Palaeobiogeographic relationships and palaeoenvironmental implications of an earliest Oligocene Tethyan ichthyofauna from Egypt
Bibliographic record
Abstract
The Fayum Depression of Egypt has produced a great diversity of fossil material, including marine and freshwater fishes. In contrast to the Eocene formations of the Fayum, the Oligocene Jbel Qatrani Formation has been more or less consistently considered to be deposited in a freshwater environment; however, the ichthyofauna indicates a more complex picture. Cenozoic fishes have been convincingly used to interpret the palaeoenvironment in which sediments were deposited. Based on the elasmobranch and osteichthyan faunas of the Jbel Qatrani Formation, we interpret that this formation was not deposited entirely in fresh waters, but had some marine influence, particularly in the lower part of the formation. The mixture of freshwater elements, such as polypterids and alestids, with brackish and marine elements, including myliobatid stingrays, in the Quarry E site suggests a local palaeoenvironment that was very close to the shoreline, in a less protected area, or under more seasonal influence than the rest of the sites in the formation. Additionally, the early Oligocene elasmobranch fishes from Quarry E have a strong biogeographic relationship with sites in Oman and Pakistan, in the eastern Tethys, representing a restricted fauna possibly limited in distribution by cooling global temperatures.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".