The project is gaining momentum as 12 permanent land piles north of the Clarence River have been built.
There are now sixteen permanent piles in the Clarence River which were built using two barges. Marine piling is taking place on the northern and southern banks of the Clarence River, moving towards the centre of the river. Pile excavation and concrete installation for both land and marine permanent piles is now underway. The project team is continuing to work closely with Roads and Maritime Services, its delivery partner Pacific Complete, to deliver the 1.
The project team is now fully established at the site compound on the north of the Clarence River and is growing in number as the project progresses.
A bridge across the Pacific
The upgrade is expected to be completed by Key Features Construction of the new bridge involves: Design and construction of a new 1. The length of the bridge over the Clarence River will span meters, with a vertical clearance above the river of at least 30 metres for marine traffic to pass.
The new bridge will be a dual carriageway bridge, with two lanes in each direction. If that's the case, the island species would need to be old -- very old. Using "molecular clock" analysis of living iguana DNA, Noonan and Sites found that, sure enough, the island lineages have been around for more than 60 million years -- easily old enough to have been in the area when the islands were still connected via land bridges to Asia or Australia.
Fossil evidence backs the finding. Fossils uncovered in Mongolia suggest that iguanid ancestors did once live in Asia.
Building a bridge across the Pacific
Though there's currently no fossil evidence of iguanas in Australia, that doesn't necessarily mean they were never there. So if the iguanas simply migrated to Fiji and Tonga from Asia or possibly Australia, why are they not also found on the rest of the Pacific islands?
Noonan and Sites say fossil evidence suggests that iguana species did once inhabit other islands, but went extinct right around the time humans colonized those island.
That's an indication that iguanas were on the menu for the early islanders. But Fiji and Tonga have a much shorter history of human presence, which may have helped the iguanas living there to escape extinction. The molecular clock analysis combined with the fossil evidence suggests a "connection via drifting Australasian continental fragments that may have introduced [iguanas] to Fiji and Tonga," Noonan says. The researchers say that their study can't completely rule out the rafting hypothesis, but it does make the land bridge scenario "far more plausible than previously thought.
A Superhighway Across the Bering Strait
Materials provided by University of Chicago Press Journals. Note: Content may be edited for style and length. Science News. Journal Reference : Brice P. Noonan and Jack W.
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Sites Jr. ScienceDaily, 14 January University of Chicago Press Journals. Raft or bridge: How did iguanas reach tiny Pacific islands?. Retrieved June 26, from www.