This is the "Fossil Friday" post #91. Expect this to be a somewhat regular feature of the website. We will post any fossil pictures you send in to [email protected]. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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Back in Mazon Monday #65, we spotlighted Paleocaris typus. And today, we have sweet little specimen from the Mazon River just outside Morris, IL. These syncarid shrimps are often mistaken for Acanthotelson stimpsonii (spotlighted back in Mazon Monday #52), which is also a syncarid shrimp. The major distinguishing characteristic between the two, are their tails. P. typus has a proper telson, while A. stimpsonii has a spiky tail. Unfortunately, this specimen is missing the tail. Some prep work might be able to bring it to light. However, there are other differences between the two species that can be used for identification. P. typus tends to be slimmer than A. stimpsonii, which is why we are calling this one P. typus.
This concretion was collected at the August 2020 I&M Canal Fossil Collecting event. It sat in a bucket for almost a year, finally pulled out to empty a bucket for the 2021 event. It took a little over 5 months of freeze/thaw to open it up, which would be about 40 cycles.
