Characterizing Modern and Fossil Gymnosperm Exudates Using Micro-Fourier Transform Infrared Spectroscopy
Bibliographic record
Abstract
Infrared absorption spectra of exudates from 65 species of gymnosperms were measured using micro–Fourier transform infrared (FTIR) spectroscopy. On the basis of the infrared spectra, three compositionally distinct groups of exudates can be distinguished: resins, volatile-rich resins, and gums. Resins and volatile-rich resins are mainly composed of terpenoids, whereas gums are polysaccharides. Resins and volatile-rich resins are restricted to conifers (Pinophyta). Gums, on the other hand, are produced by some conifer families including Araucariaceae and Podocarpaceae; nonconifer gymnosperms including Ginkgo (Ginkgophyta), cycads (Cycadophyta), and Welwitschia (Gnetophyta); and angiosperms. Using spectral band ratios, conifer resins can be subdivided quantitatively into two distinct resin types that reflect compositional differences in their terpenoid constituents and broadly parallel different conifer families. The first type of resin (pinaceous resin) is produced by members of Pinaceae and consists mainly of diterpenes that are based on abietane/pimarane skeletal structures. The second type (cupressaceous resin) is associated with members of the Cupressaceae, Sciadopityaceae, Araucariaceae, and Podocarpaceae and consists mainly of diterpenes that are based on the labdanoid structures. Variability within the resin spectra correlates with the number of free hydroxyl groups, and it can be used to assess the degree of resin polymerization. Volatile-rich resins are found exclusively within Pinaceae, reflecting a generally higher abundance of volatile mono- and sesquiterpenoids in resins of this family. The results of the FTIR spectroscopy have direct implications for the assessment of the fossil potential and the chemotaxonomic interpretation of modern and fossil gymnosperm exudates.
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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 | 0.001 | 0.001 |
| 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) | 0.001 | 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".