Some type of trace fossil?

[Pearl]

Can someone tell me if this is some sort of trace fossil? I find them often in the clay in a creek bed that contains fossils of the upper Cretaceous period. Thank you! 

[Rockwood]

Pholad borings would be one possibility to consider.

[Pearl]

11 hours ago, Rockwood said:

Pholad borings would be one possibility to consider.

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Wooster’s Fossil of the Week: A bivalve boring from the Upper Ordovician of southern Ohio

 Mark Wilson  December 16, 2012 1:35 am

Found a lot of photos of Petroxestes trace fossils and they look very similar but not sure they existed during the Cretaceous. 

 

[Kato]

5 minutes ago, Pearl said:

← Wooster Geologist in Ireland

Geological fieldwork on the streets of Dublin →

Wooster’s Fossil of the Week: A bivalve boring from the Upper Ordovician of southern Ohio

 Mark Wilson  December 16, 2012 1:35 am

Found a lot of photos of Petroxestes trace fossils and they look very similar but not sure they existed during the Cretaceous. 

 

 

I think so, too.

[Rockwood]

8 minutes ago, Pearl said:

not sure they existed during the Cretaceous

It's doubtful. That's a long time with a huge bottle neck (PT) in the way. 

[Kato]

A snippet from the Wooster article....

 

This week’s fossil is from close to home. In fact, it sit in my office. The above is a trace fossil named Petroxestes pera. It was produced on a carbonate hardground by a mytilacean bivalve known as Modiolopsis (shown below). Apparently the clam rocked back and forth on this substrate to make a small trench to hold it in place for its filter-feeding. This particular specimen of Petroxestes was found in the Liberty Formation (Upper Ordovician) of Caesar Creek State Park in southern Ohio. This is a place many Wooster paleontology students know well from field trips.

 

The original Petroxestes was at first known only from the Cincinnatian Group, but now it is known from many other places and time intervals, even including the Cretaceous and Miocene. It is a good lesson about trace fossils. They are defined by their morphology, not what organisms made them. It turns out that this slot-shaped trace can be made by other animals besides Modiolopsis, which went extinct in the Permian.

[Pearl]

38 minutes ago, Rockwood said:

It's doubtful. That's a long time with a huge bottle neck (PT) in the way. 

 

They look different also.  The ones I find have a tadpole-like shape. More rounded on one end. 

[Pearl]

24 minutes ago, Kato said:

A snippet from the Wooster article....

 

This week’s fossil is from close to home. In fact, it sit in my office. The above is a trace fossil named Petroxestes pera. It was produced on a carbonate hardground by a mytilacean bivalve known as Modiolopsis (shown below). Apparently the clam rocked back and forth on this substrate to make a small trench to hold it in place for its filter-feeding. This particular specimen of Petroxestes was found in the Liberty Formation (Upper Ordovician) of Caesar Creek State Park in southern Ohio. This is a place many Wooster paleontology students know well from field trips.

 

The original Petroxestes was at first known only from the Cincinnatian Group, but now it is known from many other places and time intervals, even including the Cretaceous and Miocene. It is a good lesson about trace fossils. They are defined by their morphology, not what organisms made them. It turns out that this slot-shaped trace can be made by other animals besides Modiolopsis, which went extinct in the Permian.

 

And although these have more of a "tadpole" shape, these are still some type of bivalve trace fossil, correct?

[Rockwood]

41 minutes ago, Pearl said:

some type of bivalve trace fossil, correct?

These two look especially convincing of it to me.

[Pearl]

2 hours ago, Rockwood said:

These two look especially convincing of it to me.

Great! Thanks so much for the ID!