New taphonomic and sedimentological insights into the preservation of high-relief Ediacaran fossils at Upper Island Cove, Newfoundland
Bibliographic record
Abstract
Southeastern Newfoundland, Canada, is home to the oldest Ediacaran fossils in the Avalonian Assemblage mostly being preserved beneath tuffites in association with microbial matgrounds. A unique fossiliferous surface at Upper Island Cove, known as the Allison Surface, exhibits three-dimensional preservation of Ediacaran fronds without an associated tuffite or microbial matground. Previous models have invoked entrainment of fronds within turbidity currents, or by their felling into erosive scours. Our work demonstrates that the fossils were preserved within beds before being partially exhumed and cast by a subsequent sandy turbidite. Many of the structures previously identified as rangeomorph stems are longitudinal erosional features within obstacle sours. Additional observations of stemmed/erect organisms coinciding with reclined taxa suggest crosscutting/palimpsesting of frondose taxa with deeply emplaced holdfasts. Many of the fossil organisms are found within the top of a Td unit, with early pyritization probably aiding in their three-dimensional preservation. Most fronds are incomplete and oblique to the axis of the surrounding scours, indicating they were partly exhumed after burial. The scours likely formed in the lee of erect stemmed rangeomorph and arboreomorph taxa, which are commonly preserved as holdfasts on the surface, and occasionally crosscut buried fronds. The crosscutting of frondose taxa by holdfasts and the presence of pyritic tubes in the overlying sedimentary units suggests the preservation of three separate communities: 1) the initial Td entombed mainly reclined organisms; 2) a pre-turbidity current community of erect taxa with bulbous holdfasts that were the loci of obstacle scours; and 3) a later community of erect organisms preserved as holdfasts/stems.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".