I’ve been told these blastoids appear to be Mississippian and I have some questions

[SilurianSalamander]

I’ve been told these blastoids appear to be Mississippian in age. That surprises me because the rocks in Dane county Wisconsin are late Cambrian - early Ordovician and the nearest Carboniferous rocks are a long ways away. I’ve done some research into the history of the buildings on the UW Madison campus where I find these fossils and they were supposedly quarried only a few miles from where they now lie.

 

I was also told that blastoids didn’t appear until the Carboniferous. From a quick google search I got the impression that, while they massively diversified in the Carboniferous, they first appeared during the Ordovician.
 

I’m just confused and curious as to how old these rocks are. They’re packed full of fossils and I often find tiny fossils that have eroded out of them and fallen to the ground to collect.

 

attatched are the 2 or 3 blastoids and some of the other fossils I’ve found in these rocks. Any help as to what the age could be would be wonderful!

 

also any IDs on some of the other fossils more specific than “gastropod” or “cephalopod” or “crinoid” are also appreciated. Thank you so much! Y’all are great.
 

[Tidgy's Dad]

Blastoids have been reported from the Ordovician of a couple of US states, but these claims are rather dubious and they definitely don't belong to the two recognized orders. They are probably cystoids and, as blastoids are thought to be derived from cystoids, may possibly be stem-group  blastoids at best. 

Blastoids are present in the Silurian but are very rare, I have a few and have seen others from the Devonian, but none look like your specimens. Blastoids only became common in the Mississippian after the extinction of the cystoids.  

Your oval, synarthrial crinoid columnals seem to be from Platycrinites, another common Early Carboniferous genus, though it also appears rarely in the Devonian and Permian.