The Gondwana connection 2012

A living museum...... World Heritage Protected Australian rainforests have long been continents which gradually drifted Welcome to ‘Tropical Topics’, a considered poor cousins of rainforests apart. Australia was the last continent newsletter designed to help you in other parts of the world. to break away, about 45 million years keep up to date with natural ago. science and conservation news The ‘jungles’ of Africa, Asia and and issues of north Queensland.This South America conjure up romantic For 30 million years Australia’s life innovative monthly newsletter will visions of exotic paradise and ‘Tarzan’ evolved in isolation. As the climate provide you with interesting reef and movies. So much so that we are became drier many species died. rainforest facts. constantly trying to emulate them by Others adapted to the drier conditions What’s so special about the Wet landscaping our gardens and resorts and survived to colonise the vast Tropics? with introduced foliage. (Which in areas of dry open forests, grasslands To be selected for World Heritage many cases has resulted in the and deserts which cover much of the listing, an area must satisfy at invasion of our native forests by continent today. Only the least one of the following criteria. ‘runaway’ exotics.) mountainous regions of the east coast It must represent: remained constantly moist. It is here • a major evolutionary stage of What respect we have held for our that the last remaining refuges of the earth; native flora in the past has generally Australia’s ancient tropical rainforests • a continuing process of been reserved for the distinctly survive, with many species little geology, evolution, or man and- Australian flora of the drier parts of changed since the evolution of the environment; the continent; our famous wattles, first flowering plants. • superlative natural beauty; or eucalypts, banksias and grevilleas. • a habitat that shelters threatened Most scientists believe that these plants and animals. plants all originated from the ancient stock of Gondwana, the living The Wet Tropics satisfies all four! descendants of which can be found in the Wet Tropics. This month ‘Tropical Topics’ will provide an insight into how the Wet Tropics represents a major Gondwana - a supercontinent which evolutionary stage of the earth, existed hundreds of millions of years and why it could have gained ago - comprised the southern World Heritage listing on this continents as well as India and parts basis alone! of southern Asia. (The northern continents were joined in a similar landmass called Laurasia.) Some plants such as the idiospermum from Cape For millions of years life evolved Tribulation did not evolve. They appear today much as they did across these supercontinents. millions of years ago. Dinosaurs came and went and More primitive flowering flowering plants developed. At plants are found in the Wet Tropics than anywhere else times much of the land (including on earth. what is now Australia) was covered by rainforest.

About 180 million years ago Gondwana started to break into Wet Tropics rocks What have rocks got to do with the rainforest?

Everything! Rocks are the foundations and have the texture of porcelain of the landscape and the origin of the • Granites formed from the injection formed in the southern and western soil. They even affect the weather. For of magma (molten rock) into overlying parts of the Wet Tropics about 250 example, the north-south alignment of rocks about 200 to 300 million years million years ago. More recently (about coastal mountains of north Queensland’s ago. Magma is rich in quartz and one to three million years ago) basalt Wet Tropics traps rain-laden clouds from cools slowly, deep below the surface, lava, which contains no quartz, erupted the moist ocean breezes. In normal years forming coarsely crystalline, lightgrey and flowed over the Atherton rain erodes the rocks at an imperceptible to pink rock which is only Tableland and other parts of the Wet rate creating the lofty crags, ridges, exposed where overlying rock has Tropics. The basalt, often containing valleys, gorges and spectacular eroded. bubbles, formed a layer of black, finely waterfalls which form the dramatic crystalline rock which weathered to landscape. Rock fragments removed • Volcanics formed when lava erupted bright red soils. in this sculpting process accumulate onto the surface of the land and cooled on lower slopes to form a variety of quickly. Some light-pink and grey soils which in turn support a range of volcanic rocks which are rich in quartz forest types.

Rocks weather differently. Grain size and mineral composition of rock 1. Sediments accumulate determine how fast it erodes, the on the bottom of an ancient depth of the soil it produces, its ocean extending west of texture and nutrient content. Soils in today’s shoreline. the Wet Tropics vary from thin, stoney, leached and infertile ‘lithosols’ of some ridge-tops to the deep, red, rich and fertile basalt derived soils of the Atherton Tableland. 2. Crustal movements compress the sediments, The large-scale structure of the rocks, folding and melting them into along with their variable resistance to metamorphic rocks. weathering provides the landscape master plan. Cracks and fractures in the rock can form lines of weakness that stretch for kilometres, often directing the flow of creeks. Rocks without cracks are most resistant to 3. Molten granite magma erosion and may be left as pinnacles is injected into the when surrounding rocks are eroded. metamorphics and solidifies slowly. Three main types of rock form the Wet Tropics landscape; metamorphics, granites and volcanics. Each type has its own characteristic combination of chemical and structural properties: 4. Millions of years of erosion removes the rock overlying • Metamorphics were formed about the granite . Granite is more 360 million years ago when sediments resistant to weathering on the bottom of an ancient ocean and remains proud of the were compressed by movements in landscape to form the highest the earth’s crust. The sediments fused mountains (eg. Bellenden Ker, into a layered and folded block of Bartle Frere and Thornton mixed composition extending for Peak). hundreds of kilometres along the coast and for a hundred kilometres inland. Folds and layers give rise to 5. Basalt lava erupts from characteristic weathering patterns volcanoes to flow over the such as those found in shale and Atherton Tableland and other slate. places.

Tropical Topics 2012 “The cat’s caught a rat!” Facts and stats What’s so special about that? believed to have migrated to Australia on Wet Tropics WHA Plenty when the rat turns out to be a from Papua-New Guinea thousands of prehensile-tailed rat. As its name years ago when there was a land bridge Having been around for more then 100 suggests, this rare nocturnal rat has a across Torres Strait. million years, rainforests of the Wet tail which it curls upwards to grip Tropcis World Heritage Area are the twigs when climbing. It can even hang Little is known about the habits and oldest, continuously surviving rainforest by its tail. distribution of this beautiful, little rat. on earth. Sadly, domestic cats have been The prehensile-tailed rat (along with responsible for most of the finds. The Conifers and cycads of the Wet Tropics are living remnants from the times, the cuscus and tree kangaroos) is first one discovered in Australia was 200 million years ago, when dinosaurs brought into the lodge at Lake Barrine roamed the earth. by a cat in 1974.

Since then, several have been caught in Kuranda, also by cats. Two have been collected from Gordon Creek, near Iron Range and an owl pellet from Mt Lewis contained the remains of one.

A prehensile-tailed rat nibbles on the fruit of a pandanus.

The World Heritage Area covers nearly 900 000ha, extending more than 400km between Cooktown and Townsville. It covers only 0.1% of Australia’s total land mass but has: • 40% of Australia’s bird species • 30% of Australia’s mammal species • 60% of Australia’s butterfly species • 21% of Australia’s reptile species • 21% of Australia’s cycad species • 29% of Australia’s frog species • 65% of Australia’s fern species • 30% of Australia’s orchid species

About 300 000 people live in or within 50km of the Wet Tropics World Heritage Area. Want to know more about the evolution of the plants and animals of the Wet Tropics? contact the WTMA office on 40520533 to grab an A1 The Wet Tropics currently receives about size Evolution poster, part of the animals of the Wet Tropics series. 2.5 million visits per year.

Tropical Topics 2012 The Gondwana connection

With a family tree dating back at least 20 million years, musky ratkangaroos are considered the most primitive of living kangaroos. Four million years ago, their west Victorian relatives died out, leaving them as the sole survivors of the genus Hypsiprimnodon.

The land masses of the world were once joined into a super-continent called Pangaea. This separated into two smaller land masses, Laurasia in the north and Gondwana in the south. Australia was part of Gondwana.

Until recently, north Australian rainforests were thought to have invaded from Asia when the continental plates collided. More recent theories suggest that Australian rainforests are largely inherited from the ancient stock of Gondwana. This is particularly true of upland and southern forests, while lowland forests have mixed Asian and Gondwanic origins with refugial areas, such as Noah Creek in the Daintree, where Gondwanic plants predominate.

180 million years ago Gondwana started to break into continents which gradually drifted apart. Australia broke away about 45 million years ago.

Compare the skull of a modern platypus (left) with the 15 to 20-millionyear- old fossilised skull (right) of a platypus ancestor found at Riversleigh Station, north-west Queensland. A giant platypus Ribbonwood ancestor (known from a 10 milllion-year- (Idiospermum old fossilised jaw from Lightning Ridge, australiense) is a rare NSW) was Australia’s oldest mammal, and primitive flowering and possibly the largest mammal in the plant, found only in world at that time! the Wet Tropics World Heritage Area. Thirteen of the nineteen families of primitive flowering

Flowers and seedling plants occur in this area. of ribbonwood (Idiospermum australiense)

Tropical Topics 2012 In 1982, the fossilised remains of what is thought to be a giant treekangaroo (about the size of a present day red kangaroo) were found in the Wellington Caves, New South Wales. The age of the bones is uncertain but they are at least 50,000 years old.

Millions of years ago rainforest covered much of Australia. As ‘Where do I come from?’ the climate began to change, many species of the Australian mammal fauna is Proteaceae family (including grevilleas, banksias and acacias) dominated by marsupials, a group and the Myrtaceae family (eucalypts and bottlebrushes) found in few other parts of the world. began to adapt to the drier conditions. These now dominate the Treekangaroos, (along with cuscuses and landscape and are distinctly Australian. some possums and gliders) are also found in New Guinea. Ancestors of these plants still exist in the Wet Tropics. The bull oak (Proteaceae family) is one such plant. Some theories suggest these animals migrated to Australia some time in the last 120 000 years when land bridges existed between the two land masses. Like the new theories about the origins of Australian rainforests, there are suggestions that these amazing animals also originated in Australia and migrated north.

Perhaps future fossil finds will hold the answer.

Australia slowly moved northwards, completely isolated from other land masses. About 15-20 million years ago it collided with the Asian plate. Some plants and animals were able to move between the two continents.

Logrunners live only in rainforests. When they search for food, they lean back on their tails and toss leaf-litter sideways. Because of this odd habit, they have distinctive leg bones. Small, fossilised, logrunner bones have been found at semi-arid Riversleigh Station, along with the fossilised remains of many other At times during the last 120 000 years, sea water became rainforest ancestors. bound in ice. This caused lower sea levels and the gap between Australia and Asia became narrower. More species crossed over.

Tropical Topics 2012 Nature notes A diary of natural events creates a pleasing journal which grows richer with the passage of time. Watching for the recurrence of an event after noting it in a previous year, and trying to understand what could have caused changes in timing, is intriguing.

Trees used for communal nesting by Golf ball-sized fruit will be dropping During very low shining starlings will fall silent this from the north Queensland tides, marine month as the birds fly to New Guinea, macadamia (Macadamia whelanii). organisms not or northern Cape York for the cooler The brownish, granular surface of this usually exposed months. Around the base of each fruit is characterised by an off-centre to direct sun and nesting tree will be a thick carpet of protrusion. Unlike the well-known air will endure a seedlings, representing the fruits macadamia of commerce, (which is difficult time, but which were fed to the young starlings. native to more southerly latitudes) the for humans a very fruit of Macadamia whelanii is low tide provides poisonous to humans. an opportunity to view a world that is usually awash.

Grey goshawks which raid Migratory waders will fly north this the nests month, leaving our shores in order to of shining The woody nuts are only a temporary enjoy summer in the northern starlings to obstacle for rodents which eat the hemisphere. Two of the largest and devour their kernels, leaving ‘igloos’ for ants seeking most recognisable species, the eastern offspring a dry refuge for their pupae. curlew and its smaller relative, the will be whimbrel, will head for the coasts of snacking elsewhere as most Korea and the coastline around starling youngsters have fledged Vladivostok. Migratory birds must and will fly north with their elders. In need particular fortitude to fly between Mossman Gorge it is not uncommon to the two hemispheres, never knowing see a grey goshawk delving into a nest, what changes may have overtaken while the adult starlings watch from a their destination since last they saw it. nearby tree. These gregarious birds do not combine to mob a predator. Nest defense is left to concerned individuals which occasionally dive-peck the offending goshawk. Honeyeaters and butterflies will visit the lofty crowns of pencil cedar As the weather cools crocodile watchers (Palaquium galactoxylum) when they are likely to be rewarded with sightings set clusters of short-stemmed creamy of estuarine crocodiles. These reptiles flowers. These trees with their climb ashore to warm up in the impressive buttresses are common in winter sun but are likely to reenter lowland rainforests. They shed the the water after dark, when water characteristic, knobbly-stemmed twigs temperature is warmer than the which are an aid to identification and night air. produce tasty, egg-shaped, pale yellow Where briar silky oak, also known as fruit which will be ripe towards the end findlay’s silky oak (Musgravea of the year. heterophylla) is found, the forest floor is likely to be littered with spent stems from its flower spikes. Although the flowers are cream coloured, the buds have an orange- brown appearance, quite noticeable when viewing the crown of the tree in good light.

Tropical Topics 2012