Deep shelf trilobite biofacies from the upper Katian (Upper Ordovician) of the Grangegeeth Terrane, eastern Ireland
Bibliographic record
Abstract
Abstract The trilobite fauna of the upper Katian (mid‐Ashgill in terms of Anglo‐Welsh chronostratigraphy) Oriel Brook Formation in the Grangegeeth Terrane, eastern Ireland comprises 16 species. It is dominated numerically by mesopelagic cyclopygids (Cyclopyge cf. marginata Hawle and Corda and much rarer Symphysops sp.), which comprise 63% of the 156 identifiable sclerites known unequivocally from the formation. Other elements of the trilobite fauna include species of Staurocephalus, Phillipsinella, Nankinolithus and the agnostids Trinodus and Sphaeragnostus. The abundance of cyclopygids in a terrane interpreted as lying within the Iapetus Ocean closer to Laurentia than the Anglo‐Welsh sector of Avalonia is consistent with the Late Katian spread of cyclopygids onto low latitude shelves seen in Quebec and Maine in eastern North America, Girvan in SE Scotland and Co. Clare in the Irish Central Terrane. With the exception of the agnostid trilobites, whose mode of life is strongly debated, associated benthic trilobites lacking eyes are fairly rare and the bottom‐dwelling fauna does not conform to the atheloptic assemblages that typified many mid‐ to high latitude Ordovician outer shelf and upper slope settings. The benthic assemblage can be considered in terms of a bathymetrically arranged spectrum of faunas and is closest to that of the deep shelf Phillipsinella parabola—Staurocephalus clavifrons fauna, known from the Upper Ordovician of Avalonia and Baltica and to some extent marginal Gondwana and South China. This is the first record of such a fauna from Laurentia or its marginal terranes and reflects the Late Ordovician breakdown of provincialism in the Iapetus Ocean. The deep‐water setting is compatible with that of the associated Foliomena brachiopod fauna. Copyright © 2010 John Wiley & Sons, Ltd.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".