Jacob Perkins’s The Dinosaurs is a meditation on sobriety and female friendship. It unfolds within a women’s and trans-inclusive alcohol-recovery group dubbed the Saturday Survivors, a nod to the day of the week they meet over coffee, scones, and doughnuts in a bland, white, windowless community room with folding chairs (scenic design by dots). Under Les Waters’s direction, the 70-minute play, which features a remarkable ensemble of actors, slides from a naturalistic mode into an experimental one, as time and identity are upended. The experiment, however, proves frustratingly vague rather than provocative.