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Description
Alongside the possums, potoroos and macropodids, one final group of marsupials has now given rise to a notable radiation of arboreal mammals - the dasyurids. Although the order Dasyuromorphia has long been associated with marsupial carnivores, for much of the Cenozoic it was a lineage of diprotodontians, the thylacoleonids, that were the main group of tree-dwelling predators in Australia. The drying of the continent saw the extinction of all smaller members of the family and left only the larger, more terrestrial species, and this left new opportunities for other carnivores to exploit. Of course it was the dasyurids that took the helm, specifically in the somewhat arboreally-inclined quolls, but with these pouched predators now also being on the way out the position has once again been left open. The spreading forests of Recurocene Australia would encourage a new group of tree-dwelling marsupicarnivores to diversify like never before.

Arborgales, tribe Arborgalini, are a diverse group of arboreal dasyurids descended from the Brush-tailed Phascogale. Back in the Holocene the phascogales were already the most well-adapted for arboreality of all of Australia's marsupial carnivores, but the expansion of forests that occurred as the Recurocene drew on and the diversification of tree-dwelling mammals that followed also caused the phascogales to radiate. Although a few are still shrew-like and resemble their ancestors, most arborgale species now share a closer resemblance to the larger members of Dasyurini (quolls and devils) with more thickset jaws and a powerful frame. Nonetheless all arborgales are small, with none growing larger than the average cat and the majority being smaller still. Given the widespread decline of larger dasyurids it may seem bizarre for a new clade to arise in the face of intense competition from carnivorans, but their success has largely come from their dexterity - while felids and canids have paws, dasyurids still have proper hands, and this has granted them much greater grasping ability and agility among the trees. In accordance with their habits they have now also developed an opposable thumb, which comes in handy not only for climbing but also for grasping at prey. Their tails on the other hand are not prehensile and therefore cannot grasp, but instead serve as a balance when racing along branches. With such a suite of arboreal adaptations, the dasyurid arborgales have been able to dominate the trees despite the presence of semi-arboreal carnivorans like tree foxes and wildcats.

With a distribution spanning all of eastern and northern Australia, arborgales have mustered a considerable diversity of 18 species with the greatest number of species occurring in New Guinea, many being restricted to specific forest types or altitudes and therefore allowing many species to coexist within a small area. Their diets are generally pretty variable, ranging from birds and lizards to insects and even some fruit and nectar, but for the vast majority of species other mammals are their preferred prey. Arborgales are the chief predators of possums, the Honey Potoroo, tree shrews, taisers, smaller macaque and tree kangaroo species, squirrels and arboreal murids, and therefore they serve as some of the top predators in the forest canopy. They are mostly ambush predators, usually leaping onto the back of their prey and then going for the throat to quickly dispatch it, but if they are seen they will also give chase through the treetops. With most species being smaller than any wildcat or tree fox arborgales remain vulnerable to predation by carnivorans, but their far greater speed and agility almost always allows them to make a quick and easy escape as long as they are not ambushed. A far greater threat is presented by birds of prey like eagles and large owls, which arborgales will usually respond to by taking refuge within dense foliage or forcing themselves into whatever crevice they can find.

Perhaps the most unique species is the Maned Arborgale (Xerogale hydrophroure), monotypic within its genus, which inhabits an environment quite unlike that occupied by any other arborgale. The largest species of arborgale at 3.6 kilograms, it is a specialised inhabitant of the harsh Australian interior and lives almost exclusively along watercourses, which despite often being dry for years on end are still able to support groves of taller river gums which make suitable habitat for an arboreal predator. The main downside to living in such an environment is not just the harsh conditions, but also the fact that very few other arboreal mammals live here - the large and aggressive Western Brushtail Possum occurs in the western half of their range but besides that the arborgales are on their own, and as a result they have had to change their behaviour and hunting strategies significantly to adapt to a different mix of prey. On some nights a Maned Arborgale will stealthily slink down from the trees to hunt other mammals in the surrounding aridlands, but this is not what they are built for and puts them at considerable risk from other predators. Instead, their more preferred hunting strategy is to wait until dawn and then watch quietly from a branch sitting over a small remnant puddle. Birds will flock to these watercourses from many kilometres away to drink, and when they do the arborgale is waiting for them. The Maned Arborgale is the most frequent user of a trick known as "dropbearing" that is also used by some other species of arborgale, waiting for unwary prey to pass beneath and then leaping down from the trees to ambush them. Often the birds will be killed on impact, and then their bodies will quickly be taken up into the trees where the arborgale can eat at its leisure. Usually the birds will catch onto which puddles house a waiting arborgale after a few days, and thus they must regularly rotate among watering points within their territory to keep up with the wits of their prey. They are the only arborgale species to specialise in birds rather than mammals.

Like many inland species they see a significant change in behaviour in response to the drought-breaking rains that bring relief across the interior every few years and see an enormous boom in the abundance of many aridland organisms. The once dry rivers are soon overflowing and immense flocks of waterbirds arrive to take advantage of the newly formed bounty. This also means an abundance of prey for the Maned Arborgales that have spent so long scraping a living around drying puddles, and are now treated to a smorgasbord of large plumb waterbirds which do not have much experience with such a predator. Their hunting strategy remains largely similar, except now they have to leap into the water to catch their prey but this presents little problem as they are still able to swim efficiently. Not only that, they will also take advantage of the large number of Fringefoots that flock to the waterways at this time, waiting until they swim past beneath and then leaping down to attack. Fringefoots are by no means pushovers due to their powerful mammal-crushing jaws, but the Maned Arborgale is larger and more powerful still and therefore in a direct confrontation it usually comes out on top. Like most inland species the coming of the rains also triggers breeding amongst the arborgales, and with the abundance of food meaning territories are no longer worth protecting the usually solitary predators are able to mingle with each other for once. A male with mate with as many females as possible, who will then spend the next 6 months raising the young alone.

For the speculative evolution project Australia: The Next 54 Million Years. See more here: specevo.jcink.net/index.php?sh…

Description
Alongside the possums, potoroos and macropodids, one final group of marsupials has now given rise to a notable radiation of arboreal mammals - the dasyurids. Although the order Dasyuromorphia has long been associated with marsupial carnivores, for much of the Cenozoic it was a lineage of diprotodontians, the thylacoleonids, that were the main group of tree-dwelling predators in Australia. The drying of the continent saw the extinction of all smaller members of the family and left only the larger, more terrestrial species, and this left new opportunities for other carnivores to exploit. Of course it was the dasyurids that took the helm, specifically in the somewhat arboreally-inclined quolls, but with these pouched predators now also being on the way out the position has once again been left open. The spreading forests of Recurocene Australia would encourage a new group of tree-dwelling marsupicarnivores to diversify like never before.

Arborgales, tribe Arborgalini, are a diverse group of arboreal dasyurids descended from the Brush-tailed Phascogale. Back in the Holocene the phascogales were already the most well-adapted for arboreality of all of Australia's marsupial carnivores, but the expansion of forests that occurred as the Recurocene drew on and the diversification of tree-dwelling mammals that followed also caused the phascogales to radiate. Although a few are still shrew-like and resemble their ancestors, most arborgale species now share a closer resemblance to the larger members of Dasyurini (quolls and devils) with more thickset jaws and a powerful frame. Nonetheless all arborgales are small, with none growing larger than the average cat and the majority being smaller still. Given the widespread decline of larger dasyurids it may seem bizarre for a new clade to arise in the face of intense competition from carnivorans, but their success has largely come from their dexterity - while felids and canids have paws, dasyurids still have proper hands, and this has granted them much greater grasping ability and agility among the trees. In accordance with their habits they have now also developed an opposable thumb, which comes in handy not only for climbing but also for grasping at prey. Their tails on the other hand are not prehensile and therefore cannot grasp, but instead serve as a balance when racing along branches. With such a suite of arboreal adaptations, the dasyurid arborgales have been able to dominate the trees despite the presence of semi-arboreal carnivorans like tree foxes and wildcats.

With a distribution spanning all of eastern and northern Australia, arborgales have mustered a considerable diversity of 18 species with the greatest number of species occurring in New Guinea, many being restricted to specific forest types or altitudes and therefore allowing many species to coexist within a small area. Their diets are generally pretty variable, ranging from birds and lizards to insects and even some fruit and nectar, but for the vast majority of species other mammals are their preferred prey. Arborgales are the chief predators of possums, the Honey Potoroo, tree shrews, taisers, smaller macaque and tree kangaroo species, squirrels and arboreal murids, and therefore they serve as some of the top predators in the forest canopy. They are mostly ambush predators, usually leaping onto the back of their prey and then going for the throat to quickly dispatch it, but if they are seen they will also give chase through the treetops. With most species being smaller than any wildcat or tree fox arborgales remain vulnerable to predation by carnivorans, but their far greater speed and agility almost always allows them to make a quick and easy escape as long as they are not ambushed. A far greater threat is presented by birds of prey like eagles and large owls, which arborgales will usually respond to by taking refuge within dense foliage or forcing themselves into whatever crevice they can find.

Perhaps the most unique species is the Maned Arborgale (Xerogale hydrophroure), monotypic within its genus, which inhabits an environment quite unlike that occupied by any other arborgale. The largest species of arborgale at 3.6 kilograms, it is a specialised inhabitant of the harsh Australian interior and lives almost exclusively along watercourses, which despite often being dry for years on end are still able to support groves of taller river gums which make suitable habitat for an arboreal predator. The main downside to living in such an environment is not just the harsh conditions, but also the fact that very few other arboreal mammals live here - the large and aggressive Western Brushtail Possum occurs in the western half of their range but besides that the arborgales are on their own, and as a result they have had to change their behaviour and hunting strategies significantly to adapt to a different mix of prey. On some nights a Maned Arborgale will stealthily slink down from the trees to hunt other mammals in the surrounding aridlands, but this is not what they are built for and puts them at considerable risk from other predators. Instead, their more preferred hunting strategy is to wait until dawn and then watch quietly from a branch sitting over a small remnant puddle. Birds will flock to these watercourses from many kilometres away to drink, and when they do the arborgale is waiting for them. The Maned Arborgale is the most frequent user of a trick known as "dropbearing" that is also used by some other species of arborgale, waiting for unwary prey to pass beneath and then leaping down from the trees to ambush them. Often the birds will be killed on impact, and then their bodies will quickly be taken up into the trees where the arborgale can eat at its leisure. Usually the birds will catch onto which puddles house a waiting arborgale after a few days, and thus they must regularly rotate among watering points within their territory to keep up with the wits of their prey. They are the only arborgale species to specialise in birds rather than mammals.

Like many inland species they see a significant change in behaviour in response to the drought-breaking rains that bring relief across the interior every few years and see an enormous boom in the abundance of many aridland organisms. The once dry rivers are soon overflowing and immense flocks of waterbirds arrive to take advantage of the newly formed bounty. This also means an abundance of prey for the Maned Arborgales that have spent so long scraping a living around drying puddles, and are now treated to a smorgasbord of large plumb waterbirds which do not have much experience with such a predator. Their hunting strategy remains largely similar, except now they have to leap into the water to catch their prey but this presents little problem as they are still able to swim efficiently. Not only that, they will also take advantage of the large number of Fringefoots that flock to the waterways at this time, waiting until they swim past beneath and then leaping down to attack. Fringefoots are by no means pushovers due to their powerful mammal-crushing jaws, but the Maned Arborgale is larger and more powerful still and therefore in a direct confrontation it usually comes out on top. Like most inland species the coming of the rains also triggers breeding amongst the arborgales, and with the abundance of food meaning territories are no longer worth protecting the usually solitary predators are able to mingle with each other for once. A male with mate with as many females as possible, who will then spend the next 6 months raising the young alone.

For the speculative evolution project Australia: The Next 54 Million Years. See more here: specevo.jcink.net/index.php?sh…