The Mesozoic/Defining Disciplines: Late Nineteenth-Century Debates Over the Jurassic-Cretaceous Boundary
Bibliographic record
Abstract
The last two decades of the nineteenth century were exciting times in American paleontology, with disputes over Jurassic dinosaurs between Edward Drinker Cope and Othniel Charles Marsh appearing in the press. Less well known is the dispute over defining the Mesozoic that began in 1888 when Marsh invited Lester Frank Ward, a colleague with whom he had been working on the Potomac Formation for the United States Geological Survey, to speak on the plant fossils found there. Initially agreeing with Marsh that the Potomac was a Jurassic formation, work on fossil cycads led Ward to conclude that the Potomac was Lower Cretaceous. As Ward and Marsh grappled with the question of how to determine the age and identity of Mesozoic systems, they joined other paleontologists and geologists such as William J. McGee, Albert Charles Seward, and Samuel W. Williston in a debate that often reflected scientific training and sub-specializations as much as stratigraphic principles, becoming caught up in a trans-Atlantic dispute in which their reputations were on the line as they claimed that ‘their’ fossils were key determinants of Mesozoic systems. In the end, Marsh's reputation as a paleontologist was far better established than that of Ward, who moved on to another career as a sociologist at Brown University, but cycad discoveries from Maryland, Colorado and Wyoming, and fieldwork, trumped laboratory studies—even when performed by a master systematist—as the Potomac Formation proved to be Lower Cretaceous.
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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 | 0.008 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.016 | 0.060 |
| Scholarly communication | 0.011 | 0.010 |
| Open science | 0.001 | 0.005 |
| Research integrity | 0.004 | 0.010 |
| 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".