Rhenaniformes of the Asterosteidae family
from the Lower Devonian of Bundenbach,
Karl Albert Frickhinger, 1995.
|The rhenanidas are the placoderm equivalent of rays. They had flattened bodies with large wing-like pectoral fins and eyes on top of their heads. Their skulls were formed of smaller bones then other placoderms and they had a smaller trunk shield. The tail had many bony platelets of varying sizes. This group was marine and is known only from Europe and North American marine sediments of the early Devonian. One fossil, a sclerotic capsule found near Taemus in New South Wales of Australia demonstrated that the eyes of placoderms had the same pattern of complex eye musculature and nervous, arterial and venous anatomy as do modern fishes. Unlike modern fishes their eyes were heavily invested with bone and each eyeball was connected to the brain case by a pedicle of bone or cartilage called the eyestalk. The eyestalk is another feature seen in both sharks and placoderms.|