Redescription of a Middle Devonian placoderm from Manitoba and comments on the polyphyly of <i>Eastmanosteus</i> (Arthrodira: Eubrachythoraci)
Bibliographic record
Abstract
Arthrodires are the most common and diverse placoderms, an extinct group of early jawed vertebrates. Although commonly found, numerous taxa remain poorly known, thereby complicating the establishment of their taxonomic affinities. An excellent example of this is the genus Eastmanosteus: originally assigned to the wastebasket Dinichthys, it now comprises several species whose description was based on highly incomplete material. Thus, it has been suggested that Eastmanosteus, in turn, has become a wastebasket taxon. Here we redescribe Elmosteus lundarensis gen. et comb. nov., previously assigned to Eastmanosteus. An updated description is provided based on new material recovered from the Elm Point Formation, Middle Devonian (Eifelian–Givetian), near Lake Manitoba, MB, Canada, including gnathal elements, the median dorsal plate, and a ventral view of the skull roof. Parsimony and Bayesian phylogenetic analyses were performed, in which the more complete species of Eastmanosteus were included. Elmosteus is recovered as a basal dunkleosteid and all analyses support the polyphyly of Eastmanosteus. A brief discussion about intraspecific variation in El. lundarensis is also provided. Revisions of taxa described long ago, such as Eastmanosteus, using modern techniques like computational phylogenetics is essential for further improved taxonomy. This will lead to a better definition of relationships within placoderms and a better understanding of their diversity, and in turn help us trace the early evolutionary steps of vertebrate traits among stem gnathostomes. https://zoobank.org/urn:lsid:zoobank.org:pub:C52D3188-ED7F-4C7B-83C6-4A78C88B1591
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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".