Thermal physiology and the origin of terrestriality in vertebrates
Bibliographic record
Abstract
The adaptive reasons for the evolutionary transition between obligatorily aquatic lobe-finned fish and facultatively terrestrial early tetrapods have long been debated. The oldest adequately known amphibians, Acanthostega and Ichthyostega , from the final stage in the Upper Devonian (Famennian), can be clearly distinguished from the most advanced choanate sarcopterygian fish from the next older stage (Frasnian) by the presence of large pectoral and pelvic girdles, limbs generally resembling those of later Palaeozoic land vertebrates, and the absence of bones linking the back of the skull with the shoulder girdle. Upper Devonian and most Lower Carboniferous amphibians, like their aquatic predecessors, differed significantly from modern amphibians in their much larger size, up to a metre or more in length. Animals of this size, resembling modern crocodiles and the marine iguana, could have raised their body temperatures by basking in the sun and sustained them upon re-entry into the water. It is hypothesized that the physiological advantages of thermoregulation were a major selective force that resulted in the increasing capacity for the ancestors of tetrapods to move into shallow water, and later to support their bodies against the force of gravity and increase the size and locomotor capacities of the limbs.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".