The missisquoiid trilobite 'Parakoldinioidia' Endo 1937 in the uppermost Cambrian of Oklahoma and Texas, and its biostratigraphic significance
Bibliographic record
Abstract
Missisquoiid trilobites are widespread in Laurentian North America but most occurrences have been reported under a single name, 'Missisquoia typicalis' Shaw 1951 (now = 'Parakoldinioidia stitti' Fortey 1983). The base of the 'Parakoldinioidia' Zone (= 'Missisquoia typicalis' Subzone of older publications) is usually defined by the first appearance of the eponymous genus. In central Texas, the type area of the zone, three species have been recorded, and only one species is reported from correlative strata in Oklahoma. Restudy of archival collections from southern Oklahoma made by J.H. Stitt, as well as type and figured material from Texas and western Canada, revealed unexpected diversity of missisquoiid species. Our revision shows that there are at minimum ten species of 'Parakoldinioidia' and three species of 'Lunacrania' recorded in the uppermost Furongian successions of the southern Midcontinent and the southern Canadian Rocky Mountains. This indicates that Missisquoiidae underwent a significant radiation following the extinction interval at the base of the 'Eurekia apopsis' Zone. It also demonstrates the potential for a high-resolution species based zonation of at least regional utility. New species are 'Parakoldinioidia akerfeldti', 'P. lindgreni', 'P. mendezi', 'P. lopezi' and 'P. akessoni'; three additional new species are placed in open nomenclature.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 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".