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Chunk of North America is part of Australia


Posted on Tuesday, 23 January, 2018 | Comment icon 16 comments

Earth's continents were laid out very differently in the distant past. Image Credit: CC BY-SA 3.0 NikoLang
Scientists have identified an area of Australia that broke away from North America 1.7 billion years ago.
The region in question, which today is known as Georgetown, is home to sandstone sedimentary rocks found nowhere else in Australia but that closely resemble rocks found in present-day Canada.

Researchers from Curtin University concluded that the whole area must have broken away from North America around 1.7 billion years ago before colliding with what is now northern Australia.

"This was a critical part of global continental reorganization when almost all continents on Earth assembled to form the supercontinent called Nuna," said doctoral student Adam Nordsvan.

When Nuna broke apart again 300 million years later, the Georgetown region remained attached to Australia as the North American landmass drifted away.

The discovery is important because it not only reveals more about Australia's history but also provides further clues as to the shape of the Nuna supercontinent and how all the landmasses fitted together.

Evidence was also found to suggest that Georgetown's mountain range also formed around this time.

"This mountain belt, in contrast to the Himalayas, would not have been very high, suggesting the final continental assembling process that led to the formation of the supercontinent Nuna was not a hard collision like India's recent collision with Asia," said study co-author Zheng-Xiang Li.

Source: Live Science | Comments (16)

Tags: Australia

Recent comments on this story
Comment icon #7 Posted by Piney on 24 January, 2018, 17:40
They crossed Antarctica and through South America, which was all marsupial until it connected to North America.
Comment icon #8 Posted by Carnoferox on 24 January, 2018, 18:01
Believe it or not, platypuses took the same route into South America. https://en.wikipedia.org/wiki/Obdurodon#Monotrematum_sudamericanum
Comment icon #9 Posted by paperdyer on 24 January, 2018, 19:06
Interesting.  Wasn't Australia originally thought to be from Antarctica like India.  Do all the Aussies have to start saying EAH? at the end of every sentence now?
Comment icon #10 Posted by oldrover on 24 January, 2018, 20:31
****PEDANT ALERT**** Not quite, there were Eutherians in South America before the formation of the Panama isthmus. Although I did used to (1990's style) understand the where and when quite well, as Carnoferox has patiently pointed out many times, my knowledge outside of one species is now badly out of date. So I won't expand.  But yes to all the rest of your post. 
Comment icon #11 Posted by Piney on 24 January, 2018, 20:53
It's really out of my archaeology sphere but I tried.
Comment icon #12 Posted by Carnoferox on 24 January, 2018, 21:33
South America actually had a lot of native eutherians before the Isthmus of Panama formed sometime in the middle to late Miocene, including New World monkeys and xenarthrans like armadillos, sloths, and anteaters, as well as endemic extinct groups like notoungulates (i.e. Toxodon) and litopterns (i.e. Macrauchenia). 
Comment icon #13 Posted by Socks Junior on 25 January, 2018, 2:38
Antarctica, Australia, and India were all close friends in Gondwana - but Gondwana formation didn't finish until early Cambrian, say 520 Myr ago. 1700 Myr ago is over 3 times longer than that! That's when Columbia was supposedly coming together. Then Rodinia, then Gondwana (not technically a supercontinent but quite an amalgamation), then Pangea (which included Gondwana). The basement of Precambrian geology is incredibly deep. "No vestige of a beginning, no prospect of an end" and all that. All that being said - this should really be in the Earth Science forum.
Comment icon #14 Posted by oldrover on 25 January, 2018, 17:20
Macrauchenia, I remember buying a little plastic model of one of these when I sas very young, the first time I realised there were cooler things than dinosaurs.  By chance I watched a very informative (but annoyingly delivered) lecture today by Thomas Holtz. In which he said that DNA had been extracted from both Toxodon and Macrauchenia, and they were both closer to each other than anything else, and outside of which were most closely akin to the Perissodactyls.
Comment icon #15 Posted by Carnoferox on 25 January, 2018, 18:20
According to the paper (first link) DNA was only successfully recovered from Macrauchenia. Its close relationship to Toxodon was confirmed based on earlier protein analyses (second link). I'm surprised that Holtz was giving the lecture considering he specializes in dinosaurs. https://www.nature.com/articles/ncomms15951 https://www.nature.com/articles/nature14249
Comment icon #16 Posted by oldrover on 25 January, 2018, 21:00
It was a run through only, but very interesting and included several groups I'd not previously heard of. As I say though, the humour grated a bit, as did the audience participation. 


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