The first <i>Otodus megalodon</i> remains from Canada and their predicted range limit
Bibliographic record
Abstract
Otodus megalodon (Agassiz, 1835) is an extinct species of giant lamniform shark known from Neogene deposits around the world. Despite having been found decades ago, Canadian specimens of O. megalodon have never been formally described. Here, we identify and describe eight of these specimens, all of which were recovered by scallop dredging activities on Georges Bank, Nova Scotia. Although all these specimens are ex situ, they probably came from Miocene-aged surface deposits on Georges Bank. Similar-aged deposits on the Grand Banks of Newfoundland that have also been dredged for scallops have not yielded any O. megalodon fossils to date. However, several sites with abundant O. megalodon teeth are known from Miocene deposits along the northeast coast of the USA. We therefore cautiously interpret the Canadian specimens as occurring at or near the northern range limit of the species, and discuss the potential limiting factors of this species’ range.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.005 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".