Mucrospirifer vs Mediospirifer Characteristics

[PHFossilGuy]

As I've been cataloging my Devonian finds, in my research I've come across both mucrospirifer and mediospirifer. I'm not certain of the characteristics that would set the two apart. Can anyone provide some clarity or point me towards a resource that could?

[Isotelus2883]

Field Guide to the Devonian Fossils of New York, Karl A. Wilson.

[Fossildude19]

From: 

"Devonian Paleontology of New York David M. Linsley. ©1994"

 

Mediospirifer:

 

 

 

Mucrospirifer:

 

 

 

 

[Misha]

The interarea of Mucrospirifer is generally thin and linear whereas in Mediospirifer it is much taller, more triangular with a larger Delthyrium 

(Though I should mention that's not always the case I've seen some Mucrospirifer specimens with a more Mediospirifer-like interarea)

Mucrospirifer also has much "rougher" shell ornamentation, with larger ribs and more prominent growth lines, these are smoother and finer on Mediospirifer

 

@Tidgy's Dad may be able to add/ correct me if I said anything incorrectly 

[PHFossilGuy]

This has all been very informative and helpful thank you!

[PHFossilGuy]

1 hour ago, Misha said:

The interarea of Mucrospirifer is generally thin and linear whereas in Mediospirifer it is much taller, more triangular with a larger Delthyrium 

(Though I should mention that's not always the case I've seen some Mucrospirifer specimens with a more Mediospirifer-like interarea)

Mucrospirifer also has much "rougher" shell ornamentation, with larger ribs and more prominent growth lines, these are smoother and finer on Mediospirifer

 

@Tidgy's Dad may be able to add/ correct me if I said anything incorrectly 

@Misha the term interarea is new for me. Does interarea equate with hinge line?

 

[Misha]

I believe it is the flat area of the back of the pedicle valve, it contains the Delthyrium opening. Above the hinge line in this image.

 

I hope I'm using the proper term, I think from what I've seen that's what it's called 

[PHFossilGuy]

7 hours ago, Isotelus2883 said:

Field Guide to the Devonian Fossils of New York, Karl A. Wilson.

That book looks fantastic. I just ordered it. Thanks for passing that on.

[Tidgy's Dad]

On 1/17/2024 at 5:17 PM, Misha said:

 

@Tidgy's Dad may be able to add/ correct me if I said anything incorrectly 

A first-class summary, in my opinion.

 

On 1/17/2024 at 6:27 PM, PHFossilGuy said:

Does interarea equate with hinge line?

No.

It's the flat region in the posterior between the beaks. It often doesn't occur at all, may only occur on one valve or on both. Usually the interarea when it occurs is wider on the pedicle valve, but the reverse does occur and they are quite often equal. It follows the hinge line, but not always for the whole length. Intereareas are often triangular but also often almost rectangular.

[PHFossilGuy]

15 hours ago, Tidgy's Dad said:

A first-class summary, in my opinion.

 

No.

It's the flat region in the posterior between the beaks. It often doesn't occur at all, may only occur on one valve or on both. Usually the interarea when it occurs is wider on the pedicle valve, but the reverse does occur and they are quite often equal. It follows the hinge line, but not always for the whole length. Intereareas are often triangular but also often almost rectangular.

Thank you for that explanation. 😀