The Order PHACOPIDA
At the PHACOPIDA it is about a great variable Order.
The size is varying from only a few up to more than 30 cm. All Suborders
are connected by a similiar
The PHACOPIDA are including the Suborders Calymenina
(Superfamily Calymenoidea), Phacopina (Superfamilies Phacopoidea,
Dalmanitoidea and Acastoidea) and the Cheirurina (Superfamily Cheiruroidea).
The image shows a representative of the Suborder
Phacopina (Superfamily Dalmanitloidea).
Ordovician to Upper
It's obvious at the imaged Odontochile, the
representatives of the Phacopida featuring only a relative small
preglabellar field bzw. none. The
are normally running, with exception from the representatives of the Calymenia (gonatoparian),
The typically furrowed glabella has up to 4 pair of glabellar furrows.
If eyes are present, schizochroal
eyes are to be found at the Phacopina, on the other hand, the
type is to be found at the Calymenina and Cheirurina. Except from
some representatives of the Phacopina, featuring a
hypostome, the remaining
representatives featuring the
type. According to this, with the exception of the representatives of
Phacopina, a rostral plate is present.
thorax has 8 up to 19 segments, sometimes featuring prominent furrows.
The rachis is prominent developed, in addition widish at some species.
size and structures the pygidium varied species-specific. As a rule it
is sized smallish relative to the cephalon, though sometimes reaching
cranidiums size (Gr.- skull).