Need Help Identifying a Fossil

[John Turgeon]

Can anyone help me identify this item? I found it near the Badlands in South Dakota in the late 90s. It measures 2.5 " long and 2" wide. I have always been curious, but the internet wasn't so helpful back then. 

[val horn]

It looks like a suture from an ammonite or a baculite.

[DPS Ammonite]

Part of an ammonite showing sutures circled in red.

 

[Fossildude19]

I agree it is an Ammonite chamber section.

Sometimes these ammonite sections are colloquially called "buffalo calling stones".

[Ivaldir]

27 minutes ago, Fossildude19 said:

I agree it is an Ammonite chamber section.

Sometimes these ammonite sections are colloquially called "buffalo calling stones".

Just looked up the story behind it, I've never heard of it. Thanks, very interesting fun fact!

Edited Thursday at 11:23 AM by Ivaldir

[BobWill]

In the interest of clarity I will add that what some are calling sutures are actually septa. They are the walls that seal off chambers to provide buoyancy for swimming. The sutures are the folded lines where the septa attach to the inside if the shell as seen in the image of the large ammonite, center-left on the plate DPS Ammonite included.

[John Turgeon]

Thank you so much everyone for the great information! It's nice to have a place to start now.

[DPS Ammonite]

3 hours ago, BobWill said:

In the interest of clarity I will add that what some are calling sutures are actually septa. They are the walls that seal off chambers to provide buoyancy for swimming. The sutures are the folded lines where the septa attach to the inside if the shell as seen in the image of the large ammonite, center-left on the plate DPS Ammonite included.

Thanks Bob. I keep getting those mixed up.