Abstract:
A new genus and species of tetraodontiform fish, Eospinus daniltshenkoi, is described from the Lower Eocene of Turkmenistan (Danatinsk Formation). It is referred to the Balistoidea because it has three large dorsal-fin spines; the pelvic fin reduced to a rudimentary but prominent structure apparently composed of two partially fused spines at the posterior end of the pelvis; and enlarged scale plates that form an incomplete carapace or loosely articulated armature around much of the body. It differs from all other balistoids in having a long median spine projecting forward from the snout and another spine projecting posteriorly from the middle of each side of the body; lower jaw teeth twice as long as the upper jaw teeth; and in lacking encasing scales around the rudimentary pelvic spine. Eospinus is the first record of a balistoid fish from the Eocene with three dorsal-fin spines and the pelvic spines fused together at the end of the pelvis, as otherwise only occurs in balistids, which are first recorded from the Oligocene.
