Show us your Inoceramus!

[Thecosmilia Trichitoma]

Inoceramus are one of the most widespread and commonly found Mesozoic marine bivalves, ranging from the Early Jurassic to the Late Cretaceous. They are found in deposits all over the world, and can be small, or huge. So show us your Inos!

 

Here are two I have found.

 

The first is a plate with two of them from Holzmaden, where they are extremely common. The second is a larger weathered one from a local State Park tide pool. ( Of course, I didn’t collect it.)

[Thecosmilia Trichitoma]

The second one came from the Point Loma formation.

[Thomas.Dodson]

Here's a plate of Inoceramus labiatus (Greenhorn Formation, Cenomanian/Turonian) I collected from a roadcut in Kansas while passing through.

These Inoceramus fibrosus come from the Trail City Member of the Fox Hills Formation (Upper nicolleti assemblage zone) in South Dakota. You'd think I'd have a lot of these but Inoceramus are absent from the Fox Hills Formation in North Dakota so the few from South Dakota are the only Fox Hills Inoceramus I have.

They are present in the Pierre Shale in North Dakota but they're not as well preserved. However, the more fragmentary nature of the Pierre Shale specimens means you can often see the calcite shell layering present in Inoceramus sp. without slicing up any specimens.

 

[Creek - Don]

Found in Austin Chalk/Santonian formation. North Central Texas. 

[Norki]

Here's a big one in the field, from the Bearpaw formation. The shell extended all the way to the edge under that matrix on the left.

 

[Ludwigia]

Here's a German one. Found in a quarry in Ibbenbueren, Nordrhein-Westfalen. Late Cretaceous Campanian.

 

 

[KansasFossilHunter]

Here's one you might enjoy. This is from the L. Cretaceous (Santonian) Smoky Hill Chalk mbr in Kansas. The hammer is appx. 28cm long. 

 

 

 

[Jeffrey P]

A small Inoceramus from the Merchantville Formation, Upper Cretaceous from Mattawan, New Jersey.

 

[Wrangellian]

Here's a couple I found at a local site here on Vancouver Island (Santonian or lowermost Campanian), which I have since donated to the Geological Survey:

I am not sure of the ID, or whether they are the same - they seem different to me but maybe just variation within the species, in which case they might all be I. vancouverensis. The 2nd one has both valves.

I miss collecting at this site.

 

Here is a larger one, an internal mould, from another site. Also donated to the GSC.

 

From large, to larger, to largest: I've shown this one before, but it still stands as the largest one I ever attempted to collect. It was somewhat of a mess when I found it (as seen in the annotated pic), and I made more of a mess in my attempt to remove some rock so I could lift it into the car trunk. If I had had more time and equipment I would have just taken the whole boulder.

Arrows mark the edge of the valve, though most of the shell on top was missing.

I had no room for this one so I gave it to somebody, and I'm not sure where it is now.

[Norki]

On 1/16/2021 at 7:20 AM, KansasFossilHunter said:

Here's one you might enjoy. This is from the L. Cretaceous (Santonian) Smoky Hill Chalk mbr in Kansas. The hammer is appx. 28cm long.

Wow, I knew there were big inoceramids in the Smoky Hill Chalk, but that thing is just monstrous. According to Oceans of Kansas fossil fish can occur inside of them, have you ever checked?

[KansasFossilHunter]

15 hours ago, Norki said:

Wow, I knew there were big inoceramids in the Smoky Hill Chalk, but that thing is just monstrous. According to Oceans of Kansas fossil fish can occur inside of them, have you ever checked?

Oh certainly! I've found over a dozen of those type of specimens. Including a very rare eel species and one clam with over 50 smaller fish inside. I think the largest number inside a single bivalve was nearly 100 fish. I had hoped to further my study of this occurrence at the University of Michigan but it didn't work out. Here was my proposal for that research:

 

Tiny fishes in giant clams: a unique taphonomic window into the evolutionary

history of Acanthomorpha

 

 

And here is that eel fossil (Urenchelys abditus). Donated to the Sternberg Museum in Hays, Kansas. One of my first major discoveries as a high school student. Only the second of the genus discovered. But I have also come to learn of the existence of other unpublished specimens in the course of my research. 

 

 

 

There were also several other fishes associated with the eel specimen. Including what I believe to be a Pycnodontid.

 

[Missourian]

I have found some of these fish embedded in inoceramid shells in the Niobrara Chalk. None are nearly as nice as the specimens in the post above:

 

 

 

 

Some Pseudoperna congesta encrusted on inoceramid shells:

 

 

I must say these pelecypods, though interesting in their own right, can be downright frustrating when hunting for other fossils in the chalk. These fragmented shells can resemble vertebrae, jaws, teeth, etc. as they are fragmented into billions of pieces and scattered across the surface of the chalk.

 

[historianmichael]

Adding my two Upper Cretaceous inoceramids because I just had the fortunate of finding a second to add to my collection. I found the first one many years ago in the Ramanessin Brook and I recently found the second among the C&D Canal dredge piles.

 

 

 

 

 

[AK hiker]

These Inoceramus are from Alaska with large ones occurring in the Matanuska Formation in the Talkeetna Mountains. 

These Inoceramus are in the Tuxidni Formation along the west side of Cook Inlet locally abundant along the beach and cliff exposures.

 

[Wrangellian]

On 7/17/2021 at 7:57 PM, AK hiker said:

These Inoceramus are from Alaska with large ones occurring in the Matanuska Formation in the Talkeetna Mountains. 

 

These Inoceramus are in the Tuxidni Formation along the west side of Cook Inlet locally abundant along the beach and cliff exposures.

Dang... too bad you can't take this one home.