Brachiopods from the Serpukhovian Tonka Formation of Carlin Canyon, Elko, Nevada (USA): Systematics and biostratigraphy
Bibliographic record
Abstract
Systematic study of a brachiopod assemblage from the upper Mississippian Tonka Formation in Carlin Canyon, Elko, Nevada, USA, led to the recognition of 13 species, representing 12 genera and seven orders: ?Antiquatonia sp., Flexaria sp., ?Marginatia sp., Echinoconchus sp. of the Productida, ?Orthotetes sp. of the Orthotetida, Rhipidomella sp., Schizophoria sp. of the Orthida, Cleiothyridina cf. sublamellosa Hall, 1858, Composita sulcata Weller, 1914 of the Athyridida, Anthracospirifer shawi shawi Gordon, 1975, Anthracospirifer aff. A. shawi of the Spiriferida, Punctospirifer sp. of the Spiriferinida, and Girtyella indianensis Girty, 1909 of the Terebratulida, with the addition of one undetermined linoproductid and one genus and possibly two undetermined species of the Delthyridina. The assemblage shares affinities with late Chesterian (middle Serpukhovian) Carlinia phillipsi and C. amsdeniana associations from western North American units, though the presence of Composita sulcata makes it also close to latest Chesterian faunas (Rhipidomella nevadensis and Composita popsiensis zones). The recorded faunal association, in terms of composition at the genus-level, is characteristic of brachiopod Unit 16 of Carter (1990a). Unit 16 spans the middle Chesterian (Gnathodus bilineatus conodont Zone) to upper Chesterian (Rachistognathus muricatus conodont Zone), corresponding to the upper Visean–Serpukhovian interval. A monospecific Volgegnathus postcampbelli conodont assemblage from the same locality confirms a late Chesterian (Serpukhovian) age of the fauna.
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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".