Wednesday, September 6, 2023

Some recent finds from Charleston, SC waterways - August

For those of you unaware, Sarah and I recently both resigned from our positions at the College of Charleston - we had been contemplating this for quite some time. Neither of us has been terribly happy there. We put up with a toxic work environment, decreasing liberties, and some pretty unfair work practices. For a while, the incredible fossil collection made it worth it. Eventually I got sick of carrying someone else's water and doing work for someone else's paycheck. That's all I'll say for now. But, I've left academia and am no longer an overworked, underpaid, and exploited adjunct.

Since mid-August, I've been working for Charleston Fossil Adventures as a fossil tour guide, as well as taking the occasional tour for Palmetto Fossil Excursions - a big thank-you to both Ashby Gale (CFA) and Skye and Josh Basak (PFE) for rescuing me. After a few days on the job I realized when I came home in the evenings that I was actually happy and relaxed - normally I'd be stewing over something a shitty colleague said to me at the office or some petulant student mouthing off to me, or stressed about having to do something without pay amongst other mounting demands. Being out on the boat, seeing wildlife, getting a nice tan, exercise, and showing folks how to find fossils and identifying them has been a lot of fun and surprisingly relaxing. And I get tipped! What a foreign concept - I still am surprised most days when I get tip money. "OH right, I'm in the hospitality industry now!" I have to remind myself, and thank them profusely.

Anyway, here are some of my finds, and the finds of our clients, over the past few weeks on our boat tours through Charleston Fossil Adventures.

This distinctive tooth is a rather well-preserved specimen of the snaggletooth shark, Hemipristis serra. These are by far and away the most common (and distinctive) 'medium-sized' shark teeth at our sites. Most of the teeth at this spot are all derived from the Oligocene Ashley Formation; all of these sand grains are bits of limestone and Oligocene shell fragments. For example, the little cylinder to the left of the tooth is a sea urchin spine!

A rather large tympanic bulla (earbone) from a large xenorophid dolphin - initially I thought it was so huge, it had to be something new - however, I realized that it's just slightly larger (by 1-2 mm) than the very largest earbones of
Xenorophus sloanii. This specimen has a modern oyster shell stuck in the tympanic cavity. Almost certainly from the Oligocene Ashley Formation.

One of our clients took the patient, fine-scale approach of sitting down and searching the immediate sand/gravel near her - and it paid off. This is a tooth of Parotodus sp., an unnamed species of "false mako" and progenitor of the "other" megatoothed shark, Parotodus benedeni. This unnamed species frequently retains cusplets (like its possible ancestor Otodus obliquus) and is only found in Oligocene strata - making it a very rare shark indeed. Absolute killer find! Probably from the Oligocene Ashley Formation.


One of my favorite personal finds from the past few weeks - a gorgeous inner ear bone (periotic) of a squalodelphinid dolphin. This one is very similar to
Notocetus and Araeodelphis (the former known from the early Miocene of Argentina and Calvert Cliffs, the latter only known from Calvert Cliffs).

 This periotic even has a few bite marks on it! Here's a couple more views. Squalodelphinids are longirostrine dolphins, and some of the only extinct species that seem to truly form a sister group with the Ganges River dolphin Platanista - in other words, some of the only really convincing fossil Platanistoidea. Squalodelphinids are quite diverse, and include some taxa that were formerly considered to be platanistids (e.g. Araeodelphis, Dilophodelphis). Most squalodelphinids have absurdly inflated zygomatic processes of the skull and thickened bone over their orbits, perhaps a precursor of the incredible bony ridges over the orbits in modern Platanista gangetica. This specimen is almost certainly early Miocene in age, and probably derived from the Marks Head Formation.

 Hammerhead shark teeth (genus
Sphyrna) are uncommon, but usually if you pick up enough teeth that look like reef shark teeth, after cleaning the sand off at the end of a tour, there's usually at least one. I estimate a regular sort of hammerhead - perhaps Sphyrna zygaena - is found for every 40-60 reef shark teeth (Carcharhinus). This is an actually quite rare tooth - great hammerhead, Sphyrna mokarran. It is much larger than all the other hammerheads, and is unique in having serrated cutting edges and a very deep nutrient groove. This one was found by a client, and is probably Pliocene or Pleistocene in age.

 We always keep our eyes peeled for wildlife - and I'm a habitual tidepooler. I saw this cute little mud crab (
Panopeus herbstii) that was unusually blue in color, and had to get a photo. Usually they are, well, mud-colored. I've accidentally introduced two of these into my saltwater tank before (and fished them out and threw them into the pond near my house before they did any serious damage!).

 Here's a tympanic bulla of a pygmy sperm whale - family Kogiidae. There's a surprising amount of the fragile outer lip that was still preserved, despite the bulla being so beat up. This is probably Pliocene in age.

"Hubbell teeth" are small heart-shaped teeth from juvenile Carcharocles megalodon; there are probably only a couple of tooth positions that produce these funny, stubby little teeth. On rare occasions you can find "Hubbell teeth" of the older megatoothed shark Carcharocles angustidens - like these two, found a few days apart. Probably Oligocene Ashley Formation.

 Last earbone for this post: a beautiful, pale blue periotic of the early Miocene odontocete
Eoplatanista. Eoplatanista is a preliminary ID, but these basically resemble the periotics of eurhinodelphinids like Xiphiacetus and Schizodelphis, but are much smaller and more compact. Both Eoplatanista and Eurhinodelphinidae are longirostrine dolphins and possibly quite closely related to one another. Eoplatanista has not yet been reported outside Europe and I am looking forward to publishing these records.

An Oligocene reef shark tooth embedded in a tiny chunk of Ashley Formation limestone. This is a tooth of Carcharhinus gibbesi. Same Gibbes as the discoverer of the original skull of the early dolphin Agorophius pygmaeus, and the same family as the Gibbes Museum in downtown Charleston. "Matrix" specimens like this are uncommon here in South Carolina, but locally common at this location.

And an exciting one to finish with: Ashby found this very, very rare example of a sawshark rostral spine - Pristiophorus sp. NOT sawfish (Pristis/Pristidae), but sawshark - Pristiophoridae. These are smaller than sawfish, and are true sharks within the Selachii (sharks) rather than the Batoidea like the sawfish (Pristidae) and the extinct sclerorhynchoids. These rostral spines differ from the substantially more common sawfish in having enameloid rather than only being composed of osteodentine. Oligocene Ashley Formation.



RA said...

New reader here. Love the photos and detail you provide.
I have to say that your feelings about academia ring true with me. For years, I considered becoming a professor a dream-come-true only to see the institution transform into something toxic. Year after year, it became less bearable. Congratulations on your choice.

Robert Boessenecker said...

RA - many thanks. Sadly, my experience is hardly unique.