Complex wound response mechanisms and phellogen evolution – insights from Early Devonian euphyllophytes
Bibliographic record
Abstract
We analyze the oldest fossil occurrences of wound-response periderm to characterize the development of wound responses in early tracheophytes. The origin of periderm production by a cambium (phellogen), an innovation with key roles in protection of inner plant tissues, is poorly explored; understanding periderm development in early tracheophytes can illuminate key aspects of this process. Anatomy of wound-response tissues is characterized in serial sections in a new Early Devonian (Emsian; c. 400 Ma) euphyllophyte from Quebec (Canada) - Nebuloxyla mikmaqiana sp. nov. - and compared to previously described euphyllophyte periderm from the same fossil locality to reconstruct periderm development. Characterizing development in these oldest periderm occurrences allows us to propose a model for the development of wound-response periderm in early tracheophytes: by phellogen activity that is poorly coordinated laterally but bifacial, producing secondary tissues initially outwardly and subsequently inwardly. The earliest occurrences of wound periderm pre-date the oldest known periderm produced systemically as a regular ontogenetic stage (canonical periderm), suggesting that periderm evolved initially as a wound-response mechanism. We hypothesize that canonical periderm evolved by exaptation of this wound sealing mechanism, whose deployment was triggered by tangential tensional stresses induced in the superficial tissues by vascular cambial growth from within.
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 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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".