Evolution of the late Ordovician orthid brachiopod <i>Gnamptorhynchos</i> Jin, 1989 from <i>Platystrophia</i> King, 1850, in North America
Bibliographic record
Abstract
Gnamptorhynchos , a rhynchonellid-like orthid brachiopod, evolved from Platystrophia in Maysvillian (early Ashgill) time, and survived both the end-Richmondian and end-Hirnantian episodes of the latest Ordovician mass extinction. The name of the type species of Gnamptorhynchos, G. inversum Jin, 1989, is rejected and replaced by Gnamptorhynchos globatum (Twenhofel, 1928), which is a senior synonym. Gnamptorhynchos manitobensis new species is described here from the Selkirk Member (Maysvillian) of the Red River Formation, southern Manitoba. The new species is characterized by a transversely extended, strongly biconvex to globular shell with prominent umbones, relatively numerous costae and a notothyrial cavity supported dorsally by a short median ridge. It constituted part of a Late Ordovician epicontinental fauna that once spread widely in shallow, equatorial seas of North America. The new species is a morphological intermediate between Platystrophia and Gnamptorhynchos , with Platystrophia -like interareas, hingeline, and cardinal process, but Gnamptorhynchos -like shell posterior and notothyrial platform. Previously, Gnamptorhynchos was known from Hirnantian to mid-Aeronian rocks. The new species extends the lower range of the genus to Maysvillian.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".