Image from Wikimedia commons by Nobu Tamura: see Development Notes for more details
Cambyses, a dry xerogaian world discovered in 5699 in the Perseus Rift and located thirty light-years from the nearest wormhole, was terraformed with cometary water and settled by a mixture of augmented human agriculturalists affiliated to the Solar Dominion, and an independent coalition of mammal provolves and rianths, who together created a temperate rainforest biome on the maritime edge of all three new continents. By 7300 the forest covered two million square kilometres.
In small, high tech settlements, a clade of capybara provolves combined a scavenging life style with a close connection to the Known Net. These so-called 'cyberbaras' successfully used handtech and obedient robot workers to maintain their lifestyle.
Meanwhile a small clade of lazurogened and provolved marsupial lions (Thylacoleo Sapiens) were living as predators in nearby wilderness areas, and developing an idiosyncratic culture based around hunting and dominance within small family groups. Over time they became increasingly reticent and eccentric. Although they were expected by the other citizens of this world to avoid predation of sophont beings, the thylacoleos would repeatedly kill, and eat provolved capybaras and other citizens, even killing human tourists on occasion. It seemed to be evident that the thylacoeo provolves had somehow reverted to presapience, as they no longer responded to attempts at dialog, and did not appear to use tools or language any more.
At length the alpha male cyberbaras instigated a bounty system to restrict the thylacoleo population; any marsupial lion lazurogen that entered capybara territory could be shot. After only thirty years of this policy the thylacoleo was apparently extinct. Since the lions had reverted to presapience this loss was regrettable but not generally considered to be sophonticide, although most animal rights proponents and pansophontists were outraged.
Neither the cyberbaras nor the Dominion agriculturalists on this world were willing to let Genen specialists revive the missing clade, and most of the forest provolves were glad to see the predators removed from the food chain. However persistent reports over the next six hundred years appeared to show the survival of a small relic population.
Many unsubstantiated sightings, poor video recordings, stock maulings and mutilations, and intermittent deaths of Cambyses citizens of various nations were attributed to the elusive lions. Finally a sweep of the millions of hectares of inaccessible deep forest using a nano defence goo, supplied by the Dominion hierarchy, found no living lions (and no remains of dead lions less than six hundred years old).
After only fifteen years, the reports started again, and tourists have once again been drawn to the remote world by engeneration and beamrider link, and soon the volume may justify a full wormhole link to replace the nano connection. Whenever cynics venture to suggest that the tourist trade mainly drives the thylacoleo phenomenon yet another spectacular sighting or disappearance rumour appears on the Known Net.
As the marsupial lions were originally sentient, it is believed they may have developed sophisticated defenses against scanning at some point in their history, and that these defences were still active; however no electronic or nanochemical trace of this have ever been found.