Serezelles and Razorgrasses
Serezelles
above: two species of serezelle; the warcrest (left} and the zebirb. The former is a browser, feeding on the sparse trees of the savannah, while the latter is a highly gregarious grazer. The zebirb is monomorphic, without external sex differences, but the male warcrest earns its name with a brightly colored, extendable crest of red and blue plumage that wraps around the back of its neck, which has been likened to the headdresses worn by the Native Americans.
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Serezelles are a group of cursorial, herbivorous placental birds evolved within the ornkey clade, which are native to the interior plains of the supercontinent, 228 million years post-establishment. Ranging considerably in size from shy, fox-sized thicket dwellers up to herd-dwellers as large as horses, the twenty or so living species are highly divergent from other ornkeys, having left the trees and adapted a cursorial, deer- or antelope-like in form and behavior. Serezelles are obligate quadrupeds, with their hind limbs positioned at the end of the body and their center of balance set forward, inhibiting prolonged bipedal locomotion. The wings are modified into lanky walking limbs, with the wrists being highly elongated. Descended from primitive knuckle-walkers, the serezelles still put weight on their knuckles, but the bones have subsequently joined back together, shortened substantially, and become bound in a rubbery pad of soft tissue, their claws projecting as sharp spurs from the inner wrist and used for defense. The hind feet are extremely elongated in a digitigrade posture with the ankle being set more than halfway up the limb. All weight is born on the very tips of the third and fourth digits, which are fused except at their tip and extraordinarily long. The hallux and second toe are raised high off the ground and are still well-developed despite serving little functional purpose, suggesting that the ancestors of the serezelle adapted their cursorial habits very quickly, without much time for the spare digits to be reduced.
Serezelles are notably very often marked with bold, contrasting patterns of stripes and spots, which likely serve to hide their outlines when moving in large groups; because even some largely solitary species also sport them, however, it's plausible that the patterns evolved originally to break up the animals' form in the dappled light of sun and shade at the forests' edge, where the group first established itself, as in such Earth mammals as the okapi and the young of many deer. In addition to serving as a distracting maze of color to predators, the dark patches are also mask ultraviolet patterns visible to the birds themselves that may have significance in attracting mates and communicating over distances. The main predators of the serezelles, tribbetheres, cannot see in this spectrum, and thus these messages can be sent in a sort of secret code.
All serezelles are mostly herbivorous, and lacking the specialized feeding mechanics of such extinct herbivores as vivas, their method of feeding is primitive and involves cropping vegetation and grinding their food in a gizzard with the aid of gastroliths in the manner of primitive birds. Their stomachs are large and capable of rumination, well-suited to break down grass and twigs and other cellulose-rich foods, though seeds and fruit as well as large insects are taken opportunistically by many species.
The young of serezelles, unlike earlier ornkeys, are born large and extremely well-developed, able to walk within minutes of birth. Though their mother protects them for the first few months of their lives, she does not provide them with any sort of nourishment, either through regurgitation or with a crop milk secretion, as many earlier bird groups have done. Though the parent will lead her young to food sources as she fills her own stomach and shows her young indirectly what is and is not suitable to consume, the chick must feed itself.
Serezelles are a young group, appearing within only the last ten million years, but like many pioneer lineages - groups that arise rapidly in response to the ecological vacuum following a mass extinction - they are already beginning to decline in diversity in the face of new competitors as the rest of the biosphere recovers around them. Though their method of reproduction gives them an advantage over more primitive bird groups, and indeed was likely at least partially responsible for their own displacement of the earliest wave of flightless grazing waterfowl which proliferated at the start of the Pangeacene, now it seems that their primitive method of feeding is catching up with them in the face of yet another newly evolved plant, and a vigorous up and coming group of competitors.
Razorgrass
Razorgrasses are a new clade of spreading, perennial plant of the cactus-like sunflower lineage, which have convergently evolved a grass-like appearance with creeping horizontal stems and thin, blade-like leaves. Having evolved in the hot interior of the new supercontinent roughly ten million years ago from a less vigorous bush-like ancestor, they are notable for sporting extraordinarily sharp leaf blades and stems embedded with very high concentrations of silica phytoliths. Many true grasses already incorporate silica into their tissues as a defense against grazers and have done so for hundreds of millions of years - indeed, Earth animals such as elephants which lose and regrow teeth throughout their lives have developed such adaptations specifically in response to the destructive effect this mineral has on their teeth. Razorgrass, however, deposits them not simply within its leaves but also as a dense covering of microscopic barbs over all of its tissues that makes them highly unpalatable and additionally served effectively to guard against evaporation in the hot, arid climate of the interior desert where they originated. In recent millennia the new smaller and spreading razorgrasses have crept out from the desert and begun establishing in more equatorial regions, aided by airborne seeds that can spread far and wide on the breeze, and displacing more palatable plains vegetation such as true grasses and clovers. This has had a negative effect on the ranges of the serezelles and other grazing birds reliant on these food sources, pushing them northwards.
Like the assassin grasses before them, but for a very different reason, razorgrasses are unpalatable as a food source. Whereas assassin grasses produced toxic chemical agents, it is the physical nature of the razorgrass that makes it hard to consume - quite literally. Heavily armored as it has become with mineral deposits, regular consumption is highly destructive to the toothless bills of grazing birds, literally sanding off the ridges required to grasp and process plant foods and in extreme cases filing down the keratin of the beak down to the underlying bone. Furthermore birds such as the serezelles are unable to chew, meaning that in order to break down their food they must swallow it and process it in their gizzards, a method which is effective enough with most foods but with the thin, brittle, and knife-like blades of razorgrass can result in physical injury. Razorgrass rapidly takes over grasslands in dry climates, proliferating into dense, dangerous mats of sharp blades during the dry season when actual grasses must go dormant. Though serezelles can manage to consume small quantities of razorgrass foliage during the wetter seasons, when it dies back substantially and is deprived of sunlight by the the choking growth of the true grasses, a diet of exclusively such as is often all that's available during the rest of the year results in starvation. As their bill is worn down and becomes raw and the esophagus suffers numerous cuts and abrasions, feeding becomes painful and the animal wastes away before the rains return. Areas where rainfall is reliable throughout the year, such as across the equator, are not suitable for colonization by razorgrasses but also typically support only short-lived grasslands at best, for these environments are rapidly invaded by the seedlings of trees and eventually give way to shaded forests. It is these forests - which the serezelles originally evolved out of - that may soon become their final refuge as the grassland environment is altered drastically by this new invasive species.
Razorgrass is unpalatable to all birds and is also very rarely eaten by insects - even leaf-cutting ants struggle to trim it. There is a group of animals that are able to process it, however, a group which can lay claim to one thing the grazing birds have not: teeth.