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Spec Mammalia: Xenotheridia

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INTRODUCTION

Specworld mammals are perhaps one of the greatest enigmas of this timeline. That they were present in great numbers was not unexpected; that they had come to such a prominent fore front was quite surprising. Spec mammals are probably not quite as numerous species wise as their HE counterparts; however, a greater diversity of forms exists, with several archaic clades surviving to the present day. This has been a boon for mammalogists, who have had to revise much speculation to conform with existing reality.

Spec is home, for instance, to living multituberculates. These mammals, situated somewhere between the rest of the furry creatures and the monotremes; are greatly reduced from their former glory as "the rodents of the Mesozoic", but multituberculates are still present on almost all continents, and some form important parts of the ecology of their habitats. The gondwanatheres, a further group of frustrating, enigmatic, gnawing mammals; have shown themselves as the last of the plagiaulacoid multies. These very derived critters form a southern hemisphere analogue to the cimolodontans. The beaked mammals, the monotremes, have expanded far beyond our world's evolutionary pathways, producing not only a small number of platypus and odd terrestrial raccoon/glutton and mole like forms in Australia and Aotearoa , but a variety of giant marine forms, including the walducks, among the largest mammals on Spec.

Perhaps the strangest and most astonishing of the archaic mammal clades are the volaticotheres. These are the original bats of both timelines. Volaticothere remains extend from the Jurassic into the Maastrichian of both timelines; with putative remains uncertainly assigned to them from the Paleocene of both as well. HE either lost all it's volaticotheres at the end K or the PETM to be replaced by true bats. Spec never saw that event, although all modern volaticotheres can trace their ancestry close to certain Messel specimens. True bats never established themselves in Spec, and the bizarre egg-laying volaticotheres have remained supreme denizens of the nighttime skies.

Theria is well represented in Spec, though not as diverse as they were hoped to be. There are a few remnants within Quirogatheria, often called dryolestids. Metatheria in Spec has been a boon, since a large diversity of Boreometatherians and Notometatherians aside from Marsupialia is often well represented. This clade has spun out many weird and wonderful forms. However, the teasing South American Myrmecodelphidans and the Australian Specuperamelemorphans strongly indicate that true marsupials were present before the K in both timelines.

The Eutherians of Spec tend to be a mystery. They have a rather un-storied history for much of the Paleogene except for a few spectacular fossils causing much gibbering consternation to this day in both timelines. They have retained the archaic Madagascartherans. These bizarre eutherians are early birthers like metatherians, but their genetic and morphological profile allies them with their more advanced placental brethren. They are in fact the last of the zhelestids. There is an even odder critter, the Spec bibymalagasy; which may be the last of the Asioryctitherans.

Aside from that, all Spec eutherians frustratingly tease researchers. The remaining clades are obviously placental mammals; yet they mix known quantities with off the wall critters unlike anything known on HE. Several ancient clades are known, the xenarthroid Antarctitheria, the Afrotheria, the Glimates and even some apparent Laurasiatheria. The most likely fossil candidate for K placental diversification; the controversial Eulipotyphla, is rare in Spec, with just the bizarre almiquimorphic hellrats extant in Spec. 

Aside from the head scratching, the placentals of Spec have done their HE cousins proud in becoming the most morphologically diverse mammal clade of either timeline. They burrow under soil in the form of pig-shrews and bastardsloths, terrorize prey in the form of pokemurids and hellrats, swim the oceans as algae and kelp grazers, graze the toughest browse from mountain high to valley low, fly the daytime skies and rule as the preeminent muroids of much of the world. 

HISTORY

Xenotheridians ("little strange beasts") probably evolved in Asia during the Paleogene. They did not diversify into hopping lagomorphs or arboreal scurians, but instead stayed small ground-dwelling generalists. Xenotheridians are not true rodents, however; they possess four, rather than two, ever-growing incisors, and their pedal structure is bizarrely similar to that of the pokemusoids - unique primitive primates. This last trait may be convergent, but in any case, xenotheridians are clearly distinct from true rodents and rabbits (neither or which live on Spec). Although they are not true rodents, xenotheridians are commonly called 'specworld rodents', and indeed, a casual observation would place a xenotheridian right beside a homely mouse or guinea pig.

The mammals of Spec were mostly inconspicuous critters during the Paleogene. The late Oligocene/early Neogene saw the arrival of many novel clades and larger sizes, especially among aquatic groups. This more or less remained a steady state until the Pleistocene, when the evacuation of vast numbers of diapsids from much of the globe resulted in an explosion of mammalian diversity and size along with the feathery maniraptorans. Spec mammals today may reach up to 800 kilos on land and up to 10 tons in marine environs. This explosion of synapsid diversity is not limited to the cold zones, many clades are invading the tropics, where they have interesting effects on the local ecosystems. 

BIOLOGY

Specworld rodents are almost as diverse and successful as their Home-Earth counterparts, with representatives on every continent but Australia and Antarctica. Some species are tiny, while others grow to almost a meter in length. Some are aquatic, while others climb trees, hop on stilt-like legs, or spray poison on their attackers. While not as flashy as some of Spec's other fauna, the xenotheridia are nonetheless worthy of attention.

XENOTHERIDIA

Modern HE is unique in having basically just one small gnawing mammal clade, the rodents. Spec is more typical in having several such clades. The multis, the bilmys and various xenarthran clades. Not to mention the horning in of the bizarre bantam oviraptors.

Nevertheless, the spread of the Miocene grasslands gave rise to a sheer explosion of placental eutherian rodentimorphs. Both Spec and HE witnesses the rise of jerboid and muroid gnawing critters at this time that eventually swept away many archaic lines. The muroid critters in both timelines have been especially ruthless at exterminating competition. Spec had several Therian clades attempt to fill rodent niches during the Paleogene. All these groups were marginal critters that went extinct by the Oligocene. However, the spread of the early Neogene grasslands was quite a different scenario. Not only did many dinosaur groups adapt to the new conditions, so did a nascent clade of mammals.

The xenotheridians are distant relatives of the paraselenodonts. Together, they make up Spec's glires. Spec did have basal rodents at one time, some fossil remains are know from Paleocene and a few Eocene sites. They were never common compared to the multis. Many forms resembled HE's ancient rodents; However, they seem to have not been able to displace the djads and digga-dumdums prevalent across the Northern Hemisphere. Indeed, the late Eocene actually sees a complete extirpation of all these critters. 

However, the Oligocene is much more interesting, with a few strange lagomorphic limbic fossils and partial mandible known from Indian deposits. These reveal some strange relationships, possibly tying Spec's glires with leporid lagomorphs but not considered definitive, they are simply too scrappy. It is an area in need of much more research, especially after the recent molecular and genetic studies.

The Miocene grasslands are both a boon and a curse to Spexplorers. They show a sudden explosion of xenotheridians and paraselenodonts practically the world over except in South America, Australia and Madagascar (of course Antarctica was mostly frozen over and Aotearoa was too far away by this time). Both clades were already well distinct from each other at this time.

It is the xenotheridians we will concentrate on in this text. Like their paraselenodonts relatives, xenos (as they are informally called) suddenly show up across much of the world during the earliest Miocene. This has given rise to a hypothesis that won't die, that Spec's (and possibly HE's) Glires are Indian in origin. Given advanced HE leporids likely were already present by the earliest Eocene if not much earlier, it is possible that Spec and HE may well have had both the leporid and pika clades present before the end K. 

The xenotheridians ("little strange beasts") themselves may have evolved in India during the Oligocene. Superficially at least, they strongly resemble the rodents of our timeline. Xenotheridians are not true rodents, however; they possess four, rather than two, ever-growing upper incisors. They have pneumatic skulls, but also have vertebrate and limbic processes somewhat resembling pokemurideans. The xenotheridians share several morphological features with both HE hares and Spec paraselenodonts. They have anterior scrotal sacs, precocial birth and caecal consumption.

Xenotheridians are clearly distinct from true rodents and rabbits (neither or which live on Spec). Although they are not true rodents, xenotheridians are commonly called 'Specworld rodents', and indeed, a casual observation would place a xenotheridian right beside a homely mouse or guinea pig. Specworld "xeno" rodents are almost as diverse and successful as their Home-Earth counterparts, numbering almost 2,000 species. They have representatives on every major continent but Australia and Antarctica. Most species are tiny, while others grow to almost a meter in length. Some are aquatic, while others climb trees, hop on stilt-like legs, or spray poison on their attackers. While not as flashy as some of Spec's other fauna, the Xenotheridia are nonetheless worthy of attention.

Xenotheridians seem to have seized the cursorial muroid and jerboid niches since the Miocene. The clade has spread across Eurasia, North America, Africa and South America. Amazingly, two representatives have very recently made their way to Madagascar within the last ten thousand years. A very small sample consisting of both generic and specialized critters is presented here. 

Drh-opthamys

Spectacled Mouse,Opthamys kiddi (Eurasia and North America)

Spectacled Mouse (Opthamys kiddi)

The spectacled mouse (Opthamys kiddi) is a common if unremarkable species, in a common family of Specworld rodents found across Eurasia and North America.  A closely related species, the greater spectacled rat (O. primus), was discovered in the Japanese Archipelago.

Venom Rat (Venenitheridum excruiciatus)

Drh-venomrat

Venom Rat, Venenitheridum excruiciatus (East Asia)

The venom rat (Venenitheridum excruiciatus) is a large, plump, slow rodent almost completely oblivious to its surroundings. Protected from the many predators of its east Asian homerange by the streaks of pale hair down its sides, and its saliva.

The hairs are highly absorbant, and are permeated by an unidentified oil from glands along the rat's sides. The few predators that have been observed trying to eat one of these rodents soon suffer severe stomach spasms and frothing at the mouth. Additionally, the rats' bite is now known to cause excruitiatingly painful swelling in any predator or mammalogist unlucky enough to be bitten.

On the other hand, the animal does offer fair warning of its defenses - a striking black & white colour scheme (making it yet another mammal on or off Specworld to do so) and its habit of raising its coat impressively whenever it feels threatened.       

Numrat (Myrmecomys kalahariensis)

Drh-numrat

Numrat, Myrmecomys kalahariensis (Africa) 

The numrat (Myrmecomys kalahariensis) is a small, termite and ant-eating rodent. Usually nocturnal, and very alert, it uses its incisors to gnaw into the sides of ant and termite nests, and feeds hurriedly on the inhabitants.

Florida pseudorat (Disneymus inexspectatus)

Rat

Florida pseudorat, Disneymus inexspectatus (Southeastern North America: Everglades)

A typical-sized mammal, the 20-centimeter-long Florida pseudorat eats a variety of food, from small plants to seeds of any kind of plant to insects and bird eggs.

Pararat (Dendrorattus sinensis)

(southeast Asian rainforest)

A crepuscular arboreal rat like xenotheridian of tropical Asia, the pararat is specialized for branch-running and climbing, feeding mainly on anything protein-rich, but predominantly on nuts and flower buds. Pararats use their long, stiff tail to balance as they forage high in the rainforest trees. Their tail ends in a radiating tuft of very stiff hair; when threatened, the animal dives off the nearest branch and glides to the forest floor using its tail tuft as a makeshift parachute.

Earmouse (Pterocephalomys dumbo)

(central African rainforest)

The earmouse is a little creature, no bigger than a large mouse. It is a little seen, cryptic xenotheridian that feeds mostly on nectar. Found in the deepest Congo jungle, away from the undaur highways, its ears are its most notable feature. It is portrayed here using its large ears to glide from a tree branch, a behavior which has apparently been observed once, but is hitherto undocumented at this point, the reliability of the witness being slightly questionable.

Hog-Nosed Rodden (Susrattoides europa)

The hog nosed rodden can be found across much of temperate Europe. This fairly large half kilo xeno snuffles for food in the leaf litter as well as tearing apart bark during the harsh winters. They provide an invaluable service for bantams, since the grouse like strek relatives prefer to access the softer cambium. Female hog nosed rodden birth 3 to 5 precocial young who soon follow her within days along the forest paths.

Swamp Chomper (Phoborattus rodloxi)

(lower Nile)

In the Nile delta and some distance upstream, big herbivores live off the reeds, water lilies and other plants. Some are very big, like the mokeles. Some are quite small, like the pseudovoles (Pseudarvicolidae, see below). And some are, well, middle-sized. Most notable among these is the swamp chomper, a xenotheridian the size of a small afanc. Most of its diet is made up of reeds and other plant matter, but its long, sharp incisors allow it to open all manner of eggs to the size of those of a small mokele. The same incisors are used when the quite fearless creature thinks it should defend itself against hungry mattiraptors or nosy spexplorers. Swamp chompers have also been seen eating fish... and being eaten by disappointingly unimpressed crocodiles.

Amazon Treehugger (Nothromys amazoniensis)

(Amazon rainforest)

The Amazon treehugger, is a bizarre nocturnal sap-drinking arboreal xenotheridian, is most often found clinging to the trunks of rainforest trees with its massive foreclaws. It subsists mostly by gnawing through bark to get to the nutrient-rich sap, though it also extracts grubs for protein and eats bark layers for fiber. Its coloring is usually cryptic but extremely variable; moss and algae often propagate in the fur on the back, providing extra camouflage when the animal sleeps.

Stiltleg (Madagascomyolagus benseni)

(tropical grasslands of Madagascar)

The stiltleg is an interesting diurnal, long-legged species adapted to the tall grass of the tropical grasslands of Madagascar. Without the legs, its size is similar to that of a Home-Earth guinea pig. It feeds on the tops of the grass, always on the alert for predators. If alerted, it can put on a good turn of speed, bounding with its long legs. Its call is an unusual grating trill, evolved to carry across the ground. This is one of the two native Madagascan xenos. The lack of comparable relatives on the African mainland indicates a long isolation.

Black Midgetmouse (Micromys niger)

One of the smallest xenotheridians, the black midgetmouse can be found in the blackberry thickets of England. Different species of midgetmice are distributed all over Eurasia in just about any well vegetated habitat. They feed mostly on berries and insects.

Curly-Tailed Pampas Rat (Curleyomys lalai)

The curly-tailed pampas rat is a fairly unremarkable nocturnal granivore, eating grass seeds as it forages under the moon on cold pampas nights. It does, however, make an unusual humming noise during mating.

Mongolian Springer (Jerryomys springeri)

Most xenotheridians are mainly herbivorous. Plant matter is, however, scarce in the Gobi desert. Nevertheless, a large nocturnal rodent lives there. The Mongolian springer feeds mainly on reptiles made sluggish by the twilight. It is also quite aggressive towards its own species; any meeting involves a lot of fighting and gnashing of teeth, punctuated by their odd bleeping call, and, occasionally, with copulation. When combined with the communal calling (je-RI! je-RI!) of Mongolian mole crickets Sandgroperus chooi, one cannot help but be sent into a revelry of primal thoughts.

Black-Footed Hopper (Saltomus nigripes)

Hoppers live throughout the savanna and semi desert of subsaharan Africa. They are active by day and live in groups of up to 50 (in the black-footed hopper, a species from the Kalahari. They move much like miniature kangaroos, and often make odd yipping noises like small dogs when agitated. Their main sustenance is grass seeds and roots, with the occasional insect or small lizard for protein.

Eastern Long-Tailed Rabbit-Ear (Lagomys brevinasus)

The rabbit-ears are closely related to the Mongolian springer. However, they are omnivorous, eating leaves, fruit, nuts, berries, insects and small vertebrates. They are mainly found along forest edges all over temperate and subtropical Eurasia. However, every little clearing has its own forest edge; it is therefore not surprising that, for example, the eastern long-tailed rabbit-earextends from central Europe to about the Ural and from some Aegean islands to southern Scandinavia.

Long Tailed Rabbit-Ear (Lagomys abbrevionasus

Lagomys are a european genus related to the Mongolian springer. Lagomys however are omnivorous, eating leaves, fruit, nuts berries, insects and small vertebrates. They are mainly found in forested areas with adequate cover to hide.

Reedmouse (Caudomys sp.)

Reedmice are riverine animals that look and behave somewhat like the field mice of Home-Earth, making nests in reeds or tall grass near riverbanks. They use their long prehensile tails to reach out and grab nearby stalks as they search for seeds and insects. They are a diverse cosmopolitan genera ranging from Africa through Eurasia into both Americas.

Pied Pipingrat (Vociferomys piperi)

The pied pipingrat and similar pipingrats Vociferomys sp., are ubiquitous in any vegetated habitat in their range, from the prairies to the dense forests, even in the Great Black Swamp. They can eat anything digestible, they can climb, dig, run and jump, and they are prey for harracks and courours, as well as for avisaurs and larger mammals. When agitated or seeking a mate, pipingrats make a high-pitched piping whistle.

Black Swamp Stinker (Malodoromys morrisi)

The Black Swamp stinker is a foul and sluggish thick-furred black-and-white xenotheridian that lives only in the Great Black Swamp. It can swim reasonably well in order to find dead fish and hard-shelled mollusks, and its claws are long and curved enough that the animal can also climb trees to gorge on chestnuts during the nut-glut. The fame of this animal comes from its ability to generate a horrible smell from its anal glands and to fire foul-smelling feces from its rectum at an assailant.

Pythontail (Ophiuromys pettigrewi)

While unrelated, the pythontail of China's dense bamboo forests behaves in a similar manner to the reedmice Caudomys, albeit on a larger scale. It eats grubs that it extracts from the core of the bamboo, as well as bamboo leaves. When confronted with a predator, it moves its tail in front of its body and hisses loudly as it undulates its tail. This decent impression of a snake certainly frightens off most avian or mammalian predators.

Antmouse (Formicomus pixaris)

The antmouse is actually a termite symbiote. This tiny critter is eusocial, with one massive queen living among abandoned termite chambers. She births up to 18 young every three months They are the most altricial xenos babies known, actually having their eyes closed for week before opening. Wet nurse sisters tend to the babies while worker siblings go out every night onto the African grasslands to find succulent herbs and grass stems to return. The antmouse defecates within certain chambers. The waste is utilized by the termites for their fungal gardens.

To varying degrees, many xenotheridians have gone underground to eat roots and tubers. They take advantage of the burrowing efforts of multis, pig shrews and glyphons in access of an easy meal. One such clade are the pseudovoles, Pseudarvicolidae of the holarctic. When they come out of their burrows, they frequently end up as depicted above. Pseudovoles, along with several other xenos such as the spectacled mice, form a bulk mainstay for a vast array of predators both dinosaurian and mammalian.

Jumprat (Mariomys superbus)

Marius-superbus

Jumprat , Mariomys superbus ( Italy)

The jumprat is certainly an impressive sight in the mountains, forests, clearings and alpine meadows of Italy. It is about the size of a potoroo or rabbit. Its jumping abilities are unparalleled among Spec's mammals. Jumprats mainly jump to avoid enemies. They are, however, particular in their aggression towards turtles, presumably because they compete with them for food. They repel them by bouncing off their shells. Jumprats feed on flowers, wild cherries and mushrooms, which give them lots of energy for their prodigious jumps.

Hognose Ozrat (Suinomys sp.) 

This genus of diurnal forest dwelling, rat-sized Xeno is found in most forested parts of Australia and Papua, from the montane rainforest to the temperate and semi arid Sclerophyl forest, even the cool forests of Tasmania. There are many species that vary in colour from smoky grey (S.florestanoi) to rich chestnut brown (S.beatrixpotteri). They feed on all matter of organic matter on the forest floor, from gumnuts, and herbage to invertebrates, which they often uncover with their leathery upturned nose.

Sooty Ozmouse (Australomys matthewi

This mainly nocturnal species belongs to a genus widespread over all Australo-Papuan habitats, from desert to rainforest. The vertically erect tail is typical of the genus, desert species have light coats, the more densely vegetated the habitat is, the darker the pelage. The sooty Ozmouse is from the dense cool rainforests of Tasmania.

Unowl

A striped scowl, Allostrix rowlingae, with a captured hemming, Xenomarmota sp. (Northern Eurasia)

Specrodents

Picture by Timothy Morris, odder Specworld rodents from all over the world. To scale

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