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tribbetherium · 5 months ago

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The Early Rodentocene: 5 million years post-establishment

(Remastered from this entry)

In the Middle Temperocene, a hundred and fifty million years after life was put onto this planet, the creatures that roam and live and thrive upon its surface have attained a pinnacle of diversity, with such a diverse range of sizes, shapes, colors and niches that it seems improbable, impossible even, to fathom that they once had a common origin, from a single humble species.

But this was not always the case: early on, when the world was young and its creatures small and unassuming, the animals that filled its forests, plains and grasslands were still clearly of close kin, recognizable as hamsters- or at least a similar related rodent. Yet they had already begun to fill the niches that were open in the empty ecosystem, quickly diversifying in a short period of time into grazers, seed-eaters, insectivores, omnivores, foragers and predators. In a retrospective view, these early species were the forerunners of peculiar, very derived, and unexpected descendants, yet already bearing the beginnings of the defining characteristics of these clades. But during the time in which they lived, they were but ordinary creatures: living their lives blissfully unaware of the grand future to come.

Among the first pioneers of the tree-tops in the Early Rodentocene was the speckled peachpitter (Archaeosciurucricetus punctus), a descendant of the hairy-tailed hamster subspecies Cricetulus griseus hirsutolongicauda. Their long, hairy tails proved useful to balance as they clambered up the trunks and branches of the abundant stonefruit trees, and the atavistic re-emergence of a fifth digit on each paw, independent to that of Cricetulus griseus pentadactylus, would prove an advantage in scaling and getting a grip on the rough bark.

In this lush, predator-free environment, the speckled peachpitter was a bold, fearless and abundant creature, leaping from branch to branch in great numbers out in broad, open daylight: entirely unconcerned by aerial attackers which had not existed at this point. It was the influence of this miniscule arboreal hamster, in fact, that would greatly shape the evolution of HP-02017's plant life. Feeding on the large, single-seeded fruits of the earliest stonefruit trees, the peachpitter destroyed countless forests in its time by eating too many of their large, vulnerable seeds, and created a selective pressure toward smaller, harder seeds and more protected pits: bringing about the early forebearers of the many-seeded pebblefruit and the hard shelled disnuts, both of which remain highly successful in later eras.

With hardly any enemies to concern them, the speckled peachpitter is active all day round, resting intermittently and foraging day, night, or Beta-twilight. In temperate areas where snow is present they may reduce activity and reproduction during the cold winter months, but in tropical climes they forage and breed all year round, producing large population spikes from time to time depending on local food availability. With hardly any enemies, speckled peachpitters are also rather neglectful parents, producing many young in litters of six to ten on average, nursing them only for two weeks until their fur grows in and their eyes open, and almost immediately leaving them behind to fend for themselves. With little else to threaten them, their population is instead leveled off by high mortalities from harsh competition during periods of food scarcity. Until something emerges to keep their numbers in check, they will continue this boom-and-bust cycles of population, and live a risky but fearless lifestyle, all the while shaping the world they live in, by forcing other life-forms to adjust to their ravenous numbers.

Agile in the treetops, this early species will, in time, become the ancestor of the Arbocricetidae: a vast, diverse lineage of tree-climbing species with prehensile grasping limbs and fur-covered tails that are skilled acrobats among the branches of their canopy home. While many of them would remain similar to the speckled peachpitter as small, recognizeable rodents, two particular lineages of interest would arise from this group. One, developing opposable digits, larger body sizes and larger brains from acquiring complex social behaviors, would become the primate-like lemunkies. Another, developing membranous webs of skin between their limbs to travel from tree to tree, would eventually progress into powered flight: giving rise to the earliest ratbats.

Meanwhile, across the continents of Nodera, Westerna, Ecatoria and Easaterra, a descendant of Cricetulus griseus pentadactylus would instead spread far and wide across the plains and grasslands, its efficient bipedal locomotion allowing them to cross the land bridges before they sank early on. The most widespread of these, the common plains jerma (Dipodoeocricetus saltus) would make it to all four of the major continents and in time dominate the open grounds. Only the isolated Peninsulaustra and Borealia, having separated earlier, would be out of their reach, though these would eventually be reached far later by small species rafting or migrating over times of briefly-lowered sea levels.

The common plains jerma is distinguished by its long and powerful hind limbs, and, perhaps surprisingly, its long tail, which compared to some of its later descendants was still relatively short and stiff, comprised of few but elongated caudal vertebrae derived from those of the ancestral Cricetulus griseus, which had proportionately long tails for hamsters. These structures allowed them to balance and run and leap on two legs, enabling them to cover large expanses of ground in search of food and evade some of the earliest predators of the Early Rodentocene.

The common plains jerma is both a skilled runner and hopper, moving about quickly on its two hind limbs while its forelimbs are relegated to grooming, digging burrows and holding and grasping its food, which may consist of grasses, seeds, fruit, and the occasional small insect if it can catch them. Common plains jermas breed all-year round, with their young being fairly precocial for hamsters, born larger and fully-furred and more developed. Their eyes are open in about a week's time, and almost right away are able to follow their mother as she leaves the burrow to forage. Unlike the speckled peachpitter, which shows little concern to its young, the common plains jerma is a more dedicated parent, leading its young toward food and shelter and away from danger in the more precarious ground level of the open plains as opposed to the safer treetops.

The descendants of the common plains jerma would, over time, diverge as the geographical isolation of its extremely widespread population becomes fragmented by the continents' separation. One lineage, specializing as walkers and burrowers, would become the long-tailed, facultatively-quadrupedal furbils, which continue to exist worldwide as small, "typical" rodents filling niches similar to voles, mice and rats. The other main lineage, becoming even more specialized hoppers, would develop longer, stronger hind limbs and even more flexible tails with increased numbers of vertebrae, giving rise to the jerryboas, from which the many bipedal clades, such as the oingos, walkabies, rhinocheirids, boingos, drundles, podotheres and pterodents would eventually descend from.

While the common plains jerma and its kin dominate the plains and grasslands, another herbivore is rising in prominence in the bushy scrublands, forest floors, and other areas of low-to-mid-height vegetation. Larger than most other hamsters, about the size of a large guinea pig and even taller due to long, slender legs, the scrubland goutie (Protoacaudamus altipus) is one of the biggest animals of its time, a trend that will only continue with some of its descendants.

Still possessing a vestigal nub of tail that will be entirely lost in future species, this descendant of Cricetulus griseus acauda has adapted to be a herbivorous grazer, turning its attention on grasses, leaves and stems, rather than the seeds, fruit and insects that other hamsters specialize on. Traveling in small groups, they forage on the tender stems of the earliest grasses, sometimes overgrazing small patches of grass when their numbers grow too plentiful. This degree of damage would over time pressure the grasses themselves to retaliate with defensive measures: some producing toxic, foul-tasting compounds to deter them, while others developing thorns or hard woody stems to make them more difficult to eat. This increased scarcity of easily-edible and palatable food, as well as the rising numbers of early predatory hamsters, would gradually keep the destructive effects of the scrubland gouties' grazing under check, with its presence heralding dynamic changes in the food web, both in the evolution of the plants it eats, as well as the first predatory hamsters that eat it, in turn.

Scrubland gouties are fast runners and live nomadic lives, traveling long distances in search of food. They do not dig burrows, merely seeking shelter in natural structures such as rocky outcrops or the shade of trees, and are constantly on the move. To compensate for this, they instead give birth to very precocial and well-developed young, in smaller litters averaging three or four at a time. Born fully furred, open-eyed and much more well-developed, they are able to walk within minutes of being born and are able to follow their mothers around in just a day or two. They remain in the care of their mother, safe from the small, predatory hamsters thanks to her large size and sharp teeth, for up to six months until they are weaned. Once weaned, however, the mother typically chases away the now subadult young, as, by this point, she is usually now preparing for and expecting her next litter.

With a stocky body and long limbs, the scrubland goutie is one of the largest hamsters of the time, and, as the eons go on, this trend carries on to its descendants, to whom large size affords them protection from the early predatory hamsters that, in this day and age, grew no larger than a rat. In time, as its descendants grow bigger still, two clades out of them become prominent and eventually dominate in the successive eras. One clade are the slender, fleet-footed hamtelopes, which, while playing second-fiddle to the boingos in the Therocene, eventually come to colonize Borealia by rafting or migrating at intermittent periods of lower sea levels, eventually producing the hoofed ungulopes: the dominant herbivores as of the Temperocene. The other clade, specializing on larger sizes and bulkier bodies, are the cavybaras, among which arose species such as the mison, the bumbaas, the hammoths and the piggalo, some of which becoming the biggest land animals the planet had ever seen.

Hamsters, however, are not the only animals introduced to the planet. With the need for detritus-scavengers, soil-burrowers and plant pollinators to create a functional ecosystem, a diverse array of insects were also introduced to the planet: beetles such as the darkling beetle, known for its mealworm larvae, as well as moths, ants, wasps and bees to act as vital agents to enable plants to reproduce. These are among a vast array of invertebrate life that also included free-living soil nematodes, earthworms, terrestrial isopods and springtails, as well as marine gastropods, some of which became terresteial independently of true earth land snails.

But such a diversity of invertebrate life would not go unnoticed for long. A descendant of Cricetulus griseus vulgaris, the forest shrewbil (Eomyotalpa polyvora) would quickly take advantage of this buffet of invertebrates, becoming a specialized insectivore that hunted insects, burrowed to search for worms underground and proliferated in the niche of small insect-eater rummaging through the leaf litter in the forest floor, searching for bugs to eat. Breeding all year round, mother shrewbils developed expansive cheek pouches to hoard large quantities of food for her fast-growing pups. Able to bear as many as four litters a year, and able to reproduce at six months old and keep breeding for the rest of their five-year lifespan, their numbers would come to swell rapidly in the Rodentocene: spelling trouble for invertebrates that lacked any means to deter these new enemies.

The emergence of this species would end up playing a significant role in what was basically the planet's first mass extinction: while occasionally eaten by hamsters beforehand, the local terrestrial invertebrates would never have been hunted at such a large scale as this before. Countless numbers of the initial invertebrate species would be eaten into oblivion by the ravenous shrewbils, leaving only those that had defenses, were able to quickly escape, or reproduced in even greater numbers to increase the chances that some would survive. Flying insects would remain mostly safe for now, but ground-dwellers, including large, slow-moving beetles and their fleshy, vulnerable larvae, and the first wave of terrestrial gastropods, would be completely decimated. One unlucky victim in these early days would be the twigbeetles: long-bodied, slender beetles that mimicked the appearance of twigs in the leaf litter of the forest floor, unable to fly or run fast but was gifted in stealth, staying entirely motionless to hide from attackers. An effective visual disguise against other predators, it unfortunately proved no match against the forest shrewbils' keen sense of smell, and would ultimately die out early into the Rodentocene.

With its insectivorous diet and burrowing habits, the forest shrewbil would be the precursor of the molemice: small-eyed, keen-nosed digging burrowers that spent much of their time underground. While rather typical creatures at first, in fact, the shrewbil may indeed actually have gone the most bizarre evolutionary path of all the initial species of the Early Rodentocene, even in comparison to the other clades' surprising descendants. The rattiles, ectothermic armored creatures converged upon a saurian form that became extremely successful in the Temperocene, the shieldears, with armored pinnae forming false jaws enclosing the head, and the cave dwelling daggoths, with their plethora of appendages and lack of any mammalian resemblance into borderline alien forms, each one among the strangest and most derived of hamster lineages, all owe their existence to the humble and mundane-looking forest shrewbil.

Shrewbils may have not been the first hamsters to develop a taste for fellow animals, but they were the most prominent. That was, until the emergence of the first proper carnivores, among them the golden huntster (Venatocricetus ferox). While cannibalistic tendencies had always been present since the original seeded hamster species, and interspecies predation had occured sporadically among earlier species, none had specialized to such a degree as with the golden huntster, with hooked claws on its forepaws for restraining struggling prey, pointed incisors for piercing bone and flesh, forward-facing eyes for better binocular vision, and a shorter digestive tract better suited for processing animal meat than plant matter. While no larger than a rat, the golden huntster was, in its time, the undisputed apex predator of HP-02017.

Like all other apex predators, the golden huntster ended up completely changing the dynamics of the world and its creatures upon its first appearance. Suddenly, this predator-free safe haven of plenty, a hamster's paradise, had once again become a battleground for survival, from one of their own coming to recognize its fellow hamsters as an abundant food source left unexploited by an empty niche. While the tree-dwelling peachpitters would remain complacent, down upon ground level other species would be pressured into defensive adaptations. The jermas would evolve into faster and more agile leapers, the gouties would grow ever larger to become more difficult to hunt, and the small burrowing shrewbils becoming even better tunnellers to hide from their newfound enemy. While the first wave of evolutionary radiation in the Early Rodentocene would simply be them diversifying to exploit empty niches and take advantage of new food sources, the coming of the golden huntster would kickstart another burst of adaptive radiation, as different species found new ways to survive its predation and defend themselves, flee, or hide in inaccessible places.

Golden huntsters, like all predators, are much more few and far between than their prey, but, like typical rodents, retain their extremely fast reproductive rate, especially now with a far more nutritious food source. During periods of population spikes, their numbers can be devastating to local populations of prey species, but fortunately, their numbers are kept in check by a most unlikely failsafe: themselves. Aggressive, solitary, and opportunistically cannibalistic, golden huntsters are not above eating one another when prey species becomes scarce or when huntster populations become too dense. While litters are born every few months, of up to eight babies each, few of those actually reach adulthood, with many falling prey to rivals raiding burrows seeking to eliminate competition, to their stronger, hungrier siblings while they share a nest, or even the mother herself, if she lacks the resources to care for many pups or is stressed enough to turn on her young. In a way, their own savagery to their own kind is a blessing in disguise, as it generally keeps them from getting too numerous enough to become an ecological menace.

The golden huntster would eventually give rise to the clade known as the hammibals: becoming the primary predator clade of the Early Rodentocene. But as of the Middle Rodentocene, they would find themselves gradually being edged out by two new clades of unrelated carnivores: both descendants of Cricetus griseus hirsutolongicauda. One clade would become the ferrats, mustelid-like predators able to tackle prey larger than themselves, which proved useful in hunting the ever-bigger descendants of the gouties, while another, the rat-like scabbers, became ambush hunters that lured in small, insectivorous prey. Pushed to the margins and relegated to becoming mere mesopredators hunting small prey, this dethroned pioneer lineage would only find success in the continent of Ecatoria. Here though, in the absence of competition, they would produce the large predatory hamyenas, which in turn would eventually give rise to the intelligent, adaptable and sociable zingos, a canid-like group that enjoys great success and wide diversity as of the Temperocene.

While other clades have begun to take shape as they occupy vacant ecological niches, some have instead taken refuge in the familiar. The banded dawndusk (Eocricetus linea), descended from Cricetulus griseus vulgaris, has remained basically unchanged in the last 5 million years, even as other lineages became hoppers and climbers and hunters and grazers. A small, crepuscular seed-eater with no notable anatomical changes, it is, basically, just a forest hamster. While adapted to living in burrows in the forest floor as opposed to their ancestor's desert habitat, its lifestyle is practically identical, emerging at dawn and dusk to hoard seeds in its cheek pouches that it then carries back to its burrow to stash away for later. Like its ancestor, it is also a frequent, opportunistic breeder, bearing litters of up to a dozen blind, hairless young that are dependent on their mother for the first few weeks.

The banded dawndusk, thus, is an illustration of the nonlinearity of evolution: while some branches of a taxonomic branch become more derived, in some cases extremely and unrecognizably so, others remain virtually unchanged. Evolution is not a race to be better or stronger, but merely a contest of surviving to reproduce, being simply sufficient to pass on its genes. And if the initial form is capable of persisting in its niche, then it continues to exist: alongside other divergent relatives far different from both it and the ancestral form they trace back heritage from.

Banded dawndusks are part of the group that would become the duskmice: a clade of abundant but mundane short-tailed hamsters that fill typical rodent niches along with the furbils. These change little over the course of the Therocene, Glaciocene and Temperocene, persisting in abundance as small and basal hamsters. And while, perhaps ironically, one related lineage, the aquatic pondrats, would emerge from the duskmice and dominate watery environments in beaver-like, seal-like and eventually whale-like forms in the cricetaceans, the direct descendants of the banded dawndusk would be the far more mundane hampters: a clade so remarkable in being so unchanged that it may in a loose sense be seen as a sort of living fossil.

Yet a future as an unchanged relic now prey to other lineages' more derived descendants is ultimately still a more fortunate outcome than no future at all. And yet, that is ultimately the tragic fate of the black-pawed dendend (Melanopodocricetus ultimus).

Very early on, at about one million years post establishment, as many as twenty separate subspecies would arise from the basal Cricetulus griseus subspecies. But of these, four of them would come to dominate: C. griseus vulgaris, C. griseus pentadactylus, C. griseus acauda and C. griseus hirsutolongicauda.

Other lineages would continue to persist in the margins, but as the "big four" began to diversify, one by one the other species' lineages would be outcompeted by the new species emerging from the four and occupying different niches. As of the Early Rodentocene at 5 million years post-establishment, only four other lineages survive: the descendants of C. griseus musculus, mouse-like forms eventually outcompeted by the furbils, the descendants of C. griseus macrotia, big-eared desert species that eventually lose out to the jerryboas, the descendants of C. griseus giganteus, large-bodied omnivores ultimately crowded out by the cavybaras and hamtelopes, and the descendants of C. griseus mirabilis, to which the black-pawed dendend belongs.

The black-pawed dendend would be the last one standing, persisting in the massive influx of new species from the four main clades. An adaptable omnivore, it persisted as a generalist despite the competition, by being able to consume a wide variety of food, switching from one to another even if it had no sole monopoly on each. Yet the final straw that would end up spelling its doom would be its eventual specialization on leafy grasses that would coincide with the emergence of defensive grass species fending off the gouties, as well as the rise of the huntsters. A combined double blow of a relatively sudden lack of palatable grass and the coming of a new predator that reproduced quickly would prove too much for them to overcome, and the black-pawed dendend would finally disappear shortly before the beginning of the Middle Rodentocene 10 million years post-establishment. There were winners and losers in the game of life, and in the competitive environment of the Early Rodentocene in the midst of rapid evolutionary radiations, the black-pawed dendend would, sadly, not come out victorious.

It would leave no living descendants, and be relegated as merely another footnote and experiment in the cladogram's family tree, while the descendants of the main four subspecies move on to greater things in the eras yet to come.

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#speculative evolution #speculative biology #speculative zoology #spec evo #hamster's paradise

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