The sabre-toothed cat <i>Smilodon fatalis</i> (Leidy, 1868) (Felidae, Machairodontinae) in the late Pleistocene–early Holocene of South America (Dolores Formation, Uruguay): new insights about its paleodistribution, taxonomy, and status of the genus
Bibliographic record
Abstract
The sabre-toothed cat Smilodon fatalis (Leidy, 1868) was an iconic predator in the Americas during the Ice Age. While its distribution in North America is abundant, its record in South America is very scarce and is restricted to only a few locations. In the present contribution a new skull assigned to Smilodon fatalis is described. The specimen comes from the Dolores Formation (late Pleistocene–early Holocene, Lujanian Stage/Age) in southern Uruguay. This skull is elongated and narrow in its general shape; its nasals are not markedly high and, in the posterior part, the large lambdoid crest is anteroventrally straight, converging in the same plane with the mastoid process, characteristics observed in S. fatalis that clearly differentiate it from Smilodon populator Lund, 1842. Body mass estimations, according to allometric equations for extant felids, and the quantitative analyses (bivariate graphs) provide results consistent with the aforementioned taxonomic assignment. Based on this finding, which turns out to be, to date, the southernmost record for this species in the Americas, some paleobiogeographic and taxonomic implications in a regional context are discussed.
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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 | 0.001 |
| 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".