Taxonomic diversity, stratigraphic range, and exceptional preservation of Juro-Cretaceous salamanders from northern China
Bibliographic record
Abstract
Since the late 1990s, eight localities in volcanic shale-rich lacustrine deposits of Middle Jurassic through Early Cretaceous age in northern China (western Liaoning Province, northern Hebei Province, and southern Inner Mongolia) have yielded thousands of exceptionally well-preserved salamander specimens. With 10 species published and several new taxa yet to be named and described, the fossil samples from northern China represent the most species-diverse, individually abundant, and exquisitely preserved salamander fossil assemblage known from the Mesozoic Era. The stratigraphic range of the fossil record covers a geologic time span of roughly 40–45 million years from the Middle Jurassic (Bathonian) through the Early Cretaceous (Aptian). In contrast to the well-known stem-group salamanders Karaurus and Kokartus from the Middle to Late Jurassic of Middle Asia, the Chinese record contains the earliest known crown-group salamanders, including Jurassic representatives of both Cryptobranchoidea and Salamandroidea. The Chinese Mesozoic record includes numerous examples of virtually complete larval, juvenile, young adult, and fully grown adult individuals that collectively provide key information on the life histories and developmental patterns of the earliest known crown-group salamanders. Many specimens show preservation of soft tissue structures, including body outline, eye, liver, and external gill filaments. This kind of soft tissue preservation is unusual for fossil salamanders, so the Chinese Mesozoic specimens are important for furnishing otherwise unavailable information on the life history, diversity, and ecological adaptations of early crown-group salamanders.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".