Order Corynexochida, Suborder Illaenina, Superfamily Illaenoidea,
Geologic Age: Middle Ordovician
is 80 mm long
From: Wolchow River Region, Asery Horizon, St Petersburg, Russia
Remarks: A superb example of trilobite effacement of both cephalon and
pygidium, an evolutionary adaptation though to have aided
in traveling through seafloor substrate in search of food. This species
is celebrated high profile of the cephalon. Note the curved
genal spines from which the species is named do to the bull horned shape.
Typically, the large cephalon is pulled under likely a result of
at death. This one, however, is quite prone. Making for a dramatic and
uncommon presentation of this unusual taxon. The Illaenidae
some 25 members, and the genera has some 50 species.
The Cephalon and
pygidium are highly effaced and