Trilobita - Agnostida - Ptychagnostidae

Alternative combinations: Acidusus atavus, Agnostus atavus

Belongs to Ptychagnostus according to S. R. Westrop et al. 1996

Sister taxa: Ptychagnostus (Ptychagnostus), Ptychagnostus acidusus, Ptychagnostus aculeatus, Ptychagnostus aksayensis, Ptychagnostus convexus, Ptychagnostus cuyanus, Ptychagnostus intermedius, Ptychagnostus karatauensis, Ptychagnostus leptus, Ptychagnostus punctuosus, Ptychagnostus seminula, Ptychagnostus sinicus, Ptychagnostus spinosus

Ecology: nektonic suspension feeder