THE OCCURRENCE AND SIGNIFICANCE OF ULCERATIVE SHELL DISEASE (USD) ON GEOEMYDID TURTLES, MIDDLE EOCENE, SOUTHWESTERN WYOMING, UNITED STATES
Bibliographic record
Abstract
Abstract Fossil turtle carapace and plastron bones from the earliest Bridgerian (Ypresian, early Eocene) lowermost Bridger Formation in the Bridger Basin of southwestern Wyoming are characterized by numerous biogenic bone modification features. These include the ichnotaxa Karethraichnus and Thatchtelithichnus (interpreted as invertebrate parasitism traces) and the ichnotaxa Nihilichnus and Linichnus (interpreted as predation/scavenging traces). Carapace and plastron bones with ovoid to amorphous depressions of etched or corroded bone occur at several horizons and are particularly abundant (∼ 80%) at one horizon. In some examples the external cortical layer is corroded away and the underlying upper trabecular layer is exposed. However, in more severe cases, the deterioration of the shell bone penetrates halfway or more through the trabecular layer. These depressions occur solely on the external surface of bone elements and are consistent with the ichnotaxon Gunnellichnus. Comparison of the Bridger turtles with modern emydid turtle taxa affected by various shell disease suggest that these corrosion depressions record the occurrence of ulcerative shell disease (USD) on Eocene turtles. Ulcerative shell disease occurs rarely on Baena (Baenidae) and Baptemys (Dermatemydidae) but is particularly common on geoemydid turtles of the genus Echmatemys (E. septaria, E. wyomingensis, and Echmatemys sp.). It is notably absent on trionychid and carettocheylid turtles. The prevalence of USD on Echmatemys spp. is interpreted to reflect differing environmental preferences of Bridger turtles. The abundance of turtles with USD within one narrow stratigraphic horizon which may reflect a short interval of increased rainfall and cloud cover resulting in decreased basking efficacy, which is a primary factor in the occurrence of USD in modern turtles.
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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 | 0.000 | 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) | 0.001 | 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".