Goniatite from Jacksboro Texas

[BobWill]

Here are three views of a 9 mm "Peritrochia sp." Girty 1909. It was found at the Lost Creek Lake spillway in Jacksboro. This proves that even a broken, partial fossil is worth taking home.

In the first position you see the elaborate suture pattern characteristic of these Goniatites on the outermost whorl preserved. Notice the slight horizontal groove near the bottom edge.

As it turns to reveal the next whorl below you can see the siphuncle as a vertical line and the outer edge of a septum, or chamber wall, at the bottom.

Turning into the innermost whorl the septum comes into view at the top and the siphuncle is visible again. Here you also see another shallow groove crossing horizontally. These "constrictions" are found on some Pennsylvanian Goniatites.

 

[Jeffrey P]

Gorgeous specimen. Very interesting the way the internal chambers are  exposed. Congratulations and thanks for sharing. 

[Manticocerasman]

I love this specimen