Blastoids from Michigan

A few years ago a member of the Fossil Forum gave me these two blastoids in matrix. What I know about them is that they came from the Alpena area of Michigan and are Devonian in age. I reached out to my friend Joe K. for some ID help and he suggested that it comes from the Thunder Bay formation and would be classified as a Heteroschisma subtrunctatum.

Specimen #1

Specimen #2

I need to get both specimens cleaned and prepped so that they are more visible. The Thunder Bay formation (or limestone, depending on who you are talking to) is the uppermost layer of the Traverse group in Michigan which places it as latest Givetian stage of the Devonian.

Cryptoblastus melo from Missouri

Blastoids are a favorite fossil group of mine, possibly because I find so few and they are so strange. Here is a Cryptoblastus melo from the Burlington Limestone near Sedalia, Missouri. It's still embedded in the matrix but sticks up a little to make for a nice presentation.

The Burlington Limestone is dated to the Osagen stage (N American series) or the Tournaisian to Visean stages (ICS series) of the Mississippian (Lower Carboniferous).

Crushed Devonoblastus from the Widder Fm.

I have another Blastoid to add to my collection from Arkona. It's a partially crushed specimen of what I think is Devonoblastus whiteavesi. I took some pictures of the 9.5mm long specimen with my Zorb microscope camera.

Crushed base of the specimen

Side views

View of the crushed side

To give you an idea of scale, here is the specimen held in my fingers.

Some close ups

The specimen was collected from the Hungry Hollow member of the Widder formation near Arkona, Ontario, Canada. The Widder formation is middle Devonian in age (Givetian) with the Hungry Hollow member being equivalent to the Centerfield member of the Ludlowville formation in New York, USA.

Heteroschisma canadensis from Hungry Hollow

Heteroschisma canadensis is the last of the three blastoid species that I've found at Arkona. It's the smallest and is often referred to as "ice cream cones". As you can see they are about the size of rice grains so one has to be looking really close to find them. All four specimens that I found came by sifting through some eroded gravel.

Oral surface (top)

Side views

Basal surface (where the stem attached)

The other two species that I have from Arkona are Nucleocrinus elegans and Hyperoblastus reimanni. All three were found in the Hungry Hollow member of the Widder formation (Devonian, Givetian stage).

Nucleocrinus elegans from the Widder formation

This past July I was up collecting at Hungry Hollow near Arkona, Canada and ran into a couple of fellow fossil collectors. We chatted for a bit and one of them gave me the fossil below, a Nucleocrinus elegans.

Oral surface (top)

Basal surface (where the stem attached)

Side views

I think he felt bad for me as I complained that I hadn't found many blastoids at the site (despite their relative local abundance). I gave him some pieces of North Evans Limestone that are loaded with micro fossil fish and conodont teeth as a thank you. Sadly I didn't write their names down or I could give proper credit.

This is my third blastoid species from the Hungry Hollow member of the Widder formation (Devonian, Givetian stage) after Hyperoblastus reimanni and Heteroschisma canadensis.

A couple of Permian echinoderms from Indonesia

I was at home of a fossil dealer not to long ago when he brought out some echinoderms that he'd picked up at the Tuscon show. They were from Indonesia, more specifically the island of Timor and are Permian in age.

The first one is Timorocrinus mirabilis which I think is a type crinoid but it's hard to find any information online.It looks very similar to a blastoid but I can't see any ambulacra (mesh like openings) in the gaps between ridges as one would expect.

Anterior

Posterior

These next two specimens are true blastoids called Deltoblastus

Specimen 1, anterior

Posterior

Specimen 1, anterior

 Posterior

The label that was included with all three specimens stated that the fossils came from the Maubisse formation near Basleo on the island of Timor.

Hyperoblastus filosa

Blastoids are a cool fossil to find and previously I thought they only could be found in Carboniferous aged rocks. It wasn't until I visited Arkona and spoke with local expert Joe K. (Crinus on the Fossil Forum) that I found out otherwise. During my visit to Arkona last fall I got lucky and found the below specimen of Hyperoblastus reimanni filosa.








The Blastoids from Arkona are very small and must be found while crawling on the ground or by getting lucky and screening the fossil gravels formed from the weathered rock of the formations. I found this at the base of a slope along the Ausable river in an area of washout gravel that had eroded from the Arkona formation.

Blastoid with brachioles

Blastoids are a common fossil from Carboniferous aged rocks but rarely do they have their brachioles (feeding organs) preserved. This specimen, which I purchased on E-bay, has some brachioles preserved in near life positions.







Unlike Crinoids, Blastoids had very short cillia like arms (brachioles) that lined the edges of ambulacrul grooves (the five petal shaped areas) on the theca (body of the animal, similar to the crinoid calyx). This specimen has parts of those presevred with it which indicates a very rapid burial with little disturbance afterwards. Most blastoids are found without the brachioles because after the animal dies they fall apart at the joints and scatter in the currents.