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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.