Parasitic Gastropod?

[minnbuckeye]

On my way to Clermont Iowa last week, I stopped at a road cut on Hwy 52. Spent about 10 minutes looking at the potential of this rock when I found a Liospira with a Gastropod which I will call a Bellerophon attatched to it. The more I studied this, the more I began to think could the bellerophon be preying on this liospira? The positioning of the gastropod is perfect but I can see NO damage done to the "prey" If anyone with insite into the lifestyles of such gastropods would like to comment, I would love to hear from you. Thanks!

[FossilDAWG]

That's a pretty cool combo! Very photogenic. I don't think it's a predator/prey situation, though, for two reasons. First, that would be a tough location to drill through, as the curvature of the shell would effectively increase the thickness the predator would have to drill through compared to the flatter parts of the shell. Secondly, I think the smaller shell is a Sinuites, and that was a monoplacophoran (not a snail) and was not a "driller". I assume the site was Ordovician, at least the big gastropod looks like one of the Ordovician forms such as Liospira? Holes have been noted in Ordovician shells, but they are uncommon and there is a lot of debate about whether they reflect predation or some other activity such as boring by sponges or barnacles to create a living space.

Don

[minnbuckeye]

Thanks for the response. Though it is a disappointment this is not predator /prey in action, I am still very happy with my find. Your response and my further research has led me to wonder if Bellerophon and Sinuites are not one in the same??If anyone can clarify this, I would be grateful. For all novices like me, my further research has provided an interesting fact about the Sinuites. As Don mentioned, Sinuites is a monoplacophoran, NOT a Gastropod. This group of mollusks almost disappeared by the Devonian era . The interesting fact is that gastropods may have evolved from this group of mollusks!!! So I have a Pre- Gastropod attached to a Gastropod!!! I will keep it.

[ZiggieCie]

Very interesting find. An x-ray wold show if there would be any drilling involved. Interesting how the small shell forms around the edge as if it grew there.

[Auspex]

I do not think that they would have stayed together during interment if it were an interrupted act of predation. Most probably their association is a postmortem accident.

[RJB]

That is one cool gastro!

RB

[FossilDAWG]

Bellerophon is not the same as Sinuites. Bellerophon is the type genus of the family Bellerophontidae, whereas Sinuites belongs to a different family, the Sinuitidae. However all these forms are characterized by having a single shell that is planispirally coiled, that is coiled in a single plane instead of in a helix like a more typical gastropod (snail). Actually, true Bellerophon is not present in the Ordovician, but there are a number of related genera, which are collectively called "bellerophontids" (meaning Bellerophon-like). Whether these are actually gastropods or tergomyids (monoplacophorans) is still a matter of controversy. The internal anatomy is different (gastropods are "torted" or twisted, even if the shell is planispiral as in some modern land snails) and monoplacophorans are not. This is sometimes reflected in shell features such as the position of muscle scars, but this requires exceptional preservation and even then may be open to interpretation. There seems to be a consensus that Sinuites and Cyrtolites (and a few other Ordovician forms) really were monoplacophorans, but it is unclear if this also applies to other bellerophontids.

Here is an excellent site where you can compare images of bellerophontids (listed under Gastropoda) and tergomyids such as Sinuites.

Don

[minnbuckeye]

I want to thank everyone who responded. When posting something as simple as this, a wealth of information is always provided to me, feeding my insatiable desire to learn. TFF has been great.

[Auspex]

You did the heavy lifting, by asking. Now the information is here for thousands to enjoy!

[siteseer]

Don or anyone,

Years ago, I read that "driller" gastropods did not appear until the Cretaceous. Maybe some finds have been reinterpreted but have there been confirmed Paleozoic or Triassic-Jurassic drill holes? I've seen Pliocene shells with apparent drill holes in them. It's a pretty clean circle.

Jess

That's a pretty cool combo! Very photogenic. I don't think it's a predator/prey situation, though, for two reasons. First, that would be a tough location to drill through, as the curvature of the shell would effectively increase the thickness the predator would have to drill through compared to the flatter parts of the shell. Secondly, I think the smaller shell is a Sinuites, and that was a monoplacophoran (not a snail) and was not a "driller". I assume the site was Ordovician, at least the big gastropod looks like one of the Ordovician forms such as Liospira? Holes have been noted in Ordovician shells, but they are uncommon and there is a lot of debate about whether they reflect predation or some other activity such as boring by sponges or barnacles to create a living space.

Don