Independent corroboration of a previously proposed Palaeozoic link between eastern Australia and eastern North America
Bibliographic record
Abstract
A new finding by Ebach & Humphries (2002) published in the Journal of Biogeography and reported in Science (Holden, 2002) amounts to independent corroboration of my earlier proposal (Dobson, 1992, 1996) that eastern Australia may have collided with eastern North America in the Paleozoic. They conclude, based on cladistic analysis of Lower Devonian trilobites, ‘New South Wales … has a closer association to the Appalachian province than it does to Victoria. The areas may be adjusted by aligning the palaeolongitude of Laurentia so it is closer to the eastern Australian coastline.’ In the mid-1990s, I tested the hypothesis that Australia and eastern North America met in rotational collision during the Palaeozoic with the corollary that the New England fold belt of Australia, rather than the Reguibat promontory of Africa, collided with the Alleghanian orogen in the central Appalachians (Dobson, 1996). Substantial corroborating evidence was presented in this journal: Identical Lancefieldian stage, zone 1 (Early Ordovician) graptolites of the Anisograptid family are found in identical environments in Newfoundland, Norway, and the Lachlan fold belt of Australia. Paleozoic granites are consistent with a tectonic model in which the Lachlan fold belt caused mechanical deformation of the Canadian Appalachians. The Lachlan and New England fold belts of Australia and the Alleghanian orogen of North America are tectonically consistent with this east coast hypothesis. Major deformations and magmatic episodes are coeval from Silurian to Permian. I concluded, ‘The tectonic, paleontologic, lithologic, and geometric evidence for this position is more abundant and precise than the stratigraphic evidence for a west coast location of Australia relative to North America.’ According to Holden (2002), ‘Ebach and Humphries…say that trilobites living in what is now the southern and central United States were more like ones from eastern Australia than those in Africa or South America. This suggests that accepted maps of the ancient landmasses of Gondwana (covering South America, Africa and Australia) and Laurentia (which included North America) are way off. ‘‘They moved right around the world 8000 kilometers west of where scientists originally placed them,’’ Ebach says.’ So far, so good, but there is a troubling contradiction in the interpretations offered by Ebach and Humphries. Their statement (p. 437) matches their cladistic diagram (Fig. 10, p. 438), but their map (Fig. 11b, p. 439) does not. The text and cladistic diagram fully support my east coast hypothesis, but their map inexplicably asserts a west coast hypothesis. Only they can explain the discrepancy.
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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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.012 | 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".