debivort Posted July 18, 2022 Share Posted July 18, 2022 Sadly, this tooth was broken in several places when I found it at the foot of a Cretaceous fossil cliff on the coast of Portugal. I imagine a precise ID is impossible, but am grateful for any taxonomic information that can be inferred. Red asterisks mark a doublet of bumps in the middle of the root. Link to comment Share on other sites More sharing options...
Randyw Posted July 18, 2022 Share Posted July 18, 2022 I could very well be wrong but it looks like a sand tiger shark tooth to me. But I’m sure the others will be on soon to give you a positive I.d. 1 Link to comment Share on other sites More sharing options...
debivort Posted July 20, 2022 Author Share Posted July 20, 2022 Bump for extra eyeballs please Link to comment Share on other sites More sharing options...
ThePhysicist Posted July 20, 2022 Share Posted July 20, 2022 Very partial teeth are usually difficult to ID, so in some cases you have be comfortable not knowing. The only thing I can say with confidence is it's Lamniform. My first thought was Scapanorhynchus, but I don't see a clear nutrient groove, and the striations at the crown foot don't extend very far - the enamel is otherwise glass smooth. These also make me doubt that it's sand tiger. One possibility is Leptostyrax, since the ridges are more prominent on the labial face than the lingual face. ^ Welton & Farish 1993 3 "Argumentation cannot suffice for the discovery of new work, since the subtlety of Nature is greater many times than the subtlety of argument." - Carl Sagan "I was born not knowing and have had only a little time to change that here and there." - Richard Feynman Collections: Hell Creek Microsite | Hell Creek/Lance | Dinosaurs | Sharks | Squamates | Post Oak Creek | North Sulphur River | Lee Creek | Aguja | Permian | Devonian | Triassic | Harding Sandstone Instagram: @thephysicist_tff Link to comment Share on other sites More sharing options...
Jared C Posted July 20, 2022 Share Posted July 20, 2022 8 hours ago, ThePhysicist said: I don't see a clear nutrient groove, and the striations at the crown foot don't extend very far - the enamel is otherwise glass smooth What is preventing this tooth from being a posterior Ginsu? I have a few teeth like it that I now realize I may have wrongly assigned “Not only is the universe stranger than we think, it is stranger than we can think” -Werner Heisenberg Link to comment Share on other sites More sharing options...
jonnyquest Posted July 20, 2022 Share Posted July 20, 2022 If you didn't say cretaceous cliff I'd be inclined to say possible hemipristis. 1 Link to comment Share on other sites More sharing options...
ThePhysicist Posted July 20, 2022 Share Posted July 20, 2022 3 hours ago, Jared C said: What is preventing this tooth from being a posterior Ginsu? I have a few teeth like it that I now realize I may have wrongly assigned Off the bat, the enamel ridges preclude ginsu since their crowns are completely smooth. The general shape also doesn't match. Ginsu posteriors have crowns which aren't so erect, they're oriented posteriorly - a common feature in many sharks, it helps prevent food from escaping! ^ Bourdon & Everhart (2011) 1 hour ago, jonnyquest said: If you didn't say cretaceous cliff I'd be inclined to say possible hemipristis. For comparison, a lower hemi: Hemi lowers don't have ridged enamel, have a nutrient groove, a high lingual root protuberance, and a broader crown base, to name a few features. 2 "Argumentation cannot suffice for the discovery of new work, since the subtlety of Nature is greater many times than the subtlety of argument." - Carl Sagan "I was born not knowing and have had only a little time to change that here and there." - Richard Feynman Collections: Hell Creek Microsite | Hell Creek/Lance | Dinosaurs | Sharks | Squamates | Post Oak Creek | North Sulphur River | Lee Creek | Aguja | Permian | Devonian | Triassic | Harding Sandstone Instagram: @thephysicist_tff Link to comment Share on other sites More sharing options...
debivort Posted July 21, 2022 Author Share Posted July 21, 2022 20 hours ago, ThePhysicist said: Very partial teeth are usually difficult to ID, so in some cases you have be comfortable not knowing. The only thing I can say with confidence is it's Lamniform. My first thought was Scapanorhynchus, but I don't see a clear nutrient groove, and the striations at the crown foot don't extend very far - the enamel is otherwise glass smooth. These also make me doubt that it's sand tiger. One possibility is Leptostyrax, since the ridges are more prominent on the labial face than the lingual face. As a professional (non-paleo) biologist IRL, I am comfortable with not knowing, as long as I know as much as I can. So thank you for the thoughtful analysis! Glass smooth is really the right description - I was amazed at the surface quality when I first cleaned it up. Is the "double bump" in the root diagnostic? I see it in some photos labeled Leptostyrax but not others. 1 Link to comment Share on other sites More sharing options...
ThePhysicist Posted July 21, 2022 Share Posted July 21, 2022 23 hours ago, debivort said: As a professional (non-paleo) biologist IRL, I am comfortable with not knowing, as long as I know as much as I can. So thank you for the thoughtful analysis! Glass smooth is really the right description - I was amazed at the surface quality when I first cleaned it up. Is the "double bump" in the root diagnostic? I see it in some photos labeled Leptostyrax but not others. I think the double bump you're referring to is just a product of the root lobes, I wouldn't call it diagnostic for Leptostyrax. The variability you notice may be due to position - the "V" of the lobes seems to go deeper into the root in some positions compared to others. ^ Welton & Farish 1993 1 "Argumentation cannot suffice for the discovery of new work, since the subtlety of Nature is greater many times than the subtlety of argument." - Carl Sagan "I was born not knowing and have had only a little time to change that here and there." - Richard Feynman Collections: Hell Creek Microsite | Hell Creek/Lance | Dinosaurs | Sharks | Squamates | Post Oak Creek | North Sulphur River | Lee Creek | Aguja | Permian | Devonian | Triassic | Harding Sandstone Instagram: @thephysicist_tff Link to comment Share on other sites More sharing options...
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