(2016) reporting the Orcadian Basin acanthodian
, Diplacanthus crassisimus Duff 1842 in the Moroch Beds.
Few Silurian vertebrate sites have been described from the USA, and even fewer have been studied for vertebrate microfossils (hereafter microvertebrates) such as thelodont and acanthodian
Meanwhile, some acanthodian
species turned out to be primitive sharks, while others were relatives of the common ancestor of sharks and bony fishes.
In addition, acanthodian
fish scales and a portion of a fin spine, and numerous actinopterygian and sarcopterygian fish scales and tips of actinopterygian teeth from the MNSC were identified by Kenaga and Sellepack (1995).
These substages correspond to the acanthodian
zones established by Valiukevicius .
A conodont, thelodont and acanthodian
fauna from the Lower Pridoli (Silurian) of the Much Wenlock Area, Shropshire.
The lowermost vertebrate-bearing layer (layers 7 and 8) yields rare isolated skeletal elements of the psammosteid Psammolepis sp., arthrodire Plourdosteus livonicus (Eastman), antiarch Asterolepis sp., acanthodian
Haplacanthus sp., an unidentifiable dipnoan fish, as well as porolepiforms Glyptolepis sp.
A fin spine identified as belonging to the acanthodian
Ankylacanthus incurvus (NBMG 11976) (see Burrow et al.
2002); very rare acanthodian
scales may occur in a few samples.
More juvenile dipnoan tooth plates as well as acanthodian
scales and conodonts were obtained from a new sample.
Don and Eldon collected skull roofs of haplolepidid fishes and a fin-spine of a small acanthodian
fish (Gyracanthus) that Don later described in detail (Baird 1962a, 1978a).
According to a report in National Geographic News, the specimen is of a 415-million-year-old Ptomacanthus, which is only the second known example of a braincase from an Acanthodian
, a long-extinct group of fossil fish.