LINGULIDE BRACHIOPODS AND THE TRACE FOSSIL <i>LINGULICHNUS</i> FROM THE TRIASSIC OF WESTERN CANADA: IMPLICATIONS FOR FAUNAL RECOVERY AFTER THE END-PERMIAN MASS EXTINCTION
Bibliographic record
Abstract
Abstract The environmental distribution of lingulide brachiopods in western Canadian Triassic marine successions, their relationship with other infaunal organisms occupying the same ecospace, and their role in the aftermath of the Permian-Triassic extinction event is summarized. Western Canada is an ideal location to assess lingulide distribution patterns as upper Paleozoic and lower Mesozoic strata are extensively exposed, and lingulides (cf. Lingularia Biernat and Emig) and the trace fossil Lingulichnus Hakes are both common. A distribution comparison of in situ lingulides and Lingulichnus Hakes with concordantly emplaced lingulide shells and shell beds shows clearly that the latter is a poor indicator of true environmental distribution of these infaunal suspension feeders. Lingulides are rare in uppermost Paleozoic strata in the study area. Most occurrences consist of isolated valves or abraded material in erosional lags. Lingulides remain minor components of infaunal communities during the earliest Triassic (Griesbachian). Although lingulide valves and valve fragments are the dominant body fossil observed, trace fossil analysis indicates that lingulides were minor components of earliest Triassic infaunal communities. Lingulides increase in abundance and importance during the Dienerian and Smithian. Shallow and marginal marine trace-fossil assemblages of this age are dominated commonly by Lingulichnus. Lingulide fossils are less abundant but are found in many shallow and marginal marine lithofacies. Lingulides comprise only a minor component of late Smithian through Anisian infaunal communities. Canadian lingulide abundance reached an acme during the latest Middle Triassic (Ladinian). Fossil material is common in many environments, however, in situ lingulides and the trace fossil Lingulichnus occur primarily in tempestites in proximal offshore through lower shoreface settings and in intertidal flat settings. Although quantitatively more abundant in the Middle Triassic, lingulides were proportionally more abundant in Lower Triassic successions. Regardless of relative changes in abundance, the environmental distribution of lingulides did not differ between Early and Middle Triassic successions. Lingulides comprise only a minor component of Upper Triassic infaunal communities. Early Triassic lingulides did not occupy any environmental settings from which they were excluded prior to the Permian-Triassic extinction or after the postextinction recovery interval. Thus, lingulides were not postextinction disaster taxa but rather were ecological opportunists that dominated some Early Triassic shallow and marginal marine successions.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 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) | 0.002 | 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".