It lived during the Botomian and Toyonian stages (Olenellus-zone), 522 to 510 million years ago, in what is currently North-America, part of the palaeocontinent Laurentia.

[4] Olenellus means small Olenus, after a genus belonging to the Ptychopariida, to which the type species O. thompsoni was originally assigned.

O. parvifrontatus has been collected in the Olenellus-zone of the Yukon Territory, Canada (Unit 6 of the Upper Illtyd Formation, Wernecke Mountains).

Like all other members of the superfamily Olenelloide, the eye-ridges emerge from the back of the frontal lobe (L4) of the central area of the cephalon, that is called glabella.

Olenellus also shares the typical character of whole family Olenellidae that the frontal (L3) and middle pair (L2) of lateral lobes of the glabella are partially merged.

It can be distinguished from the other two genera in the family, Mesolenellus and Mesonacis, because the angle in the back rim of the cephalon is less than 15°, making the head approximately semi-circular.

The genal spines are reaching back no further than the 6th thorax segment, making them 4-5 times as long as the most backward lobe of the glabella (occipital ring or L0)1.