Data from: Parallel evolution of jugal structures in Devonian athyridide brachiopods

Here, we describe Sinathyris crassa gen. et sp. nov., a new early Emsian
(Early Devonian) athyridide brachiopod with a double spiralium from the
Guangxi Province of southern China. Unlike the majority of genera of the
subfamily Helenathyridinae, which possess accessory spiral lamellae
developed directly from the jugal branches, the form described here shows
these lamellae arising from a distally bifurcating jugal stem. These
differences suggest that the double spiralium in S. crassa might have
appeared independently from the double spiralium of the helenathyridins.
To test the subfamily assignment of Sinathyris gen. nov., we carried out
phylogenetic analyses, which indicate that the new genus is more
appropriately referred to the Didymothyridinae. The cladistic analyses of
the athyridides indicate that double spiralia have developed independently
among these brachiopods at least five times during their evolutionary
history.