In search of the kingdom's Ediacarans: the first genuine Metazoans (macroscopic body and trace fossils) from the Neoproterozoic Jibalah Group (Vendian/Ediacaran) on the Arabian Shield
Bibliographic record
Abstract
Ediacarans make up the oldest known truly diverse metazoan assemblages and are known globally. However, few sites have produced abundant fossils, and until recently such fossils were unknown in Arabia. Generally restricted to the late Neoproterozoic, the best known assemblages occur in China, Newfoundland, the White Sea in northern Russia, the Flinders Ranges of South Australia and southern Namibia in Africa. Less diverse assemblages are known from Siberia, Ukraine, UK, and a few sites in Asia, and North and South America. Ediacarans occur primarily in shallow marine derived sands and clays with the exception of Newfoundland forms that may have inhabited light free depths in a volcanically active terrane. They are known in rock sequences dating from 630 Ma to 540 Ma, the Ediacaran or Vendian period, the youngest division of Precambrian time. New discoveries in Saudi Arabia over the past 5 years have brought to light the presence of Ediacarans, both traces and body fossils, suggesting that further investigation most likely will yield a much more diverse assemblage, and one that may well have inhabited less saline environs that is typical for other Ediacarans. Fossils similar to Harlaniella, known elsewhere from the late Precambrian and Cambrian, and megascopic frond-like forms have been discovered in a single layer that is overtopped by a volcanic ash, dated at 569 ± 3 Ma, thus giving both good preservation and precision dating of the Dhaiqa formation in the Dhaiqa basin and its enclosed Ediacarans. In addition, the discovery of Horodyskia-like fossils in the Jif ’n basin is a first occurrence for Saudi Arabia. They have a similar Neoproterozoic age to forms found in China, both of which are signifi cantly younger than the more than 1 billion year old forms found in North America and Australia.
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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 | 0.001 |
| 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 | 0.001 | 0.002 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".