New<scp>M</scp>iddle<scp>C</scp>ambrian bivalved arthropods from the<scp>B</scp>urgess<scp>S</scp>hale (<scp>B</scp>ritish<scp>C</scp>olumbia,<scp>C</scp>anada)
Bibliographic record
Abstract
Abstract The morphology of two new bivalved arthropods,Loricicaris spinocaudatusgen. et sp. nov. andNereocaris briggsisp. nov. from themiddleCambrian (Series 3,Stage 5)BurgessShaleFormation (CollinsQuarry locality onMountStephen,YohoNationalPark,BritishColumbia,Canada), is described. The material was originally assigned to the genusBranchiocaris, but exhibits distinctive character combinations meriting its assignment to other taxa.Loricicaris spinocaudatuspossesses an elongate and spinose abdomen comparable to the contemporaneousPerspicarisandCanadaspis, as well as chelate second head appendages and subtriangular exopods, comparable toBranchiocaris.Nereocaris briggsipossesses a laterally compressed carapace, elongate and delicate appendages and a medial eye located between a pair of lateral eyes on a rhomboidal eye stalk. Although undoubtedly congeneric withNereocaris exilisfrom a slightly younger horizon of theBurgessShaleFormation,N. briggsidiffers in overall proportions and segment number, warranting assignment to a new species. The newly described taxa were coded into an extensive cladistic analysis of 755 characters, and 312 extinct and extant panarthropods, including a variety ofCambrian bivalved arthropods from both theBurgessShale and theChengjiangLagerstätten. Cambrian bivalved arthropods consistently resolved as a paraphyletic assemblage at the base ofArthropoda. Important innovations in arthropod history such as the specialization of the deutocerebral head appendages and a shift from a nekton‐benthic deposit feeding habit to a benthic scavenging/predatory habit, the symplesiomorphic feeding condition ofEuarthropoda (crown‐group arthropods), were found to have occurred among basal bivalved arthropods.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".