A very late Spectember entry, but I was inspired by @alphynix 's "Dicyny World" where archosaurs and cynodonts never got to take over and the planet was instead dominated by the descendants of the dicynodont Lystrosaurus (which was famous for dominating in the aftermath of the Great Dying that ended the Permian).
So here's a bunch of random species, playing around with the idea of dicynodonts having superficial or convergent features of mammals, squamates and birds to fill niches similar to all of those, as well as the idea that drab coloration and color-blindness in mammals were a side effect of their nocturnal Mesozoic ancestry so other synapsids could probably be quite colorful.
Clockwise from top:
• The Tookey, an arboreal species adapted for climbing, similar to primates, squirrels and the arboreal synapsid Suminia, that feeds on leaves, seeds and insects in the treetops, using prehensile paws and a balancing tail to navigate among the branches.
• The Tuskbird, part of a pterosaur-like flying clade. This species is mostly ground-dwelling, however, similar to galliform birds, with males sporting brightly-colored iron-rich tusks for display. They eat primarily seeds, which they crack open with their short, blunt bills, as well as other plant matter.
• The Goliphant, a megafaunal herbivore that grazes on low-lying vegetation such as ferns and shrubs and grass-equivalents. Older bulls sport bright colors on their faces to display to conspecifics. Populations at different latitudes have differing amounts of body hair, being furrier in colder regions.
* The Puffrus, a semi-aquatic omnivore that spends most of its life at sea, feeding on marine plants and shellfish, but returns to land to breed as it is oviparous like most other non-therian therapsids, forming colonies on the shore where they guard their eggs in densely-clustered nests until hatching.
* The Spearbill, a plains-dwelling omnivore with a long beak that can be used to probe into burrows for small animals, break into insect nests like an anteater and pick up seeds and fruit-analogues. Its comb-like tusks are used for grooming, and its long limbs make it an adept runner.
* The Leazle, a small carnivore analogous to something between a mustelid and a monitor lizard, with a long body and short limbs ideal for chasing small prey down their burrows, both in the ground and up in tree trunks. A hooked beak and fang-like tusks help hold on to struggling prey.
