Painting of Hugh Miller (Stromness Museum)

"I traced the formation and upwards this evening along the edges of the upturned strata, from where the great conglomerate leans against the granite, till where it merges into the ichythyolitic flagstones; and then pursued these from older and lower to newer and higher layers, desirous of ascertaining at what distance over the base of the system its more ancient organisms first appear, and what their character and kind And, embedded in a greenish colour layer of hard flag, somewhat less than 100 yards over the granite, and about 160 feet over the upper stratum of the conglomerate, I found what I sought, -- a well marked bone, -- in all probability the oldest vertebrate remain yet discovered in Orkney."

Hugh Miller 1849. Footprints of the creator; Or, the Asterolepis of Stromness.

 

 

 

 

 

 

 

 

 

Spine or keel of median-dorsal plate of Homostius, the Asterolepis bone found by Hugh Miller (collection Stromness Museum).

Spine or "keel" of median dorsal (after Miller, 1849).

Homostius milleri Traquair

This very flat, heavily armoured placoderm is only known from Orkney from the sediments above the Sandwick Fish Bed. The fish is mostly found as disarticulated dermal plates. It is well described by Heintz (1934) together with a species from Estonia (Homostius sulcatus). Later Mark-Kurik (1993) made a new reconstruction with some corrections. The body is covered with thick dermal plates but nothing is known about the tail.

Complete specimens are very rare but the picture shows a cast of a specimen in the National Museums of Scotland Edinburgh, together with a drawing of this specimen by Traquair.

The fish probably was a bottom dweller filtering mud and eating small crustaceans. The lower jaws do not have teeth at all but show a rounded surface.

Since Homostius sulcatus from Estonia is so well reconstructed by Heintz (1934) and resembles very much Homostius milleri, I will also show some of  the drawings by Heintz.

Cast of specimen showing head and body (collection N.M.S., © N.M.S.).

Posterior part of the head, internal view (nuchal and paranuchal plates).

Median-dorsal plate, internal view (collection Stromness Museum, © S.M.)

Median-ventral plate, internal view.

Median-dorsal, external view.

Median-dorsal, internal view.

Nuchal and para-nuchal, external view.

Nuchal and para-nuchal, internal view.

Reconstruction of cast (N.M.S.) (after Traquair, 1889).

Reconstruction of Homostius sulcatus (Heintz, 1934).

Reconstruction of body in lateral view (Mark-Kurik, 1993).

Drawing of incomplete head, external view (after Miller, 1849).

Drawing of head, internal view (after Miller, 1849).

Reconstruction of head, internal view (after Miller, 1849).

Reconstruction of median-dorsal plate, internal view (after Miller, 1849).

Reconstruction of head of Homostius sulcatus , external view, of(Heintz, 1934).

Reconstruction of head of Homostius sulcatus, internal view (Heintz, 1934).

Reconstruction plate limits of head-plates of Homostius sulcatus (Heintz, 1934).

Reconstruction of body carapace of  Homostius sulcatus (Heintz, 1934).

Reconstruction of median-dorsal plate of Homostius sulcatus, internal view (Heintz, 1934).

Reconstruction of  nuchal plate of Homostius sulcatus, internal view, (Heintz, 1934).