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The Chondricthyans (including the sharks and rays) have been around and keeping the ocean's ecosystems healthy for about 420 Million Years. Today, in celebration of this, I've decided to do a little fun post and list the eight times in Earth's history truly massive chondricthyans have emerged. Hope you all enjoy!!! The First is the Devonian, where there is at least one confirmed fossil (CMNH 5238) of a large currently unnamed Ctenacanthiform shark that reached lengths of 4.2-5 meters (13-16 feet) in length. https://www.mdpi.com/1424-2818/15/3/318 The Second is the Mississippian stage of the Carboniferous (358.9-323.2 Million Years ago), a golden age for chondricthyans. The Early Carboniferous saw the emergence of Giant Ctenacanthiform sharks like Saivodus striatus, which grew up to 10-11 meters (32-36 feet) in length. https://www.uky.edu/KGS/fossils/fossil-of-the-month_2022-07_Saivodus.php https://www.uky.edu/KGS/fossils/fossil-of-the-month_2022-07_how-big.php https://www.nps.gov/articles/000/fossils-of-the-2023-national-fossil-day-artwork.htm The Third is the Pennsylvanian stage of the Carboniferous (323.2-298.9 Million Years ago). Like the Mississippian, the Pennsylvanian was also a golden stage for Chondricthyans where large Ctenacanthiforms continued to thrive and large Eugeneodontida edestoids like Edestus (which could grow up to 6.7 meters (22 feet) in length) emerged. Large Ctenacanthiforms from this time include the unnamed Graham Formation Gilkmanius sp., which grew up to 7 meters (22 feet) in length. https://bioone.org/journals/journal-of-vertebrate-paleontology/volume-37/issue-3/02724634.2017.1325369/A-Pennsylvanian-Supershark-from-Texas/10.1080/02724634.2017.1325369.short The Fourth is the Permian (298-252 Million years ago). There were some large sharks, like the Ctenacanthiform Kaibabvenator (which grew up to 4.8-5.48 meters (16-18 feet) in length). But Eugeneodontida by this point contained the largest Chondricthyans alive at this time including Helicoprion (which grew up to 7.6 meters (25 feet) in length) and Parahelicoprion (which could grow up to 12 meters (36 feet) in length). https://www.academia.edu/29941296/Chondrichthyan_and_actinopterygian_remains_from_theLower_Permian_Copacabana_Formation_of_Bolivia https://doi.org/10.1002%2Far.24046 The Fifth is the Early Cretaceous (145-100 Million Years ago). Though the time's aquatic ecosystems was dominated by large marine reptiles, large sharks managed to emerge and fill ecological niches from time to time. This includes the Early Cretaceous Shark Leptostyrax, which grew up to 6.3 meters (20 feet) in length. https://www.researchgate.net/publication/277782424_A_Gigantic_Shark_from_the_Lower_Cretaceous_Duck_Creek_Formation_of_Texas The Sixth is the Late Cretaceous (100-66 Million years ago). Aquatic ecosystems still were dominated by marine reptiles, but large sharks were indeed present. This includes Cretodus crassidens (which grew up to 9-11 meters (29-36 meters) in length) and Ptychodus (which grew up to 10 meters (32 feet) in length). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0231544 https://www.cambridge.org/core/journals/journal-of-paleontology/article/morphology-and-paleobiology-of-the-late-cretaceous-largesized-shark-cretodus-crassidens-dixon-1850-neoselachii-lamniformes/A670012A44DDC68FC098BB8C73368408 The seventh is the Miocene-Early Pilocene (23-3.6 Million Years ago). This period saw the rise and reign of some of the largest sharks known currently in the fossil record, including Carcharocles (Otodus) megalodon (which grew up to 17 meters (55 feet) in length). https://www.uv.es/everlab/PUBLICACIONES/2017/2017 Martinez-Perez et al HB miocene sharks.pdf https://www.science.org/doi/10.1126/sciadv.abl6529 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9385135/ The eighth is the Early Pliocene-Late Pleistocene (3.6-0.012 Million Years ago). This period saw the last remnants of the large 20 foot + in size carnivorous sharks from the Miocene-Pilocene mega shark era not including the non-Great White shark (Carcharodon carcharias) and not including the large plankton eating sharks make their final stand. These include Hemipristis serra (which grew up to 6 meters (20 feet) in length) and Parotodus benedeni (which grew up to 7.6 meters (24 feet) in length). https://www.app.pan.pl/archive/published/app63/app004542018.pdf https://www.researchgate.net/publication/364591134_A_previously_overlooked_highly_diverse_early_Pleistocene_elasmobranch_assemblage_from_southern_Taiwan https://www.cambridge.org/core/journals/paleobiology/article/chondrichthyan-fossil-record-of-the-florida-platform-eocenepleistocene/2835CCEC27DC8EE0B24A5B62B1416618 I hope this is helpful?

I was able to acquire a nice Giant Thresher (Alopias Grandis, non-serrated form) that came from Lee Creek (Aurora, NC). It's the third in my collection. I'm curious to know how rare/uncommon they are from that location. Giant Thresher shark teeth seem to be found with some regularity in South Carolina, although they be from the Oligocene. Giant threshers are also found in Maryland along Calvert Cliffs (Miocene). I've seen a few other Giant Threshers from Lee Creek in other people's collections and have heard about a few others. Curious to know, especially from some of the long-time LC collectors, how often they heard of a Giant Thresher being found in the mine. Daryl.

Any day out on the river is a great day but today was something special, plentiful teeth and a couple of rarities! My wife started the day off right by finding a symphyseal cow shark tooth, I still can't hardly believe that she found it! Later on I stepped over a log to find a Meg leaning up against another log. Later on in the day, my daughters were hunting together and when I got home and checked out what they found, there was an Alopias grandis there! I finished the day off by spying a 2 1/2" Mako sitting high and dry...I couldn't ask for a better day on the river with my family! Total haul. Definite trip maker here! I was very pleased with this! My wife was not going to be outdone and found her own. Of course my kids got into the action as well. I closed out the day with this beauty.

Of all the teeth I've seen come out of Lee Creek (Aurora) over the years when it was open to collecting, I never saw a Giant Thresher shark tooth (Alopias grandis) be found. I know there are pics of a couple on elasmo.com, and recently I saw online (FB) where a young child actually found one in one of the spoil piles in front of the museum. I'm sure more have been found over all the years in Lee Creek, quite possibly with some folks not really knowing what they were. A good friend of mine found one at Calvert Cliffs many many years ago, before I had ever heard of them. I was at the beach that day when he found it and showed it to me. We both figured it was either a pathological mako, or perhaps an odd position of a regular mako that we hadn't seen before. I've seen/heard of other collectors going back into their collections and discovering that they actually had one among their collection of "makos". The particular type of Giant Thresher shark tooth that I've seen is the Alopias Grandis, the non-serrated version. There is also a serrated version of the Giant Thresher shark tooth, found in MD and VA, and I think NC? Just curious to see pics or stories of any other Giant Threshers found in Lee Creek.

Here are a few photos of an Alopias grandis (a little over 1 1/4 inches), I found yesterday morning on the Potomac River, VA side. It was my very first find of the day, after I stepped on it, and it is the first one I've ever found in 10 years of collecting/hunting. This one has serrations down both sides, though they are a little worn, which makes it even more special. It was a gorgeous weekend hunting and collecting along the Pamunkey on Saturday and Potomac on Sunday, despite the huge thunder storm at noon on Saturday that dumped 2 inches of rain in 45 minutes which equaled 50 gallons of water in each of the 2 boats. Fortunately for me, my wife enjoys fossil hunting too and we got to spend the weekend fossiling with TFF's own "Joyce." She is absolutely hilarious and a hoot to hunt with along with being extremely knowledgeable about marine fossils.

It has very minute serrations as well.