Pennsylvanian Brachiopods from Olgesby, Illinois- PART DEUX

[deutscheben]

Thanks for the updated ID! I actually have one Peripristis tooth from that site in my collection, but only the labial side is exposed, and no serrations are visible. The coloring is actually very similar, though, funny enough. 

[dalmayshun]

aren't crystals inside brachiapods cool. I have several also, as I was admiring yours, I started wondering why they form....is it because of the specialized chemicals in the soft body tissue that stays trapped as it decomposes inside the shell....or is it, that water with minerals leaches into the shell and with the space the crystals grow...in other words, I guess I am trying to figure out if the crystals grow inside because the shell is merely a fissure, or does the animal actually contribute to the process. In the Conasauga Trilobites found near Dalton, Georgia, most of them have a sort of iron looking blow ring around them, which I've read, is caused by the decomposing fleshy parts...one of the ways to distinguish between a molt and an enact animal. So I hope someone knowledgeable about such things provides an answer. Thanks. And great finds, especially the peripristis. 

[Archie]

2 hours ago, deutscheben said:

Thanks for the updated ID! I actually have one Peripristis tooth from that site in my collection, but only the labial side is exposed, and no serrations are visible. The coloring is actually very similar, though, funny enough. 

As it happens I found this lower tooth of the chondrichthyan Pristodus benniei last week that also has very similar coloring showing where the crown transitions from the base, interestingly Pristodus and Peripristis are also very similar in that they are both presumed to have had single upper and lower tooth files with the upper teeth being multicuspid and the lower tending to be more triangular with few or no cusps. So @deutscheben your tooth without serrations is most likely a lower dentition tooth while @Nimravis's is likely an upper. 

[Nimravis]

1 hour ago, Archie said:

As it happens I found this lower tooth of the chondrichthyan Pristodus benniei last week that also has very similar coloring showing where the crown transitions from the base, interestingly Pristodus and Peripristis are also very similar in that they are both presumed to have had single upper and lower tooth files with the upper teeth being multicuspid and the lower tending to be more triangular with few or no cusps. So @deutscheben your tooth without serrations is most likely a lower dentition tooth while @Nimravis's is likely an upper. 

Great find- Congrats.

[Nimravis]

1 hour ago, dalmayshun said:

aren't crystals inside brachiapods cool. I have several also, as I was admiring yours, I started wondering why they form....is it because of the specialized chemicals in the soft body tissue that stays trapped as it decomposes inside the shell....or is it, that water with minerals leaches into the shell and with the space the crystals grow...in other words, I guess I am trying to figure out if the crystals grow inside because the shell is merely a fissure, or does the animal actually contribute to the process. In the Conasauga Trilobites found near Dalton, Georgia, most of them have a sort of iron looking blow ring around them, which I've read, is caused by the decomposing fleshy parts...one of the ways to distinguish between a molt and an enact animal. So I hope someone knowledgeable about such things provides an answer. Thanks. And great finds, especially the peripristis. 

You are correct about the Conasauga trilobites, but I am not sure about the brachiopods, maybe Tony @ynot might be able to answer that question.

[Tidgy's Dad]

2 hours ago, dalmayshun said:

aren't crystals inside brachiapods cool. I have several also, as I was admiring yours, I started wondering why they form....is it because of the specialized chemicals in the soft body tissue that stays trapped as it decomposes inside the shell....or is it, that water with minerals leaches into the shell and with the space the crystals grow...in other words, I guess I am trying to figure out if the crystals grow inside because the shell is merely a fissure, or does the animal actually contribute to the process. In the Conasauga Trilobites found near Dalton, Georgia, most of them have a sort of iron looking blow ring around them, which I've read, is caused by the decomposing fleshy parts...one of the ways to distinguish between a molt and an enact animal. So I hope someone knowledgeable about such things provides an answer. Thanks. And great finds, especially the peripristis. 

I understand it is due to minerals dissolved in water leaching into the empty spaces.

[Tidgy's Dad]

8 hours ago, Archie said:

Oh yes I'm definitely convinced this is a Peripristis in lingual view with these photos, awesome find! Glad to be of help  

Sam

Nice one, Sam! 

[deutscheben]

2 hours ago, Archie said:

As it happens I found this lower tooth of the chondrichthyan Pristodus benniei last week that also has very similar coloring showing where the crown transitions from the base, interestingly Pristodus and Peripristis are also very similar in that they are both presumed to have had single upper and lower tooth files with the upper teeth being multicuspid and the lower tending to be more triangular with few or no cusps. So @deutscheben your tooth without serrations is most likely a lower dentition tooth while @Nimravis's is likely an upper. 

 

Fascinating! And excellent find as well. 

[Archie]

2 hours ago, Nimravis said:

Great find- Congrats.

 

1 hour ago, Tidgy's Dad said:

Nice one, Sam! 

 

56 minutes ago, deutscheben said:

Fascinating! And excellent find as well. 

 

Thanks guys!  

[Archie]

I've also wondered that about the brachiopod geodes in the past but was thinking the soft innards could well have rotted away before the shell was even buried in sediment, let alone before the crystal growth began?  

[Tidgy's Dad]

1 minute ago, Archie said:

I've also wondered that about the brachiopod geodes in the past but was thinking the soft innards could well have rotted away before the shell was even buried in sediment, let alone before the crystal growth began?  

Indeed. 

There may sometimes be staining due to the decay of soft tissues, the effects of microorganisms etc. but I don't see that it would have any marked effect on major crystal formation. 

[ynot]

8 hours ago, dalmayshun said:

crystals inside brachiapods....... I started wondering why they form.

Crystals will form inside voids in rocks - whether from a crack or an unfilled shell.

Mineral saturated water flowing through the void will deposit the minerals on the void walls. It is not a recrystallization of soft body parts, which are made from different elements than the crystals.

[Nimravis]

Thanks for the info Tony @ynot

[Wrangellian]

More nice big brachs!

I like Peat Burns' idea......

[dalmayshun]

thanks , I know I can always count on my fellow FossilForum-ers...LOL. It is such a great learning site. I get to see so many cool fossils  I won't ever be able to collect myself and I always discover new insights into how things work. So glad for the many "experts" as well as "novices" who are as curious about things as I am. And again, I learned about the peripristis tooth, and crystals just because others are as intrigued and as curious as I am. So thanks everyone.