Anyone found a good fossil?

WhiteKiboko

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all i have as far as fossils are concerned are just bivalve pieces and some augers...not really exciting, dont knowq much about them and theyre not cephs.... :|
 

Architeuthoceras

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Here is a fossil I found, from the Ordovician (about 450 mya) of Utah. You can see why they call Nautilus a living fossil. This is Plectolites, at least a fossil of the shell. Most of the chambers were broken and got filled with seafloor sediment, the left side is missing altogether. The chambers in the very center were still hollow when the sediment was turned to limestone, and latter the void was filled with calcite crystals, this destroyed the septa. The Siphuncle is a little different than in Nautilus

A fairly large file (196K) for detail

:ammonite:
 

Phil

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Wow! That's a beauty!

It's amazing to thing how similar this nautilus is to the modern species. I wonder which group of nautiloids it belonged to? According to my references the order of nautiloid that gave rise to our modern species did not appear until the early Devonian. So if yours is from the even more ancient Ordovician then it must belong to a separate long extinct nautiloid order.

Yet it is so similar! Amazing. I'll see if I can find out some info on Plectolites.

Phil
 

Phil

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That is a fantastic find.......do you find stuff like this regularly? Do you keep the fossils or sell them on?

Totally jealous!
 

Architeuthoceras

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Hi Guys!
The Goniatites are all in a single concretion. I found it in a wash after a gully-washer washed it out. It is the only concretion of that age I have found that still shows the nacreous luster of the original great-great-grandmother of pearl. I watch the National Weather Service page all the time and if I see a good storm go over that area, then I go see if any more wash out.
I usually keep the good ones an leave the others for other collectors. They are found on US Public Land (BLM) so I can only collect them in reasonable quantities, for personal use, and cannot sell or trade.
:ammonite:
 

Architeuthoceras

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It's hard to take a picture of the nacre in normal light, so I took a picture of a small piece of broken shell from the same concretion, then took a picture under the microscope with the light just right to show the colors. This is a piece of shell from Goniatites multiliratus, you can see the small ridges (lirae) that gives it it's name.
 

Phil

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If anyone is wondering why these ammonoids do reflect the light so beautifully as demonstrated in Kevin's picture above, it is because the shell of the ammonoid was composed of alternating layers of aragonite and conchiolin. The mantle secreted each layer as the creature grew and added chamber following chamber to its shell. Aragonite, composed of vertical prisms reflected light at a different wavelength to the conchiolin below. With four or five layers this means that intact shells of ammonoids often exhibit a rather nice subtle rainbow effect.

Ammonoids are found in many different colours, but this is an artefact of the type of mineral that precipitated into the gaps in the cells of the creature during the process of fossilisation. So a greenish ammonite does not necessarily mean that was the colour of the creature when it was alive. It seems highly likely that the ammonoid would have employed some form of countershading as a defense, much like the nautilus, though the exact form of which is anyones guess!
 

Architeuthoceras

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Thanks for that great explanation Phil,

Here is another picture from the same concretion, I believe this is a shell fragment from an orthocerid nautiloid. I don't know why but it seems the fragments are alot more colorful than the shell on a complete fossil.
:ammonite:
 

Steve O'Shea

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Can anyone help me out with this ammonite. It is unlocalised (was just given to us yesterday). I'd love to know what it is (genus maybe, if possible), how old it is and where it has come from (if any of this is possible). It could have come from New Zealand, but it could have come from Mars.

It is rather distinctive. It's greatest dimension is 24cm (to the end of that pretty bizarre spike). Oooops, Phil has just corrected me - 'spike' = lappet. I should stick to squid and octopus :biggrin2:

Cheers
Steve
 

Clem

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Steve,

I found another lappet-bearing ammonite, online. Of course, the image was posted sans identification, but it makes for an interesting comparison with your new fossil. You can see the outline of the bisected lappet in the stone, extending to the edge of the photo.

Clem

ps: I had no idea the proper term was "lappet," either.
 

Steve O'Shea

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Thought I'd post another image of some more stunning ammonites that have 'turned up' on the desk of late.

Upper left: Phylloceras sp. Albian (Cretaceous), Madagascar.

Lower left: Lamberticeras sp. Upper Calvian (Jurassic), Russia.

Lower right: Hoploscaphites nicolletii. Fox Hills formation, South Dakota (Late Cretaceous)

Upper right: Desmoceras cf. mahabobokensis, Albian (Cretaceous), Madagascar.

There are some other truly stunning bits and pieces, images of which I'll post another time (they're actually in the display cabinet at home :madsci: ). I really have been spoilt lately.

Cheers
O
 
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