Ontogeny and Astogeny of the Graptolite Genus <i>Appendispinograptus</i> (Li and Li, 1985)
Bibliographic record
Abstract
SUMMARY Graptolites of the genus Appendispinograptus feature prominently in Late Ordovician biostratigraphy and studies of biodiversity. Well-documented, but enigmatic, secondary structures extend along the basal spines in mature specimens of three of the four common late Katian species of the genus : A. supernus, A. longispinus , and A. venustus . Using SEM imaging of isolated, three-dimensional specimens of A. supernus , we provide a detailed description of its early growth, as well as confirm that its secondary structures are composed of hollow tubes extending from the sicular and thecal apertures (‘parasiculae’ and ‘parathecae’, respectively). We also describe a collection of Canadian (northern Yukon) appendispinograptids that possess a large heart-shaped, sheet-like basal structure. Detailed comparison (width, thecal length and thecal inclination) with immature specimens from our collection, as well as collections from Russia, China, and Nevada, identifies these specimens as A. leptothecalis , a species not previously known to exhibit any secondary spine modification. The observation of spine modification in A. leptothecalis allows previously unclassified specimens from China, Siberia, and Nevada to be assigned to this species, clarifying our understanding of appendispinograptid biogeography and diversity. However, these structures are difficult to explain functionally. Unlike structures found in other Appendispinograptus species, those in A. leptothecalis decrease usable thecal space, shift drag proximally, and provide no obvious feeding advantage.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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 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".