Serilopes

65 Million Years Post-Establishment

We are now 15 million years into the Cryocene. 65 million years PE, the global climate on Serina has changed little since the start of the era, but life continues to evolve.

Aardgeese continue to diversify, and are now almost uncontestedly the dominant megafuna group on land over Serina's eastern landmass, as well as being ecologically diverse, if less monopolizing, in the west. High levels of competition between the different flightless canaries, both vivas and other groups, continues to produce waves of new radiation, as new groups diverge with increasingly complex specializations that give them just a little bit more of an edge against their competitors. The earliest aardgeese were flightless, cursorial grazing canaries which evolved within just a few million years on Serina's lush grassy plains. They swallowed leaves, seeds, and strips of grass whole, tearing and pulling with a serrated bill, and practiced hind-gut fermentation to digest it all. This primitive method of plant digestion is less efficient than rumination but worked well for breaking down the coarsest plant foods, such as dry grass, and allow the animal to survive on a diet of lower quality than other herbivores could, by letting them constantly take in small quantities of food throughout the day. The earliest aardgeese were thus mainly grazing animals, and had to spend almost all of their waking hours feeding to survive.

The aardgeese in turn gave rise the vivas, which appeared now over 40 million years ago. Defined by the co-evolution of internal egg incubation and a primitive chewing ability, resultant from scraping a ridged tongue against the roof of the mouth, which improved their ability to digest tough plant foods, they too were herbivores, entirely flightless and well-adapted to run. They developed more efficient digestive systems and chambered stomachs and the ability to ruminate, regurgitating food back to the mouth and chewing it multiple times, just as mammals as diverse as deer, giraffes, and even kangaroos - which also evolved the behavior independently - do on Earth, which no longer required they feed quite as often. The first vivas evolved as browsers, but some of their descendants reverted to grazing behaviors. Unlike ancestral aardgeese however, they were now more selective. Rather than feed on large quantities of whatever they could find, like a horse, they picked and chose only the most tender bits and the newest growth. Many Earth ruminants have similar tastes, such as gazelles and wildebeest, which despite being advanced ruminants do still feed on grass, but in different ways then the zebras they coexist with.

By fifty million years PE, the vivas in turn had radiated significantly away from this ancestral niche and produced not only a myriad of new grazers and primitive browsers, but also omnivores and even a group of obligate carnivores, the raptorial banshees, which in multiple environments have carved out a niche among other predators despite being heavily adapted as herbivores, due to the much more efficient method of rearing their eggs which the group had evolved compared to other birds - a great advantage in cold climates. In the common ancestor of the omnivorous group which diversified into animals as distinct as the banshees and the shimmersnoot, the chambered, complex stomach rapidly and dramatically reduced in size and length, for a diet of animal protein is easily broken down and indeed can sour if it stays in a lengthy digestive system for too long. Carnivorous vivas did not lose their modified chewing tongues, though - rather, in the banshees, the organ became armored in barbed spines, a tool perfect to strip flesh from bones - while in the shimmersnoot it became a bony implement to pulverize mouthfuls of ants and break up their exoskeletons before swallowing them.

Now sixty five million years have passed since the canaries were introduced, and the vivas have given rise to another highly successful lineage, the serilopes. Serilopes evolved initially as one of those selective grazers just touched upon above, and notably have evolved the most efficient chewing apparatus as yet evolved in any bird. The tongue is large, strong, and highly muscular with a bony core, and is covered upon its upper surface in a series of keratinous plates which mimic molars and grind in a circular motion against a series of similar plates that cover the roof of the mouth. As an advantage over mammals' teeth, the serilope's tongue and jaw plates don't wear out, as they constantly grow outwards as they are worn down through the process of chewing. To prevent food from falling from the mouth, and allow the serilope to chew, swallow, and then regurgitate mouthfuls of food to chew again as it ruminates, they have evolved fleshy cheeks that run along most of their jaw. The jaws are almost completely soft and fleshy, with gums where once was a hard beak, save for multiple rows of tooth-like keratin plates in the upper jaw. Indeed, while the beak of most vivas still covers most of both jaws, on serilopes it now only covers the very distal edge of the jaws and functions only to crop plant material, like a set of incisor teeth. Serilopes evolved in the northern plains of Serina's eastern continent but rapidly spread; some still-omnivorous species, able to cross over winter sea ice and perhaps feed on carrion along the way, have even reached the west.

Above: top: Banshee, a specialist predatory viva, showcasing barbed flesh-stripping tongue.

bottom: Serilope, a specialist herbivore viva, showcasing the skull and bony grinding "tonguejaw" and extent of soft tissue.

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Serilopes were the first canaries to produce true live birth, but the retaining of the eggs inside the mother's body until after hatching - a seemingly simple step that marks the final culmination of the process of internal incubation - will over time occur in other viva lineages.