Diversity analysis of the Early Ordovician <i>Sinorthis</i> Fauna (Brachiopoda) from the Meitan Formation of Zunyi, northern Guizhou, South China
Bibliographic record
Abstract
ABSTRACT The lower Meitan Formation (Floian, upper Lower Ordovician) at the Dajiaosi section, Zunyi District, northern Guizhou Province of South China, contains a moderately rich and diverse Sinorthis Fauna, with 22 species attributable separately to 15 families and seven orders of brachiopods. The fauna can be differentiated into three associations: the Paralenorthis serica, the Sinorthis typica, and the Tarfaya intercalare associations. These occupied a relatively wide palaeoecological range from lower BA3 to upper BA2 settings and from silty to clay substrate conditions. In South China, the Early Ordovician brachiopod radiation was marked by the diversification of the orthide-dominated Sinorthis Fauna, which first appeared and diversified in the middle part (relatively deep water) of the Upper Yangtze Platform in the Didymograptellus eobifidus Biozone, but rapidly declined in the succeeding Corymbograptus deflexus and basal Azygograptus suecicus biozones. During the latest Floian and early Dapingian, it expanded into comparatively shallow-water settings in the onshore direction (Changning area, southern Sichuan), offshore carbonate platform (Yichang, Hubei), and areas adjacent to the submergent Qianzhong Arch (such as the Zunyi area). The first appearance datum of the Sinorthis Fauna in shallower-water settings generally postdates that in the deeper-water environment in the central Upper Yangtze Platform, probably as a result of the fauna tracking a favoured BA3 setting during a gradual marine transgression.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".