this species!
A school of about a dozen Pacific barracuda. They are long, silvery, with some faint barring, and a yellow tail. Kelp can be seen in the distance A school of about a dozen Pacific barracuda. They are long, silvery, with some faint barring, and a yellow tail. Kelp can be seen in the distance A school of about a dozen Pacific barracuda. They are long, silvery, with some faint barring, and a yellow tail. Kelp can be seen in the distance
October 18, 2025 at 4:42 PM
tetrameryx.bsky.social
M17 - The Omega Nebula
🔭 #astronomy #astro #astrophoto #astrophotography
a red nebula in a dark starfield
October 19, 2025 at 4:17 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
#fossilfriday One of my favorite recent discoveries - the youngest record of the early ~7 myo 'dwarf' fur seal Pithanotaria starri, from the Purisima Formation of northern CA - only 90-100 cm long as an ADULT! I'll be presenting on this little cutie at SVP next month in the UK! #2025SVP 🦖🐬
A photo of a fossil consisting of two lower jaws stuck together with a bit of hard sandstone; each jaw has two triangular cheek teeth and a stout canine. The bones are preserved as a grayish brown color and the teeth are a brownish cream color; the whole thing is only about 11 cm long.
October 17, 2025 at 5:16 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
Happy #nationalfossilday and #whalewednesday! This is Waharoa ruwhenua, a critical fossil for understanding the early evolution of baleen whales. Waharoa was discovered in 26 million year old limestone in New Zealand, and likely had both baleen AND vestigial teeth. 🧵1/
A whale skull in four different views (top, right, bottom, left). The skull is white and orange with reddish iron oxide staining, and the mandibles are preserved in situ; the rostrum is flat and narrow, and overall the skull is shaped like a surfboard.
October 15, 2025 at 4:08 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
Starting right now!
te-ara-paerangi.community Te Ara Paerangi Com - Research Advocacy Capability @te-ara-paerangi.community · Oct 7
We'd love to have a huge turn out for Nic's talk. Please help spread the word. There are downloadable pdf adverts in the link below. They can be emailed or printed. If you work in a public space (e.g. Library) you could help by printing and posting one of the flyers. Ngā mihi nui!
October 13, 2025 at 10:00 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
New blog post: tracking the slow exposure and erosion of a small fossil baleen whale skull in the Pliocene Purisima Formation on the northern California coast. This is the fifth skull of the dwarf baleen whale Herpetocetus that I've discovered, and still need to dig up! #whaleontology 🧪🦖🐬
A new Herpetocetus specimen awaiting excavation
During a field day in May of 2023, I was out scouting for fossils and came across an interesting bit of skull in a horizontal rock face belo...
coastalpaleo.blogspot.com
October 13, 2025 at 3:54 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
We also had some fantastic out-in-the-open lobster sightings! Usually these guys are tucked inside crevices and you just see their face and antennae, but we saw several out and about in broad daylight. California spiny lobster, Panulirus interruptus. In the last 2 pics it's eating a mussel!🤿🦑🦀
A California spiny lobster on a flat, algae covered slab; it's a tan/brown color, with black and orange striped legs, very long antennae with purplish bases. A California spiny lobster on a flat, algae covered slab; it's a tan/brown color, with black and orange striped legs, very long antennae with purplish bases. The antennae are pointed right at the camera. A California spiny lobster on a sandy bottom in a deep tide pool channel; it's a tan/brown color, with black and orange striped legs, very long antennae with purplish bases. It is eating a california mussel. A California spiny lobster on a sandy bottom in a deep tide pool channel; it's a tan/brown color, with black and orange striped legs, very long antennae with purplish bases. It is eating a california mussel.
October 12, 2025 at 5:03 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
🦀Minus tides are coming! Our first daytime minus tide of the fall is today (in SoCal anyway), though I probably won't go out until tomorrow. But, you know what that means: more nudi pics! And by that I mean nudibranchs, lovely colorful little sea slugs:

coastalpaleo.blogspot.com/2024/03/nudi...
Nudibranch hunting in northern California: snapshots from winter tidepooling in Half Moon Bay, CA
This post has more to do with the coastal part of the title and less to do with the paleo part - I'll be doing more of these, since I figure...
coastalpaleo.blogspot.com
October 7, 2025 at 4:38 PM
tetrameryx.bsky.social
This cat KNOWS he's pretty, and loves to ham it up for pictures 🖤🤍@coastalpaleo.bsky.social
Large long haired black and white cat posing for a picture next to a sliding door
October 10, 2025 at 5:26 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
#whalewednesday The spectacular early toothed whale Xenorophus sloanii from the Oligocene (~28 mya) of South Carolina! This is a critical transitional fossil, known from about a dozen skulls and partial skeletons. Read more about Xenorophus here on my blog: coastalpaleo.blogspot.com/2024/03/the-...
A black and white skeletal reconstruction of Xenorophus sloanii, and a pair of photos of the skull and neck vertebrae of the best known specimen in top and side view.
October 8, 2025 at 6:34 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
For #worldoctopusday here is my favorite photo I've taken of an octopus, in a hole in a rock about 10 feet down while snorkeling. Octopus are quite hard to spot unless they're moving! This one is a rather small (perhaps ~2' wide) American Octopus, Octopus americana. 🦑🦀🧪🤿
An underwater photograph of an octopus in its hole; the arm is wrapped around the eye, and pale red, whereas the head is bluish green.
October 8, 2025 at 8:17 PM
Reposted by Sarah Boessenecker, MSc. 🏛️🔭
coastalpaleo.bsky.social
#fossilfriday I find early whale and dolphin teeth to be quite beautiful and unusual. This is a lower molar of an extinct, as-yet unnamed simocetid dolphin (?Olympicetus) from the early Oligocene Makah Formation of Washington, USA. Acid prepared; collected by Jim Goedert. 🦖🐬 #whaleontology
A well-preserved molar of an extinct dolphin with dark brown enamel and a tan root; the crown is triangular with several accessory cusps. The lingual side has several short vertical ridges. The mesial edge of the tooth is serrated.
October 10, 2025 at 3:15 PM