The Liberty Gun — Martin Sketchley

The Liberty Gun, the third instalment in Martin Sketchley's Structure series, sees Delgado and Ashala catapulted into a future Seriatt occupied by the Sinz - a three-species race of humanoid, avian, and amphibian form. Delgado immediately seeks a way back to the point that changed his life completely, but his plans are arrested when he and Ashala are captured by a Seriattic resistance group headed by Cowell, an enigmatic Seriatt vilume.
Cut off from their distant home world of Hascaaza, the Sinz on Seriatt have established a barrier around the planet to protect them while they await reinforcements, plundering its resources as they prepare to invade other, neighboring worlds. But despite their apparent strength the Sinz are vulnerable, reliant on the basillia - a gigantic subterranean organism - for their existence.
Realizing this weakness, Structure's Commander Supreme, General William Myson, orders Colonel Viktor Saskov to go to Seriatt to kill the basillia and retrieve the time gate. Yet despite what they would wish, more discrete and potentially powerful forces are at work than anyone can know. Meanwhile, the integrity of time itself is threatened - and it is in the power of one man alone to ensure that stability is maintained and that the course of events runs true.