Aulacostephanid ammonites from the Kimmeridgian (Upper Jurassic) of British Columbia (western Canada) and their significance for correlation and palaeobiogeography
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
We present the first description of aulacostephanid (Perisphinctoidea) ammonites from the Kimmeridgian of Canada, and the first illustration of these ammonites in the Americas. These ammonites include Rasenia ex gr. cymodoce, Zenostephanus (Xenostephanoides) thurrelli, and Zonovia sp. A from British Columbia (western Canada). They belong to genera that are widely distributed in the subboreal Eurasian Arctic and Northwest Europe, and they also occur even in those Boreal regions dominated by cardioceratids. They are important markers for a narrow stratigraphic interval in the Cymodoce Zone (top of Lower Kimmeridgian) and the lower part of the Mutabilis Zone (base of Upper Kimmeridgian) of the Northwest European standard succession. In Spitsbergen and Franz Josef Land, the only Upper Kimmeridgian aulacostephanid-bearing level is the Zenostephanus (Zenostephanus) sachsi biohorizon, which very likely belongs to the Mutabilis Zone. Expansion of Zenostephanus from Eurasia, where it is present over a large area, into British Columbia, is approximately correlative with a transgressive event that also led to expansion of the Submediterranean ammonite genus Crussoliceras through the Submediterranean and Subboreal areas slightly before Zenostephanus.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 it