The early Silurian pentamerid brachiopod<i>Costistricklandia canadensis</i>(Billings, 1859) and its biostratigraphic and paleobiogeographic significance
Bibliographic record
Abstract
Costistricklandia is a common, easily recognizable pentamerid brachiopod in upper Llandovery to lowest Wenlock rocks of eastern Laurentia, Avalonia and Baltica. In this paper, the poorly known Costistricklandia canadensis (Billings) is re-described from the upper Telychian Rockway Dolomite of the Niagara Escarpment, Ontario. Compared to the relatively complete record of the Stricklandia-Costistricklandia evolution in the Welsh Borderland and the Baltic region, true representatives of the Stricklandia lens lineage are sporadic in North America, including those from the Merrimack Formation of Anticosti Island, the Red Mountain Formation of Alabama, the Hopkinton Formation of Iowa, and the Nonda Formation of the northern Rocky Mountains. Although the exact mode of speciation in the Stricklandia-Costistricklandia and the Pentamerus-Pentameroides transitions remains debatable, the common association of Costistricklandia and Pentameroides make them a useful concurrent biozone for correlating middle to upper Telychian rocks of North America and Europe. Paleobiogeographically, the Pentameroides-Costistricklandia Fauna marks the third major pulse of pentamerid faunal migration between Laurentia and its adjacent paleo-plates during the Early Silurian, following the limited intercontinental dispersal of the early Llandovery Virgiana Fauna and the quasi-cosmopolitan dispersal of the middle Llandovery Pentamerus Fauna.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".