Background and Discovery
Back in 2018 a new fossil site opened up in Ladson, South Carolina, just about a half hour drive from our apartment at the time in West Ashley. I got a panicked phone call from a friend and fossil collector, that it was raining, and there were two fossil dolphins weathering out. One had just been carted off a few hours prior, without landowner permission. My friend, however, happened to be the brother in law of a regional manager for the construction company that was building at the site. My friend explained that he had a second fossil dolphin, exposed in really soft rock, and that he was worried about it weathering out in the rain that night. "It's 11 pm" I told him. "I'm not leaving the apartment tonight. I'll meet you out there tomorrow. Cover it with a tarp and it will be fine." I headed out the next day to check out the fossil, and it was indeed some sort of long-snouted dolphin in the Chandler Bridge Formation. It was exposed on the side of a spectacular stormwater retention pond which had been dug to a depth of about 30 feet. I was perhaps less interested in the dolphin than I was at the prospect of sampling in situ fossils at this locality. Later on, the subdivison was called McKewn Homes - referred to in our study as the McKewn subdivision or McKewn site. (A frustrating part of Charleston paleontology is that these construction sites never have names until homes start being put up, typically long after you've already started collecting; you always have to call it something - and then that name invariably gets changed later on).
Stratigraphy of the McKewn site - from Miller et al. (2021).
Individual formations exposed within the enormous pond at the McKewn site, with Ashby Gale for scale on the right side. Two members of the Ashley, the Chandler Bridge and an unusual upper sandy unit, and the overlying Ten Mile Hill Formation were all exposed. Photo by the author.
You see, the Ashley Formation and the Chandler Bridge Formation - despite producing what is perhaps the world's largest assemblage of marine vertebrates, and certainly marine mammals and sea turtles of Oligocene age (34-23 Ma) from anywhere on earth - are quite poorly exposed. Most of the exposures are temporary: either they are construction sites, or stream or river exposures that erode away or might be covered by slumps or vegetation. The South Carolina lowcountry is quite flat, and there is very, very little natural topography - it's also subtropical, so plants grow very quickly there. When I looked around this excavation for the stormwater retention pond, I saw fossils everywhere, and five clear layers: the Runnymede Marl and Givhan's Ferry members of the Ashley Formation, the typical Chandler Bridge Formation, an unidentified clean 'beach sand' unit where the dolphins had come out of, and the Pleistocene deposit on top (later determined to be the early late Pleistocene Ten Mile Hill Formation). I envisioned being able to sample directly from each layer, without any guesswork. Frequently, local collectors without any grasp of stratigraphy would tell me, confidently, that their 'megalodon' or mastodon tooth had come from the Chandler Bridge Formation. "What makes you say that?" I'd ask - and usually the only reply would be a couple of blinks and a surprised face. Folks don't really press each other for details or demand proof of things down there. I'd have to explain that not all shark teeth in Charleston came from the Chandler Bridge; some were from the Ashley Formation, and many others were from overlying Pleistocene units. It could be tough to tell the Chandler Bridge from the overlying muds and sands, but generally, if it was a fossil that was clearly Miocene or Pliocene (e.g., a megalodon tooth) or Pleistocene (e.g., a mastodon or mammoth tooth) - it was assuredly not from the Chandler Bridge, which is much older. In some cases, We'd receive donations and the stratigraphic unit marked would be a big fat '?'. In others, based on some adhering sediment and a geologic map (or occasionally a photo of the fossil in the ground), I'd be able to do some homework and figure out a likely layer that it was derived from. But, there was always a degree of uncertainty. Most of the fossils in our little museum had some degree of stratigraphic uncertainty. This was my first opportunity to collect specimens locally that required no guesswork.
Ashby Gale looking for bones in the upper Chandler Bridge Formation at the McKewn site in May 2018.
Fortunately, spring semester at the college had just ended, and I had all summer to do fieldwork at this new locality. Unfortunately, summer was just beginning. My initial foray at the McKewn site with Ashby Gale was on an overcast day in May where it was only about 80 degrees or so; I still roasted. Fieldwork began a few weeks later, and by early June, the thermometer was already hitting triple digits. Every time I went out, rain water and groundwater seeped into the pit and began filling it up. With this in mind, I began targeting the layers lower down first - I spent quite a bit of time quarrying into a bonebed at the boundary between the two members of the Ashley Formation, collecting both macrofossils, and saving microfossil-rich matrix. I would stuff about 10 lbs of micro matrix into walmart shopping bags, and put one bag on the front and back of my jacob's staff (a wooden pole marked off in 10 cm black and white bands) and carry it out with the pole over my shoulder.
Carcharocles angustidens teeth found during quarrying of the Ashley Formation, before it was indundated with pond water. Photos by the author.
In addition to the quarrying efforts in the Ashley Formation, I carted off about 200 lbs of Ashley bonebed matrix for screening. The very same thunderstorms exposing new fossils a few times a week were leveraged at home - I put the matrix into my box screen which I left under the edge of the roof where a ton of water came off. I remember hearing thunder late at night and leaving the living room (or even the dining room table) to dump another bag of matrix into the screen before it began dumping! Inset shows a small scallop (?Aequipecten) and a snaggletooth shark tooth (Hemipristis serra). Photos by the author.
On one afternoon, I spent about four hours quarrying into this bonebed - alone, since Sarah was in the UK for a couple weeks for graduate school, in 104 degree heat (and something like 80-90% humidity). I made about 7 or 8 trips with the walmart bags, and on my second to last trudge through the hot mud, my camelback hose ran dry. I had already filled it with the rest of my emergency water kept in the car an hour or so earlier - and I hadn't peed once. I still had two bags full of matrix and my field gear at my little quarry. Worse, my honda didn't have AC. I made the trek back, dropped everything off in the car, and drove a couple of miles to a Spinx gas station in Ladson and bought a gatorade and just stood below the AC vent in the convenience store. I bought another gatorade for the drive home. And, because tap water gets no colder than about 75 degrees or so in the South Carolina summer, I poured a "cold" tub and dumped every ice cube in the fridge into the tub.
The second pond at the McKewn site the day I began finding loads of Carcharocles angustidens teeth. Photo by the author.
The collection of Carcharocles angustidens teeth made in just a couple of visits to the new pond. Photo by the author.
A the night before Sarah returned, I went out to the construction site at 5pm (we had permission to collect, so long as we started after daily construction work was done). There was a second pond that I hadn't really prospected much, and so I wanted to check it out. It was small - maybe 1/4 the size of the main pond, and filled up a little more - the water level was just about a foot below the Ashley-Chandler Bridge contact. I walked around on the Ashley limestone to look for fossils in the basal phosphatic bonebed of the Chandler Bridge. I spotted the distinctive reddish root and pale greenish gray enamel of a large tooth - a juvenile tooth of a Carcharocles angustidens, the ancestor of Carcharocles megalodon. These teeth are large and beefy, but still have comparatively dainty crowns and most are more curved than the broadly triangular crowns of C. megalodon teeth. Further, they retain the lateral cusplets seen in older species of the same lineage, including Otodus obliquus (the last non-serrated species in this lineage, from the Paleocene and earliest Eocene), and the middle-late Eocene Carcharocles auriculatus, commonly known in the Eocene rocks of Harleyville closer to I-95.
A few minutes later, I spotted another root. I gently wiggled it - and it also had a complete crown. I pulled a few more teeth. After about 15 minutes, I had found nearly ten teeth. I couldn't wait to show Sarah this locality once she returned. I immediately began thinking about this. All of these teeth were from juveniles - most between 1-3" in length (~3-7 cm). A colleague of mine, Bob Purdy, had published some observations in a 1996 book chapter including that the Chandler Bridge Formation was likely to be a megatoothed shark nursery, and that of a sample of about 100 specimens, only a few were from large adult teeth and most were juveniles. Purdy had mentioned this in a couple of paragraphs and shown a photo comparing a small and large tooth, but nothing had been published aside from this. These specimens had been collected as part of a controlled excavation in the Chandler Bridge Formation, also in Ladson, but about a mile away from the McKewn site - and long since built over by some apartments; my colleague Jonathan Geisler showed me the apartments a few summers later when he stayed with us for a couple weeks of research. Sarah flew back in, and I excitedly told her about the teeth from the new locality - and we went out the night after she flew back. She and I found another half dozen or so teeth in the span of 30 minutes.
Two of the Carcharocles angustidens teeth that Bob Purdy figured from the original sample of 95 specimens from the Chandler Bridge excavation, a few miles away, in his 1996 book chapter. The big one is ChM PV 540 and you can see it below in our figure.
Sarah giving into the mud during the search for fossils in the Chandler Bridge Formation. She has a habit of getting a lot filthier than me when we go do fieldwork - and this was exaggerated in the muddy lowcountry! Photo by the author.
Sarah Boessenecker showing off one of the larger juvenile Carcharocles angustidens teeth - and some of the other teeth we found at that pond that night, and two evenings prior. Photos by the author.
We first met Addie Miller around 2018 as a museum docent and she began working as a teaching assistant for my labs shortly thereafter - one of my favorite TAs! Addie worked extensively with us in the museum and was one of our very favorite students. She also spent considerable time helping Sarah and I clean, repair, and paint the Dorudon atrox (archaeocete whale) skeleton, "Manaia" - given to us by my California colleague Doug Long, who had himself rescued it from the Discovery Channel store in San Francisco and kept it in his Tiki Bar after several northern California museums passed on it. Sarah, Addie, and I spent hundreds of volunteer hours fixing this thing up and getting it ready for exhibit without any assistance.
Over the rest of the summer, Sarah and I continued to return to the site, and by the time that the pond had filled up completely around Labor Day, we had collected 32 teeth of Carcharocles angustidens. I was, at the time, focusing on working on papers on the gigantic dolphin Ankylorhiza (published in 2020) and a monograph on the archaic dolphin Xenorophus (published in 2023) and figured I would get to it later, or assign it to a particularly enterprising student. A few months later, I had my student: Addie Miller was in my 'Applied Paleontology' course that fall, a special topics course all about learning methods in paleontology. She really shined quite brightly, and I encouraged her to undertake an independent study with me at some point. A few semesters later, she and I had a chat, and we agreed to have her work up our assemblage of Carcharocles angustidens teeth for a Spring 2020 independent study. After a few weeks of discussing our modest assemblage of about 30 teeth, I wondered if the specimens that Bob Purdy had mentioned in 1996 were located in Charleston Museum collections: many specimens that had been in Al Sanders' office had been separated from their documentation after his retirement. I contacted Matt Gibson, and inquired about the specimens. He told me that there was indeed a large sample of 95 teeth (I suspect Purdy - or, very likely Al Sanders - rounded the number up to 100) from one locality in the Chandler Bridge, identified as Bed 3 of the Chandler Bridge - ours was mostly from Bed 1 and 2. He spent some time tracking down specimens and doing some cataloguing work for us.
We visited Charleston Museum on February 19 and Addie measured all of the teeth, and took cell phone photos for preliminary identification of their position in the jaw. We had planned on bringing a bigger DSLR camera and getting publication quality images later on; Addie had already taken all the photos needed for the specimens from our locality. We're lucky that we visited when we did - only day after our friend Jane Kelly had returned from the American Association for the Advancement of Science meeting (AAAS) and told us that the country was probably unprepared for the novel coronavirus that was beginning to spread beyond China. Ten days later the first US death from Covid-19 occurred, and within three weeks, the USA - and even South Carolina, for a brief time - were on lockdown. Later that fall, Matt Gibson obliged us in taking the required photographs since we wouldn't be allowed back into Charleston Museum for another 16 months or so in mid 2021.
Shark Nurseries and sampling bias in the Lowcountry
Shark nurseries or nursery areas have generally been proposed to be shallow, warm, semiprotected embayments where certain species of sharks may visit and give birth in, with the pups and juveniles sticking around for some time while they grow - eventually growing large enough to leave. These areas are generally thought to be relatively scarce in oceanic predators, including other sharks of the same species. Bulls Bay, South Carolina, is one such example, being host to a number of species including sandbar, blacktip, dusky, smooth dogfish, hammerhead, and several other species.
The major problem with studying fossil sharks and establishing whether or not the assemblage reflects a nursery has nothing to with establishing whether or not the environment was appropriate. The Charleston Embayment was shallow, certainly tropical to subtropical thanks to certain fossil fish and pollen, and based on microfossils, was likely shallow marine and protected, even trending to brackish/estuarine settings by the top of the unit (Bed 3). The major problem is that of collections bias. Shark teeth are popular finds for collectors of all ages - and what do collectors like? Trophies. Carcharocles angustidens teeth are some of the most desired of all trophy species from Charleston, right up there with C. megalodon and the extinct 'false mako' Parotodus benedeni, a close relative (these teeth are perhaps the most prized by the diggers and divers who have been doing it the longest; I judged collectors experience based on how many Parotodus teeth they had found - and judged their skill based on how many cetacean skulls they had properly excavated). But I digress. If a paleontologist has access to a site shared with amateurs, the scientist is more likely to have an unbiased sample. However, the amateurs might get to the site earlier in the day, more frequently, or visit at night with headlamps, and find larger teeth, leaving smaller teeth behind - thereby biasing the sample.
In the case of our locality in the McKewn subdivision, the construction firm that owned the land and was developing it had been pretty blunt with fossil collectors and word got out fast that they didn't want anyone other than a handful of folks with strict permission to be out there. The folks who carted off an Oligocene shark-toothed dolphin skull without permission did not return, and I was instructed by the regional manager of the company to warn anyone I suspected of fossil poaching to get off the property. A small price for access, I suppose; the company got some good PR with the local college and museum, and got a free security guard in return. Generally speaking, I saw a couple of folks who said they were looking for arrowheads (I myself had found a couple), and saw some poachers looking in all the wrong spots - I suppose for megalodon teeth. Nobody, not even my friend who had found the dolphin, was looking in the pond excavations. By July Sarah and I had moved into our house in North Charleston, a four minute drive away, and we were always the first onsite right after a rain - and, truth be told, we didn't really see anyone else out there, and in between afternoon thunderstorms, there weren't any new fossils eroding out. All told, we were reasonably certain we had an unbiased sample. The Chandler Bridge excavation site, quarried in 1970-1972, was even more of a slam dunk because all teeth had been kept by the Charleston Museum crew and there simply wasn't any private collecting permitted. Every vertebrate fossil from the 21x21 meter gridded excavation pit was kept by the museum.
How do you tell a shark's age?
Determining the age of live animals is difficult, unless they're pets, in a zoo, or tagged while young juveniles. For dead animals, it's a bit more difficult. Tooth wear can often be used in modern mammals, especially herbivorous ungulates. Growth bands in teeth (growth layer groups) are often useful as the deposition of dentin slows in the winter, leaving annual banding that is visible under a microscope. For sharks, it's quite a bit more difficult. Vertebrae have similar growth rings, and if sectioned properly (they are calcified cartilage, not bone) growth bands can be counted. Changes in DNA relating to growth can be sampled and analyzed, called DNA methylization. Shark tissues can also be radiocarbon dated - a greenland shark (Somniosus microcephalus) had lens nuclei dating to over 272 years in age, and surprisingly, many specimens around two meters in length had lens nuclei showing the 'radiocarbon bomb spike' from the 1950s-1960s spate of nuclear tests.
While counting growth rings offers a degree of precision, it is less useful for fossil assemblages like ours since it is always tricky to identify shark vertebrae to the species level - and in our case, we had a ton of teeth, rather than vertebrae. Teeth are formed, temporarily brandished in the mouth, and then shed - practically the opposite of an archive of growth, unlike the vertebrae. They are, instead, more akin to a 'snapshot' - roughly how large the shark was at the time the tooth was shed. Tooth size is much more rough, but with teeth, you get a much larger sample. Was this really a nursery assemblage? We would need a few data points first.
Fortunately, our colleague Kenshu Shimada had published a few papers about two decades prior where he took measurements of teeth from sharks of known body length and plotted tooth size v. body length, generally resulting in a linear relationship. Sharks grow slow and apparently close to isometrically - their growth rate is constant. Us mammals grow rapidly when we're juveniles and slow down after puberty. Birds grow even more absurdly rapidly, condensing most of their growth into their first year of life. Precisely how slow ancient 'reptiles' and dinosaurs grew has been a huge debate during the course of my entire career, and what sort of curve best fits that of dinosaurs - and if some mathematical assumptions of one curve over the other has completely messed up some estimates of dinosaur aging.
Addie's first task was to identify each tooth to position - and then enter her measurements into the linear regression equations that Shimada had demonstrated for the modern great white shark. We don't think that they are particularly closely related, but given the broad similarity of the teeth, it's probably good enough. This was necessary because the teeth are different sizes: the largest teeth are from the front of the mouth, and they decrease in size further posteriorly. As a result, if we were just to plot tooth size - we would be underestimating the size of the sharks that had shed the lateral teeth. The only established method results in a body length estimate, so we figured we could plot all of the body length estimates for all 32 teeth - and the 95 teeth from the Purdy sample. This would give us a population curve of sorts, and tell us what body lengths were the most common - and the most rare. We followed a paper by Pimiento et al. (2010) on a Carcharocles megalodon nursery from Panama.
Next up, we needed to know what the maximum size of the species Carcharocles angustidens was. This is actually a pretty difficult problem - since we would need to measure the largest known teeth of this species. Large teeth of C. angustidens are trophy specimens. Fossil collectors in the lowcountry might hand over fragmentary cetacean skeletons after much negotiating and encouragement, but they rarely ever cough up prized shark teeth. The shark teeth are the whole ball game down there: us whaleontologists got fossil cetaceans donated because they were discovered during the search for shark teeth. Shark teeth are big business in the southeast. Fortunately, there was one large tooth in the college collection which we were able to figure and measure, and a handful of similar to slightly larger specimens in Charleston Museum collections. Once we had our maximum size of C. angustidens from these specimens, we subdivided the size estimates into three categories: neonates, juveniles, and adults. We took the maximum length estimates of C. megalodon from the earlier Pimiento study and 'shrunk' them to fit the smaller maximum body length of C. angustidens - this resulted in the neonate-juvenile cutoff at 2.6 meters, and the juvenile-adult cutoff at 6.8 meters. The single largest tooth, Charleston Museum specimen 7267, was estimated to be a whopping 11.25 meters (37 feet). While I have not seen them personally, I am certain that larger specimens probably exist in private collections - and I had no interest in trying to beg and plead for such specimens to be donated for our study. What collector is going to donate a specimen after I tell them they have the world's largest?
This is not the largest tooth I've ever found, nor is it the largest Carcharocles angustidens specimen out there - but ironically, it is a trophy specimen of mine which even I never donated - for a number of reasons. I've also intentionally left the barnacles and bryozoans on it, lest it become just another tooth. I found this in July 2020 with Ashby Gale and Sarah. Photo by the author.
As it happens, we got this right under the wire: there have been a slate of papers that came out in the next couple of years and have reignited the debate over the maximum body size of megatoothed sharks, specifically C. megalodon. Reignited is perhaps too soft a word: exploded may be more appropriate, in more ways than one. It now seems as though the Carcharodon carcharias based estimate of about 15-16 meters (~45-50 feet) based on tooth size from the 1990s is far too conservative, and new papers using the maximum dimensions of the jaws based on associated tooth sets indicating sizes up to 20 meters (Perez et al. 2021) and even 24 meters based on rediscovered gigantic vertebrae from Denmark (Shimada et al. 2026). It's likely that these methods, if applied to C. angustidens, may result in some changes in the maximum length, but are unlikely to change the cutoffs used in our study, and in any event, will not change the juvenile-dominated pattern.
Histograms of reconstructed Carcharocles angustidens body lengths from the McKewn subdivision sample (top) and the Chandler Bridge excavation (middle), and the two combined together (bottom). As you can see, the sample realy is dominated by juveniles. From Miller et al. (2021).
Scientific Results from the hot mud of the Lowcountry: a nursery sample after all?
When Addie entered all of the data in and generated a graph (histogram) of the sizes, I was actually a bit surprised. I knew that juveniles were common, but I did not really expect them to be essentially the only specimens in our sample from the McKewn subdivision. There was one neonatal tooth, 31 juveniles, and zero adults. I was further blown away by the Chandler Bridge excavation sample from bed 3 - out of 95 teeth, there were three neonates, six adults, and the remaining 86 were from juveniles. Addie combined the two datasets together, and the result was a rather pleasing near-normal distribution of body sizes, with a peak around four meters body length - 31 specimens, about 1/4 of the entire sample. Most of the adults were on the right-hand tail of the curve, and two enormous teeth were outliers at around 10-11 meters - with zero teeth representing body sizes from 7.5 to 10 meters. This strongly suggests that most of the adults are the tail end of the resident juvenile population, with a few true adult giants visiting rarely. Altogether, this supports Purdy's original proposal that the Charleston Embayment was in fact a nursery for megatoothed sharks - and the only established nursery for the Oligocene epoch.
A nursery assemblage of Carcharocles megalodon teeth from the upper Miocene Gatun Formation of Panama. From Pimiento et al. (2010).
Nurseries have also been proposed for C. megalodon in Panama, the western Mediterranean, Salisbury Embayment (Calvert Formation), Florida (Bone Valley Formation), and the Chucunaque Formation of Chile. There has been a bit of back-and-forth over these, with certain researchers squabbling over small sample sizes and what statistical approaches were appropriate or not.
What's really remarkable is that this shark assemblage essentially demonstrated the process of repeatability in paleontology. You can argue until the cows come home about fossils sitting in museum collections, but sometimes, the only way to test a historical hypothesis is to go out and dig up a bunch more fossils. In this case, Bob Purdy had made a hypothesis based on a sample of teeth from an excavation conducted in the early 1970s - and we had essentially tested the hypothesis using a completely different sample of teeth from the same rock unit a few miles away, and under somewhat different conditions. We failed to reject Bob's hypothesis, instead reinforcing it. Given that Bob had never published the original specimens, we decided to include that and produce a much more robust study.
The Chandler Bridge excavation pit is now partially built over, and the pond at the McKewn Subdivision is completely flooded. Neither locality is now accessible - the former being much more permanent, given that some ponds can be pumped out and drained - after all, we dug at the Austin Sand Pit in 2022, four years after the owners flooded it. Now it's a motorboat test pond and won't get drained again until there's new management. At McKewn, the pond is encircled by duplexes and townhomes, and probably won't ever be drained. We'll have to wait for another construction project - but there's not many fossiliferous areas left in the Charleston area to dig down into.
I probably ought to write an entire blog post about this - but we decided to stick with the genus Carcharocles instead of Otodus. We have a taxonomic discussion and outline the fact that use of Otodus relies upon a bunch of untested phylogenetic assumptions. These assumptions may turn out to be true - but in the ten years since this taxonomic proposal has been made, dozens of papers have accepted it blindly and zero have tried to test any of the underpinning phylogenetic assumptions. We viewed - and I still view, five years later - the move to place the species of serrated megatoothed sharks in Otodus as premature. I briefly followed along in 2019, but not a single followup study attempted to make a strong case for it, so I decided to appropriately backtrack. Another strenuous argument in favor of continuing to use Carcharocles was made by Kent (2018). I could be wrong! I'm not afraid to be wrong - but someone needs to prove it first.
First records of Carcharocles angustidens from the Ashley Formation
In addition to the sample from the Chandler Bridge Formation, we also reported about nine teeth of Carcharocles angustidens from the Ashley Formation at the McKewn subdivision. Surprisingly, none had ever been found in situ before, anywhere - loads and loads of isolated teeth have been reported from riverbanks, riverbottoms, and beaches over the past 150 years. However, these were all found ex situ - possibly eroded our of the Ashley Formation, Chandler Bridge Formation, or - heaven forbid - the poorly known Edisto Formation. Unsurprisingly, virtually all of the teeth from the Ashley Formation were also from juveniles or possibly large neonates. Altogether, this suggests that the Charleston Embayment served as a megatoothed shark nursery for several million years.
You can read our open access paper in Palaeontologia Electronica online here for free.
Further Reading
Cicimurri, D.J. and Knight, J.L. 2009. Late Oligocene sharks and rays from the Chandler Bridge
Formation, Dorchester County, South Carolina, USA. Acta Palaeontologica Polonica, 54:627-
647. https://doi.org/10.4202/app.2008.0077
Cooper, J.A., Pimiento, C., Ferrón, H.G., and Benton, M.J. 2020. Body dimensions of the extinct
giant shark Otodus megalodon: a 2D reconstruction. Scientific Reports, 10:14596.
https://doi.org/10.1038/s41598-020-71387-y
Gottfried, M.D., Compagno, L.J.V., and Bowman, S.C. 1996. Size and skeletal anatomy of the
giant “megatooth” shark Carcharodon megalodon, p. 55-66. In Klimley, A.P. and Ainley, D.G.
(eds.), Great White Sharks: the Biology of Carcharodon carcharias. Academic Press, San
Diego.
Gottfried, M.D. and Fordyce, R.E. 2001. An associated specimen of Carcharodon angustidens (Chondrichthyes, Lamnidae) from the Late Oligocene of New Zealand, with comments on Carcharodon interrelationships. Journal of Vertebrate Paleontology, 21:730-739.
https://doi.org/10.1671/0272-4634(2001)021[0730:AASOCA]2.0.CO;2
Herraiz, J.L., Ribé, J., Botella, H., MartÃnez-Pérez, C., and Ferrón, H.G. 2020. Use of nursery
areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes).
Biology Letters, 16:20200746. https://doi.org/10.1098/rsbl.2020.0746
Kent, B.W. 2018. The cartilaginous fishes (chimaeras, sharks, and rays) of Calvert Cliffs,
Maryland, USA. Smithsonian Contributions to Paleobiology, 100:45-157.
Miller, A.E., Gibson, M.L., and Boessenecker, R.W. 2021. A megatoothed shark (Carcharocles angustidens) nursery in the Oligocene Charleston Embayment, South Carolina, USA. Paleontologia Electronica, 24:a19.
Perez, V.J., Leder, R.M., and Badaut, T. 2021. Body length estimation of Neogene macrophagous lamniform sharks (Carcharodon and Otodus) derived from associated fossil dentitions. Palaeontologia Electronica, 24:a09. https://doi.org/10.26879/1140.
Pimiento, C., Ehret, D.J., MacFadden, B.J., and Hubbell, G. 2010. Ancient nursery area for the extinct giant shark Megalodon from the Miocene of Panama. PLoS ONE, 5:e10552. https://doi.org/10.1371/journal.pone.0010552
Purdy, R.W. 1996. Paleoecology of fossil white sharks, p. 67-78. In Klimley, A.P. and Ainley, D.G.
(eds.), Great White Sharks: The Biology of Carcharodon carcharias. Academic Press, San Diego.
Purdy, R.W., Schneider, V.P., Applegate, S.P., McLellan, J.H., Meyer, R.L., and Slaughter, B.H.
2001. The Neogene sharks, rays, and bony fishes from the Lee Creek Mine, Aurora, North
Carolina. Smithsonian Contributions to Paleobiology, 90:71-202.
Sanders, A.E. 1980. Excavation of Oligocene marine fossil beds near Charleston, South
Carolina. National Geographic Research Reports, 12:601-621.
Shimada, K. 2002. The relationship between the tooth size and total body length in the white
shark, Carcharodon carcharias (Lamniformes: Lamnidae). Journal of Fossil Research,
35:28-33.
Villafaña, J.A., Hernandez, S., Alvarado, A., Shimada, K., Pimiento, C., Rivadeneira, M.M., and
Kriwet, J. 2020. First evidence of a palaeo-nursery area of the great white shark. Scientific
Reports, 10:8502. https://doi.org/10.1038/s41598-020-65101-1
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