 Description:
I was privileged to pick up a small batch of fossil fish from fossil
Lake Gosiute at the 2011 Tucson Mineral and Fossil Show. This collecting
area has been closed to the public for many years. According to
the vendor, these fossil fish came from a collection dating back
to the 1960s. The fossil fish from Lake Goisute have a different
type preservation compared to the more commonly found “split
fish” or “18 inch layer” fish from Fossil Lake.
The Lake Gosiute shales are often dolostones, limestones, or oil
shales. Though the fish in both lakes comprise the same species,
the ones from Lake Goisute have a different look and presence.
They exhibit very good bony detail and a somewhat ghostly appearance.
Their distinctive look makes them instantly recognizable to the
knowledgeable collectors eye. The fossil fish from Lake Gosiute
are also difficult to acquire since the prohibition of collecting
in these beds a few decades ago.
This
particular fish is Knightia alta, a close relative of Knightia
eocaena. Knightia was a schooling fish, which is sometimes found
in mass mortality layers, confined to a single plane, indicative
of a single event. Theories as to the reasons include stratified
water turnovers as well as poisoning due to blooms of blue-green
algae.
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