Fig. 2

Perfectly preserved 400-million-year-old left eye capsule of a placoderm fish, acid-etched from Lower Devonian limestones of the Burrinjuck area, New South Wales, Australia (Murrindalaspis, first described by Long and Young 1988). a External view showing the dermal sclerotic ring; b XCT scan revealing the inside of the eye opening, to show structures on the retinal wall (CT scanning and imaging by Prof. T. Senden and Dr A. Limaye, ANU); c internal view of the sclerotic cartilage enclosing the eyeball, showing scars for eye muscle attachment, the eyestalk attachment and openings for the optic nerve, and arteries and veins supplying the eyeball