|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Xiphosura - Sessilia - Scalpellidae
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.
|M. J. Vendrasco and B. Runnegar 2004||Thick, massive subconical intermediate and tail valves with a barbed arrowhead-shaped outline in dorsal view, two tunnels in valve interior, elongate (length/width between 1.5 and 2.0), large embayment along the anterior margin, long apical area; intermediate valves shorter and wider than tail valves; head valves flat, holoperipheral growth style, subcentral mucro.|