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Description
One of the first mammal groups to leap over from Sulawesi as the Recurocene drew on belonged to one of the most peculiar and bizarre of all primate groups, the tarsiers. These miniscule rainforest specialists are the last of the once widespread primate infraorder Tarsiiformes, previously ranging across Europe, northern Africa, and North America but becoming restricted to the islands of south-east Asia by the Quaternary. By then, isolated Sulawesi and its satellite islands had become the global epicentre of the infraorder's diversity, being home to the vast majority of surviving tarsier species, and therefore it may perhaps come as no surprise that they were among the first of Sulawesi's mammals to make the crossing as the Recurocene drew on. Arriving in Australia 1.9 million years ago and therefore predating the physical collision of the two landmasses, they became the first primates to reach the continent since humans disappeared some 4 million years earlier and the very first to arrive by entirely natural means.

In some ways, the colonisation of Australia has given the tarsiers a second chance at diversifying on a continental landmass, and they have taken this opportunity with great haste. The diversity of tarsiers remaining in Sundaland now pales in comparison to that of Australia, which is now home to no less than 21 of the 24 remaining species which can be found in most forested environments across the north and east of the continent. Many of these are still members of the ancestral genus Tarsius, the typical tarsiers, which are mainly found in rainforest, vine thicket, and dense tropical dry forest in New Guinea, the Sulawesi Peninsula, north-eastern Queensland as well as in patches of suitable habitat just south of the Arafura Floodplain. Typical tarsiers may vary in some areas of their behaviour, such as the size of their social groups (some are solitary while others live in groups and are much more sociable), but in terms of hunting preferences all prefer the tangled undergrowth over the lofty forest canopy, leaping through curling vine thickets and between vertical saplings throughout the night in search of large insects and small vertebrates. Most Tarsius tarsiers, and indeed most tarsiers overall, were already specialists of understory environments, but this has only become more compounded in the radiation of the bizarre nocturnal primates upon their arrival on the Australian continent.

Once again, the eucalyptus forests of Australia's east coast would foster the appearance of a new group of tarsiers which have experienced a considerable change of behaviour to adapt to this new environment. The understory of eucalypt forests is quite different to that of the rainforest, the more open canopy letting much more light reach the forest floor and therefore leading to the growth of much denser, more leafy vegetation. This made it much harder for the tarsiers to move about and hunt, and so they were forced higher in the search of a suitable environment for them to live and hunt. This lead to the evolution of the canopy tarsiers (Altatarsius), a new group specialised to live in the crowns of tall trees rather than in the undergrowth below them. With trees often being significantly further apart than the stems, branches and vines of the tangled rainforest understory, some of their most notable modification has been centered around their locomotion. Tarsiers were already extremely well adapted for leaping, possessing very long and powerful hindlimbs, but the increased distances they now have to jump have seen the canopy tarsiers take this to a whole other level. Further elongation of the hind legs has made them way out of proportion of their more normal-sized forelimbs, leading to an appearance perhaps most comparable to that of the extinct sifakas of Madagascar or even the numerous tree frogs they share the canopy with. While this increased stride has worked wonders for their jumping ability, allowing them to pass through gaps in the forest with ease, it does make them extremely ungainly on the ground to the point they have trouble walking, and thus most will spend their entire lives up in the treetops and far away from the understory or forest floor. Some species have even begun developing a flap of skin linking their elbow to their chests, the earliest signs of a patagium that may one day allow them to glide.

Upon developing their new adaptations to life much higher in the trees the canopy tarsiers quickly spread back into the rainforest where they were free to hunt high above the heads of their more plesiomorphic, understory-dwelling cousins, but it is those that remained in the eucalyptus forests that have perhaps become the most innovative. Tarsiers are ancestrally active hunters, leaping nimbly from branch to branch in search of a meal, but the unique composition of Australia's flora would lead to quite a different hunting strategy for those found along the east coast. The continent's dominant trees outside of rainforest environments are undoubtedly eucalypts, with all the runnerups being similar plants such as acacias and melaleucas, and this leaves it in a unique position of having flowering plants as by far its most abundant and prominent vegetation. This was largely what was responsible for Australia's great diversity and density of nectarivorous animals, and it would be this diversity that lead to the adoption of ambush hunting in the continent's tarsiers. Although they will utilise the typical active hunting technique of most tarsiers, most of the canopy tarsiers of Australia's eucalypt forests instead prefer to wait in the crowns of blooming trees and wait for their prey to come to them. Most often their victims will be nocturnal flying insects, especially moths, but they will also prey on other small mammals like pygmy possums, tree shrews, small petaurids and even miniscule necativorous pteropodids like blossom bats. For arboreal mammals the tarsiers will wait for the right moment to pounce atop them and catch them offguard, but for bats and insects they often prefer to catch them in mid air, propelling themselves upwards with their powerful hind legs to snatch them out of the sky and quickly dispatching them with their small but vicious teeth. The constant attraction the flowers provide throughout the night means that the canopy tarsiers of the eucalyptus forest can gain an even greater amount of food than their active-hunting rainforest relatives while expending far less energy.

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

Description
One of the first mammal groups to leap over from Sulawesi as the Recurocene drew on belonged to one of the most peculiar and bizarre of all primate groups, the tarsiers. These miniscule rainforest specialists are the last of the once widespread primate infraorder Tarsiiformes, previously ranging across Europe, northern Africa, and North America but becoming restricted to the islands of south-east Asia by the Quaternary. By then, isolated Sulawesi and its satellite islands had become the global epicentre of the infraorder's diversity, being home to the vast majority of surviving tarsier species, and therefore it may perhaps come as no surprise that they were among the first of Sulawesi's mammals to make the crossing as the Recurocene drew on. Arriving in Australia 1.9 million years ago and therefore predating the physical collision of the two landmasses, they became the first primates to reach the continent since humans disappeared some 4 million years earlier and the very first to arrive by entirely natural means.

In some ways, the colonisation of Australia has given the tarsiers a second chance at diversifying on a continental landmass, and they have taken this opportunity with great haste. The diversity of tarsiers remaining in Sundaland now pales in comparison to that of Australia, which is now home to no less than 21 of the 24 remaining species which can be found in most forested environments across the north and east of the continent. Many of these are still members of the ancestral genus Tarsius, the typical tarsiers, which are mainly found in rainforest, vine thicket, and dense tropical dry forest in New Guinea, the Sulawesi Peninsula, north-eastern Queensland as well as in patches of suitable habitat just south of the Arafura Floodplain. Typical tarsiers may vary in some areas of their behaviour, such as the size of their social groups (some are solitary while others live in groups and are much more sociable), but in terms of hunting preferences all prefer the tangled undergrowth over the lofty forest canopy, leaping through curling vine thickets and between vertical saplings throughout the night in search of large insects and small vertebrates. Most Tarsius tarsiers, and indeed most tarsiers overall, were already specialists of understory environments, but this has only become more compounded in the radiation of the bizarre nocturnal primates upon their arrival on the Australian continent.

Once again, the eucalyptus forests of Australia's east coast would foster the appearance of a new group of tarsiers which have experienced a considerable change of behaviour to adapt to this new environment. The understory of eucalypt forests is quite different to that of the rainforest, the more open canopy letting much more light reach the forest floor and therefore leading to the growth of much denser, more leafy vegetation. This made it much harder for the tarsiers to move about and hunt, and so they were forced higher in the search of a suitable environment for them to live and hunt. This lead to the evolution of the canopy tarsiers (Altatarsius), a new group specialised to live in the crowns of tall trees rather than in the undergrowth below them. With trees often being significantly further apart than the stems, branches and vines of the tangled rainforest understory, some of their most notable modification has been centered around their locomotion. Tarsiers were already extremely well adapted for leaping, possessing very long and powerful hindlimbs, but the increased distances they now have to jump have seen the canopy tarsiers take this to a whole other level. Further elongation of the hind legs has made them way out of proportion of their more normal-sized forelimbs, leading to an appearance perhaps most comparable to that of the extinct sifakas of Madagascar or even the numerous tree frogs they share the canopy with. While this increased stride has worked wonders for their jumping ability, allowing them to pass through gaps in the forest with ease, it does make them extremely ungainly on the ground to the point they have trouble walking, and thus most will spend their entire lives up in the treetops and far away from the understory or forest floor. Some species have even begun developing a flap of skin linking their elbow to their chests, the earliest signs of a patagium that may one day allow them to glide.

Upon developing their new adaptations to life much higher in the trees the canopy tarsiers quickly spread back into the rainforest where they were free to hunt high above the heads of their more plesiomorphic, understory-dwelling cousins, but it is those that remained in the eucalyptus forests that have perhaps become the most innovative. Tarsiers are ancestrally active hunters, leaping nimbly from branch to branch in search of a meal, but the unique composition of Australia's flora would lead to quite a different hunting strategy for those found along the east coast. The continent's dominant trees outside of rainforest environments are undoubtedly eucalypts, with all the runnerups being similar plants such as acacias and melaleucas, and this leaves it in a unique position of having flowering plants as by far its most abundant and prominent vegetation. This was largely what was responsible for Australia's great diversity and density of nectarivorous animals, and it would be this diversity that lead to the adoption of ambush hunting in the continent's tarsiers. Although they will utilise the typical active hunting technique of most tarsiers, most of the canopy tarsiers of Australia's eucalypt forests instead prefer to wait in the crowns of blooming trees and wait for their prey to come to them. Most often their victims will be nocturnal flying insects, especially moths, but they will also prey on other small mammals like pygmy possums, tree shrews, small petaurids and even miniscule necativorous pteropodids like blossom bats. For arboreal mammals the tarsiers will wait for the right moment to pounce atop them and catch them offguard, but for bats and insects they often prefer to catch them in mid air, propelling themselves upwards with their powerful hind legs to snatch them out of the sky and quickly dispatching them with their small but vicious teeth. The constant attraction the flowers provide throughout the night means that the canopy tarsiers of the eucalyptus forest can gain an even greater amount of food than their active-hunting rainforest relatives while expending far less energy.

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