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The era between the Miocene and Pliocene (23-2.3 Million Years ago) was, like the Carboniferous era 300 Million Years before, a golden age for the Chondricthyans. Not only was there a massive explosion in the diversity of grey sharks, but there was the emergence of perhaps the largest number of large macropredatory shark genera (sharks greater than 3 meters (10 feet) in length) currently known in Earth's geologic history. This includes the Giant Thrasher Shark Alopias grandis (which grew up to 13 meters (feet) in length) and the famous Carcharocles (Otodus) megalodon (which grew up to 17 meters (55 feet) in length). https://www.science.org/doi/10.1126/sciadv.abm9424 But this golden era of the giant macro predatory sharks wouldn't last, for between 3.8-2.4 Million Years ago there was an extinction event of large marine fauna that killed at least 14% of large marine fauna genera, including Carcharcoles (Otodus) megalodon. Though it's not entirely clear what caused this extinction event (some have hypothesized it could've been a mild gamma ray burst), C.megalodon's decline was due to the closing of the Isthmus of Panama by 4.5 Million Years ago (an area that was a C.megalodon nursery), a decline in diatoms that caused a decline in the food sources of many whales like Cetothere whales including Cetotherium (a known food source of C. megalodon), and Competition with the recently emerged Great White Shark (Carcharodon carcharias) and Orcas (Orcinus). By the extinction events end, most of the Miocene's large predatory sharks were extinct. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6377595/ https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084857 https://www.researchgate.net/publication/318160879_The_Pliocene_marine_megafauna_extinction_and_its_impact_on_functional_diversity https://royalsocietypublishing.org/doi/10.1098/rsbl.2020.0746 But there was a few genera that survived the extinction event 3.6-2.4 Million Years ago and lived long after it. These surviving taxon (likely surviving due to relying on different food sources then other large sharks of the miocene-pliocene) lived previously alongside C. megalodon and some survived up to at least the early Pleistocene (120,000-100,000 years ago). Here's a list of the large (non Great White Shark (Carcharodon carcharias)) macropredatory sharks of the late Pliocene-Early Pleistocene (If I'm missing any examples, let me know and I'll quickly add them). Hemipristis serra (Hemigaleidae, grew up to 3-5 meters (10-16 feet) in length) (Miocene-Pleistocene (Pleistocene strongholds: What is now Indonesia, Taiwan, South Carolina (U.S.), Alabama (U.S.), and Florida (U.S.)), 23.03-0.012 Million Years ago) Reconstruction 1 and 2 Image by artist @Tetrtophoneus, Image credit: https://www.deviantart.com/teratophoneus/art/Hemipristis-serra-871902574 Image by artist @HodariNundu (the two sharks below and next to the juvenile C.megalodon at the middle top are adult Hemipristis serra), Image credit: https://www.deviantart.com/hodarinundu/art/Mobbing-Meg-885731702 http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=83182 https://www.fossilguy.com/gallery/vert/fish-shark/hemipristis/hemipristis.htm https://www.researchgate.net/publication/364591134_A_previously_overlooked_highly_diverse_early_Pleistocene_elasmobranch_assemblage_from_southern_Taiwan Parotodus benedeni (Otodontidae, grew up to 7.6 meters (24.9 feet) in length) (Oligocene-Pleistocene (Pleistocene strongholds: What is now South Carolina (U.S.)), 33.9-0.012 Million Years ago) Reconstructions 1 and 2 Image by artist @imAdro, Image credit: https://www.deviantart.com/imadro/art/Parotodus-benedeni-908901669 Image by artist @SameerPrehistorica, Image credit: https://www.deviantart.com/sameerprehistorica/art/Parotodus-Size-882947974 http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=389883 https://www.petit-fichier.fr/2013/01/27/kent-b-w-1999-taille-parotodus-benedenii/? https://www.researchgate.net/publication/337937278_2019-canevet-a-review-of_the-extinct-genus-Parotodus https://www.app.pan.pl/archive/published/app63/app004542018.pdf http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=389883&max_interval=Quaternary&country=United States&state=South Carolina&is_real_user=1&basic=yes&type=view&match_subgenera=1 https://www.cambridge.org/core/journals/paleobiology/article/chondrichthyan-fossil-record-of-the-florida-platform-eocenepleistocene/2835CCEC27DC8EE0B24A5B62B1416618 Cosmopolitodus hastalis (Lamnidae, grew up to 5-7 meters (16.4-22.9 feet) in length) (Oligocene-Pleistocene (Pleistocene strongholds: What is now Japan, South Carolina (U.S.), Alabama (U.S.), and Florida (U.S.)), 30-0.012 Million Years ago) Reconstruction Image by artist @artbyjrc, Image credit: https://www.deviantart.com/artbyjrc/art/Going-to-need-a-bigger-boat-Lamnid-sharks-837971394 http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=265174 https://actapalrom.geo-paleontologica.org/Online_first/Chan_Cosmopolidus_planus.pdf Note: Cosmopolitodus hastalis was an ancestor to the extant Great White Shark (Carcharodon carcharias), along with living alongside the Great White Shark (Carcharodon carcharias) between the Miocene-Pleistocene. However, Cosmopolitodus hastalis’s being a member of the genus Carcharodon has yet to be confirmed). I hope you all find this helpful?

Took my first trip out to Calvert cliffs state park this weekend. Got there as early as I could, which started me at high tide. Beach loaded up with people throughout the day. And from what I saw, nobody else found any teeth. So I consider myself lucky with the hastalis I found. The roots were just barely showing, I think a wave may have just uncovered them. It was a long day round trip from NY but worth it. Also found some scallops.

This was a prep I've last year, but for some reason I've never posted it on the forum. So I thought I might change that. Last year I was fortunate enough to take a visit to the Ernst Quarries and dig for some shark teeth. Although most of the fossil I've taken home are either bones, four partial regular-sized teeth, and mostly tiny partials (some of which I accidentally damaged while digging ), the biggest find of the day was this large Cosmopolitodus hastalis tooth with its crown partially sticking out of the matrix. When Rob noticed the tooth, he initially estimated it to be ~2 inches long and insisted that I keep the tooth in the matrix, saying something like "The tooth itself is worth about $15. If you keep the tooth in the matrix, it'll be worth $60". Although my reason for visiting the Ernst Quarries was to find shark teeth to keep rather than to sell, I for some reason decided to keep the tooth in the matrix. However, I still had to prep this baby when I got home! Below is the tooth how I found it. This was going to be my first (and so far only considerate) prep I've ever done. Rob told me that the matrix can easily be scratched away using a fingernail and so taking his words and some advice I've gotten from the forum regarding something else, I grabbed one of my mom's needles and started quite literally digging off the siltstone. After around 10 minutes, a perfect root base showed up. This tooth is obviously going to be a perfect whole, so you just gotta keep scraping off the matrix. One really helpful thing I've realized at this point is that the needle I was using was perfect for such beginner's prep- it was strong enough to remove matrix effectively but not enough to do any damage to the tooth itself.

Hello all! I found this cosmopolitodus tooth. It appears to have fine serrations. If these are serrations it would be a lower anterior C. Escheri. Can anyone confirm? It’s over 1.5 inches long.

Hello! This was my first time (3/25/2018) at Brownie's Beach in Maryland and it was a great day! I arrived at around noon and only stayed for 2 hours or so... the wind was piercing. There weren't many collectors and I found quite a few small teeth and the best of the day was what I believe is a Cosmopolitodus hastalis. I do have a few questions about some teeth I found and also the park itself. I noticed the red sign to the south (right) that mentions staying away from the cliff zones, but it's pretty ambiguous. Am I to assume you cannot go beyond the red sign or just close to the cliffs? I saw several people go down that may be guilty myself) (I may and have read trip reviews here that mention going far south. I completely understand the hazards with the cliff but there is a considerable gap between the actual cliffs and where the water breaks. I just wanted to clarify - but anyways here were my finds for the day! This is the first tooth I'm not too sure about - maybe a Whaler Shark? And here is the second - possibly just a worn Mako?: Some Cow Shark's I believe: A Snaggletooth Shark? A cool little Tiger Shark? And my favorite of the day Cosmopolitodus hastalis? I was pleasantly surprised by the variety of teeth I was able to find here as opposed to some of the other parks in the area. Thanks for all the interest and help!

I have some questions surrounding the extinct species of Giant White Shark, Cosmopolitodus hastalis. I think it was a fascinating creature, but for reason it doesn't seem to be brought up much. As far as I know, it was a very large shark that lived during the Miocene Epoch, and scientists believe it to be a possible ancestor to the extant Great White Shark, the biggest and meanest shark of our present day oceans. What I'd like to know is what was this shark really like? Did it look similar to the Great White? How do we think it behaved? How exactly does it fit into the lineage of the Great White? How big was it? Did it share the seas, or even possibly become prey for, the mighty O. megalodon? And finally, WHY do people call it "Mako" if it clearly isn't one?? Obviously, not all of these questions have concrete answers but I'd like to hear what you all know about the species. Google search results can only tell so much. Do you know of any good sources where I could read up about it in greater detail? I just think it's a really cool species, and I'd love to know more about it. Thanks!

Realized this while talking to a buddy who doesn't know much about FL fossils, since (almost) everyone can agree Cosmopolitodus/Carcharodon hastalis was much more related (I mean ancestral) to the modern great white rather than modern mako's, shouldn't we be calling them "white sharks" instead of "mako's"? By not saying "great" imo you clearly don't mean Carcharodon carcharias & iirc paleontologists only though they were ancestors of modern mako's because they had no serrations.. sorry if this is a rhetorical question, but I couldn't hold it in any longer.

This tooth was found along the base of the Calvert Cliffs in Maryland during one of my trips to Brownie's Beach. It made the Hop 5 of that trip because it's a decent size and cool-looking tooth, but now I've run into a problem. Of the few species of Mako shark found in the Cliffs, I don't know which one this is. I had it classified as an Isurus desori tooth in the Hop 5, but I'm beginning to reconsider that identification. After studying descriptions and pictures of specimen from both Cosmopolitodus hastalis and Isurus desori (supposedly the two most common Mako species in the area), I can't make a confident verdict. The tooth has a slant height of slightly over an inch, a thick root center, and broad crown with a smooth and defined cutting edge. It's size isn't much of a help because as far as I understand, C. hastalis is larger than I. desori but this tooth is right in between the average for the two species. It really could be either, but I'm sure there's got to be a good way to tell them apart that I'm just not aware of. The two sharks are really quite different after all. Although we hunters call them "Makos", C. hastalis was truly a Giant White Shark. Anyway, I'd love some help on this one. I'll attach a few pictures, including one with a scale, as well as the ones I posted in my Brownie's Beach trip report from 12/26/17. Thanks!