A cautionary note on the use of invertebrate trace fossils for correlation in the Triassic-Jurassic Fundy Group
Bibliographic record
Abstract
Red-bed strata generally considered to be of Triassic age are present in outcrop at Point Lepreau and St. Martins, New Brunswick. These successions preserve assemblages of invertebrate trace fossils that are similar to one another. Some authors have taken this as evidence that the successions are of similar age. However, all ichnotaxa that are common to the two successions (Ancorichnus cf. ancorichnus, Gordia marina, Palaeophycus isp., Planolites isp., and Skolithos isp.) are long-ranging forms that provide no useful age constraints in Triassic strata and cannot support the suggested correlation. Similarities between the ichnofaunas reflect the continental depositional setting of the two successions, in which trace-makers produced a Scoyenia ichnofacies. This does not falsify correlation between the Point Lepreau and St. Martins successions, which can be supported on other grounds. Instead, it reinforces the need for caution when using trace fossils for biostratigraphic purposes in much of the stratigraphic record.
 
 RÉSUMÉ
 
 Des couches de roches rouges dont on estime généralement qu’elles remontent au Trias affleurent à Point Lepreau et à St. Martins, au Nouveau-Brunswick. Ces suites pétrographiques préservent des assemblages de traces de fossiles d’invertébrés qui se ressemblent. Certains auteurs ont considéré qu’il s’agissait là d’une preuve que ces séquences sont plus ou moins du même âge. Toutefois, les traces de fossiles propres aux deux séquences (Ancorichnus cf. ancorichnus, Gordia marina, Palaeophycus isp., Planolites isp., et Skolithos isp.) sont des formes de longues durées qui n’offrent aucun indice utile de datation dans les strates du Trias; il est donc impossible de soutenir la corrélation alléguée. Les similitudes qui apparaissent dans les traces de fossiles d’invertébrés correspondent à un phénomène de sédimentation de deux séquences dans lesquelles les traces d’organismes ont produit un ichnofaciès de l’espèce Scoyenia. Par ailleurs, cela n’infirme en rien la corrélation entre les séquences de Point Lepreau et de St. Martins, laquelle peut être établie par d’autres indices. De fait, cela met encore plus en lumière le devoir de prudence lorsqu’il s’agit d’utiliser dans une large mesure des fossiles à l’état de traces à des fins d’analyse biostratigraphique pour l’établissement d’une fiche stratigraphique.[Traduit par la redaction]
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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 | 0.001 | 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".