Species of criniods and blastoids of michigan

[Keichhorn]

I'm a collector from michigan and have a large amount of specimens to prep. I am starting this topic to help others and myself on the ID'S of criniods and blastoids I commonly find in michigan. 

I'll start this with a worn, but otherwise nice criniod my sister found last summer up in partridge point. I believe it is one of 3 species of Megistocrinus. Im waiting for my sister to send me the specimen so I can get a better look at it and add photos to this post. I'm leaning towards an M. regularis due to its shorter height than the other two examples. 

Just under 6cm in length and width and a little over 3cm in height. Please share your thoughts on which one you might think it is. Any additional papers or resources on echinoderms is appreciated! 

 

Classification

Common: criniod

Kingdom: Animalia

Phylum:   Echinodermata

Class:      Criniodia

Order:      Camerata

Family:    Reteocrinidae? 

Genus:    Megistocrinus 

LOCATION

Country: U.S.A.

State:     Michigan

County: Alpena township

City:       Alpena

Latitude: 45.0056405

Longitude:  -83.4332667

Geochronology

Eon:      Phanerezoic

Era:       Paleozoic

Period: Devonian

Epoch: Middle Devonian 

Lithostratigraphy

Group:         Traverse group

Formation: Partridge point

Member:    Thunderbay limestone

Dimensions

Length (cm)  6

Width (cm)    6

Height (cm)   3.7

Notes

Identifier Kyle Eichhorn 

Collector Kyle Eichhorn 

Event Date 02/01/2021

Field Notes: exposed by tides at partridge point park. 

Edited January 10, 2022 by Keichhorn
Added/ updated information

[westcoast]

Based entirely on what I see in those images I would be leaning towards nodosus.

[Keichhorn]

Thank you. @westcoast I said regularis, but I agree with you. A closer look at the spacing of plate bumps (can't remember actual term, my apologies) looks more like nodosus.

[FossilDAWG]

@crinus is very familiar with this fauna and he may stop by to offer an opinion.  He doesn't check in as often as he used to, though, so you might need to be patient.

 

BTW this is not a comatulid.  The Comatulida is exclusively Mesozoic (lower Triassic) to recent, and includes all modern crinoids.  Your crinoid is a camerate (Order Camerata), one of the Paleozoic orders.  It is characterized by a rigid calyx with the brachial plates (making up the lower part of the arms) and interbrachials incorporated into the calyx, and all the calyx plates somewhat fused to each other.

 

Don

[Keichhorn]

@FossilDAWG thank you for the information. I will fix it accordingly. I'm not new to collecting but am very new to data/information gathering. I currently have two sources for finding information outside the internet. Do you know of anything I can use to help me learn more about this? I tried gathering info from Google searches, but i am finding there are a lot of details and differences to drudge through. Anything you can think of would be a great help! 

[Kane]

Can I assume you already know about the UMMP database? http://michiganbasinfossils.org

 

They also have a good number of freely accessible academic papers for download. 

 

And just having a peek at the Thunder Bay Fm, the above-mentioned database had a good number of specimens for visual comparative purposes: http://michiganbasinfossils.org/search?fm=Thunder Bay

 

 

[Keichhorn]

@Kane yes, I downloaded the devoinian strata of alpena/presque isle counties book from the U of M site and they have a link there. I will go back to it! Thank you. 

Edited January 10, 2022 by Keichhorn

[crinus]

That is a sphaeralis.