What does it mean to find a middle Miocene bivalve species in sediments of only three distinct countries (Egypt, India and Portugal)?
Probably you are talking about a Middle Miocene marine bivalve species. Without taxonomic details and the facies in which it occurs, it is practically impossible to make any paleobiogeographic deductions.
The species name or image 3D is necessary to know more détails about this fossile.
It means that the bivalve was spread in the maine basins stratching from Portugal to India. The fact that it was only found in those particular three locations could very well represent a collection bias:
- it was searched in other countries from the same general region where Miocene marine sediments exist;
- or: quality outcrops of Miocene marine rocks are not easily found in other countries of the same bioprovince.
The species in actual fact is not restricted to the counties mentioned but only limited to the countries worked upon. Stefan Vasile is right in his submission but could go further to imply that the fossil evolved and probably goes into extinction during the time frame in this region. Therefore, the species could be a reliable form for regional correlation of facies.It may as well be useful for paleoenvironment of deposition deduction if compared with other known environmental fossil indicators. Such occurrences have been reported in the past. It may suggest an evidence supporting plate tectonics that the universe was a body known as Pangea before it fractionated into present position due to plate tectonic theory. Similar (fossil) palynomorphs have been reported in Brazil and Nigeria of two different continents.
Are these bivalves related in any way? If they do not show any phylogenic similarites, then they are restricted to these distinct regions in terms ecology and stratigraphic caliberation, although they are all middle Miocene species.
If you are talking about one particular species, the observation can be explained by : either the collection bias, OR the actual biogeographic control on the distribution of the species.
Thank you all for your contributions.
The species which I recorded is Placuna (Indoplacuna) miocenica
The occurrence of this species in regions other than you mentioned cannot be ruled out. Please check available database. Best wishes.
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