britishcanuk 174 Report post Posted January 10 I have these two Hybodus spines from Morocco and was wondering in anyone could identify them from these pics? I am also wondering if there is a way to distinguish the dorsal and pectoral spines from eachother? Thanks for looking! Share this post Link to post Share on other sites
Darktooth 1,764 Report post Posted January 10 Can't help with ID but they look to be in great shape! Share this post Link to post Share on other sites
Archie 559 Report post Posted January 11 Cant help either sorry but those are really nice! Share this post Link to post Share on other sites
Anomotodon 376 Report post Posted January 11 4 Hybodonts are known from Ifezouane formation (I assume that's where your spines are from): Asteracanthus, Tribodus, Distobatus and Lissodus. Here are some spines from the Oxford clay. Asteracanthus aegyptiacus is known from Kem Kem, so your left spine should be it. Right one is probably Tribodus, its spines were similar to 'Hybodus' type spines plus they have strongly bifurcating lateral ridges (more than in Hybodus on pic 1) and very fine rows of posterior denticles (they look almost like two parallel rows even though they are alternating. At least strong bifurcation is present on your spine. Lissodus had few ribs, not sure about Distobatus, can't find info on its spines. Those are dorsal spines. https://www.sciencedirect.com/science/article/pii/S0031018299001674 https://search.proquest.com/docview/577686774?pq-origsite=gscholar 1, 3 - Hybodus, 2 - Asteracanthus Tribodus spine Share this post Link to post Share on other sites
Archie 559 Report post Posted January 11 As for dorsal fin vs pectoral fin spines, Hybdodus had two dorsal fin spines but no pectoral fin spines. Share this post Link to post Share on other sites
britishcanuk 174 Report post Posted January 11 26 minutes ago, Anomotodon said: 4 Hybodonts are known from Ifezouane formation (I assume that's where your spines are from): Asteracanthus, Tribodus, Distobatus and Lissodus. Here are some spines from the Oxford clay. Asteracanthus aegyptiacus is known from Kem Kem, so your left spine should be it. Right one is probably Tribodus, its spines were similar to 'Hybodus' type spines plus they have strongly bifurcating lateral ridges (more than in Hybodus on pic 1) and very fine rows of posterior denticles (they look almost like two parallel rows even though they are alternating. At least strong bifurcation is present on your spine. Lissodus had few ribs, not sure about Distobatus, can't find info on its spines. Those are dorsal spines. https://www.sciencedirect.com/science/article/pii/S0031018299001674 https://search.proquest.com/docview/577686774?pq-origsite=gscholar 1, 3 - Hybodus, 2 - Asteracanthus Tribodus spine This is very helpful, thank you! R~ Share this post Link to post Share on other sites
siteseer 847 Report post Posted January 11 When I saw the spine on the left in the first photo, I thought Asteracanthus, and if it is from the Ifezouane formation, that must be one of the youngest confirmed occurrences of the genus as far as I know. Most of the specimens I've seen are Late Jurassic. It's an Interesting specimen and in fantastic shape. Share this post Link to post Share on other sites
britishcanuk 174 Report post Posted January 12 Thanks for the info everyone. Update: the person who sold me the spine on the left sent me the following data. Is there any reason to doubt this data? “ ASTERACANTHUS ORNATISIMUS. LOCALITY: KEMKEM, MAROCCO. AGE: CRETACEOUS CENOMANIAN.” Share this post Link to post Share on other sites
Anomotodon 376 Report post Posted January 12 Left one is not A. ornatissimus but Asteracanthus aegyptiacus, while the right one is definitely not Asteracanthus. If you want a genus ID on the right one then go with Tribodus sp., however I am uncertain on how similar to it were spines of Distobatus, so Hybodontidae indet. would be more accurate. Locality looks correct - likely Ifezouane formation, Kem Kem beds, Morocco. Share this post Link to post Share on other sites
Pemphix 186 Report post Posted January 12 4 hours ago, Anomotodon said: Left one is not A. ornatissimus but Asteracanthus aegyptiacus, while the right one is definitely not Asteracanthus. If you want a genus ID on the right one then go with Tribodus sp., however I am uncertain on how similar to it were spines of Distobatus, so Hybodontidae indet. would be more accurate. Locality looks correct - likely Ifezouane formation, Kem Kem beds, Morocco. I agree with that - good statement ! We have the same problem in the european marine triassic sediments: identification of Genus/Species of shark remains. There are no articulated fossils of sharks known in these sediments. So since morphology of teeth varies with place in the mouth, it's very hard to determine species, whereas genus is mostly possible. Same is with spines - some of them you can identify on genus only.... So it's always better to stay with the "sp." instead of an uncertain species-name... Share this post Link to post Share on other sites
DE&i 329 Report post Posted January 12 10 hours ago, Pemphix said: I agree with that - good statement ! We have the same problem in the european marine triassic sediments: identification of Genus/Species of shark remains. There are no articulated fossils of sharks known in these sediments. So since morphology of teeth varies with place in the mouth, it's very hard to determine species, whereas genus is mostly possible. Same is with spines - some of them you can identify on genus only.... So it's always better to stay with the "sp." instead of an uncertain species-name... I actually think that Asteracanthus needs a proper look at. The type of A. ornatissimus is a spine that appears to be the same as that with teeth of H. obtusus. The associated spines with true Asteracanthus teeth from the Callovian are different and thus probably should go back to the old name within Strophodus….while conducting my own research from collecting hybodus spine fragments mid Jurassic Peterborough Formation I found hybodont spines are coming round to being useless taxonomically; I know of a Hybodus obtusus with a fin spine of "Asteracanthus" and "Asteracanthus" fin spines also seem to be associated with Tribodus and at least one other genus. Share this post Link to post Share on other sites
