<i>Treptichnus pedum</i>and the Ediacaran–Cambrian boundary: significance and caveats
Bibliographic record
Abstract
Abstract The Ediacaran–Cambrian (E-C) boundary is based on the first appearance of the ichnofossil Treptichnus pedum . Investing an ichnotaxon with such biostratigraphic pre-eminence has been the focus of criticism. Points of contention have revolved around four main issues: (1) ichnotaxonomy, (2) behavioural significance, (3) facies controls and (4) stratigraphic occurrence. First, confusion results from the fact that Treptichnus pedum was originally referred to as Phycodes pedum and, more recently, some authors have placed it in Trichophycus or Manykodes . However, the overall geometry of these burrows indicates they belong in Treptichnus. Second, regardless of its precise mode of feeding, the behaviour involved is iconic of the Cambrian explosion. Third, objections are based on the idea that trace fossils show a closer link to facies than body fossils. Notably, in contrast to common assumptions, T. pedum is not only present in the low-energy offshore of wave-dominated marine settings, but it occurs at considerably shallower water in intertidal and shallow-subtidal zones of tide-dominated systems, as well as in mouth bars of deltaic systems and lower shoreface to offshore transition zones of wave-dominated marine settings. Its broad environmental tolerance supports evolutionary innovations rather than facies controls as the main mechanism underlying the observed vertical pattern of distribution of T. pedum in most E-C successions comprising shallow-marine deposits. Fourth, although treptichnids have been documented below the E-C boundary, T. pedum is not known from Ediacaran rocks. The delayed appearance of T. pedum in E-C successions should be analysed on a case-by-case basis.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.003 | 0.014 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.004 | 0.005 |
| Science and technology studies | 0.003 | 0.004 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.005 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.014 | 0.002 |
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".