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Ammonite (?) found near Ramallah, West Bank


U-ri-za-a

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Hi everyone,

I made a trip in the Judean Mountains around the city of Ramallah yesterday. It was there that I found this specimen. The scale provide is in cm: the specimen is about 6 cm long, that is about 2.5 inches.

 

I found it on a high hill at an altitude of about 800 m (2600), on the ground among countless rock fragments. The hill was subject to severe erosion and bedrock was visible all over with patches of earth and smaller rocks in between. The rock seemed to be limestone, with many features that I as a novice can only describe in the most casual terms:

  • many spherical holes
  • turtle shell pattern on the surface of rock
  • large and small pebbles embedded in the rock, apparently slightly more resistant to erosion

 

I would like to ask you the identity ofthis specimen, and would also be interested to read tips on how to identify promising spots to find more fossils based on altitude, surrounding rock, layers...

 

Thank you for your time!

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Looks like the valve of a bivalve to me. 

Something along the lines of Trigonia, perhaps?

But that's really a wild guess. 

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Does look to be the steinkern (internal mold) of a bivalve or maybe brachiopod. Do you know the age of the specimen? This can be ascertained by looking at a geological map of your area.  

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Im with these guys.  looks more clamish than ammo.

 

RB

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Thanks for your input! I'm psyched. I just discovered how a geological map works... The Israel Geology Institute has 1:50000 maps of the whole place available. I'm on this one: Ramallah (lithology attached). Looks like the fossil is from the Kefira formation of the middle Albian but it may have come down from the hilltop which represents the Giv'at Yearim formation from ... the somewhat later Albian :ank:

On a sidenote, contrary to the Ramallah map, the Jerusalem map has a special icon for fossils in its lithology profile! That's just making it too easy! Jerusalem is just a dozen km south, so am I guessing correctly that those layers would be of interest to me here as well? Especially since even the formation names are the same... (Second pic labeled J for Jerusalem - spirals represent fossils in case the symbol isn't universal).

lqyers.PNG

j.PNG

Edited by U-ri-za-a
correct mistaken formation Soreq -> Giv'at Yearim
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As @Tidgy's Dad suggested, Trigonia seems like a good guess. This is a Trigonia Emoryi for reference from the Sam Noble Museum in Oklahoma. This Trigonia specimen came from the lower Cretaceous, placing it in the same timeframe as yours. 

Trigonia-emoryi-OU42341-187x164.jpg

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Thanks, I'm convinced! Final question: if the specimen is a steinkern, does that mean that the non-shell side of the fossil (pictured above) is an imprint of the fleshy bits of the animal? The non-shell side does have a large indent on one side, might that be the space where the dentition was?

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Chances are, the soft flesh would have rotted out during the fossilization process. I think the non-shell side is much more likely to be an imprint of the sediment that replaced the flesh right after the animal died. It is a cool find, regardless! 

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Looks like Trigonia, I agree.
I propose Pterotrigonia (Scabrotrigonia) scabra (LAMARCK, 1819) for a tentative ID.

 

Pterotrigoniascabra2006_1.thumb.jpg.59f9c2c8e1836cafe3e2317f552fda8b.jpgPterotrigoniascabra2006_2.thumb.jpg.7535cb47f963a53a0474f9d7c5babb0e.jpg

excerpt from El-Hedeny, M. M. 2006. Pterotrigonia (Scabrotrigonia) scabra (Lamarck, 1819), a polymorphic bivalve from the Upper Cretaceous (Coniacian-Santonian) of Egypt. Revue de Paléobiologie, 25(2): 709-722.

 

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