Fishes from the Upper Cretaceous Prince Creek Formation, North Slope of Alaska, and their palaeobiogeographical significance
Bibliographic record
Abstract
Abstract The Upper Cretaceous Prince Creek Formation (PCF) of northern Alaska offers a unique glimpse into northern high‐latitude, non‐marine vertebrate assemblages, providing critical data on polar ecosystems during the late Campanian ( c . 73 Ma). This study presents a comprehensive taxonomic assessment of fish fossils from the PCF, including macrofossils and microfossils obtained through bulk sampling. The assemblage demonstrates lower species richness compared with penecontemporaneous formations in mid‐latitude North America, with notable absences of typical taxa such as Myledaphus , lepisosteids, and amiids. Teleost fishes dominate the assemblage, comprising both endemic species and taxa shared with the Western Interior. New esocids ( Archaeosiilik gilmulli gen. et sp. nov. and Nunikuluk gracilis gen. et sp. nov.), the earliest known salmonid ( Sivulliusalmo alaskensis gen. et sp. nov.) and the earliest known cypriniform suggest that these fishes possessed unique polar adaptations. The presence of the elasmobranch Squatina , as well as sturgeon and paddlefish in this assemblage further emphasizes the distinctive composition of this high‐latitude ecosystem. These findings suggest that the polar environment significantly influenced fish diversity and distribution, supporting the hypothesis that some taxa, such as esocids and salmonids, were already adapted to higher‐latitude environments during the Late Cretaceous. Additionally, the study expands our understanding of the latitudinal biogeography of Laramidian vertebrates, providing additional support for the hypothesis that a distinct polar faunal province, named the Paanaqtat Province, was present. This research not only enriches the palaeontological record but also offers new insights into the evolutionary and ecological dynamics of polar ecosystems during the Late Cretaceous.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".