Proetid

[Kane]

Just cleaning up a few finds from the Hungry Hollow Member (Mid-Devonian, Arkona, Ontario). I am awful at discerning between proetids based on certain fragments, so was hoping for an assist as to whether it is a Pseudodechenella or Crassiproetus. If memory serves, one has a bigger anterior cephalic brim. I can usually tell them apart if I have the pygidium (Crassiproetus has a more rounded, effaced one). I’m leaning more toward Pseudodechenella.

 

Once the genus can be nailed down, I have a question about size ranges that I haven't come across in the literature. When measured around the curve of the glabella, I get 2.5 cm. That seems fairly large for examples I've seen elsewhere. That would have made this trilobite, whole, about 7+ cm (sag.). That seems a bit too big for most proetids I've encountered. 

[piranha]

When comparing maximum size range, a simple straight line measurement should be used instead of measuring around the curve.

[Kane]

1 minute ago, piranha said:

When comparing maximum size range, a simple straight line measurement should be used instead of measuring around the curve.

Brings it down to 2 cm.

[daves64]

Is the red circled area part of an eye? 

[Kane]

2 hours ago, daves64 said:

Is the red circled area part of an eye? 

 

Unfortunately, just a bit of coral or bryozoan. The fragment pretty much ends before then. 

 

Hopefully I can get this figured out as it will help indexing these layers a bit better to guide my search for a complete one.