Partial articulated specimen of the Early Devonian putative chondrichthyan<i>Polymerolepis whitei</i>Karatajūtė-Talimaa, 1968, with an anal fin spine
Bibliographic record
Abstract
ABSTRACT Polymerolepis whitei Karatajūtė-Talimaa, 1968 was described based on isolated polyodontode scales recovered from the Ukraine, and originally was thought to be heterostracan (Agnatha). Additional scales with neck canals were described years later, and as a result, P. whitei was reclassified as a bradyodont holocephalan because it had scales similar to those of Listracanthus Newberry & Worthen, 1870. Until now, no articulated body fossils were known, and so the classification of this taxon has remained uncertain and based only on the original authors opinion. New specimens of P. whitei from the Mackenzie Mountains, Northwest Territories, Canada, show articulated scale patches from the head, with the best specimen showing part of an anal fin, caudal peduncle, and caudal fin. This new material confirms that the original account of scale variation was accurate, but also that P whitei possesses an anal fin spine, a feature that, until recently, was thought to be a synapomorphy of acanthodian fishes among Palaeozoic fishes. Several primitive chondrichthyans (Obtusacanthus Hanke & Wilson, 2004; Lupopsyroides Hanke & Wilson, 2004; Kathemacanthus Gagnier & Wilson, 1996; Seretolepis Karatajūtė-Talimaa, 1968a, 1968; Doliodus Traquair, 1893; Antarctilamna Young, 1982, and also problematic taxa such as Gyracanthides Woodward, 1902, and now Polymerolepis Karatajūtė-Talimaa, 1968a, 1968), are known from articulated remains and show a fin-spine complement like that of acanthodian fishes. They also have placoid scales or polyodontode scales that grew by areal rather than superpositional accretion. These taxa blur the distinction that exists in historic literature between acanthodians and early chondrichthyans.
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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) | 0.004 | 0.001 |
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".