Paralepidotus ornatus, juvenile

Paralepidotus ornatus Agassiz 1833
Upper Triassic
Norian
Wiestal near Hallein, Salzburg
Austria
Juvenile Paralepidotus, Length 6cm / 2"

Paralepidotus ornatus is a rather common semionotid in most Norian marine localities of Europe, ranging from a few centimeters up to 50cm in standard length. Specimens of Paralepidotus have been recorded from other localities and have often been described under new specific names such as Lepidotes fimbriatus, L. parvulus, L. latus, Heterolepidotus dorsalis, Colobodus elongatus…
Juveniles are more slender than adults and their dentition is not like the powerful crushing one of large species. This implies a change in environment during the live of an individual Paralepidotus from superficial open waters to shallow mollusc banks. A change in diet is also implied by the change in dentition. It is thought that juvenile Paralepidotus lived on crustaceans whereas adult Paralepidotus had a strictly durophagous dentition and fed exclusively on molluscs.
The slender body of young Paralepidotus suggests that they lived quite far from the bottom and were rather fast swimmers. Adult Paralepidotus were probably shell eaters, slowly swimming just above the bottom.

Lit: Tintori, A. Paralepidotus ornatus (Agassiz 1833-43) a Semionotid from the Norian of Europe.
Mesozoic Fishes – Systematics and Paleocology, G. Arratia & G.Viohl (eds.):pp167-179.