Canitheres and Molodonts

25 million years have come and gone since the Thermocene-Pangeacene boundary, Serina's worst extinction event to date. The world of birds has since healed, a green one spanned by forest and field, supporting a varied tapestry of life in a mild climate with few cold winters. But the creatures of the Pangeacene world are unlike their Thermocene equivalents. Such a drastic cataclysm as the end-Thermocene reduced life to a fraction of its former diversity, but survivors included both very primitive animals and creatures far more derived. Waterfowl canaries resembling ducks were among the survivors, and now they have radiated into many lineages of larger plant-eating megafauna whose appearance harks back to the earliest flightless canaries of the Tempuscene. Such living fossils live alongside metamorphic birds, whose adults are ordinary, but which begin their lives as grub-like larvae in soil, water, and animal carcasses and which undergo remarkable transformations at adulthood. Bumblets, the only surviving vivas, proliferate as burrowers living secretive subterranean lives. Most live most of their lives out of sight, but now some forms are venturing into the sun again, and they're doing so walking on four legs, not two. But for sure, the most unusual of any of these new animals are the tribbetheres, three-legged descendants of livebearer fishes which have taken over the land in this new green era. 

The tribbetheres are already a diverse lineage. Their hopper ancestors' long, bounding legs have carried them far and wide over the interconnected world of the Pangeacene, and their earlier teleost fish ancestor's incredibly versatile, extensible jaws have enabled them to exploit many kinds of diets. A new clade of specialist seed-eaters, the snipmunks, have recently appeared on the grasslands of Striata, characterized by fused beaks of many small, ever-growing teeth at the front of their mouths. Descendants of the nutcracker of 15 million years earlier, they have stumbled onto a winning evolutionary niche, using their highly flexible mouthparts to flex their sharp upper jaw inward at the distal edge and cut away at hard plant foods by pushing down their upper tooth against a tooth plate on their lower jaw with a series of sawing motions. In this way, they can cut open a large, well-protected seed to access the 'meat' within. But some snipmunks have taken to feeding on grass, less nutritious but much more abundant. Demonstrating that their new teeth are versatile, tribbetheres like the snippet have jaws that resemble a pair of hooves. With each bite, it pinches foliage between its upper and lower teeth and tears it from the ground, roots and all. Chewing is done further back in the mouth, with smaller batteries of peg-like molars.

The snippet is a small animal, similar to a rabbit, and though itself very quick and wary, it faces formidable enemies. A canithere is an apex predator of the Pangeacene world, a comparative giant at almost 100 lbs. Long-legged and lean, this descendant of the necksnapper has become quick and exceedingly nimble, able to turn on a dime and bound along with great endurance to chase smaller prey to exhaustion. When so threatened, the snippet will seek to trick its predator, who relies strongly on smell to trail its quarry, by doubling back on its tracks and taking cover in a thicket off to the side of its scent trail. With luck, its pursuer will fail to notice and keep going until the scent drops off suddenly; by then, the snippet will have bolted away back the way it came and taken safe refuge in its burrow. But this method only works if the snippet has the advantage of a lead against its enemy. A canithere which can keep sight on its target will not be fooled by scent tricks, and the snippet is in real danger. If it cannot quickly find cover, somewhere the larger canithere cannot follow, it is likely to be overtaken. The canithere's jaws, like the snippet's, are highly flexible, but rather than folding inward to bite, they reach far ahead of its snout like a set of grasping arms, doubling its skull length at maximum extension. It uses these terrible mouthparts to snatch up its victim when closing in at the last moment, just before it can pull away. With its soon-to-be meal captured, the jaws retract and slicing molars are pulled into contact, immediately severing the snippet's spinal cord. By flexing its jaws back and forth, the canithere chews its prey, its teeth shearing together to slice flesh and bone like a pair of kitchen shears. Compared to the simple, non-chewing jaws of most living birds, and certainly any of comparable size, it is an extremely efficient way to eat.

The snippet represents a very early offshoot of the new snipmunk lineage, one which has appeared very recently and immediately spread far and wide over the world, taking advantage of the limitless green food of the Pangeacene grasslands. It survives less by skilled tactics to avoid predators and more through sheer numbers, reproducing often and with litters of several precocial young in each which mature in only a short time and need only brief parental attention. That most young ultimately meet their ends in the jaws of carnivore relatives is inevitable; only a few need to survive to sustain the population. But these are not the only members of this new group. Much less numerous, but also less likely to be killed in this way are smaller, squirrel-like snipmunks called molodonts. These tribbetheres feed differently than other snipmunks, even more efficiently opening seeds and nuts. Their upper tooth plate is larger, and it has a wider range of rotation, letting it operate like a wheel to slide back and forth over a food item which is held in place against the lower jaw. The jaws of the molodont work like a mortar and pestle, a grinding implement which the creature uses to efficiently chew its food until it is cracked open. The molodont has only a few vestigial cheek teeth, with much of its jaw taken up by its two two plates instead. This very specialized method of chewing has come at the expense of its tongue, which is very small and moved to the very back of the mouth. It is often injured in feeding, and in adults is largely unused; the animal has acquired taste buds throughout the inner surfaces of the mouth to compensate, and this organ is now of little necessary function.

While other snipmunks give birth to offspring which are born able to run from danger, and so need little from their mothers, molodonts have altricial young which require a lot of attention in their first few weeks but with the trade-off that they grow up quicker to reach maturity. Hidden away in nests in trees or thickets, and fed regurgitated seeds by their mothers, molodont pups have a higher individual chance of survival than snippets. For now they are much less common, if only because they have more recently evolved and had far less time to travel. For now their rarity is to their benefit, making it so they avoid the most of unwanted attention from the many predators of this new age. Which of the two new seed-eating tribbethere lineages, if any, may do best in the times yet to come remains to be seen. There are clear advantages to both groups. For now, both remain in the shadow of far larger avian grazers; such competitors, along with heavy predation pressure, dictates how big they can become in a way the canithere, without enemies of its own, is not so limited. For an herbivore tribbethere to reach any substantial size may require an even more efficient feeding method, or a diet that few other animals can make use of. Until then, they may remain specialists. For the canithere, though, there seems little primed to impede their immediate success.