| Basic info | Taxonomic history | Classification | Included Taxa |
| Morphology | Ecology and taphonomy | External Literature Search | Age range and collections |
Helmetia expansa
Taxonomy
Helmetia expansa was named by Walcott (1918).
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 1918 | Helmetia expansa Walcott |
| 2025 | Helmetia expansa Losso et al. p. 5 |
Is something missing? Join the Paleobiology Database and enter the data
|
|
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Helmetia expansa Walcott 1918
show all | hide all
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| S. R. Losso et al. 2025 | A large helmetiid with prominent anterolateral cephalic spines. Six thoracic tergites with progressively larger posterior-facing pleural spines, and two pairs of posterolateral spines on pygidium. Dorsal exoskeleton with serrated margin throughout, except for rounded anterior sclerite. A pair of lateral eyes located underneath slightly domed exoskeletal bulges on cephalon, and two medial eyes underneath the anterior sclerite. 15
pairs of biramous postantennal appendages, three below cephalon, six below the thorax and five below the pygidium. |
Measurements
No measurements are available
|
|
||||
|
|||||
|
|
||||
|
|
||||
| Source: g = genus | |||||
| Reference: Hendy et al. 2009 | |||||