The earliest known fungal-induced biomineralization in fossil bones and its role in the marine ecosystem
Bibliographic record
Abstract
Formation of microtubes, defined as small internal borings, in fossil and modern bone is a well-attested phenomenon. However, determining whether microtubes were created by microbial activity or abiotic processes is challenging, particularly in fossils. Here, we report abundant microtubes in compact bone from numerous specimens of the marine reptile Keichousaurus from the Middle Triassic of southwestern China. Light and scanning electron microscope imaging of osteological thin sections, and CT-based three-dimensional reconstruction of the microtubes, reveal geometric features typical of fungal hyphae, such as bifurcation and tight helical coiling. Some microtubes contain what may be the first known fossilized fungal vacuoles. The microtubes are thus likely to be of fungal origin, produced by saprobic marine fungi during decomposition. Furthermore, fluorine is abundant in the compact bone, and even more prevalent in the infillings that occur in many microtubes. The fungi evidently released calcium ions, took up fluorine from the reptiles’ bodies and promoted the formation of fluorite in the microtubes. The infillings represent the earliest known instance of fungal-induced biomineralization within fossil bone, demonstrating that some Middle Triassic fungi were capable of impacting global biogeochemical cycling by taking up substantial amounts of fluorine.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".