CONODONTS ACROSS THE LOWER-MIDDLE ORDOVICIAN BOUNDARY IN THE HUANGHUACHANG SECTION OF YICHANG, HUBEI
Bibliographic record
Abstract
This paper describes in detail the conodont zonation and some important conodont species across the Lower Middle Ordovician boundary at the Huanghuachang section of Yichang. The first appearance datum (FAD) and the content of the Oepikodus evae , Baltoniodus triangularis zones etc. are revised. North American Midcontinent provincial conodonts Tripodus laevis and Protoprioniodus aranda referred to warm water fauna have been found for the first time in the lower part of the Dawan Formation at Huanghuachang section. The FAD of Tripodus laevis was found at a level, which is 0.3m above the base of Baltoniodus triangularis Zone. The first occurrence of Tripodus laevis was proposed as the base of the Middle Ordovician (see Chen Xu et al ., 2000). So its first occurrence very close to the base of the Baltoniodus triangularis Zone is very important. The evolutionary lineage of Baltoniodus crassulus B. gladiatus (= Acodus ? gladiatus Serpagli, 1974) B. triangularis can be recognized at the Huanghuachang section. So the first occurrence of B. triangularis is a better marker for the base of Middle Ordovician. The correlation of the conodont sequences across the Lower Middle Ordovician boundary among Yichang of Hubei, Newfoundland of Canada, Nevada of USA, Europe as well as Argentina is discussed here. The Huanghuachang section of Yichang, Hubei, can be proposed as a global stratotype for the base of the Middle Ordovician Series.
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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 | 0.002 |
| 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".