Contrast in Preservation of Bivalve Death Assemblages in Siliciclastic and Carbonate Tropical Shelf Settings
Bibliographic record
Abstract
Abstract Determining the selectivities, rates, and key agents of destruction in the post-mortem accumulation of skeletal carbonate is important for understanding the possible bias in the fossil record. This is particularly important for tropical settings, since they are areas of high biodiversity today and in the past. Bivalve death assemblages of the San Blas Archipelago, Caribbean Panama, were collected from ten carbonate and siliciclastic shelf environments, across a range of water depths, sediment compositions, grain sizes, water chemistries, biological communities, and porewater chemistries. Taphonomic signature can differ significantly among environments and individual sites. Shells from reefal carbonates display high levels of encrustation, macroscopic bioerosion, edge rounding, and surface alteration, while those from nonreefal carbonates display microboring, patchy to pervasive chalkiness, and pitting. Shells from siliciclastic sediments display extensive staining, moderate-high patchy surface alteration, occasional encrustation, root etching, and microboring. Patterns of damage in these death assemblages reveal strong differences in taphonomic processes among environments that bear additional testing, in particular contrasts between exposure and burial, carbonate versus siliciclastic, and microstructure and organic content. Death assemblages in siliciclastic sites show moderate-low taphonomic damage, whereas carbonate reefs show high levels of damage, and this contrasts with predictions based on temperate siliciclastics, where seasonal dissolution is intense. The differences observed in taphonomic conditions across the range of environments in this study suggest that the fossil records of these environments should be biased relative to each other.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".