Upper Miocene bivalve and coral ID

[Hapchazzard]

While waiting to go on a fossil hunting trip of my own to a different site in the upcoming months, I have received three fossils that I am now trying to ID. I didn't have much success, so I would like to ask the forums for assistance.

All three fossils are upper Miocene(Tortonian) in age, and were originally deposited in the southern slopes of the Pannonian sea.

The first fossil is obviously a bivalve, but I can't decide whether it is a cockle or scallop, since the rear parts of the fossil are missing. Is there any other characteristics beside the presence of auricles to determine which one of the two families it is(or if is something else entirely)? The fossil is 4cm long(from the front of the shell to the opposite part of the rock). Also, on the rear part of the rock, there is a small tube slightly visible in the lower central part of the rock, around 2mm in diameter - the siphon? If it is a siphon, does it mean that the fossil is a cockle(AFAIK scallops don't use siphons)?

 

 

 

The second fossil is a scleractinian, I think, but I have no idea about anything lower on the taxonomic tree. Is there any way to narrow it a bit more down, at least to the suborder or family level? Or to infer the structure of the living coral colony(whether it was massive, frondose, etc.). Also, it appears as if something had encrusted the surface of the coral, but I am unsure if it is an actual encruster(bryozoan or algae), or just deceitful ordinary rock. Length of the fossil is around 4cm.

 

 

 

The third fossil is also the most damaged. I'm pretty sure it's a bivalve fragment, but not much beyond that. Two things I've noticed:

1. It seems pretty large for a bivalve. It is 5cm long, but it is obviously only a small fragment of what was once a much larger shell. Either that, or the ribs are extremely thick.

2. The underside of the fossil has several patches of what I am 90% sure is an encrusting bryozoan(I can take a picture if needed). The way I interpreted it, the shell got disarticulated after death due to waves/currents(the matrix itself is fairly coarse sandstone, if I am correct, so the environment must have been fairly high-energy) and the underside was colonized by bryozoans. This means that the living bivalve lived on the surface, rather than buried within the substrate, which might help a bit with ID.

 

 

Input would be highly appreciated.

[tmaier]

The first one doesn't look like scallop to me. The ribs are rolling, and scallop ribs are square, being flat on top. The second one is likely a sea biscuit. The third looks like a very small fragment of a scallop shell. Notice the squarish flatness to it.

[DPS Ammonite]

The 3rd and 4th photos are of a sea biscuit or echinoid with a mouth exposed in the lower right of the photos. Compare to photos of Lovenia: https://museumvictoria.com.au/discoverycentre/infosheets/marine-fossils/echinoderms/

[Hapchazzard]

The first one doesn't look like scallop to me. The ribs are rolling, and scallop ribs are square, being flat on top. The second one is likely a sea biscuit. The third looks like a very small fragment of a scallop shell. Notice the squarish flatness to it.

The 3rd and 4th photos are of a sea biscuit or echinoid with a mouth exposed in the lower right of the photos. Compare to photos of Lovenia: https://museumvictoria.com.au/discoverycentre/infosheets/marine-fossils/echinoderms/

Thanks for the info!

First off, I would have never even gotten the idea that the second fossil was an echinoid fragment - I more or less definitely assumed it was a coral. But I looked up pictures online, and there are several fossil seabiscuits that have a texture almost exactly like the one on my fossil - so I guess it's case closed for that. The mouth I thought was just a random hole formed during diagenesis, but I was wrong about that, too. And it feels really good to have it narrowed down to genus level, when I was doubting it could get narrowed down even to family.

As for the advice on the rib difference between scallops and cockles - it will be very useful for me in the future, and I'm surprised I haven't seen this mentioned anywhere else.

[Guguita2104]

1-Pectenid fragment (scallop)

2-Irregular sea urchin

3-Shell fragment (maybe a pectenid one)

[Hapchazzard]

1-Pectenid fragment (scallop)

2-Irregular sea urchin

3-Shell fragment (maybe a pectenid one)

Hm, while there seems to be an agreement on 2 and 3, another poster mentioned that it likely isn't a scallop due to the rolling ribs. Is there any specific reason why you think it's a scallop(and not something else)?

[Guguita2104]

Hm, while there seems to be an agreement on 2 and 3, another poster mentioned that it likely isn't a scallop due to the rolling ribs. Is there any specific reason why you think it's a scallop(and not something else)?

Not all the scallops have that typical square and flat on top ribs.

For example, you can search for Hinnites sp. (Pectenidae) and notice the ribs haven't the features that tmaier previously referred.

You can also take a look at this post:http://www.thefossilforum.com/index.php?/topic/59604-pectenids/.

Regards,

[Guguita2104]

However I could be wrong...Maybe some expert can give you a more positive Id.

[fifbrindacier]

I agree with the identification of the urchin, as for the others, they are pectenids but i cannot say wether they are scallops or no.

[abyssunder]

I'm in the pectinid camp.

The shell ornamentation differs from species to species and narrowing down to the species level is hard if you have only fragments. The third specimen could be Chlamys latissimus (Pecten latissimus) fragment. https://www.google.com/search?q=pecten+latissimus&biw=1360&bih=612&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwi69_CSooDNAhXLIMAKHZJgD6wQsAQIGw#tbm=isch&q=chlamys+latissimus

The second specimen is an echinoid fragment, partially encrusted by bryozoan. You can see the autozooecia in the magnified picture. Here are some examples, although they are from the Middle Miocene of Slovakia.