First record of the archaic Eurasian cricetid rodent <i>Microtodon</i> from North America
Bibliographic record
Abstract
A new species of the archaic arvicoline-like cricetid rodent Microtodon is described from the Hoye Canyon Local Fauna (LF), Douglas County, Nevada, U.S.A. This occurrence represents the first record of Microtodon and only the second record of ancient arvicolid-like cricetids from North America. The first, Ellesmereomys haringtoni, was described from the Strathcona locality, Canadian Arctic, about 4.0 Ma. The new Microtodon is characterised by a short anteroconid complex, shallow fourth lingual re-entrant angle (LRA4), and narrow anteroconid width on the first lower molar (m1). The new species resembles other Microtodon species and differs from Baranomys and all Promimomys species by lacking LRA1 on m3. Based on biostratigraphic correlations, the Hoye Canon LF was deposited about 5.8–5.6 Ma, roughly at the same time as the first Promimomys, P. mimus from the McKay Reservoir assemblage of Oregon, entered North America. Neither the Hoye Microtodon nor Ellesmereomys haringtoni are likely ancestral to Promimomys, but the two arvicoline-like cricetids attest to a previously unknown late Miocene – early Pliocene dispersal of these taxa into North America.
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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 | 0.001 | 0.000 |
| 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".