New Members bertrand Posted July 8, 2015 New Members Posted July 8, 2015 Hello everybody Does anyone could help me in determining a microfossil in thin section ? please have a look on the attached file ! I can recognize a miliolid on the left but I'm not sure about the fossil on the right... if you have any idea !? it's could be very helpfull ! Thank you very much !! regards
abyssunder Posted July 8, 2015 Posted July 8, 2015 (edited) Welcome to the Forum! The radiating double-spiral pattern reminds me of the Ordovician Receptaculites. https://www.google.com/search?q=receptaculites&biw=1360&bih=612&tbm=isch&tbo=u&source=univ&sa=X&ei=JlOdVc3fI7GU7QbBravABw&sqi=2&ved=0CCMQsAQ Also could be a Foraminifera if the left one is that. Edited July 8, 2015 by abyssunder " 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
Herb Posted July 8, 2015 Posted July 8, 2015 agreed, Receptculites "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks
New Members bertrand Posted July 9, 2015 Author New Members Posted July 9, 2015 Hello Herb and abyssunder, thank you very much for your very fast response ! these miliolids and this receptaculites are not of the same age (miliolids appear at the end of paleozoic times) ... So, this receptaculites is certainly reworked in this bioclastic grainstone ! An other option could be a benthic foraminifera, maybe a part of an orbitolinidae ?... but the typical "V shape" is not visible ! Thank you one more time ! regards,
Auspex Posted July 9, 2015 Posted July 9, 2015 The micro size gave me pause about the receptaculites idea, and the age disparity pretty much kills it. That 1/1.618 spiral ratio is a natural form that occurs throughout the history of life; think really small in this case. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease!
Carl Posted July 9, 2015 Posted July 9, 2015 I agree with Auspex. Receptaculitids are much much bigger.
abyssunder Posted July 9, 2015 Posted July 9, 2015 According to my knowledge, the temporal range for Miliolida is from Carboniferous to recent and for Receptaculites from Ordovician through Permian,so I suppose they lived together in Paleozoic in a benthic environment.I agree that R.is much larger than M.,as shown in the picture, but could be a juvenile one,and the double-spiral pattern(clockwise and counterclockwise rows) is not characteristic for too many fossils of the Paleozoic era.Evidently someone could say that is a bryozoan,or a foraminifera. " 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
New Members bertrand Posted July 13, 2015 Author New Members Posted July 13, 2015 Finally I think that the option of benthic foraminifera is better (according to the microfossil size) : orbitolites (instead of receptaculites) associated with triloculina what do you think about ? cheers
abyssunder Posted July 13, 2015 Posted July 13, 2015 Orbitolites could be a good possibility. " 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
janislav Posted July 13, 2015 Posted July 13, 2015 My paleontology book is pretty old (1952), but large foraminifera in one cross-section will appear much like the specimen in the photo. The family at that time was called "Orbitoidids." No idea what they would be called today. Line illustrations of the genus Lepidocyclina look similar to the photo above. I didn't take the time to figure the orders of magnitude between this microfossil and Receptaculites, but I think the likelihood of this being a Recept is pretty close to nil.
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