CORYNEXOCHIDA (Kobayashi, 1935)
A morphological feature of this medium trilobites is the very longished
glabella. There are variations of glabellas shape from rectangularly to
(Suborder Leiostegiina), the dilation of the glabella towards anterior
cephalon is also to be find, remembering of a pestle at dorsal view.
The CORYNEXOCHIDA are including the Suborders
Corynexochina, Illaenina and Leisotegiina.
The image shows a
representative of the Family
Zacanthoididae, from Suborder Corynexochina.
(Source: Trilobites, Levi-Setti,
to Middle Devonian.
cephalon is normally developed semicircular and featuring genal spines
(with exception of Suborder Illaenina). Prominent furrows are present as
a rule. The sutures
run ophistoparian (Gr.- cheek) i. e. the sutures are
ending at the posterior cephalons edge. With few exceptions there are big eyes
present. The hypostome
is developed conterminant.
During CORYNEXOCHIDAS evolution, the hypostome was replaced by the
as a rule consists from 7-8 segments within a spectrum of 2 -12 (at
early species sometimes up to 18). Also as a rule the pleures are
running out in pleural spines.
varying species- specific regarding size and outline. Referring to this
the relationship to the cephalon ranges from micropygous to macropygous
in every appropriate relationships. Some species have spines.