Another idea I've entertained for over a year and a half but which I'm just now getting onto paper. To wit, future genetic modification of avian livestock leads to two distinct forms of transgenic chicken: the 4-legged "drumstick chicken" and the 4-to-6-winged "hotwing chicken." After the extinction of humanity, and perhaps all other large mammal forms (ironic transgenic bird flu, anyone?), the modified chickens disperse to repopulate vacant ecological niches, rapidly evolving into diverse specialized forms. Hilarity ensues.
These sketches depict several different "postchicken" forms, moving roughly from more basal to more divergent forms as we proceed through the alphabet.
A: Feral, flighted, "hexwing" form, with the first wing pair having evolved into flashy display devices
B: Feral "quadwing" form, converging on the role of hereditary Vietnamese jungle fowl in rainforest habitats
C: Feral "drumstick" form, likewise converging on a traditional peafowl role
D: Derived flighted "hexwing" with third wing pair evolved into display devices, converging on extinct psittacines
E: Ground-running "hexwing," converging on contemporary roadrunner or secretary birds
F: Derived omnivorous "drumstick" form, converging on prehistoric phorusrhacids
G: Even more highly derived and possibly piscivorous "drumstick" with specialized display wings
H: The "Picky Chicken": a highly derived flightless, ground-dwelling, "hexwing" form occupying an insectivorous role
I: Flightless, polar, marine/aquatic "hexwing" converging on extinct penguins
Obviously there are all kinds of crazy directions to go with this idea. The "hexwing penguins" alone could be an entire project. There is also a lot I'd like to do with the four-legged F/G-style variants as they become more derived: I'm picturing quadrupedal flamingos, spoonbills, pelicans, and herons, most or all having lost or atrophied wings, and resembling nothing so much as a second radiation of dinosaurs. Taking that theme further could obviously lead to "drumstick" sauropods, elephants, giraffes, and the like. On the other hand, retaining and accentuating the wings could lead to a true hexapodal bird lineage (returning the hexwing penguins to land could result in the same scenario via a different evolutionary pathway). And of course there are all the insane and beautiful plumage and decorative soft-tissue possibilities for even the most basal, "jungle fowl" members of the clade: Bulwer's pheasants, satyr tragopans, peacocks, etc. etc. I'll have to see where it goes.
I credit Alexis Rockman's painting "The Farm" ([link]
), featured in Peter Ward's nonfiction treatise "Future Evolution," as the inspiration behind this concept.