David in Japan Posted November 13, 2016 Share Posted November 13, 2016 Hi everyone, It's been a while. Here are two picture of a bivalve I found in Himenoura formation Japan. I have been hunting these place regularly for 2 years but it is the first time I found such large bivale there. I looked into my local documentation to put a name on it but I didn't found anything. Here is some information about the beast: Formation: Himenoura Age: late Cretaceous, santonian size: 13cm long / 9cm width I think it is a kind of veneridae because the hinge teeth (even if difficult to see on the picture and worn) looks like Mercenaria mercenaria teeth. If someone have any idea about the clam shell, I would be gratefull to hear about. ~~~~~~~~~~~~〇~~~~~~~~~~~~~ Warmest greetings from Kumamoto、 Japan Link to comment Share on other sites More sharing options...
David in Japan Posted November 13, 2016 Author Share Posted November 13, 2016 ~~~~~~~~~~~~〇~~~~~~~~~~~~~ Warmest greetings from Kumamoto、 Japan Link to comment Share on other sites More sharing options...
fossiling Posted November 13, 2016 Share Posted November 13, 2016 Looks like acrosterigma. Let's see others' opinion ! Keep looking! They're everywhere! Link to comment Share on other sites More sharing options...
tmaier Posted November 13, 2016 Share Posted November 13, 2016 The prominent umbo and fairly close bilateral symmetry makes it look like it is in the cockle family. But then it seems to also be pretty thick and have a smooth outer surface... not like something in the cockle family. I don't see the hinge teeth, they seem to be under some matrix or broken away, so that is not a help. Venus shells can have a thick shell and smooth outer surface, but then they often are not nicely symetrical and normally don't have such a large umbo. A Mercenaria clam like you mention is a Venus. So this seems to be half Venus and half Cockle (half Veneridae and half Cardiidae). That makes us back up the taxonomy tree and say it is in the the order Veneroida, but according to Wikipedia, the cockles have been thrown out of that order. Mmmm... this one is confusing. Link to comment Share on other sites More sharing options...
abyssunder Posted November 13, 2016 Share Posted November 13, 2016 Although I'm not familiar with Japan, from what I have read the Upper Cretaceous Himenoura is a Group of formations, for example in the eastern part of the Amakusa - Kamishima Island, where it is exposed, it is devided into the Hinoshima and Amura Formations (Santonian - Campanian) - according to Yuki Kojo et al. 2011. Stratigraphy and detailed age of the Upper Cretaceous Himenoura Group in the eastern part of Amakusa - Kamishima Island, Kumamoto, Japan. Jour. Geol. Soc. Japan, Vol. 117, No 7, p.398-416. pdf Compared the data from the mentioned document with your specimen, I think that could be an inoceramid, like Sphenoceramus. " 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...
David in Japan Posted November 13, 2016 Author Share Posted November 13, 2016 Thank you Abyssunder, The inoceramid that could a "little bit" looks like to this shell would be Inoceramus higoensis or Sphenoceramus elegans pseudosulcatus but they are still pretty different. I don't want to put away the inoceramid but I don't think it is one. Picture with an Inoceramus higoensis fragment ~~~~~~~~~~~~〇~~~~~~~~~~~~~ Warmest greetings from Kumamoto、 Japan Link to comment Share on other sites More sharing options...
abyssunder Posted November 13, 2016 Share Posted November 13, 2016 The variants for Inoceramus might be : Inoceramus (Inoceramus), Inoceramus (Sphenoceramus), Inoceramus (Mytiloides), Imceramus (Retroceramus), Inoceramus (Mytiloceramus), Inoceramus (Cataceramus). You may need this document : I. Hayami. 1975. A systematic survey of the Mesozoic Bivalvia from Japan. The University Museum, The University of Tokyo, Bulletin (10) Here " 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...
David in Japan Posted November 16, 2016 Author Share Posted November 16, 2016 Arg, I waited too long before looking at the link you shared Abyssunder. the link is dead now. ~~~~~~~~~~~~〇~~~~~~~~~~~~~ Warmest greetings from Kumamoto、 Japan Link to comment Share on other sites More sharing options...
abyssunder Posted November 16, 2016 Share Posted November 16, 2016 You're right, the link is dead. That is a good reference, unfortunately was not a downloadable document...wait, maybe is just a server problem. In this moment the link is working. " 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...
David in Japan Posted November 19, 2016 Author Share Posted November 19, 2016 Thank you very much to all of you for helping me to ID this fossil. Just a short message to say that I had been able to put a name on the shell thank to the help of the professor Masayuki Tashiro. It is a thorny oyster called Spondylus pseudocalcaratus. Here a link for those who want to have further information concerning this fossil (page 61) and bivalve yielded by the Himenoura formation. http://www.palaeo-soc-japan.jp/download/SP/SP19.pdf ~~~~~~~~~~~~〇~~~~~~~~~~~~~ Warmest greetings from Kumamoto、 Japan Link to comment Share on other sites More sharing options...
abyssunder Posted November 19, 2016 Share Posted November 19, 2016 The first thing that caught my eye was those spiny shapes visible on the surface of the specimen. I thought it could be Spondylus, but I excluded this because of the very large dimensions. Your specimen is almost double in size compared to the usual ones, also compared with the dimensions presented by Masayuki TASHIRO in BIVALVE FAUNAS OF THE CRETACEOUS HIMENOURA GROUP IN KYUSHU. Measurements (in mm):- Specimens Length Height Thickness KE 2115, left valve 70.0 65.0 10.0 KE 2116, left valve 56.0 54.0 KE 2117, left external mould 23.5 23.0 3.0 KE 2118, left internal mould 20.0 18.5 KE 2119, left external mould 52.0 48.0 7.0 KE 2120, right external mould 45.0+ 38.5 20.0 It's a good document. Thanks for sharing. " 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...
David in Japan Posted November 19, 2016 Author Share Posted November 19, 2016 Yes he told me that it was one of the biggest he ever seen. this formation is so exciting, so much to discover. ~~~~~~~~~~~~〇~~~~~~~~~~~~~ Warmest greetings from Kumamoto、 Japan Link to comment Share on other sites More sharing options...
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