Dipterus valenciennesi Sedgwick & Murchison
Juvenile Dipterus from Achanarras with Orcadacanthus pusillus.
Reconstruction by Agassiz 1844.
Complete specimen in lateral view showing well the paired fins. This specimen shows some cosmine on part of the scales on the belly, and a patch of cosmine on the opercular and the plate below the lower jaw. From Achanarras, Caithness.
Close-up of above fish showing the tail and the fins. af: anal fin, c: cosmine, df1: anterior dorsal fin, df2: posterior dorsal fin, pvf: pelvic fin. Note that the scales on the belly have cosmine and some of the scales on the fins also.
Big specimen from Achanarras with a lot of cosmine on the scales and the head plates (coll. R. Jones)
At the start of the 19th century the lungfish Dipterus was one of the first fish described in many papers. It has peculiar tooth plates and a strange lower jaw. Together with this, and the fact that there are still lungfish living today, it makes this a very interesting fish. On Orkney articulated specimens can be found in the Sandwick Fish Bed and disarticulated specimens almost everywhere. In the Eday Subgroup Dipterus is “replaced” by Pentlandia macroptera.
Most likely for protection against predators, and the harsh environment the fish has cosmine on the scales and headplates. Juvenile fish however had no cosmine and the scales and headplates are not shiny. The plates on top of the head, the cranial shield, are very simple in juvenile fish but become more complex in bigger specimen. In adult specimens the cranial shield as well as the other plates and scales are cosmine covered.
A specimen from the Mey beds in Caithness.
A specimen from the Sandwick Fishbed.
Two heads from the Sandwick Fishbed. CS: cranial shield, E: eye, O: opercular
Head of juvenile fish. CS). E: Eye, O: Opercular.
Head of fish from Achanarras. This head has (CS). E: Eye, O: Opercular. no cosmine but is has already a complex cranial shield.
Nice tail of specimen from Achanarras.
This is the earliest find of Dipterus from Orkney, from the Lower Stromness flags of Graemsay. It is a tiny baby fish but has all the features off Dipterus. Af: anal fin, Adf, anterior dorsal fin, Cf: caudal fin, Pdf: posterior dorsal fin.
Scales with cosmine.
Cranial shield partly with cosmine.
Cranial shields of Dipterus with full cosmine and partial cosmine in outside and inside view.
Close-up of above, tooth plates of the upper jaw.
Lower jaw with tooth plates.
Scales with and without cosmine.
Some old historic reconstructions:
Reconstruction (after Sedgwick & Murchison, 1828).
Drawing of specimen (after Miller, 1841).
Reconstruction (after Pander, 1860).
Drawing of specimen (after Huxley, 1861).
Reconstruction (after Traquair, 1895).
Reconstruction (after Foster -Cooper 1937).
Reconstructions of fish, cranial shield and lower jaw (Dean, 1895).
Drawing of lower jaw sideview
Drawing of specimen (after Miller, 1841, 1849). (after Miller, 1849).
Cranial shield and lower jaw (after Traquair 1878).
Reconstruction of lower jaw inside and outside (after Watson, 1922).
