Structurally complex, yet anatomically plesiomorphic: permineralized plants from the Emsian of Gaspé (Quebec, Canada) expand the diversity of Early Devonian euphyllophytes
Bibliographic record
Abstract
ABSTRACT The Battery Point Formation of eastern Canada hosts an Emsian (c. 400–395 Ma) flora that marks one of the rare occurrences of anatomically-preserved Early Devonian plants. We describe four new euphyllophytes from small permineralized axes in this unit. Leptocentroxyla tetrarcha gen. et sp. nov. has a four-ribbed mesarch actinostele with Psilophyton -type (P-type) tracheids and a central area of scalariform tracheids. Stenoloboxyla ambigua gen. et sp. nov. has a bar-shaped to three-ribbed mesarch stele lacking central protoxylem, with one of the ribs less pronounced, P-type tracheids, and sclerenchyma forming a discontinuous layer in the cortex. Jowingera triloba gen. et sp. nov. has a three-ribbed mesarch actinostele with central protoxylem and P-type tracheids. Tainioxyla quebecana gen. et sp. nov. has bar-shaped xylem with mesarch protoxylem strands, P-type tracheids, and anatomy typical of cambial growth initiation. These new species raise the diversity of Battery Point Formation permineralized plants to nine genera, adding significantly to the diversity of Early Devonian plants characterized anatomically. The four species encompass structural diversity of unexpected breadth and novelty for their age. They are different from both older and coeval euphyllophytes and from younger euphyllophytes, exhibiting combinations of derived and plesiomorphic characters. Their mesarch actinosteles and barshaped protosteles, histological differentiation within metaxylem and cortex, and secondary growth, represent aspects of structural complexity common in more derived Middle-Late Devonian euphyllophytes. Concurrently, the four species share P-type tracheids typical of Early Devonian basal euphyllophytes with simpler anatomies. These new fossils offer a first glimpse of a plexus of plants representing a previously unsuspected stage of euphyllophyte morphoanatomical evolution. They demonstrate significant euphyllophyte diversification and exploration of structural complexity under way during the Early Devonian, against a background of plesiomorphic-type tracheids. When more completely characterized, these Emsian plants will provide links for resolving phylogenetic relationships at the base of the euphyllophyte clade.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".