help with identifying these shells

[joaoarguello3]

Hello everyone, I need you again. Today I bought some fossils, as a gift the seller sent me a shell (I don't know if they are brachiopods or bivalves). I asked him where they were from, and he told me that they were from Costa Rica, from a place called Puntarenas, but I looked up information on PBDB Navigator and there is no fossil site in that specific place (although there are two places nearby that date from the Eocene). . Could someone give me more information?
I leave some images

[Ludwigia]

They are bivalves, but I couldn't say which.

[joaoarguello3]

4 hours ago, Ludwigia said:

Son bivalvos, pero no podría decir cuáles.

I suppose it is impossible to identify them with precision, but is there a way to know if they really are from where the seller says and what period are they from?

[FranzBernhard]

Have you found anything about the area with g. and g. scholar? What formations are exposed in and around Puntarenas? Not everything is in the PBDB. Could easily be an unreported site, not all shell sites are documented.

Franz Bernhard

[Ludwigia]

7 hours ago, joaoarguello3 said:

I suppose it is impossible to identify them with precision, but is there a way to know if they really are from where the seller says and what period are they from?

I'm sure that a bivalve expert could identify it, but that exceeds my competence.

[joaoarguello3]

8 hours ago, FranzBernhard said:

¿Ha encontrado algo sobre el área con g. y G. ¿erudito? ¿Qué formaciones están expuestas en Puntarenas y sus alrededores? No todo está en el PBDB. Fácilmente podría ser un sitio no informado, no todos los sitios shell están documentados.

Francisco bernardo

I agree, it may be an uninformed site. I checked in PBDB and found that there are two recorded sites with Miocene burdigalian fossils nearby, but I don't know if both places could be related to Puntarenas. I leave capture

[FranzBernhard]

 

9 minutes ago, joaoarguello3 said:

but I don't know if both places could be related to Puntarenas.

Any chance of finding a geological map of that area in the net?

Franz Bernhard

[joaoarguello3]

2 hours ago, FranzBernhard said:

 

¿Alguna posibilidad de encontrar un mapa geológico de esa zona en la red?

Francisco bernardo

I did not find a good result in English, only in Spanish. According to this simplified map, the area of Puntarenas is from the Quaternary. How always here I leave the captures

[FranzBernhard]

Thanks!

Ok, or Mesozoic to Cenozoic in the surrounding coastal area. Given the very vague locality, it seems to be impossible to pin down the age any further, unfortunately.

Hopefully, someone recognizes the species of the bivalves!
Franz Bernhard

[hemipristis]

small bivalves are difficult, because so many appear similar.  If you can, please take photos of the inside of the shells.  The aperture/hinge area could help with an identification.  Also, we need to know the size

 

Edited November 10, 2022 by hemipristis

[joaoarguello3]

8 hours ago, hemipristis said:

los bivalvos pequeños son difíciles, porque muchos parecen similares. Si puede, tome fotos del interior de las conchas. El área de apertura/bisagra podría ayudar con una identificación. Además, necesitamos saber el tamaño.

 

At the moment I took these photos, if more are necessary I will publish them. Measurements are in centimeters

[joaoarguello3]

I know that it is already a matter of several months, but the same distributor always gives me pieces from that mentioned area (Punta Arenas - Costa Rica). Here I leave this photo of the largest and most beautiful bivalve to my liking in this area. I leave photos from various angles. As an extra piece of information, he has also given me concretions that you can see that they also have bivalves and when hitting them the shell is more exposed (although sometimes the fossil is damaged by the blow)