Skeletal Abundance and Diversity in the Lower Ordovician Catoche and Fillmore Formations: Tracing the Roots of the Great Ordovician Biodiversification Event
Bibliographic record
Abstract
The Great Ordovician Biodiversification Event (GOBE) is known for a significant increase in skeletal abundance of benthic faunas globally, yet the progression of this evolutionary change throughout the Lower Ordovician leading up to this event is unconstrained. We examined Lower Ordovician carbonate deposits from the Catoche Formation, Western Newfoundland, Canada, and Fillmore Formation, western Utah, USA, to quantify skeletal abundance and identify depositional environment(s) which may have influenced temporal changes in abundance. Petrographic studies suggest the Catoche Formation has a low skeletal abundance of 1.7% fossil material in thin section, including unidentified skeletal material, where trilobites make up 37.1% of total fossils; cephalopods make up 22.2% of total fossils, brachiopods make up 9.3%, echinoderms make up 2.1%, and gastropods make up 0.5%. Field observations additionally demonstrate abundant peloidal and micritic sediment and an abundance of flat-pebble conglomerates, demonstrating the common occurrence of storm events at the locality. The Fillmore Formation records different skeletal abundance, where skeletal material makes up 17.0% of total counts of thin sections. Most abundant fossils of the Fillmore Formation are echinoderms (55.1%), brachiopods (19.9%), sponges (16.4%) and trilobites (6.4%). Field observations also suggest a higher-energy shallow marine paleoenvironmental setting more proximal to sponge reefs that did not undergo frequent storm events compared to the Catoche Formation. Differences in skeletal abundance and paleoenvironmental settings leads us to conclude skeletal production may have been higher in shallow marine environments, adjacent to sponge reefs, than lower-energy shallow shelves less proximal to them. My work seeks to understand the varying occurrences of skeletal biomass in the two Lower Ordovician localities and what implications it holds for the initial radiation of the GOBE.
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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 | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".