THREE-DIMENSIONAL RECONSTRUCTION OF "PHYCOSIPHONIFORM" BURROWS: IMPLICATIONS FOR IDENTIFICATION OF TRACE FOSSILS IN CORE
Bibliographic record
Abstract
Phycosiphon-like trace fossils are some of the most common and important ichnofabric forming trace fossils in marine facies. This study was conducted to reconstruct the three-dimensional (3D) morphology of a Phycosiphon-like trace fossil from Cretaceous turbidites in Mexico in order to test the validity of criteria used to recognize such fossils in vertical cross sections similar to those seen in cores through hydrocarbon reservoir intervals. The geometry of the trace fossil was computer-modeled using a series of consecutive images obtained by serial grinding. The recognition of Phycosiphon in cross section is usually based on comparison with hypothetical cross sections of bedding-parallel specimens. The authors critically reassess Phycosiphon-like burrows in the light of existing conceptual and deterministic models, for comparison with three-dimensional reconstruction of Phycosiphon-like trace fossils from the Cretaceous Rosario Formation of Baja California, Mexico. Observed morphological differences between our material and typical Phycosiphon suggest that the characteristic “frogspawn” ichnofabric that is usually attributed to Phycosiphon (sensu stricto) can be produced by other similar taxa. Our palaeobiological model for the formation of the studied Phycosiphon-like trace fossil is fundamentally different to that proposed for Phycosiphon, but produces remarkably similar vertical cross sections. We consider that identification of Phycosiphon incertum in core is not possible without detailed 3D examination of burrow geometry. We propose the term “phycosiphoniform” for this group of ichnofabric-forming trace fossils.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".