Seriola prisca

Seriola prisca Agassiz

    Eocene

    Lutetian

    Monte Bolca near Verona

    Italy

    This is a Seriola prisca from the Pesciara of Monte Bolca, about 30 kilometers north-east of Verona in Italy. The length of this fish is 36cm or about 14". Outcrops of the middle Eocene of Monte Bolca, Italy, have long been known as a rich source of fish fossils from which a large number of taxa has been described (see e.g. Volta 1796). The main location is known as Pesciara or "Fishbowl" due to its many marine fossils. The sediments from Monte Bolca are from the Eocene epoch, the Lutetian, so the fish is about 50 million years old.

    The entire, abundantly fossiliferous formation consists of 19 meters of limestone, all of which contain fossils, but interspersed in which are the lagerstätten layers that contain the highly preserved specimens. Within these layers, the fish and other specimens are so highly preserved that soft tissue preservation can is observable and even the skin color pattern can sometimes be determined.There are several other related outcroppings in the general vicinity of Monte Bolca that also carry fossils, such as Monte Postale and Monte Vegroni. The term "Monte Bolca" is often used interchangeably to refer to all the sites collectively.

    The Monte Bolca deposits where formed in a lagoon which was separated from the open sea by coral reefs. During that time, there was considerable volcanic activity. The volcanoes on the nearby mainland erupted periodically, their lavas and ashes covering the land for some time, locally causing mass extinctions. The sediment is very fine grained limestone; the preservation suggests when the fish died it was rapidly buried in fine sediment that was anoxic.

    Seriola (or amberjacks) is a genus in the family Carangidae. This family includes jacks, pompanos, mackerels and scads. Seriola prisca is closely related to the living Almaco jack or Seriola rivoliana. The Almaco jack is a pelagic species that can be found in small groups on slopes and off of reefs at depths from 5 to 160 metres. Jacks are fast-swimming predatory fishes that hunt in the waters above reefs and in the open sea. Almaco jacks feed on other smaller fish and squids; it is very likely that the same behavior applies to Seriola prisca.