Thursday, December 7, 2023

Recent finds from lowcountry waterways - early November 2023

October was great at our new off-season locality, but things really started to take off in November - one of the best months of fossil collecting in my life. 

A nice periotic of Squalodon proper! An actual, factual South Carolina Squalodon specimen. We've encountered a few teeth, but this is one of the first periotics that's been a good match. Tough to tell the difference from Ankylorhiza, though they are somewhat smaller. A bit eery that the periotic is highly convergent...
A rather large tooth fragment of a spotted eagle ray, Aetobatus. We usually just find chunks.


A beautful posterior tooth of the ancestral megatoothed shark
Carcharocles angustidens - look at how stubby this one is!

 A large sampling of snaggletooth specimens -
Hemipristis serra.

 We also had some great - but sobering - sightings of Tamenend's bottlenose dolphins (aka Altantic coastal bottlenose - Tursiops erebennus). This individual gave us an unparalleled sighting opportunity - but only because it was begging for food. Once it realized (after only about a minute) that we weren't tossing any shrimp or bycatch overboard (like the shrimpers just a few boat lengths away) it swam off into the harbor.

At one particular spot we tend to find a lot of lined sea stars, Luidia clathrata, at low tide. These are 'doomed pioneers' that venture above the low tide line on the sand flats and get stranded. I tossed about 15 of them back into the surf on this day in particular.

This one was quite possibly the most frustrating false periotic I've ever come across. I actually filmed it, I swore it was going to be a delphinid periotic bone! Just a phosphate nodule with a rough trilobate outline and a cluster of holes looking like the endocranial foramina.

A massive chunky horse tooth from the Pleistocene! Still has all the cementum on it, which is frequently spalled away.

At this locality there are tons of well-preserved steinkerns (internal molds) of ancient quahog clams (genus Mercenaria). So, we collected a bunch and I made a temporary art installation on the beach. 

A Miocene earbone (tympanic bulla) of some kind of dolphin, probably (but uncertainly) a eurhinodelphinid.

 A legend-class cutter operated by the US Coast Guard, spotted in Charleston harbor just near the main shipping channel - I think this could be the James, but there are several other cutters that are based out of Charleston: Hamilton, Stone, and Calhoun. That's 40% of the entire fleet! The only other port that operates as home base to four different cutters is also a place I call home: Alameda, California. Note that this thing is basically a lightly armed frigate - it's got a 57 mm Bofors deck gun on the bow and several antiaircraft guns. It's times like this when you remember that the US Coast Guard is officially a branch of the armed forces and a bit of a light navy.

A small lightning whelk (Sinistrofulgur perversum) in beautiful shape! These are rare, perhaps you find one lightning whelk shell for every ~25 or more knobbed whelks (Busycon carica). Knobbed whelks are the most common large gastropod along the Carolina coast.

A partial balaenopterid whale periotic - the pars cochlearis here has been busted off from the body of the periotic, showing us a great partial endocranial view of the cochlea - the spiral organ of hearing. This specimen has at least two complete turns of the cochlea.

A different periotic, and one that is also incomplete, but with an intact pars cochlearis. This is from an as-yet unidentified, but relatively common, early Miocene dolphin we keep finding - that bears similarities with an unpublished platanistoid dolphin from Europe.

A megatoothed shark tooth in the sand (Carcharocles sp.).

A decent haul from one of our longer days out there (Ashby sorting fossils on right).

Some of my favorite finds are those that others clearly walked right by. Here's a partial Carcharocles megalodon tooth right next to someone's bootprint!

A megatoothed shark tooth poking out of wet sand (Carcharocles angustidens/chubutensis).

Extruded sand from some kind of invertebrate - I think, based on prior reading, that this is from some sort of large burrowing annelid worm.

A juvenile tooth of Carcharocles megalodon in a few millimeters of water.

 Ashby called me over as he understands my inordinate fondness for intertidal invertebrates: a mantis shrimp! Based on a quick search on Inaturalist, this looks like it might be a juvenile West Atlantic Mantis Shrimp (
Squilla empusa). I carried it to the water in a large shell, but dared not get my fingers close! I'm much too attached to them. My fingers that is, not invertebrates.

 A robust tiger shark tooth -
Galeocerdo cuvier, from the Pliocene.

A colorful sea whip (
Leptogorgia virgulata) - these quite commonly wash up along certain places in the harbor. This species can be yellow or magenta. Sea whips are gorgonians - soft corals, aka octocorals - and are closely related to the sea fans, their more famous tropical cousins.

A juvenile
Carcharocles chubutensis tooth - possibly Carcharocles angustidens, as these two species really grade together around the Oligocene-Miocene boundary.

A veritable smorgasbord of fossils from one of our better days out on the harbor.

 A stingray- or skate-bitten dugong rib! These traces are formed by batoids with pointy teeth and which draw their bite posteriorly, rasping away flesh from a bone.
A large snaggletooth specimen (Hemipristis serra) propped up between two oyster shells.

We had one day out there where we found nine different cetacean earbones! Most were partial bullae, but there's an unusual mysticete periotic in there, a good waipatiid periotic, an acid-digested xenorophid bulla, and a pygmy sperm whale bulla.

Saturday, December 2, 2023

Sampling microvertebrate fossils from the early Oligocene Ashley Formation (Rupelian)

One of our sites we visit for Charleston Fossil Adventures has proven time and again to be full of surprises - mostly little surprises. Well, big surprises, science-wise, that happen to be physically small. Most of the large fossil shark teeth are from a small minority of species but make up the bulk of the fossils that are found - which is called collection bias. Simply put, it's easier to spot large fossils. Small fossils - especially small shark teeth - frequently get damaged more rapidly and perhaps are more difficult to find in a condition that is well-suited for scientific study. This is preservation bias. Critically, the majority of sharks in any fauna are rather small with tiny teeth - and there are a few gentle giants out there with absurdly tiny teeth (e.g. whale, basking, and megamouth sharks, manta/mobula rays) that you will never find if you're only going after the big trophy specimens. You're probably missing out on over 75% of a fauna unless you're looking for small teeth.

At this locality, there are loads of tiny teeth that have weathered out of relatively friable dredge spoils of the Ashley Formation - normally this rock unit is quite hard (indurated) and teeth often break as they are weathering out of limestone blocks. But at this spot, the dredging dug into what must have been an unusually soft and crumbly exposure - we do find teeth with matrix attached, but they're typically in good shape, and we find loads of small teeth amongst crumbly carbonate sand. That solves the preservation bias issue. To solve collections bias, we go out to this locality with knee pads and stare at it from a few inches away - as well as screen the matrix and pick through it for microvertebrate remains. As we've done this, we've added a bunch of species to the faunal list for the Ashley Formation - and possibly discovered some fossil shark species that are new, or the first occurrence of the genus in the fossil record ever.

Ashby, Sarah, and I heading on down the river to the spot. 

 It started off as a chilly morning - hence the chest waders - I was in a tank top by lunchtime. 20 mph wind, but blocked that day by the copse of trees. Given the strong, direct sunlight, Ashby tried collecting for a while in the shade underneath an umbrella. Sarah and I went for the direct approach. Collecting micros from the surface on a cloudy day is a bit easier, since there's no harsh shadows. At some quarries, the only way to find certain fossils is to hunt in your shadow.

A beautiful blood red tooth of the extinct devil ray Plinthicus stenodon.

That same tooth of Plinthicus. Incredible colors!

A teensy, tiny little burrfish (Chilomycterus) tooth plate. Not sure if this is Pliocene contamination.

 A tiny little orange tooth! Let's take a closer look.

It's a tooth of
Dasyatis - a very large tooth (roughly 2mm wide) of a large adult female stingray. Male teeth are frequently smaller and have a pointed crown, whereas the crown is blunt and low in females. 

Sarah inching along the sandbar - and being followed closely by the advancing tide.

A rostral spine of Pristiophorus - a sawshark! Not to be confused with sawfish, which are also known (but, as yet, unreported) from Oligocene rocks of the Charleston Embayment. Pristiophorus is known from a single oral tooth, but we've found loads of the rostral spines from this location - at least 20, and ALL found this year! Sawsharks are extraordinarily rare in the Atlantic coastal plain fossil record.

Screening matrix from the very top of the sand bar - convenient at high tide.

Sarah joined Ashby, Mike, and I for a staff day at Ashby's picking through all the matrix we had screened.

More picking - we picked hundreds of teeth, bones, and denticles out of about 60 lbs of screened concentrate.

We returned the following week and found this very large "fish otolith" - actually a roasted pumpkinseed left on the beach by Sarah the prior week. She said "I told you guys I accidentally left at least a couple behind!"

We decided to take the coarser screened fraction of the sample and just dry it out on the paddleboard, since we could pick through it in a matter of minutes - negating the need to haul all this back home.

And more picking from the coarse sample.

Sunday, November 26, 2023

Recent finds from lowcountry waterways - late October 2023

Second out of three posts for October fossil discoveries - October was a good month for several reasons, despite getting covid (for the second time) at the annual meeting of the Society of Vertebrate Paleontology (SVP).

Starting in late October, we transition to a different location with a somewhat different suite of fossils. We also transition towards nastier weather: my new boss, Ashby, bought the three of us personalized jackets and needless to say I'm pretty pleased with mine!

This nice inner earbone (periotic) was found by Mike while I was catching up with a colleague who surprised me one morning when she showed up for a tour - he gave me a pretty hard time for walking past this one, which I deserved!

This beautiful periotic is from a squalodelphinid - identical to squalodelphinid periotics from the Pungo River Limestone at the Lee Creek Mine of NC. This specimen is probably early Miocene in age.

This horse tooth was found rolling around in the surf - and capped with a cute little coral colony growing right on the chewing surface! Pleistocene, Equus.

A juvenile Carcharocles angustidens or C. chubutensis tooth, waiting to be picked up.


 A spectacular osteoderm (bony armor plate) from the back of an alligator, Alligator mississippiensis! This was found by client Lisa right when we were getting back onto the boat. Pleistocene.

An embarrassingly large mackerel shark vertebra, probably from a megatoothed shark (Carcharocles).

An interesting phosphatic coquina - coquina is a sort of limestone composed entirely of mollusk shells and fragments. We keep finding coquina that is either mixed with phosphatic sand or occasionally phospharized crusts forming on coquina.

Every day we leave past all of these shrimp boats, and it reminds me of Cannery Row in Monterey back home.

A nice tooth of Carcharocles angustidens sitting in a small stream - water pours out of the beach at low tide.


A nice delphinid dolphin periotic on the beach.

 On closer inspection, this one is probably bottlenose dolphin (Tursiops).


 A great white shark tooth - Carcharodon carcharias.

 It's worth picking up rectangular bones, even if they look like rib fragments.

 This one turned out to be a mandible fragment from Xenorophus! My colleague Kumiko Matsui went home with this specimen.

X marks the spot: this shark vertebra was broken somewhat so you can see the channels through the vertebra.

A vertebra from a lamniform (mackerel) shark.

A fantastic surprise! My marine mammal paleo colleague, Dr. Kumiko Matsui, came down to Charleston with a friend of hers and surprised the hell out of me when she walked down the dock to our boat.

 We had a great time catching up - we didn't have quite as much time to talk shop at SVP two weeks prior, so it was a great opportunity. Dr. Matsui ranks pretty high in my book because she is, as of yet, the *only* marine mammal paleontologist who has come to look at Coronodon since we published it in 2017.

A decent Carcharodon hastalis tooth - formerly "bigtooth" mako.