Phylogenetic position and stratigraphic uncertainty of a new flexible crinoid from the Ordovician–Silurian boundary of Anticosti Island (Québec, Canada)
Bibliographic record
Abstract
Abstract Fossil crinoids from the Ordovician–Silurian boundary interval (~ 443.8 million years) are known from relatively few locations worldwide due to a near-global unconformity that formed from eustatic sea-level fall. This rock record bias has severely hindered study of the timing, magnitude, biogeographic signature, and extinction mechanisms of the Late Ordovician mass extinction (LOME). Crinoids underwent a significant faunal transition between the Late Ordovician and early Silurian that resulted in major shifts between dominant clades, but the driving mechanisms and precise timing of this transition remain unclear. Anticosti Island (Québec, Canada) preserves one of the few Late Ordovician–early Silurian successions of highly fossiliferous, shallow-water rocks that includes the Ordovician–Silurian boundary, making fossils from this region instrumental for better understanding the LOME and Ordovician–Silurian crinoid faunal turnover. Here we report on a new flexible crinoid, Anticosticrinus natiscotecensis n. gen. n. sp., from the Ordovician–Silurian boundary of Anticosti Island. Phylogenetic analysis of Middle Ordovician–early Silurian flexibles recovers Anticosticrinus natiscotecensis n. gen. n. sp. as a member of family Anisocrinidae. We quantified stratigraphic age uncertainty of A. natiscotecensis using a Bayesian approach for estimating tip-occurrence times in a phylogenetic context. Although results do not provide unequivocal support for the specimen’s precise stratigraphic age, the maximum a posteriori estimate indicates a late Hirnantian age. Regardless of its true age, recognition of Anticosticrinus natiscotecensis provides additional data for evaluating the timing of extinction in flexible crinoids, their diversification and increasing dominance during the Silurian, and crinoid faunal turnover between the Ordovician and Silurian. UUID: http://zoobank.org/864738dd-3fc9-435b-a83c-e19fd4f6Ad9d
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| 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 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".