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Hybodus shark spines, but what species?

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britishcanuk

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!

DE8957E6-3293-49F9-A6A4-A7BBEA72FD75.jpeg

7BBE8F71-3257-446B-9464-9F1D2683C848.jpeg

92873F6F-46F2-413F-8549-F1931CD3B750.jpeg

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Darktooth

Can't help with ID but they look to be in great shape!

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Archie

Cant help either sorry but those are really nice!

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Anomotodon

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

�а��инки по зап�о�� asteracanthus spine

image.thumb.png.a9e282e1468eaa7cb5778316b2ca755b.png

 

Tribodus spine

image.thumb.png.727b5f73c7a6c15056850af58520106e.png

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Archie

As for dorsal fin vs pectoral fin spines, Hybdodus had two dorsal fin spines but no pectoral fin spines.

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britishcanuk
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

�а��инки по зап�о�� asteracanthus spine

image.thumb.png.a9e282e1468eaa7cb5778316b2ca755b.png

 

Tribodus spine

image.thumb.png.727b5f73c7a6c15056850af58520106e.png

 This is very helpful, thank you!

 

R~

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siteseer

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. 

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britishcanuk

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.”
 

 

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Anomotodon

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.

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Pemphix
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...

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DE&i
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. 

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