Extrinsic labyrinth infillings imply open endolymphatic ducts in Lower Devonian osteostracans, acanthodians, and putative chondrichthyans
Bibliographic record
Abstract
Acanthodians, osteostracans, and putative chondrichthyans from the Lower Devonian (Lochkovian) ‘MOTH’ locality are found to have granular labyrinth infillings located immediately posterior to the orbits and composed of fine, sand-sized particles. They were examined under light and scanning electron microscopes and an elemental analysis (EDX) was performed. The infillings contain large proportions of silica, calcium carbonate, and dolomite, as well as minor proportions of elements such as aluminum, iron, and potassium. These results were similar to elemental analysis of the rock matrix. The inability of the fish to manufacture some of the minerals confirms that the labyrinth infilling consists at least partly of extrinsic grains. Endolymphatic pores, the openings through which this material probably entered the labyrinth, are seen in osteostracans, but have seldom been reported in acanthodians and never in basal (putative) chondrichthyans. No undoubted otoliths were seen in any of the specimens. The presence of similar statoconia, including extrinsic grains, in all three groups indicates a common inner ear physiology and presence of open endolymphatic ducts. The phylogenetic distribution of this feature suggests that it is primitive for osteostracans + gnathostomes, and that placoderm ancestors also had open endolymphatic ducts that functioned to allow entry of extrinsic grains into the labyrinth.
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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 | 0.002 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 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".