Burdles of the Late Hothouse

Burdles have never been more diverse than in the late hothouse age, 290 million years post-establishment. And though highly derived groups like the (generally) rodent-reminescent murds might be the most successful burdles, and the only ones now found worldwide, morphologically primitive burdles continue to hold their own alongside them. Though the largest brutes - hothouse Serinaustra's first apex predators - have largely been displaced by other carnivores, even these lineages survive in the form of smaller, more specialized species. "Primitive" burdles today include species of every imaginable diet, from plant-eater to predator and specialized scavengers. Allied by similar appearance - especially their scaly skin and prominent osteoderms - though not all of these burdles are closely related to one another, their relationship as burdles is clearly seen. 

Murds, though, have diversified so highly so that some species are now nearly unrecognizable. No longer just seed-eating specialists, murds of the late hothouse include varicolored fruit-eaters, arboreal leaf-eaters, and even fierce predators. Though burdles are constrained by their less malleable anatomy more than other hothouse clades like the skuorcs, they have accomplished a lot with what they have, and have infiltrated a very wide variety of niches both large and small in their ecosystems. Though murds may now be found in both the northern and southern hemisphere, the diversity of burdles as a whole is still strongly centered around Serinaustra, the continent of origin of all hothouse burdle clades. 

The crown-of-thorns is a species of armored burdle related to the digdags. It is behaviorally and physically similar, being adapted to dig insect larvae out from their hiding places in the longdark swamp. Sharing the same prolonged parental investment of its relative, a mother is pictured here with her single baby, which will stay with her for more than a year. These burdles very closely resemble the digdag in shape, for they live similar lifestyles, but they have evolved even more elaborate bony horns upon their heads which radiate outward in a fan-like shape, providing protection to the neck when they arc their heads back and lie low to the ground when threatened - this makes them among the most strikingly ornamented burdles. Despite being more decorated, however, they diverged earlier, and are the more basal lineage. More than a passive defense, their horns are also used as weapons; the crown-of-thorns is sturdy, but small enough - just about 30 lbs - to still be maneuverable and light on its feet. Mothers will viciously defend their young, charging forward with head lowered and then raising their crown into the underbelly of an attacker so as to impale it, then tossing it up and to the side.

While their relatives are carnivores that feed mainly on insect larvae dug out from rotting logs, crown-of-thorns are more specialized. They usually are found in association with stands of the sugary polepoa grass, in which many large beetle grubs have evolved to spend the longday summer gorging within before they emerge from the dying stalks at the start of the longdark night. The small crown-of-thorns is well-adapted to shelter within the dense thickets of these tall plants during the summer, where their small babies are less vulnerable, and to reach up and pry the canes down with their hooked claws. Once felled, the entire stalk can be investigated top to bottom, with the burdles using their strong sense of smell to identify grubs hidden in the soft interior; when one is detected, it rips the stem open with its strong beak and plucks it out. Mothers feed their babies for months before they are strong and skilled enough to be up to the task on their own. Perhaps first incidentally, the ancestors of the crown-of-thorns would eat some of the plant too as they hunted for the bugs inside, and as it was sweet and easily digestible compared to other foliage, they benefited from it. Now this is a regular part of their diet - up to a third of it - and this species has become a true omnivore.

In winter, when the thickets die down and become barren and the grubs have turned to large beetles and flown away to breed in the dark, the young are large enough to follow their mothers to more open environments and to switch to digging up insects and worms from the ground, as well as some roots and nuts that fell to the forest floor in the fall. Here they come across their relatives more often, still competing for some resources but partitioning their niches relatively well, particularly in incorporating vegetable foods that digdags are unable to digest. 

The oblidon is a descendant of the brutes - Serinaustra's first large predators, little-changed but much bigger descendants of the burrowing burdles which rafted there at the end of the ocean age. But that was 15 million years ago; new predator guilds have arisen here at the bottom of the world, and the burdles no longer rule the landscape with such dominance. Now the brutes live on as smaller, more specialist carnivores. Of them, the oblidon - a medium-sized, stocky animal which eats mostly the large bones left behind by other hunters - is one of the most specialized. 

The Oblidon genus evolved some five million years ago as a fearsome predatory brute called the bonebruiser, but competition with the squabgolbin has reduced them today to the role of smaller obligate scavengers, which have adapted to use a resource that other predators leave behind. Prey is abundant in this wet, green land, and active predators rarely need to use every part of their prey to survive as they would in harsher habitats. Thus even now, few animals in this part of the world where no molodonts have reached have the jaw strength to break and consume large vertebrae, ribs, and limb bones, so when the meat is picked clean, they are left scattered on the ground. The oblidon has now evolved to take full advantage of this opening in the food chain, which in turn keeps it from competing with those dangerous scroungers for flesh food. With a slower metabolism than many other large animals, it does not need to eat every day, so can afford to travel the landscape in search of carcasses that are not predictably distributed. Over time as it evolved, while its body size reduced it grew an absolutely gigantic beak that can now splinter even the biggest bones to access the nutritious marrow within. Though these burdles will still eagerly eat fresh meat when they can get it, and can use their well-armored bodies and large beaks to bully their way into the fray, more than 75% of their diet is bone, a resource that they find no competition for. In general, the only time oblidons specifically seek out flesh over bone marrow is when females have young with them; their dietary preference for such a hard food means that these burdles have had to become more attentive parents, much like the crown of thorns. Mothers keep their offspring close, and will help break open bones for their young - usually born in litters of two to three - for as long as two years. For burdles, this is about as devoted as parenting ever gets.

One descendant of the brutes has taken to a much different lifestyle to survive as its environment changed around it. Living 290 million years PE, the beachbully is yet another burdle species that has become aquatic. For all the living burdles have a shared marine ancestor, and they return to their homeland readily.

These burdles descend from land-based brutes that began foraging for food along the sea coasts about 12 million years ago. They are now fish-eating predators well-adapted to swim - which, granted, is not hard for most burdles, for they all evolved originally from sea animals to begin with. With sturdy flippers and webbed hind feet, beachbullies make their homes in shallow coastal waters, where they nimbly chase and catch their slippery aquatic prey in their elongated serrated beaks, and where they avoid the many competitors on the land. Though they still have prominent back scutes which may make it harder for them to be bitten by larger oceanic predators, most of the body scales in these burdles have become smaller. Females have only small scales, and much of the body is smooth and all but scaleless. Weighing about 250 lbs, they are fairly small sea animals and are generally shy and avoid conflict. But with a name like beachbully, this is only half the story.

This burdle has extreme sexual dimorphism, meaning that male beachbullies are very different from their mates. They are huge, able to surpass 800 lbs, and they have large crests of keratin horns on their heads and throats as well as knife-like serrated scutes on the backs of their flippers. The males use these weapons, as well as their great size, for one purpose: combat. And their targets are other beachbullies.

Beachbullies only spend part year at sea. For the remainder, they live on the shore. Females need dry land to nest and brood their eggs, and males compete vigorously to claim the best beach territories for the females to choose. Beginning several weeks before the females start arriving, male beachbullies begin battling along the shoreline, rising on to their short, fat hind legs and beating one another with their slicing scutes and head crests. These fights are bloody and rough, often lasting many hours between similarly-sized males. By the time the females have come, only the strongest males have taken control of the shore, and they have their pick of the best nest sites and the fittest partners. They mate with their chosen males, and soon begin digging out a scrape in the sand in which to lay their eggs. The males, exhausted by their battles, leave soon after and do not protect their partners nor their offspring; their contribution begins, and ends, with the delivery of their genetic material. 

Burrowbreakers are the closest relatives of the oblidon, and they are the smallest of all the brutes. But it is their diminutive size - about the same mass as a badger - that is now their biggest advantage. The ancestors of these hunters, as they were gradually displaced a the top of the food chain by more active, intelligent carnivores have now found a stable niche hunting the ever-present small burrowing animals - mostly murds. They dig these small animals up from the ground with their large claws that they hold folded up so that they must walk on their knuckles, similarly to the oblidon. Finding its prey by scent, it can unearth hidden tunnels in seconds and move with surprising rapidity to catch a fleeing victim in its long, notched beak.

Similar environmental pressures, and a notable lack of northern animal groups, has shaped this burdle into a similar form to the Serinarctan gravediggers in an intriguing example of convergent evolution. Though outside it is quite distinct, for it has no feathers, still wears a thick scaly hide, and has elbows, its skull shape in particular is nearly identical save for a much smaller braincase, and could easily fool a casual observer. Like them it is also aggressive and hostile, presenting itself as it shuffles along the ground with an immense level of bravery. It backs down to almost no creature, facing up against all comers with abundant displays of threatening pose and posture that it will not hesitate to back up with a bite - and even though it is small, even much larger creatures are often unnerved by its confidence and give it right of way. If it does find itself in the jaws of bigger enemies, it will fight savagely, relying on its protective hide to blunt the blows of teeth and turning to slash its enemy with its sharp claws and vicious jaws. Of all hothouse burdles, this one still most closely resembles the Meridian ancestor of them all, the blade-beaked burrowing burdle. It is among the most generalized brutes, and the only one which is still omnivorous; in between digging up animal prey, it readily gobbles down roots, tubers, seeds and fruit - nearly anything that can give it a little bit of nutrition will be accepted. Combined with its small size and an adaptability of habitat that lets it survive in both forests and drier uplands, as well as along the sea coast, it is among the most adaptable single burdle species, and is the widest ranging Serinaustran burdle, found in every habitat on this continent. 

It manages this despite having practically no parental care; while species like oblidons have few young and care for them for years, burrowbreakers have evolved to lay large egg clutches which they abandon to the elements from day one, using only ambient temperatures to develop over a longer timespan than most burdles, but also being able to lay many more eggs than they could if they had to brood them. The female's whole contribution to her offspring's survival is to dig out a shallow burrow to hide them in, where they are safer from at least the least observant predators. An elevated, north-facing slope is usually selected, as water will not pool and drown the eggs, and sunlight on the slope will provide just enough warmth to aid in their development. When they hatch, they are independent little hunters in their own right, and they scatter into the undergrowth to avoid their own enemies that will include their own mother, unable to recognize them and non-selective in the small burdles she eagerly preys upon. 

Though murds make up most of her diet, this clade of burdles has become so varied in form and behavior that there is no reliable way for her to distinguish them from other types of burdles - and to her, any burdle which she can catch is a tasty one. But no longer just little, scurrying seed-eaters, murds have become the most varied burdle lineage of all.

 Murds are a highly-active group of burdles that utilize the consistently warm and mild climate of their environment to be almost as active and energetic as equivalent endotherm animals without the associated metabolic costs. Generally, they are adapted to be small animals, energetic and lively, and with fast metabolisms. Nonetheless, in the late hothouse, several species have reached relatively large sizes. Duikerducks, for example, can weigh as much as 60 pounds, and so they are now among the biggest of the murds. 

These animals are extremely common in Serinaustra's forests 290 million years PE, especially north of the polar circle - yet they are cryptic, shy, and very difficult to see... most of the time. They have to be elusive, for they can no longer burrow or climb trees to flee enemies. Fullyterrestrial, these quadrupeds spend most of their lives in dense forest vegetation, where they feed on seeds, green shoots and especially fruit, and so are born with camouflaged mottled brown to green skin that varies by species but always blends in to the background. They are nervous and elusive, moving in small flocks which work together to listen for any sound of potential danger. Their sight and hearing are keen, and any rustle in the leaves catches their attention and may trigger them to flight, bounding away into the densest thickets of thorns and sticks to avoid their many enemies. Yet there is an occasion, every year, where caution is thrown to the wind: the mating season.

For most of their lives, male duikerducks are identical to females. These burdles, like most, are born and abandoned immediately to take care of themselves, and so begin their lives hiding in thickets and being hunted by almost anything that hunts. At this stage both sexes are alike, though they continue to grow larger after around a year of age when females are nearly grown. Around their second birthday, however, the males undergo a rapid and dynamic change. Their color changes in a matter of weeks to brilliant shades of green, gold, violet or blue that differ dramatically in each of the otherwise highly similar-looking species. Most species develop a small horn on the upper beak, which flushes red. They begin gathering as much fruit in their crops as they can find, but not swallowing it; it is for a more important use later, and they will live off their fat stores for now without eating at all. Within a few days, with distended crops, they then gather in numbers in a more open area of the forest, often where a large tree has fallen and left a sunlit gap in the middle of a dense thicket. There they strut and display, not fighting amongst each other but posturing and showing the full splendor of their colors. Females soon arrive in the clearing, sticking to the margins, observing each male. When she finds one that she likes she approaches and inspects him closely. He will feed her some of his fruits to cement a bond, and if she is satisfied the pair will then mate. How much food to share is a complicated choice for a male; if he does not share enough, a female may find him stingy and move on to another male. Yet if he gives too much, but still does not keep her attention, she will simply leave and he may be left without any fruit to give to another partner, ensuring no breeding success. Larger, better looking males thus tend to be stingier with their gifts while smaller ones overcompensate with lavish offerings. As males do not help the female further after mating, the combination of how big and bright he looks physically, and the quality of his single offering of food, is all she has to go to determine suitability as a father for her young. By judging a mate on two qualities - both foraging abilities and appearance - she may get a better judgement of male fitness than if she only focused on one or the other.

Male duikerducks are highly visible to predators during the mating season, and though they select their display clearings based on close access to cover to bolt to in the event of danger, mortality is nonetheless much higher for males at this time than for females at any time; only 50% of males live on to the next breeding season, so that only a very few indeed live past three or four years of age. Those that don't get picked off keep their colors for less than a month, shedding the outer layer of their skin to reveal an earth-toned mottled pelage again just three weeks later, and returning to a life of secrecy for another year. 

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Life for most murds, being small and on their own, is rife with danger. Mortality among the young is always high, and most adults still face a deadly world. Nearly any hunter will eagerly gobble up a murd, including some other murds. So it is for the treetiger, a predator in its own right, whose favored victims are those closest by it on the tree of life.

High up in the branches of Serinaustra's near-polar forests 290 million years PE, a tense interaction is occurring as a fierce treetiger corners a bearded scrumble. Both of these murds are unusual in their own ways. The predator has evolved rather un-murd-like traits, such as long, sharp jaws adapted to crush the windpipes of small prey vertebrates  - a jump its recent ancestors have made from hunting insects - and now it jumps quickly and light in the branches with powerful hind-limbs to tackle its victims and overpower them. The prey - a male, showing characteristic bright yellow erectile crests of scales over its eyes - is slow-moving, a specialized, sloth-like leaf-eater, and cannot outrun its enemy, for its non-nutritive diet has made it sluggish. Its only hope now is to stand its ground, threatening its attacker with its outstretched arms, edged with blade-like scutes and a single sharply hooked claw equally suited to find grip in the branches and to wound a carnivore. It inflates a spiky, black gular pouch, making itself look larger as well as providing some protection to its throat from the treetiger's sharp beak. The scrumble will box and weave, trying to pummel its enemy while avoiding its deadly bite, and likewise the treetriger will dodge and strike to attain its goal of a meal. The fight can go either way now - it will come down to which creature has the better luck.

Both of these small animals, as different as each looks and despite their antagonistic interactions, they are among one another's closest cousins; along with the gliding hurtles, they make up their own offshoot of the murd family tree. The treetiger is the only species in its genus, and it is the most carnivorous murd and the only one adapted to kill vertebrate prey as its primary diet. There are some half a dozen species of scrumbles in two genera, meanwhile; they are all small, herbivorous animals almost partway between the niche of a squirrel and a tree sloth, mainly solitary and almost never coming to the ground. Only the bearded scrumble has either large eyebrow crests or a protective throat pouch, with its closest relatives being less adorned, but larger, and so less vulnerable to this enemy.  Neither species has parental care, but unlike many predatory burdles, the treetiger seems able to recognize its own young by scent cues and does not prey upon them. As murds, generally, have bigger brains and a greater capacity for social interaction than other burdles, this may be an artifact of this ancestry, even though the treetiger has become solitary once again.

One of Serinaustra's rarest burdle species is also one of its most primitive. The stoneslink is a late-surviving basal burdle, descended from the nightcreeper, and representing its own solitary branch from that lineage. Much littler than this ancestor, it faces significant competition from the far more derived murds as well as other animals, and is today present only upon a single, very rare habitat known to exist only within the clearview mountains: grassy balds. These treeless hilltops are uncommon, rarely more than one to two miles square, and often many miles apart. They are formed through a combination of lightning-sparked wildfires, which can only spread over the vegetation growing on the highest, most drained soils, as surrounding land is too wet, and the continued heavy grazing of large animals afterwards, which then prevent the return of the common woodland vegetation. Grasses and plains plants colonize the clearing, and with the right animal presence, forest doesn't take it over again for decades to centuries.

The rabbit-sized stoneslink is a small omnivore which seeks shelter in rocky crags and crevices on these isolated hilltops, able to flatten its ribcage and slip into holes just 3 inches high. It hides by day from many predators, especially large flying birds, and emerges by night to hunt for small animals, insects, and to graze, using its heavy beak to crop the hill grasses. It is solitary, and its numbers are low enough that males often have to leave their territories to find females on other hilltop islands, so that they may make the journey and mate only every few years. Much of their life is spent hiding in the cracks and in burrows they dig out in boulder piles, where they can spend weeks at rest without emerging to feed thanks to their low metabolism. Their lifespan, if they avoid predators, is quite long, and some individuals may live more than fifty years this way, only breeding a handful of times. Females are adapted to make the most of infrequent pairings, and can store sperm for a number of months in a chamber in their reproductive system to lay two or three clutches of eggs back-to-back from one mating. Clutches are large, consisting of ten to fifteen eggs, which hatch in just over a month and leave the mother's care almost immediately. They spend their first few days on their birthplace hilltop, but instinct tells them to migrate soon after, and at night they scatter in seemingly random directions, careening downhill for a while before seeking to climb upwards again and search out a new grassy bald. The success rate is about one in one hundred, and those which fail to find suitable habitat are likely to fall prey to other animals fairly quickly, though it is not uncommon for very young stoneslinks to survive for several months under forest logs and other suboptimal habitat before finding a suitable place to establish a lifelong territory. Though these animals don't have strong defenses, spiked scales on their inner arms can be squeezed onto enemies that attack them in a pinching manner to help buy the creature time to flee.

With their habitat scarce, and other environments poorly-suited to their needs, this relic's future is uncertain upon Serina. Yet in times now not far off, the climate will shift and the forests become drier, potentially giving this ancient survivor new land to claim, as the hothouse now nears its end. Fluctuating climate will ultimately transform Serinaustra in the eons to follow; just which of the many, varied burdles successfully adapt is unknown. Their great variety of sizes, diets, and lifestyles will work in their favor, however, guaranteeing that at least some will be pre-adapted for changes to come. For the burdles are nothing if not tenacious; having already lived through several mass extinctions and re-colonized the land not once but twice from the sea, they have already demonstrated that it will take more than climate change to keep them from thriving upon Serina.