Cyphaspis carrolli & Kettneraspis williamsi.
A rare specimen preserving two different species, "Cyphaspis (Cyphaspis carrolli)" and "Kettneraspis (Kettneraspis williamsi)", on the same matrix.
From Oklahoma, USA. Both have beautiful exoskeletons and are in excellent condition.
The one with many long spines extending from the sides of its body is Kettneraspis williamsi. The smaller trilobite that looks like it has a swollen nose is Cyphaspis carrolli.
