A “bloat-and-float” taphonomic model best explains the upside-down preservation of ankylosaurs
Bibliographic record
Abstract
It is widely held that, within the Cretaceous fluvial and marine deposits of North America, ankylosaur remains are typically preserved upside-down; however, this anecdotal observation has yet to be substantiated. Likewise, none of the various hypotheses that purport to explain the frequent occurrence of overturned ankylosaurs has been tested either. This study is the first to apply quantitative and modeling approaches to address these shortcomings. We find strong statistical support for the dominance of upside-down occurrences, and favour a "bloat-and-float" model to account for them. According to this model, ankylosaur carcasses become reworked into fluvial or marine settings where they bloat and overturn prior to their final deposition. Differential floating behaviour between ankylosaurids and nodosaurids may have implications regarding the occurrence of the latter in marine depositional environments. This consideration of ankylosaur taphonomy might similarly help to explain the purported frequency of overturned glyptodonts, which share a similar bauplan with ankylosaurs.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.005 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 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".