February 2001:
Kainops raymondi eye, Haragan Formation, Lower Devonian, Arbuckle Mts., Okla.
Paciphacops campbelli eye, Haragan Formation, Lower Devonian, Arbuckle Mts., Okla.
Differences between Paciphacops Maksimova, 1972 and Kainops Ramsköld and Werdelin, 1991
Both genera occur in the Haragan Formation,
Lower Devonian of Oklahoma (as well as elsewhere in North America, Czech
Republic, Australia, and possibly Russia). From the Haragan Formation,
Campbell (1977) described 1 species, Paciphacops raymondi, with
2 morphs: large-eyed and small-eyed morphs. These 2 morphs (as well as
some of those previously assigned to other Paciphacops species)
were determined by Ramsköld and Werdelin (1991) to actually belong
to separate species, indeed even separate genera. The large-eyed morph
of P. raymondi was assigned to the genus Kainops and the
small-eyed morph was called Paciphacops campbelli Ramsköld
and Werdelin, 1991.
Differences between Kainops raymondi
and Paciphacops campbelli are mainly in the eyes. K. raymondi
has larger eyes with 6-7 lenses in a dorsoventral file, while P. campbelli
has smaller eyes with 3-4 lenses in a dorsoventral file. The sclera in
the eyes of Paciphacops is strongly thickened, while Kainops
have “normal” sclera (which are thickened dorsally only). Also, the pygidial
axis of P. raymondi is is considerably wider than that of K.
raymondi.
These, plus a few other character differences
proved sufficient (in the phylogenetic analysis of Ramsköld and Werdelin)
to separate these species into separate genera. Kainops was erected
for a clade of 6 species formerly assigned to some Paciphacops and
Ananaspis
species (K. microps, K. ekphymus, K. guttulus, K. invius, K. raymondi,
and K. veles), while Paciphacops was generically restricted
to include about 9 species (P. birdsongensis, P. campbelli, P. crosslei,
P. eldredgei, P. hudsonicus, P. latigenalis, P. logani, P. serratus,
and P. sp. nov. Ramsköld and Werdelin, 1991).
Ananaspis
was restricted to 5 species in a monophyletic clade, with a few species
formerly assigned treated as inncertae cedis (“Ananaspis”).
If anyone has any other information regarding
this topic, please contact Kevin.
References:
Campbell, K.S.W. (1977) Trilobites of the Haragan, Bois d’Arc and Frisco Formations (Early Devonian), Arbuckle Mountains region, Oklahoma. Bull. Okla. Geol. Surv. 123:i-iv, 1-227
Ramsköld, L. and Werdelin, L. (1991) The Phylogeny and Evolution of some Phacopid Trilobites. Cladistics 7:29-74