Silurian and earliest Devonian birkeniid anaspids
from the Northern Hemisphere.
elegans shoal has preserved in a lens-like fish bed with rare ostracods and a few osteostracans (Tremataspis and Dartmuthia) occurring on the same bedding plane, while most of osteostracan and anaspid
exoskeletons were buried under more agitated water conditions.
Silurian and lowermost Devonian birkenod anaspids
from the northern hemisphere.
and sometimes with the anaspid
Rhyncholepis parvula Kiaer.
Other associated fossils include anaspids
, heterostracans, graptolites, eurypterids, nautiloids, and conodonts.
Unlike the predominantly longitudinal orientation of the scales on most of the body, at least some of the scales covering the pharyngobranchial region have an oblique long axis, being aligned anterodorsally to posteroventrally (Figs 5A, B, 6D) in a manner that suggests that the branchial pouches or row of branchial openings was also oblique, as it is in anaspids
(Blom et al.