<i>Spiniferites cruciformis</i>,<i>Pterocysta cruciformis</i>and<i>Galeacysta etrusca</i>: morphology and palaeoecology
Bibliographic record
Abstract
Miocene to modern sediments of the Ponto-Caspian basins and Mediterranean Sea are uniquely distinguished by presence of gonyaulacacean cysts with ellipsoid to cruciform endocysts and highly variable ectocystal features, including pterate (wing-like) and galeate (helmet-like) outer wall layers. The term cruciform is defined to indicate cysts with concave epicyst and hypocyst surfaces and moderate dorsoventral flattening. These features may be morphological responses to salinity stress and some biometrical studies conclude that the cruciform Ponto-Caspian species <i>Spiniferites cruciformis</i> of Wall and Dale 1973 and <i>Pterocysta cruciformis</i> Rochon et al. 2003 Rochon A, Mudie PJ, Aksu A.E, Gillespie H. 2003. <i>Pterocysta</i> gen. nov.: a new dinoflagellate cyst from Pleistocene glacial-stage sediments of the Black and Marmara seas. Palynology. 26:95–105. [Google Scholar] are morphotypes of the ellipsoidal-subpentagonal Miocene-Holocene species <i>Galeacysta etrusca</i> Corradini and Biffi 1988 Corradini D, Biffi U. 1988. Dinocyst study at the Messinian-Pliocene boundary in the Cava Serridi section, Tuscany, Italy. Bull Centres Rech Explor-Prod Elf-Aquitaine. 12:221–236. [Google Scholar]. We show that the holotypes of these cruciform and rhomboid-subpentagonal galeate taxa differ in endocyst shape, ectocyst structure and attachment points, process morphology, and sulcal plate expression, and we present new data on morphological variations, modern distribution and ecology. We list multiple criteria for distinguishing these taxa from Paratethyan dinoflagellates with shared features, including <i>Thalassiphora</i> spp., <i>Lophocysta, Romanodinium,</i> and <i>Seriliodinium.</i> Log transforms of endocyst:ectocyst (EN:EC) dimensions cannot fully capture cruciformness or galeate and pterate wall characteristics that distinguish the genera, and at DSDP Site 380, EN:EC values for Pleistocene populations of <i>Spiniferites cruciformis</i> and <i>Galeacysta etrusca</i> are significantly different. Re-examination of the history of studies on the <i>Galeacysta etrusca</i> complex and comparison with new studies of Pleistocene to recent cysts leads to the conclusion there is insufficient evidence to justify combining the cruciform species with <i>Galeacysta etrusca</i> and we provide criteria for distinguishing among the main components of the complex. Using multiple morphological features, it appears there is a replacement of large Palaeogene marine-brackish water camocavate-circumcavate taxa with elliptical endocysts first by the Miocene rhombo-subpentagonal galeate species <i>Galeacysta etrusca</i> and then by the Pliocene – Holocene semi-marine–brackish cruciform species <i>Spiniferites cruciformis</i> and stenohaline <i>Pterocysta cruciformis</i>.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.010 | 0.002 |
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; both teacher heads agree on what is shown here.
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".