Order: PHACOPIDA Salter, 1864
Family: PHACOPIDAE Hawle & Corda, 1847
The name combines Latin “adrisio” (smile) and Greek “ops” (eye). It refers to the nickname “smiley Phacops,” often used by collectors. You can clearly see this feature smile when you look at the trilobite from the front (see image of the cephalon)
At this moment only one species is found in Morocco, Adrisiops weugi. It is found in rocks from the Upper Emsian to Eifelian (Devonian period).
There may be other species in Morocco but those have not been described yet.
How to recognize Adrisiops
Head (cephalon):
- the typical ‘smile’ is the easiest way to recognize Adrisiops
- High, rounded shape
- Smooth eye ridge with only a few small bumps
- Eyes with many small lenses (about 19 vertical rows with up to 6 small lenses per row
- Mostly smooth surface except for some bumps in the center
Thorax (middle part):
- 11 segments
- Central axis about as wide as the sides
- Few small bumps on the axis, sides mostly smooth
Tail (pygidium):
- 8 central rings and 5 pairs of ribs
- Slightly rounded
- Fine granules and very small bumps
How it differs from similar trilobites:
Compared to Geesops:
- Adrisiops has a more rounded and inflated head.
- It has fewer bumps on the eye area.
- Its eyes are smaller and placed lower.
- The glabella is shorter and more swollen.
Compared to Phacops:
- Adrisiops has fewer eye lenses.
- Its glabella is more inflated and has different bump shapes.
- The front edge of the head has a ridge (not smooth like in Phacops).
Compared to Morocops:
- Morocops has many more bumps all over the surface.
- Adrisiops is much smoother overall.