Summary
Physical Description
Ecology
Life History & Behaviour
Anatomy & Physiology
Evolution & Systematics
Biogeographic Distribution
Conservation & Threats
References & Links | Evolution & Systematics
As this species is a soft-bodied organism, it is inherently difficult for fossils to occur and of yet there have been no fossil records of this species. However, other fossils that are related to P. gardineri, albeit distantly have been found. Species of the “bubble shell” snails that are related to P. gardineri, similar to Retusa and Acteocina have been discovered from the upper Triassic period (Haas et al. 1953). Other fossil opisthobranchs have been discovered in the last 10 years that originally occurred during the Tertiary period (Valdés & Lozouet 2000). Higher phylogenetic levels of species related to opisthobranchs have also been found, acteonid-fossil shells, suspected to be related to Gastropods were discovered belonging to the Carboniferous period (Bieler 1992).
Due to the scarce fossil records of this species, it is somewhat difficult to place this species in a phylogenetic tree in relation to its sister species. Many results of studies are often contradictory, despite this being a widely studied domain in science (Gosliner 1981).
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