Last week on Fossil Friday, I presented a fossil sent to me by a Fossil Friday Fan, Dan Phelps! I didn't let him answer in the comments, but he certainly did his best to taunt you. So what was this strange pod-like structure? A sloth zipper, or as NCSE's Glenn Branch suggested, a squirrel nut zipper?
From Dan Phelps:
"Rostroconchs are rather odd, and usually scarce, mollusks that are now considered to be in their own extinct Class, the Rostroconchia.
Rostroconchs look superficially like bivalves until you examine one closely and find that it is a single valve; usually described as more like a taco in shape than like a clam. The class may be close relatives of Scaphopods, but that is still uncertain. Most species are rather small, less than 20 mm long, but by the Devonian there are some that are somewhat larger.
The specimen used in Fossil Friday is Hippocardia cuneus from the Middle Devonian Jeffersonville Limestone. I found it in loose rip rap at the flood wall in Clarksville, Indiana back in the late 1980s. It was mined in one of several local quarries, but I am uncertain as to which one. I have found several over the years, but this is my best rostroconch specimen. It could be further prepared, but I will leave that to someone studying Hippocardia. Ultimately, the specimen will end up in the collections of the Cincinnati Museum Center."
So who got this week's Fossil Friday right? John Harshman! Way to go John! You win bragging rights for the week.
Thanks to Dan for sending in his picture. If you have one you want to share with Fossil Friday, send it to me at firstname.lastname@example.org. And don't forget you can follow all the excitement on Twitter at @MindaBerbeco or at @NCSE.