Ramon Posted January 11, 2017 Share Posted January 11, 2017 This fossil is an Ammonite which I think is Perisphinctes. This fossil came from the santiago formation in San Luis Potosi, Mexico, which is middle Oxfordian.The sanTiago formation is below the Taman formation which is were the Ochetoceras came from. There has been fossil coming out of the formation which are Perisphinctes (Middle Oxfordian ammonite biostratigraphy of the Lower Santiago Formation at Taman, San Luis Potosi, Mexico — with notes on Mexico–Caribbean ochetoceratins) or Bioestratigrafía de amonitas del Oxfordiano medio de la parte basal de la Formación Santiago en Tamán, San Luis Potosí, México – con notas sobre ochetoceratinos de México y el Caribe, in Spanish. Here's photos of my specimen Close up of the fossil "Without fossils, no one would have ever dreamed that there were successive epochs in the formation of the earth" - Georges Cuvier Link to comment Share on other sites More sharing options...
Pemphix Posted January 11, 2017 Share Posted January 11, 2017 Maybe Ludwigia can help - he knows good about ammonites. But i am afraid it will be difficult to tell because it's poorly preserved and the photo seems somehow a little blurry, too. Best regards, Pemphix Link to comment Share on other sites More sharing options...
ynot Posted January 11, 2017 Share Posted January 11, 2017 @Ludwigia Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
abyssunder Posted January 11, 2017 Share Posted January 11, 2017 Sure could be a Perisphinctes sp., although is hard to tell because of his preservation status. According to the cited reference Olóriz, Federico; Villaseñor, Ana B.; López-Palomino, Isabel. 2008. Middle Oxfordian ammonite biostratigraphy of the Lower Santiago Formation at Tamán, San Luis Potosí, Mexico — with notes on Mexico-Caribbean ochetoceratins. Revista Mexicana de Ciencias Geológicas, vol. 25, núm. 2, pp. 261-283. there are a few species described from the Santiago Formation, as shown in this excerpt : 1 " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
Ludwigia Posted January 11, 2017 Share Posted January 11, 2017 I agree with our Romanian friend. It appears to be a Perisphinctes, but in my opinion the preservation isn't good enough to be able to determine the species. You'd need to know the exact horizon in order to even make a guess, since there are a large number of species belonging to this genus to choose from. Just call it Perisphinctes sp. It's really not necessary to give everything a species name. 4 Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
FossilDAWG Posted January 11, 2017 Share Posted January 11, 2017 I thought that in Perisphinctes the ribs bifurcated or trifurcated about mid-flank. I don't see any evidence for that, even despite the poor preservation of the specimen. Don 1 Link to comment Share on other sites More sharing options...
abyssunder Posted January 12, 2017 Share Posted January 12, 2017 6 hours ago, Ludwigia said: ... You'd need to know the exact horizon in order to even make a guess, since there are a large number of species belonging to this genus to choose from. That's the reason I've put the stratigraphical section in front of the request. Sometimes, the specimens considered as 'type' specimens are in a worst preservation than the ulterior ones discovered by others (not in all cases). I could see the bifurcated character of the ornamenting ribs in some of the regions of the outer whorl, although the whole ammonite is strongly weathered, unfortunately. , but it is an interesting one. 1 " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
Ludwigia Posted January 12, 2017 Share Posted January 12, 2017 13 hours ago, FossilDAWG said: I thought that in Perisphinctes the ribs bifurcated or trifurcated about mid-flank. I don't see any evidence for that, even despite the poor preservation of the specimen. Don They mostly bifurcate just slightly below the venter which is why the forks are usually not visible on the inner whorls. This specimen is so weathered or damaged that the bifurcation on the outer whorls also isn't clearly visible, but in my opinion it shows enough traits to at least merit an educated guess. 2 Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
FossilDAWG Posted January 12, 2017 Share Posted January 12, 2017 Thanks Roger. You're the "go-to" person for Jurassic ammonites so I'll defer to your judgement. Don Link to comment Share on other sites More sharing options...
Ramon Posted January 14, 2017 Author Share Posted January 14, 2017 (edited) My fossil looks like (h) in the following photo. It is labeled as, Perisphinctes (Otophinctes) paturattensis. The name of the article is "Middle Oxfordian ammonite biostratigraphy of the Lower Santiago Formation at Taman, San Luis Potosi, Mexico — with notes on Mexico–Caribbean ochetoceratins". Edited January 14, 2017 by Ramon "Without fossils, no one would have ever dreamed that there were successive epochs in the formation of the earth" - Georges Cuvier Link to comment Share on other sites More sharing options...
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