Miocene_Mason Posted February 11, 2018 Share Posted February 11, 2018 On The fossil guy website on Cow Sharks, there is a tiny detail that intrigued me. “There are also some differences between male and female teeth. These differences, however, will not be discussed here.” Well then we better discuss them here! Anybody know what these are? For me the bluntnose sevengill would be more relevant, but for the sake of learning add sex differences in the teeth of any and all Cow shark species. Thanks all! “...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin Happy hunting, Mason Link to comment Share on other sites More sharing options...
caldigger Posted February 11, 2018 Share Posted February 11, 2018 Why wouldn't he discuss them I wonder. Do most sharks have a sexual difference presented in the teeth? Clueless here. Link to comment Share on other sites More sharing options...
Miocene_Mason Posted February 11, 2018 Author Share Posted February 11, 2018 8 minutes ago, caldigger said: Why wouldn't he discuss them I wonder. Do most sharks have a sexual difference presented in the teeth? Clueless here. Perhaps to technical for the average reader to understand? It’s the first I’ve heard of such a thing. “...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin Happy hunting, Mason Link to comment Share on other sites More sharing options...
Brett Breakin' Rocks Posted February 11, 2018 Share Posted February 11, 2018 1 hour ago, caldigger said: Why wouldn't he discuss them I wonder. Do most sharks have a sexual difference presented in the teeth? Clueless here. I thought I read something about Sexual dimorphism in Physogaleus teeth ... in a paper .. ahh here it is .. a brief mention but I do know that it is not the only mention that I have seen concerning sharks teeth. http://www.elasmo.com/frameMe.html?file=genera/cenozoic/sharks/physogaleus.html&menu=bin/menu_genera-alt.html " Cappetta (1987) notes that there is strong sexual dimorphism of the lower anterior teeth (the cusps of the male's are laterally compressed), otherwise male and female teeth are of similar design. The basal face of the root can often differentiate upper and lower teeth. In lower teeth, the surface is flat and straight, while in uppers, it is often concave. " Cheers, B 1 Link to comment Share on other sites More sharing options...
Brett Breakin' Rocks Posted February 11, 2018 Share Posted February 11, 2018 One other mention . specifically in Cow Sharks on a blog I use as reference occasionally. It may be a good lead to some reading material .... "This list is based primarily on paleontologist Bretton W. Kent’s Fossil Sharks of the Chesapeake Bay Region (1994, p. 2). Though he does include sexual dimorphism as a factor behind some variation in fossil shark teeth, as far as I can tell, it’s only in a very few species that sexual dimorphism has been identified. He cites it in just two fossil shark species found in the Chesapeake Bay region – Hexanchus (cow sharks), and Rhizopriondon (sharpnose sharks)." http://fossilsandotherlivingthings.blogspot.com/2017/04/sexual-dimorphism-another-challenging.html 1 Link to comment Share on other sites More sharing options...
Troodon Posted February 12, 2018 Share Posted February 12, 2018 From the elasmo.com site. All about the position of the principal cusp. Also exist in Ray teeth 89-94.pdf 2 Link to comment Share on other sites More sharing options...
Miocene_Mason Posted February 12, 2018 Author Share Posted February 12, 2018 @Troodon and @Brett Breakin' Rocks My mind is being blown! The difference is pretty stark! Also noticing that the male Hexanchus is a lot like a Notorynchus, just with finer serrations. I wonder why the teeth would differ by sex, just an accident of genetics I suppose? Thanks so much for this info! “...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin Happy hunting, Mason Link to comment Share on other sites More sharing options...
Coco Posted February 12, 2018 Share Posted February 12, 2018 Hi, 14 hours ago, caldigger said: Do most sharks have a sexual difference presented in the teeth? Clueless here. Have a look on my signature ! " Heterodontie of selachians ". Coco ---------------------- OUTIL POUR MESURER VOS FOSSILES : ici Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici Mâchoires sélaciennes récentes : ici Hétérodontiques et sélaciens : ici Oeufs sélaciens récents : ici Otolithes de poissons récents ! ici Un Greg... Link to comment Share on other sites More sharing options...
Miocene_Mason Posted February 12, 2018 Author Share Posted February 12, 2018 54 minutes ago, Coco said: Hi, Have a look on my signature ! " Heterodontie of selachians ". Coco I have to get on my computer, I can’t see them on my iPhone. “...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin Happy hunting, Mason Link to comment Share on other sites More sharing options...
Al Dente Posted February 12, 2018 Share Posted February 12, 2018 In a paper titled "Redescription of Hexanchus nakamurai Teng 1962, (Chondrichthyes: Hexanchiformes: Hexanchidae), with designation of a neotype. 2013, David Ebert, William White, Hsuan-Ching Ho. Zootaxa. : "Sexual dental dimorphism is strong in this species with the upper and lower anterolateral tooth cusp of adult males becoming higher than those of adult females; this increase in height only occurs at the onset of sexual maturity in males." Link to comment Share on other sites More sharing options...
Al Dente Posted February 12, 2018 Share Posted February 12, 2018 12 hours ago, WhodamanHD said: I wonder why the teeth would differ by sex, just an accident of genetics I suppose? Thanks so much for this info! A lot of skates and rays have differences in teeth based on gender. Male skates and rays need pointy teeth to grasp the female. Females have flat crushing type teeth. 2 Link to comment Share on other sites More sharing options...
ynot Posted February 12, 2018 Share Posted February 12, 2018 6 hours ago, Al Dente said: A lot of skates and rays have differences in teeth based on gender. Male skates and rays need pointy teeth to grasp the female. Females have flat crushing type teeth. It is My understanding that, for rays, the dimorphism is a seasonal thing. The males change their teeth for mating. 1 Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted February 12, 2018 Share Posted February 12, 2018 31 minutes ago, ynot said: It is My understanding that, for rays, the dimorphism is a seasonal thing. The males change their teeth for mating. My grandpa used to do this too A very interesting thread everybody, i had never heard of this before Fascinating Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
Miocene_Mason Posted February 12, 2018 Author Share Posted February 12, 2018 7 hours ago, Al Dente said: A lot of skates and rays have differences in teeth based on gender. Male skates and rays need pointy teeth to grasp the female. Females have flat crushing type teeth. That makes sense for rays. You have to wonder with sharks though. The makes do bite the females during mating, perhaps the ones that latched on better had a higher chance of reproduction? If so, why is sexual dimorphism not commonplace among all sharks? “...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin Happy hunting, Mason Link to comment Share on other sites More sharing options...
ynot Posted February 12, 2018 Share Posted February 12, 2018 In some species the male and female have differing eating habits, thus they use a different tooth shape. Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
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