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Last week I was on holiday in the Netherlands/Belgium for a short time and I had the chance to visit the area of Antwerp to find some shark teeth. Too bad the weather wasnt good (I think it rained the entire day). Nevertheless I found some teeth and I have to say that I am kinda satisfed with the result! I almost sieved the whole day so my body still hurts a bit The material I searched in comes from the Miocene, Pliocene and was washed up from the extension of Churchill dock in Antwerp. Here are two "in-situ" pictures: A nice tooth on the sifter: Pictures of the nicest teeth: A nice dolphin tooth with enamel (4 cm long): A dolphin ear bone: (a little bit more than 2 cm long) An Isurus retroflexus tooth (3 cm long): And an 4.2 cm long Cosmopolitodus hastalis: (I am not sure if I determined this one right ...) I think I will post some more detailed pictures of other teeth in the next days! Thanks for watching

Our final stop in the Shark program is of course the giant Sharks of the Miocene. We wrap our adventure through the timeline of shark evolution by giving the kids what they expect to see, big shark teeth. Truthfully, we do not have many large shark teeth. I went for interesting teeth not big teeth but we have a few that will grab the kids attention. We give a very brief introduction to the giant sharks with a 2 inch Otodus tooth. We can spend too much time on Otodus or the ancestors of Megalodon as it just do not have time ( plus we do not have teeth from Auriculatus, Angustidens, or Chubutensis). After that brief bit, we ask the kids a question.... What shark is the ancestor of the modern Great White ? We give the kids a chance to answer that question for themselves by connecting them to the sharks that swimming in the ocean off the coast of California 12 million years. I want to explore the origins of the most well known modern shark and connect them to the fossil rich area just 6 or so hours south of where they live so we journey to Sharktooth Hill to finish the program. Isurus planus was a fairly large shark and probably reached lengths of over 20 feet. I have not found a lot of material about planus but I would think that based on tooth size, 20 feet seems possible. I have seen 2 inch planus teeth though I have nothing that big myself. We also show the kids a couple Isurus desori teeth only to mention that they MIGHT be related to modern Short-fin Makos. We then jump into another species that is present at STH and the one the kiddos will be most familiar with, Megalodon. This is obviously a super important species to talk about because it is the most popular prehistoric shark. It is the T-rex of sharks. Biggest teeth of any shark found so far. Most likely the largest shark ever and quite possibly the largest fish. They ate whales. They were also common and the apex predator in the worlds oceans during their time. We do not know what they look like but my son is working on his version of Megalodon and it has elements of a basking shark to it along with the traditional Great White like appearance. I will tell the kids that for a long time, Megalodon was thought to be the ancestor of great whites but science has uncovered another possible contender for being the ancestor of great whites. Carcharodon hastalis was a large shark that probably reached 30 feet in length. They had large teeth and were probably fast swimming ambush predators. I remember reading somewhere, that evidence existed from STH that the Broad-tooth White Shark hunted early pinnipeds from underneath, just as modern white sharks do. I can not remember where I read that and I want to track that down again to verify before saying that to kids. Anyway, we explain that they were probably very similar in appearance to great whites and filled a similar ecological role. I will add that transitional teeth have been found that are a pretty conclusive link the chain of white shark evolution but we want them to check out the teeth and judge for themselves. Our presentation teeth Pic 1 I. planus and I. desori. These are not the exact teeth for program. I do have a few bigger teeth but these were in my desk as I am doing this lol Pic 2 Our 5.08 inch Megalodon tooth and the tooth that I suspect will be the most popular in the presentation. Not the prettiest nor the biggest but it is still a really big tooth to me. We also use a 3 inch tooth for the presentation but I did not photograph it. Pic 3 a 2 inch hastalis, a 2.5 inch hastalis, and one that I personally think is cooler than even Megalodon, a 2.54 inch Great White. It is blue. It just looks cool and I think 2.54 is pretty large for a white shark tooth. We wrap it up with questions from the kids while we go around the classroom handing out shark teeth to the students. If you happened to read all of these, you are a good soul because these are long winded posts I know lol Thank you to all who commented and offered encouragement. I will probably start putting up the marine mammal stuff next.

I've recently was lucky to have found an online copy of Purdy et al. (2001)'s paper on Lee Creek sharks, and I've found a passage that caught my interest- "In morphology, the teeth lsurus hastalis (Figure 27) are almost identical to those from large individuals (TL=3.7-4.3 m) I. paucus. The tips of the upper anterior teeth of the latter species, however (TL=2.3^1.2 m, n=9), usually lack the labial recurvature that is so well developed in I. hastalis (Figure 28a). In the small number of I. paucus dentitions available to us (n=9), only one dentition (Hubbell collection, JF91980, 2.6 m TL, female) had upper anterior teeth with tips that exhibited a strong labial recurvature. At present, we do not know how common this recurvature is in the extant species. The upper anterior teeth of Leriche's (1910:275-280, figs. 78-86, pi. 16: figs. 16-31) sample of teeth from the Oligocène of Belgium, which he identified as Oxyrhina desori and O. desori flandrica, are identical to those of the extant Isurus paucus. They lack a labial recurvature. This suggests that I. paucus may be a junior synonym of I. hastalis, but because of the small number of dentitions available of I. paucus, we hesitate in synonymizing the two species. " Traditionally, I think people believed that I. paucus evolved from Isurus retroflexus. Capetta (2012) now describes retroflexus in the genus Anotodus as an alopiid with later authors following suit, making it unlikely to have any relation with the longfin mako and making the lineage of paucus unclear. Of the few papers and articles I've read that mention Purdy et al. (2001)'s observation and its possibilities, none give an actual opinion or response to it and simply mention it without anything else, which sort of makes me feel like this observation could be a legitimate possibility. So I really want to know the opinion any of you shark experts and enthusiasts out there on this topic. What do you guys think?

One of my nice Lee creek mako teeth were sitting in one of my pockets with a few Hershey's chocolates with paper wrappers (don't ask why I was pretty hungry). after I ate them all, I looked at my tooth, and to my dismay saw that what looked like the ink from the wrappers had rubbed onto the root. Aside from the weird story, I have tried using a toothbrush with soap and water, to no avail. What would be the best way to get rid of the stain? I have attached before and after pics below. I know there are a few lighting differences, so I also put it aside one of my other lee creek makos that used to be a similar color as a reference to the darkness of the stain. Thanks.

I am thinking that this may be an extinct Mako such as Isurus Hastalis. Can anyone confirm this or have a better opinion? It is from the Cooper River of South Carolina. Thanks, Jamie

The following content is purely based on applying a mathematical equation from Ferron (2017), who obtained it from Sambilay (1990). No other source besides a few used for length measurements have been used besides Ferron (2017). I am not a mathematician and my calculations may have mistakes, which is why I've shown all of my work in case any of you want to check my math. The formulas themselves may possibly be updated/invalidated by later studies. Please take this with the finest grain of salt. Apparently, Cretoxyrhina may possibly be the one of the, if not the fastest shark known so far according to a set of equations. When reading through the scientific paper Ferron (2017), I found out that the equation he used to make his speed calculations are ones that I might be able to do myself, so here I am making a post that consists of a wall of algebraic nonsense to try to see for myself on things. Ferron (2017) used an equation that was developed by Sambilay (1990) (which I unfortunately cannot access) to calculate the maximum burst speed of a large fish: Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(PCL) + 0.3478 ⋅ Log10(AR) AR stands for aspect ratio, which is the ratio between the height and surface area of the caudal fin. PCL stands for post-caudal length and can be calculated from a shark's total length (TL) using this equation: PCL = -0.9195 + 0.8535 ⋅ TL When Ferron (2017) inputted the equation for Cretoxyrhina mantelli using Shimada (2006)'s conservative estimates for maximum size of 640 cm as total length (TL) and an unspecified aspect ratio (AR), a burst swimming speed of ≈70 km/h was calculated. This is essentially one of the highest confirmed calculated speeds of any shark ever recorded. I decided to try the equation for myself, which is shown below. I assumed that the AR used would be the conservative aspect ratio of 4.3 (The aspect ratios for C. mantelli were 4.3 and/or 4.9 depending on the type of angle used). AR = 4.3 PCL = -0.09195 + 0.8535 ⋅ TL PCL = -0.09195 + 0.8535 ⋅ (640) PCL = 546.14805 Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(PCL) + 0.3478 ⋅ Log10(AR) Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(546.14805) + 0.3478 ⋅ Log10(4.3) Log10(546.14805) = x1 x1 = Log(546.14805)/Log(10) x1 = (2.73731038736)/(1) x1 = 2.73731038736 Log10(4.3) = x2 x2 = Log(4.3)/Log(10) x2 = (0.6334684556)/(1) x2 = 0.6334684556 Log10(Sb) = -0.0659 + 0.6196 ⋅ (2.73731038736) + 0.3478 ⋅ (0.6334684556) Log10(Sb) = 1.84995107 Sb = 101.84995107 Sb = 70.7866028 Sb ≈ 71 km ⋅ h-1 Sb ≈ 44 mi ⋅ h-1 My result is a burst swimming speed of 70.8 km/h, 71 km/h when using proper rounding. Sort of off, but considering that the aspect ratio could have been different, I think this is good enough. But Ferron (2017) only used Shimada (2006)'s conservative estimates. Here, I redid the equation but used the maximum size of 700 cm as total length (TL) and a mean estimate of 4.6 for aspect ratio (AR)- AR = 4.6 PCL = -0.09195 + 0.8535 ⋅ TL PCL = -0.09195 + 0.8535 ⋅ (700) PCL = 597.35805 Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(PCL) + 0.3478 ⋅ Log10(AR) Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(597.35805) + 0.3478 ⋅ Log10(4.6) Log10(597.35805) = x1 x1 = Log(597.35805)/Log(10) x1 = (2.7762347206)/(1) x1 = 2.7762347206 Log10(4.6) = x2 x2 = Log(4.6)/Log(10) x2 = (0.6627578317)/(1) x2 = 0.6627578317 Log10(Sb) = -0.0659 + 0.6196 ⋅ (2.7762347206) + 0.3478 ⋅ (0.6627578317) Log10(Sb) = 1.8847622067 Sb = 101.8847622067 Sb = 76.6941443789 Sb ≈ 77 km ⋅ h-1 Sb ≈ 48 mi ⋅ h-1 My results show that a C. mantelli that measures 7 meters in length can swim at a bust speed of almost 77 km/h. That is essentially faster than any ocean animal except some of the billfishes according to popular estimates. Amazingly, this may possibly not be too farfetched. It has already been predicted for a long time that C. mantelli is likely a fast swimmer, potentially one of the fastest. Shimada (1997) showed that Cretoxyrhina possess a scale pattern that has superb efficiency in drag reduction (such patterns have only been found in the fastest Lamnids today). Kim et al. (2013) noted that the caudal fin of Cretoxyrhina represents the most extreme case of a Type 4 fin, where both the Cobb's and hypochordal ray angles are higher than any known shark. Type 4s are ones that are the most efficient in building speed, so maybe the "most Type 4" of them all could be the fastest? For comparison, I also applied the equation to Carcharodon carcharias, which is most similar with C. mantelli in morphology and ecological role (I assumed that the largest confirmed length is 610 cm) AR=2.7* PCL = -0.09195 + 0.8535 ⋅ TL PCL = -0.09195 + 0.8535 ⋅ (610) PCL = 520.54305 Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(PCL) + 0.3478 ⋅ Log10(AR) Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(520.54305) + 0.3478 ⋅ Log10(2.7) Log10(520.54305) = x1 x1 = Log(520.54305)/Log(10) x1 = (2.7164566524)/(1) x1 = 2.7164566524 Log10(2.7) = x2 x2 = Log(2.7)/Log(10) x2 = (0.4313637642)/(1) x2 = 0.4313637642 Log10(Sb) = -0.0659 + 0.6196 ⋅ (2.7164566524) + 0.3478 ⋅ (0.431367642) Log10(Sb) = 1.7672462077 Sb = 101.7672462077 Sb = 58.5121703926 Sb ≈ 59 km ⋅ h-1 Sb ≈ 36 mi ⋅ h-1 As far as I know, the fastest recorded speed for a great white is about 56 km/h. Considering that they probably have been clocked from smaller, more average individual, this calculation seems reasonable. However, if I input the equation to Isurus oxyrinchus using the 2013 Huntington Beach catch record of 373 cm for total length (TL)- AR=3.3* PCL = -0.09195 + 0.8535 ⋅ TL PCL = -0.09195 + 0.8535 ⋅ (373) PCL = 318.26355 Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(PCL) + 0.3478 ⋅ Log10(AR) Log10(Sb) = -0.0659 + 0.6196 ⋅ Log10(318.26355) + 0.3478 ⋅ Log10(3.3) Log10(318.26355) = x1 x1 = Log(318.26355)/Log(10) x1 = (2.502786903)/(1) x1 = 2.502786903 Log10(3.3) = x2 x2 = Log(3.3)/Log(10) x2 = (0.51851399)/(1) x2 = 0.51851399 Log10(Sb) = -0.0659 + 0.6196 ⋅ (318.26355) + 0.3478 ⋅ (0.51851399) Sb = 102.086400122 Sb = 122.0113188 Sb ≈ 122 km ⋅ h-1 Sb ≈ 76 mi ⋅ h-1 -I get a calculated burst speed of 122 km/h, completely tearing the "Cretoxyrhina the fastest shark" claim to shreds. Mako sharks already are the fastest of all extant sharks, but having a calculated speed of this much is mind-blowing. As far as I know, the fastest recorded speed for a mako shark (and therefore any shark) is about 74 km/h, but my calculation is higher than that of any ocean animal ever recorded except the sailfish whose swimming speeds is up to 130 km/h according to some sources. However, it is possible that I either messed up the math, this equation might not work on smaller fishes, or this equation calculates the dire, dire fastest speed of a large fish. If the latter is true, I'm really eager to obtain an aspect ratio for the sailfish and run it through the equation and see if it tops the peregrine falcon. What do you guys think? *AR was obtained from Ferron (2017) EXTRAS

I dug in the Pits of Pungo out front of the Aurora Fossil Museum for a few hours. Heres the haul. The shark teeth Phosphate nodules Coral Sea life burrows. Posterior lemons and coppers These teeth are sooo small I don't even know why I picked them up Bryazoa...? My favorites Some of those famous Aurora makos ( isurus oxyrinchus I think) What I think are posterior isurus oxyrinchus's though the one in the middle one looks like it has a burlette? meg? I would appreciate any feedback on these Two nice Hemipritis Double cusped carcharhinus taurus? Alligator claw core? Bird? Sea urchin spines ray teeth Fish/shark verts and partials. I would appreciate if someone s=told me the difference two of them stuck together Bone frags whale verts and frags Shells Can someone help ID them? I can't seem to find any papers or websites I also spent all my birthday money on their little gift shop. Heres what I got from there. I would be happy for any IDs for them. (I like things labeled) Dont know where from St. Claire. PA fern. What is the age and formation of this locale? Morrocan trilobite pyrite amethyst this is definitely my longest post even though its just pictures mostly

Good Evening Everyone, I have a few teeth (4) from the Eocene/Miocene of Florida .... Suwannee River. (1) Carcharhinus sp. (2) Hemipristis serra (1) Isurus desori (i believe) The hemi is probably the largest I own but trades are fun. I'm mostly looking for if possible a tooth or two (?) in trade .. not really that picky .. except that they have color,marbling,scarring,staining of some sort. Doesn't really have to be a 'shark' tooth either ... I know that sounds specific but I've been exploring color and irregularities in the teeth. Mother nature's art-form so to speak. If any of this sounds interesting lets chat. International is fine too .... Cheers, Brett

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!

Hi Looking thru an old collection of Isurus, three large and one smaller teeth showed a noticeable concave curve on the lingual side (I think I got that right). My first thought was pathological. In doing some "research" apparently there is something peculiar about the 3rd anterior tooth of Makos. Requesting your help with these. I tried to show by stacking the three curved ones with 2 regular shaped makos. Hope that shows clearly. What purpose would this "special" tooth serve? The brachiopod just could not resist getting in the picture. Thanks

Mackerel shark tooth.

Hey all, I have a tooth here, and I'm a bit confused. It comes from Hoevenen (BE), and dates from the Miocene. I'm pretty sure that it's a mako tooth, but I'm not sure what species: Isurus hastalis or Isurus oxirhynchus? Or perhaps another one? Also, how exactly can you distinguish I. hastalis from I. oxirhynchus? Best regards and have a nice Sunday! Max

This shark tooth was found on the foreshore at Beaumaris in Victoria, Australia. It is 5-6 million years old. I am confident it is a mako shark tooth but i am trying to decide which species to label it. The following shark taxa are listed in the fauna found at this location: Heterodontus cainozoicus, Carcharias taurus, Carcharodon megalodon, Parotodus benedeni, Isurus desori, Isurus oxyrinchus, Isurus hastalis, Isurus retroflexus, Lamna?, Megascyliorhinus sp., Carcharhinus cf. brachyurus, Carcharhinus sp., Galeocerdo aduncus The majority of teeth at the site are from Carcharodon hastalis (or Isurus hastalis depending on who you believe). However i feel like my tooth is too narrow to be a C. hastalis tooth. Even the first lower anteriors of C. hastalis that i have seen are somewhat proportionally wider than my example, hence why i am leaning towards one of the other species of mako but i want to know what the shark tooth experts on this forum think. I had a look in the book 'Vertebrate Palaeontology of Australasia' (which has a nice section on fossil chondrichthyans) and the closest match i could see was a first lower anterior tooth from Isurus paucus (tooth A on page 552 if anyone has the book) but this species isn't listed in the fauna for Beaumaris. Might it instead be an Isurus oxyrinchus or desori tooth? Additionally my tooth is fairly straight, and most of the other mako specimens i am seeing are more curved. It measures 24 mm long and 11 mm wide.

This shark tooth was found deep in a cave on an island which is off the Panamanian coast (Atlantic side). It appears to be a fossilized mako shark tooth; however, I haven't been able to identify the exact Isurus species. It doesn't appear to be either of the currently living mako shark species, Isurus Oxyrinchus or Isurus Paucus. That leaves eleven other extinct species. Any help would be very appreciated!