Fish Faunas from the Bissekty Formation (Turonian), Uzbekistan: Insights into biogeographic connectivity and climate-driven Faunal Turnover
Bibliographic record
Abstract
The Bissekty Formation (Turonian, Uzbekistan) provides new insights into the reorganization of aquatic paleocommunities that occurred during the Turonian thermal maximum, a period of significant climatic and faunal change. The assemblage includes four basal neopterygians and 13 teleosts. Teleosts are dominated by members of early diverging lineages, including Ichthyodectiformes, Elopomorpha, Osteoglossiformes, and Clupeomorpha. More derived teleosts present in the assemblage includes a characiform and an acanthomorph. The assemblage is distinctive compared to Late Cretaceous assemblages from North America in the high abundance of ichthyodectiforms and elopomorphs and both high abundance and large size of acanthomorphs. The Bissekty fish assemblages differs from preceding Cenomanian assemblages of Laurasia in the absence of two taxa that were dominant in the earlier Cenomanian assemblages, Scheenstia López-Arbarello and Sferco, 2011 (Lepidotidae) and a pycnodont, and the appearance of seven new taxa. One of the newly appearing taxa is a member of Characiformes, a group that is thought to have originated in Gondwana, adding to the evidence that the introduction of new taxa was a result, in part, of intercontinental dispersal events. All seven of the taxa that first appear in the Bissekty Formation are closely related to, or indistinguishable from, taxa present in the North American portion of Laurasia. However, only two of these are known to occur in North America during the Turonian, with the remaining taxa first occurring in North America in a step-wise pattern during the Late Cretaceous. Conversely, two of the taxa that first occur in the Turonian of the North American portion of Laurasia are absent in Asian assemblages.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".