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Micro ammonite from Asia


sdsnl

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This came as a pleasant surprise. I was going through some shells collected from years ago, and when I was done, I saw that some sand has fallen off, probably from inside a gastropod. Among the sand was this ammonite, only 2mm in length. I don't know which shell it came off, or where it may be from. Most of my shells are from Hong Kong, but I have also collected in several other East Asian countries.

 

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I have read that Sulciferites hongkongensis, Coroniceras sp., and Arietites sp. have been found in Hong Kong, but don't know whether there are other species. I also found this passage from page 427 of "Biostratigraphy of China" on Google Books which might be relevant:

Capture.JPG

 

Might it be possible to narrow down the ID or age from the pictures? Thanks in advance!

 

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3 minutes ago, fossisle said:

It could be a large Foram

My first thought too, but then I looked at it under the microscope and there exists an aperture, and the ribs have thickness. You can also see that it is thicker on the outside and thinner in the center. Not sure if the pics show it well enough?

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10 minutes ago, FossilDudeCO said:

Isn't that just the cutest little ammonite!!

It quickly became my favorite :wub:

It's so small, I wonder if it had just hatched?

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I agree - check out the picture on THIS WEBSITE.

Fairly similar, I think. 

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6 hours ago, Fossildude19 said:

I agree - check out the picture on THIS WEBSITE.

Fairly similar, I think. 

Only similar in superficial appearance from the top. Even at that view, you can see that it has s-shaped markings, while my specimen has 3-dimensional ribs.

 

I have forams too, please see the pictures below. The Forams lack an aperture and are saucer-shaped when viewed from the side.

 

Fri Dec 23 16-59-32.jpg

Fri Dec 23 17-21-09.jpg

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Here are some more pictures of the ammonite. Note that it has an aperture, the ribs are raised, and the outermost whorl is significantly thicker than the center.

Fri Dec 23 02-34-06.jpg

Fri Dec 23 02-42-37.jpg

Fri Dec 23 03-51-53.jpg

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It is a foraminiferan. I'm not sure what genera it is because there are many with this general shape but if you do a Google image search of Lenticulina you will see some similar ones.

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All the above are foraminifera, including the one in question mimicking an ammonite. One of the genera is Ammonia.

Maybe you are lucky to find the one in question here .

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I too believe this little treasure is a foram that is the spitting image of an ammonite. The problem in my mind is that your tiny specimen shows the existence of many chambers indicating that it is not a tiny juvenile of a larger organism but something that has been living and growing for some time. While miniature pygmy seahorses were unknown to science before 1969 because the idea of tiny seahorses less than 2 cm wasn't even thought about as a possibility, I don't see that there could be a whole class of micro ammonites when we already have something on that size scale that fits that growth form. You'd be in good company for this conclusion as: "Early microbiology researchers mistook formanifera for ammonites". See this interesting article:

 

http://www.amnh.org/shelf-life/episode-06-the-tiniest-fossils

 

Cheers.

 

-Ken

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16 hours ago, sdsnl said:

My first thought too, but then I looked at it under the microscope and there exists an aperture, and the ribs have thickness. You can also see that it is thicker on the outside and thinner in the center. Not sure if the pics show it well enough?

 

I've worked with forams for 35 years.

 

There are thousands of species of foramnifera with hundreds of shapes. You cant compare a specimen to a couple of samples and exclude it as a Foram.  Its like saying a bat doesnt look like a whale so its not a vertebrate.

 

On a positive note...this specimen may open up a whole new area of microfossils for you to explore. Foramnifera, diatoms, etc are no less fascinating than the 'big stuff'.

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2 hours ago, digit said:

I too believe this little treasure is a foram that is the spitting image of an ammonite. The problem in my mind is that your tiny specimen shows the existence of many chambers indicating that it is not a tiny juvenile of a larger organism but something that has been living and growing for some time. While miniature pygmy seahorses were unknown to science before 1969 because the idea of tiny seahorses less than 2 cm wasn't even thought about as a possibility, I don't see that there could be a whole class of micro ammonites when we already have something on that size scale that fits that growth form. You'd be in good company for this conclusion as: "Early microbiology researchers mistook formanifera for ammonites". See this interesting article:

 

http://www.amnh.org/shelf-life/episode-06-the-tiniest-fossils

 

Cheers.

 

-Ken

Ken, I would like to understand how you can tell that there are chambers in this specimen. Maybe a better photo will show some indication but I know very little about forams.  I've heard that some can have chambers but do we know the purpose of the chambers?

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Forams are amoeboid protists that construct a calcium carbonate test ("shell") perforated with tiny holes which are the source of the forams Latin name ("hole bearers"). As the foram grows it creates larger chambers which are added onto the existing structure in a very similar manner to how Chambered Nautilus or ammonites grow. The "ribs" seen in this remarkable foram mimic of an ammonite mark the chamber boundaries in the same way as the ribs ans suture lines do in the macroscopic ammonites. There are tens of thousands of species of forams currently recognized in all sorts of shapes and sizes including huge ones easily visible to the naked eye as in Nummulites:

 

http://www.thefossilforum.com/index.php?/topic/33865-adventures-in-microscopy/&do=findComment&comment=373026

 

I've found some little foram tests while sorting micro-matrix (especially the shell hash from Cookiecutter Creek where we get the Isistius teeth). Forams apparently make good indicator species due to their abundance in sand and sediments and are useful for linking together formations and indicating the ecology that formed the deposits. For several years I would collect beach sand from any far off beach I was able to visit on my travels. I donated these to a friend who used spice racks and small bottles to store (and label) the sand from hundreds of localities. She would look at samples of the sand under a microscope and search for forams and other interesting components like micro coral or shell debris. There are people who really specialize in searching for and collecting forams but I do not count myself among them (but I do have friends with this obsession). My knowledge of forams is tangential and I learn a little bit every time I run into them in my other studies.

 

 

Cheers.

 

-Ken

 

P.S.: Some forams are (like diatoms) wonderfully shaped and patterned and I can see how people go gaga for them.

 

3579h_R_Indonesie.jpg

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  • 2 months later...

Dear sdnsl,

 

you asked me in a PM to answer.

 

I think it is a foram assuming that is recent. The size excludes Hyalinea balitca, so might  be of the Operculina group, see e.g. http://forambarcoding.unige.ch/specs/50-operculina-discoidalis

 

Please note that I am amateur as you are.

 

 

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definitely foram,maybe an operculinid/orthophragminid

edit:didn't totally read Mike's post.I think he is right,though

I will rifle through some Hohenegger

 

 

 

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1 hour ago, Foram-Mike said:

Dear sdnsl,

 

you asked me in a PM to answer.

 

I think it is a foram assuming that is recent. The size excludes Hyalinea balitca, so might  be of the Operculina group, see e.g. http://forambarcoding.unige.ch/specs/50-operculina-discoidalis

 

Please note that I am amateur as you are.

 

 

Thank you very much Mike, I searched for some pictures but there are differences, does Operculina have raised and straight ribs?

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11 minutes ago, doushantuo said:

Operculina ammonoides?(no,i am NOT kidding)

vide PECHEUX

Fig-11-Variability-in-the-mode-of-coiling-in-O-ammonoides-1-Evolute-form-most.png

 

Thanks, 3 looks very similar. Are they all the same species? That's a pretty big difference in thickness!

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they are.The Pecheux article,which i have(had a Geobios subscription in 1995) deals with that very same variability.

Operculinids have morphoclines,fide e.g. Hohenegger

 

 

 

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I found another paper where it looks more like Operculina discoidalis (1-6) than Operculina ammonoides (7-12), so confused :blink:

Capture.JPG.c0459f9209cfae40e0d851b705f066c5.JPG

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