Murgon+(Qld)

=Murgon - The Queen's Land = == = The first evidence we have of marsupials in Australia comes from the 55 million-year-old fossil site at [|Murgon] in southern Queensland. This Murgon site has yielded a range of marsupial fossils, many with strong South American connections. At Murgon there is also evidence of a placental mammal, known as a condylarth. Placental mammals were also found in North America and South America at this time. =

This site is significant as the only site in Australia that records mammals dating from the early Tertiary Period (55 million years ago), approximately ten million years after the extinction of the dinosaurs.

The site includes some outstanding fossil records, including: the world's oldest fossils of songbirds the oldest fossil marsupial remains in Australia [|Tingamarra Bandicoot] a placental mammal Tingamarra Porterorum one of the world's oldest bats Australonycteris only known fossil remains of [|Leiopelmatid Frogs] and the only known fossils of [|salamanders] in Australia .... not [|this one] ...but it's just disturbing....

//Murgonemys braithwaitei//



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The location of this fossil site is a place of rolling hills, some of the higher of which are capped with basalt from lava that flowed down valley floors about 25 million years ago. The hardness of the basalt has resulted in them forming a fossil landscape as the softer surrounding rocks have been eroded down leaving elevated above the areas that were originally above them. This has prevented the valleys that contained the swamps where the fossil deposits were forming from being eroded along with the former higher ground around them. =====

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One theses basalt capped hills is Boat Mountain, named from its resemblance to an upturned boat. The exposed sides of Boat Mountain allow access to some of the fossils that are protected beneath the cap During the Early [|Eocene], about 45.5 million years ago, this site was a shallow swamp or lake. The [|Tingamarra Local Fauna] deposits formed from freshwater clays laid down at this time. It is the only known site in the Australian part of Gondwana older than 24 million years that contains marsupial fossils. At the time the Tingamurra Local Fauna deposit was forming Australia was still part of Gondwana. It is also the only known fossil site in Australia from the beginning of the great diversification of mammals after the demise of the dinosaurs. Other firsts and only include the oldest known songbird, Australia's oldest known marsupial, frog and crocodile, one of the world's oldest known bats, the only known eiopelmatid frogs, and only salamander fossils found in Australia. There were also non-volant placentals, madtsoiid snakes, trionychid turtles and birds. =====

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· Microfossils assemblages from the Late Carboniferous at Murgon include scales and teeth resembling those of neoselachians (modern sharks), these advanced forms being associated with primitive ray-fins ( [|palaeoniscoids] ). =====

** Kambara Implexidens! **

 * Kambara implexidens were a mekosuchine- an ancient group of primitive Gondwana crocodiles. This genus is the best known Palaeocene to Oligovene crocodiles in Australia!
 * Two closely related species of Kambara were found at Murgon
 * 1.5m long, from head to tail
 * They are only known to be found in Murgon.
 * Lived over 55 million years ago (early Eocene period)
 * During the early Eocene the site was a shawllow swamp or lake. The vegetation and climate in the area in this period has not yet been determined

**THE FOSSILS**

 * the fossil or the Kambara implexiden is represented by a nearly complete skull, a second partial skull and a second lower jaw. There are also other cranial/dentary fragments. Most of the fossil material appears to have been from larger adult Kambara implexidens. You can find these fossils in the Queensland Museum, Brisbane.
 * The tooth arrangement indicated that it was a crocodile, however unlike crocodiles and mroe like alligators, the teeth of their upper and lower jaw did not interlock when the mouth was closed, instead the teeth ofthe bottom jaw rest inside the teeth of the upper jaw- which is a characteristic of alligators.
 * Two closely related species of crocodiles have been found at this stie. Which is in fact an unusual situation as crocodiles are very territorial. They do not usually tolerate having their relatives around!
 * It may be that the waterhole/billabong they lived in was ephemeral, drying up frequently. The crocodiles may have forced together as the water body shrank, or they may have lived there sequentially, as when the water body refilled after a dry period, being populated by a different species from the species that occupied it during the previous wet phase.

SIMILARITIES TO CURRENT CROCODILES DIFFERENCES TO CURRENT CROCODILES
 * Their diet-
 * consiting of small vertebrate animals, small mammals, turtles, snakes and fish
 * Their envrionment-
 * swamps
 * Structure-
 * scales, long body, strong tail, large snout, sharp, carnivourous teeth


 * Size-
 * Only 1.5m long
 * Much smaller than the present day crocodile- the largest female saltwater crocodile recorded was aroudn 4.2m long.

= Djarthia = [] The discovery of fossil fragments of Djarthia, the earliest known Australian marsupial. and a subsequent study has helped to shed light on the evolutionary history of marsupials, in particular, // Dromiciops gliroides // ( Monito del Monte), a South American species. Marsupials are generally thought to have originated in South America and spread into Australia via the Antarctic continent, during a period when the three continents were connected. However, Monito del Monte appears to be most directly descended from Djarthia. It would seem that Monito del Monte evolved from a line of Australian marsupials who migrated back to South America. before the supercontinent ( Gondwana ) broke up around 40 million years ago. This new study was made possible by the discovery of the new fossil fragments of Djarthia, known only by teeth previously. The ankle and ear bones recovered in Australia allowed for a more complete comparison to be made between Djarthia and Monito del Monte. The study of the fossils was conducted by Mr. Robin Beck.

= = ** Tingamarra Porterorum **



**Lived:** 55 million years ago (early Eocene) > >
 * Size:** Length (head to tail): 20cm
 * Description:**
 * Tingamarra was a small ground-dwelling mammal that ate insects and fruit.
 * It was a condylarth — a member of an ancient group of placental mammals. These include the ancestors of placental mammals such as dogs, cats, horses and whales.
 * Tingamarra appears to be the only land-based placental mammal to have arrived in Australia before about 8 million years ago.
 * The only other native placental mammals in Australia are rodents.
 * Discovery of Tingamarra surprised scientists, because it meant that placental mammals were indeed in Australia many millions of years ago, and the marsupials survived despite the presence of competing mammals.
 * They must have died out sometime before 25 million years ago because, when the mammal fossil record picks up again in Australia, there is no sign of these tiny creatures.