The Late Rodentocene: 20 Million Years Post-establishment

The Late Rodentocene: 20 million years post-establishment

Bats All, Folks: The Ratbats

The absence of birds as airborne competition has greatly encouraged the development of powered flight in the gliding kiterats of the Middle Rodentocene. As of the Late Rodentocene, these flying hamsters have expanded in great success, and their ability to fly has allowed them to colonize every continent, and by 20 million years PE, over a thousand species of ratbats are extant, filling nearly every niche imaginable.

Many of the more primitive and basal forms are insectivores, adapted for catching bugs midair. Some larger species of the basal lineages have become hawk-like predators, such as the wingsels (Mustelovolaticus spp.), which specialize on small, ground-dwelling prey such as jerryboas and furbils.

However, others have diverged into new and unusual behavioral niches as they became increasingly specialized into other lifestyles. Some, such as the nightflyers (Noctinyctomys spp.) retain their insectivorous diet, but instead avoid competition with their other relatives by being most active at night and Beta-twilight, feasting on the buffet of nocturnal insects. Others have included new supplements to their diet, such as the blue birbbat (Cyanoptera lagocephalus), which feeds mostly on insects but also includes nectar in its diet, its long bristly tongue adapted for probing bugs out of their nests also being surprisingly well-suited for penetrating flowers to reach its sweet prize, and acting as an important pollinator in the process.

The ratbats thrive in dense forest too, where smaller species take advantage of the abundance of seeds, fruit and insects in the treetops. Some, such as the nutcrackers (Pterosciurus spp.) feed mostly on seeds and fruit, which brings them into partial competition with the arboreal squizzels and spunkmunks: but one competition that they can also alleviate due to their ability to catch flying insects out of the reach of their non-flighted rivals. Others specialize on feeding on wood-boring insects, such as the woodchippers (Xyloclastes spp.), which gnaw through bark with their incisors to reach deep into trees to feed on burrowing grubs, and also take advantage of the sugary sap that flows when they chew on the inner wood.

And as larger creatures begin to evolve in the Late Rodentocene, some ratbats have become large-scale scavengers as well, such as the mountain hawckal (Cynopteramys alpinus), a condor-like scavenger that nests on clifftops and searches out carrion of cavybaras and bumbaas that have been left behind by ground-dwelling predators. With a wingspan of over six feet the hawckal is a less agile flyer, and instead soars for long distances riding on air currents to conserve energy.

But though they closely converge upon birds in flight and in niches, the ratbats are anatomically and behaviorally very different. For one, they are quadrupedal on the ground, running on all fours with their wings, which bear two clawed fingers possessing paw-like toe pads, and to take off they utilize a vaulting launch similar to that of pterosaurs, pushing up with their front limbs to launch themselves into the sky.

Like all mammals, ratbats give live birth and nurse their young on milk. As pregnancy adds extra weight and makes flying difficult, this favored the formation of pair bonds, allowing the male to forage for food while the expectant female stays in the nest, and once the young are born the responsibility of defending them goes to the father, with the mother foraging for food and returning only to nurse the young. In some species, communal nests of related individuals are formed, with multiple mated pairs caring for each others' young and cooperatively defending them until the young are weaned and strong enough to fly on their own.

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