A late-surviving stem-ctenophore from the Late Devonian of Miguasha (Canada)
Bibliographic record
Abstract
Like other soft-bodied organisms, ctenophores (comb jellies) produce fossils only under exceptional taphonomic conditions. Here, we present the first record of a Late Devonian ctenophore from the Escuminac Formation from Miguasha in eastern Canada. Based on the 18-fold symmetry of this disc-shaped fossil, we assign it to the total-group Ctenophora. Our phylogenetic analyses suggest that the new taxon Daihuoides jakobvintheri gen. et sp. nov. falls near Cambrian stem ctenophores such as 'dinomischids' and 'scleroctenophorans'. Accordingly, Daihuoides is a Lazarus-taxon, which post-dates its older relatives by over 140 million years, and overlaps temporally with modern ctenophores, whose oldest representatives are known from the Early Devonian. Our analyses also indicate that the fossil record of ctenophores does not provide strong evidence for or against the phylogenomic hypothesis that ctenophores are sister to all other metazoans.
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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 | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 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".