Fourier Transform Infrared Spectroscopy Studies of Cretaceous Gymnosperms from the Santa Cruz Province, Patagonia, Argentina
Bibliographic record
Abstract
Premise of research. In this contribution, the spectroscopic characterization of gymnosperm fossil remains belonging to Pteridospermophyta, Cycadophyta, Ginkgophyta, and Coniferophyta collected from the Anfiteatro de Ticó and Punta del Barco Formations (Baqueró Group; Aptian) and Springhill (Hauterivian-Barremian) and Piedra Clavada/Kachaike (Albian) Formations, outcropping in the Santa Cruz Province, Argentina, is presented. From these lithostratigraphic units, specimens of several fossil taxa showing the existence of a diverse plant assemblage during the Lower Cretaceous in Patagonia were selected.Methodology. The fossils consist of foliar compressions with very well-preserved cuticles, which are chemically characterized by Fourier transform infrared spectroscopy. Foliar remains are analyzed in two sample forms: (1) compressions (Cps; including coalified mesophyll and cuticles) and (2) cuticles (Cts). Additionally, semiquantitative data are evaluated through principal component analysis, revealing the functional groups preserved at the mesophyll and cuticle levels for all analyzed fossil taxa.Pivotal results. In general, the species from the Baqueró Group show similar chemical compositions between the Cp and Ct sample forms, whereas the chemistry of the foliar compressions from the Springhill and Piedra Clavada/Kachaike Formations reveals the presence of a high contribution of aromatic structures making up the cuticles.Conclusions. The compressions of Pseudoctenis ornata, Ginkgoites tigrensis, and Squamastrobus tigrensis probably underwent, during and after diagenesis, a natural oxidation process most likely caused by the recurrent volcanic activity that occurred during the Aptian sedimentation of the Baqueró Group. In contrast, Ruflorinia orlandoi, Ptilophyllum micropapillosum, and Ginkgoites skottsbergii have cuticles presumably composed of highly aromatic structures (such as phenylpropanoids and aromatic domains) in cutins and cutans as well due to the presence of other phenolic compounds. A new term, vitrinitic compression, is proposed here for G. skottsbergii, while P. ornata, G. tigrensis, S. tigrensis, P. micropapillosum, and R. orlandoi are called liptinitic compressions.
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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 | 0.000 | 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 | 0.001 | 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".