Ductina


Ductina is a genus of extinct, small to average sized, eyeless phacopid trilobite, that lived during the Devonian.

Description

The body of Ductina is small to average, to 2 times as long as wide, blunted oval. Body without any adornment. The headshield is 2 to 3 times as wide as it is long in the direction of the axis. The cephalic axis is strongly widening forward with shallow furrows, the front curving downward to end at an approximate straight angle to the plain of the axis. Another shallow furrow, with left and right a deep pit, crosses to the back of the glabella to define a narrow band, and just in front left and right a small lobe is defined by shallow furrows and a deep pits. The back of the cephalon is often broken, obscuring the features of the occipital ring. Eyes and eye ridges are absent. The natural fracture lines of the cephalon coincide with its margin, so there are no free cheeks. The genal angles are rounded, not truncated, no genal spine. The thorax has 10 segments, and the width of the axis is about of the thorax. Tailpiece is 20 to 35% of the length of the body. The pygidial axis is pointed, ending at the border.

Distribution

The species of the genus Ductina lived during the Devonian in Europe and South-East Asia.
Fossils of D. vietnamica have been found in the Eifelian of China ; and in the Pragian of Vietnam.
Fossils of D. ductifrons have been found in the Famennian of the United Kingdom, Germany, Poland, and the Western Urals in Russia.

Habitat

All phacopids were probably marine bottom-dwellers. D. vietnamica has been found with several open water species, indicating deep and dark waters, probably poor in oxygen near the bottom where Ductina lived. It has also been found as part of a species rich community characteristic of a shallow coral sea.

Key to the species


File:Ductina ductifrons.jpg|Ductina ductifrons, from Wupperthal, Germany
File:Ductina vietnamica 2 lateral.jpg|Ductina vietnamica, lateral view
File:Ductina vietnamica 2 frontal.jpg|Ductina vietnamica, frontal view
File:Ductina vietnamica dorsal.jpg|Ductina vietnamica, dorsal view