New palynological data from Cretaceous strata in the San Juan Basin, New Mexico, do not indicate a Paleocene age for dinosaur fossils (abs.)
Bibliographic record
Abstract
Claims of Paleocene dinosaur fossils in the San Juan Basin have been largely based on palynostratigraphy---namely, that in situ Paleocene-age palynomorphs are found stratigraphically below in situ dinosaur fossils. One key locality is Barrel Springs in the west-central San Juan Basin (sec. 17, T24N, R11W), where a carbonaceous shale bed at the top of the De-na-zin Member of the Kirtland Formation supposedly yielded Paleocene-age palynomorphs below the in situ dinosaur fossils in the overlying Naashoibito Member of the Ojo Alamo Formation. We have repeatedly sampled this carbonaceous shale bed, most recently in 2009, and it yields only Cretaceous palynomorphs. Thus, the presence of Tschudypollis thalmanni and Equisetosporites multipartitus at this locality indicates a Late Cretaceous age, probably Maastrichtian. In 2009, we also sampled this carbonaceous shale bed at the top of the Kirtland Formation at Willow Wash, ~ 6 km to the northwest, and here it also yields a Cretaceous palynomorph assemblage. The presence of abundant Tschudypollis thalmanni and T. retusus at this second locality also suggests a Late Cretaceous age for the sample, probably Maastrichtian. We therefore consider the report of Paleocene palynomorphs from this bed at Barrel Spring a non-repeatable result, so it is not reliable for age assignment. Palynostratigraphy provides no support for assigning a Paleocene age to dinosaur fossils in the west-central San Juan Basin, New Mexico.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.003 | 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".