drbush Posted December 10, 2017 Share Posted December 10, 2017 Hi friends i was in an area to the north of Riyadh city this weekend and i found this fossil , it looks like ammonite ? I need ur help Link to comment Share on other sites More sharing options...
gigantoraptor Posted December 10, 2017 Share Posted December 10, 2017 Looks more like a concretion. Link to comment Share on other sites More sharing options...
Aurelius Posted December 10, 2017 Share Posted December 10, 2017 Pretty sure it's a nautilus. 3 Link to comment Share on other sites More sharing options...
gigantoraptor Posted December 10, 2017 Share Posted December 10, 2017 1 minute ago, Aurelius said: Pretty sure it's a nautilus. Why do you think it's a nautilus? Link to comment Share on other sites More sharing options...
Aurelius Posted December 10, 2017 Share Posted December 10, 2017 5 minutes ago, gigantoraptor said: Why do you think it's a nautilus? It has the exact shape of a nautilus. Look at the photo bottom-left. The centre has broken off, and you can see the hole where it fitted in. I've found hundreds of broken nautiluses exactly like this one. I'll go out on a limb and say this is definitely a nautilus! Link to comment Share on other sites More sharing options...
Taogan Posted December 10, 2017 Share Posted December 10, 2017 very eroded and incomplete, but it looks like a nautilus to me as well. Bottom left picture you can see a possible siphuncle Link to comment Share on other sites More sharing options...
RJB Posted December 10, 2017 Share Posted December 10, 2017 My vote is also for nautilus. RB Link to comment Share on other sites More sharing options...
Ludwigia Posted December 10, 2017 Share Posted December 10, 2017 I'll add my vote to the majority for nautilus, although I can't make out the septal walls or lobes clearly in the photos, which leaves the possibility open for a cadicone ammonite. @Taogan What is the position of the siphuncle? I can't make it out, but that would confirm the one or the other, since by nautili it's in the middle and by ammonites it's directly under the venter. Edit: I falsely tipped Aurelius before I noticed that it was Taogan. Sorry for any possible confusion. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
andreas Posted December 10, 2017 Share Posted December 10, 2017 one voice more for Nautilus Link to comment Share on other sites More sharing options...
Taogan Posted December 10, 2017 Share Posted December 10, 2017 @Ludwigia there is a circular feature with a hole dead centre of the chamber in the picture lower left. It may be nothing, but it is in the right place for a siphuncle on a nautilus and it could be one. I am not certain though, it is a bit small and indistinct. Link to comment Share on other sites More sharing options...
fifbrindacier Posted December 10, 2017 Share Posted December 10, 2017 I agree with the others, it's a nautiloid, but i don't see nor the siphuncle @Taogan sees, nor the suture lines of an ammonite. "On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry) "We only well see with the heart, the essential is invisible for the eyes." In memory of Doren Link to comment Share on other sites More sharing options...
Ludwigia Posted December 10, 2017 Share Posted December 10, 2017 34 minutes ago, Taogan said: @Ludwigia there is a circular feature with a hole dead centre of the chamber in the picture lower left. It may be nothing, but it is in the right place for a siphuncle on a nautilus and it could be one. I am not certain though, it is a bit small and indistinct. I see what you mean now. Could very well be. I'll stick with nautiloid. The general form fits as well. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
izak_ Posted December 10, 2017 Share Posted December 10, 2017 +1 for nautiloid Link to comment Share on other sites More sharing options...
drbush Posted December 11, 2017 Author Share Posted December 11, 2017 thank you all for the information ... could it be Eutrephoceras sp.? Link to comment Share on other sites More sharing options...
drbush Posted December 11, 2017 Author Share Posted December 11, 2017 can this help in the diagnosis ? Link to comment Share on other sites More sharing options...
Aurelius Posted December 11, 2017 Share Posted December 11, 2017 2 hours ago, drbush said: can this help in the diagnosis ? Yep. It is definitely a nautilus. No doubt whatsoever. Although I couldn't tell you the exact type. What age are the rocks there? Link to comment Share on other sites More sharing options...
Ludwigia Posted December 11, 2017 Share Posted December 11, 2017 7 hours ago, drbush said: thank you all for the information ... could it be Eutrephoceras sp.? The outer form doesn't appear to fit. You would need to research the stratigraphy of the site where you found it in order to narrow down the possibilities, since many nautili from various ages look quite similar to each other and this one is not very well preserved, which doesn't help with determination. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
drbush Posted December 12, 2017 Author Share Posted December 12, 2017 late Jurassic Link to comment Share on other sites More sharing options...
Ludwigia Posted December 12, 2017 Share Posted December 12, 2017 It might be a Paracenoceras, but again, the form doesn't quite fit since it has a flat venter. I'd leave the id at the order level Nautiloidea indet. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
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