The Cambrian-Ordovician trilobite genus Clelandia, with phylogeny and morphology of new and revised species
Bibliographic record
Abstract
The Laurentian trilobite genus Clelandia Cossmann, 1902, is represented by 12 named species that range from the late Cambrian to Early Ordovician. Species of Clelandia have been described from many localities in the United States, Canada, Scotland, and Greenland and attempts have been made to employ them as tools in biostratigraphic correlation. Nevertheless, important questions persist regarding the taxonomy and phylogeny of the group. No species-level phylogenetic analysis has been attempted for the genus and its family affinity has been unclear. Previous work often has produced limited numbers of small photographs which tend to mask subtle, but critical, morphological details and confuse taxonomic identification.\nNew collections from the Great Basin of the western United States have resulted in material representing five new species of Clelandia, three of which are formally named. Other species of Clelandia are illustrated and the type species is redescribed. C. aspina and C. bispina are reported from a new locality in east-central Nevada. The first articulated specimens from a species of Clelandia are illustrated and demonstrate multiple synapomorphies of the thorax and pygidium that strongly indicate a unique, low-diversity clade of trilobites which persisted from the late Cambrian into the Early Ordovician with similarities to the Kingstoniidae. Phylogenetic analysis shows Clelandia to contain two distinct components. One component is characterized by species with glabellar furrows, widely flared posterior projections, and exsagittal pits of the occipital furrow. A more derived component consists of species with long glabellar spines, relatively narrow posterior fixigenae, bacculae, and a unique glabellar-occipital spine structure.
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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) | 0.001 | 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) | 0.000 | 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".