| Ptychagnostus Temporal range: Cambrian |
|
|---|---|
| Ptychagnostus germanus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Trilobita |
| Order: | Agnostida |
| Family: | Ptychagnostidae |
| Genus: | Ptychagnostus Jaekel, 1909 |
Ptychagnostus is an extinct genus of blind trilobite that lived during the Cambrian period, part of the order Agnostida. Ptychagnostidae generally do not exceed ten millimetres in length.[1] Their remains are sometimes found in the otherwise empty tubes of the polychaete worm Selkirkia.[2] It probably lived in the water column. Its major characteristics are lack of eyes, two lobes on the glabella, and three lobes on the pygidium.[3]