Overview of Tribbetheres of the Early Ultimocene

Serina may have begun as the world of birds, but the past few tens of millions of years have seen an explosive success of some of its additional and once purely accessory animal groups. Modest animals introduced at first purely to stabilize an ecosystem for the survival of canaries have achieved their own greatness over the eons, rising to meet the birds on a level playing field in the game of life - and perhaps none of these secondary colonists has achieved more than the guppies. Far from the timid pond-dwelling prey of Serina's dawn, they have given rise to countless new clades in and out of the water. Yet one in particular stands out in the early Ultimocene for the sheer variety of form and function it has attained.; now nearly so far derived from their aquatic ancestry as the first canaries, here can now be found a brilliant, fully endemic assemblage of creatures unlike any before them. 255 million years PE, during Serina's golden age of biodiversity, the little blue moon has firmly become the world not only of birds, but that of the terrestrial toothed-carps; the tripedal teleosts; AKA, the tribbets.

The ancestors of tribbets, the mudwicket fishes, first emerged from the water onto the sandy shore a staggering 230 million years ago, when Serina was a young world and few other modern clades had evolved at all. The first still bipedal vivas were just beginning their first evolutionary forays into live-birth; the softbilled tentacle birds would not evolve their namesake facial appendages for almost 50 million years; and the metamorphic birds were still far off in an uncertain future, their ancestors at the time still nondescript perching birds that flitted through the background art of more notable species. The forays of these earliest tribbet ancestors were brief. Their movements, powered by sideways flicks of their tails and heaving motions of their pectoral fins, were clumsy at best. Yet in a world lacking in reptiles or amphibians, and their subsequent niches often unfulfilled, they found much to be gained in colonizing the land. Food and safety from waterborne predators were significant pressures toward improved terrestrial adaptations, and the first true tribbets were firmly established on Serina by 75 million years PE. They now had watertight skin and could breathe atmospheric oxygen exclusively with a set of lungs derived from the uppermost pocket of the stomach. The pectoral fins developed steadily stronger bases, eventually coming to form a proxy of the tetrapod forearm, with the fin rays becoming digits at the end of a wrist, while the tail formed a sturdy third leg, though early tribbets experimented considerably with different tail postures and weight-bearing designs. With fins and tails repurposed as walking limbs, some tribbets come to resemble reptiles and to fill similar roles in their ecosystems. More than one hundred million years later forms such as these earliest still persist, though in less abundance than in past eons, as ectotherms that rely on the sun's rays for warmth, with sprawling posture.

But the three-legged form was sturdy and successful, so much so that other lineages evolved over time toward more active habits. By 150 million years PE a new family of tribbet we knew as the hoppers was evolving, more energetic with the ability to regulate their own body temperatures independently of their environment and tied closely to increased care of their young after birth. To maintain the warmth they generated with their metabolism they developed a thin hair-like integument keratin from their scales, which narrowed and thinned into a heat-retaining pelt - sparse and fuzzy at first, becoming dense and furry over time. Around the same time they adopted a fully upright posture made possible by a 90 degree rotation of their tail-leg, naturally oriented to flex side to side, so that it could be pulled fully beneath the body and bent in the back and forth axis. At the very end of the Thermocene some 170 million years PE, just before the world was racked by its worst mass extinction to date, the tribbethere clade rose and became one of just a small handful of successful disaster taxa. The first tribbetheres were nimble, fast-moving carnivores that bounded on three legs - small but fierce - and preyed upon birds, eggs and anything else they could engulf in their expansive toothy jaws. Their gill arches had evolved by now into remarkably mobile ear pinnae that focused their hearing and, along with their hair coats and the form of their limbs, subsequently gave them a mammal-like outward appearance - as long as the jaws were closed. When opened their jaws extended forward and out, revealing disproportionately sharp and deadly teeth that could reach out and pluck prey. Indeed, it would become these specialized, extensible jaws - inherited as they were from their earliest aquatic ancestors, the live-bearing fishes that used them to catch their own tiny prey - that would now become the pivotal trait in their evolution. By the Ultimocene the tribbetheres had evolved into athletic pursuit predators (canitheres), secondarily aquatic fish-eaters (mertribs), seed-cracking specialists (molodonts), gracile grazers (circuagodonts), and even powered flyers (tribbats), all of which compete effectively and are perhaps at times even more competitive than birds - and every one of these clades owed at least a degree of their success to their specialized jaws. With mouths that stretch and shear, reach and retract, smash and saw, the tribbetheres exploit the resources of their world in ways no bird ever could - and at times push the birds to the margins of what was once a refuge all their own. The relative abundance of niches that Serina's land offered in earlier eras allowed explosive adaptation and gave rise to numerous unique and endemic clades that would have been impossible with mammal competitors on Earth. But today, with tribbetheres as a new and highly competitive counterpart, ancient dynamics have returned. Birds now share a world ever-evolving, as life and its interactions becomes ever more complex in the climax of our world's history. And not all birds will survive the age of tribbetheres, an ongoing ecological turnover unfolding as we speak.

~~~

The diversity of early Ultimocene tribbetheres (and some close relatives) will be presented through several chapters. As a precursor to familiarize the reader with the relationships therein, the positions of notable tribbethere clades on their evolutionary tree can be observed in the cladogram below.