Ancient turtle rode freshwater wave to migrate from Asia to North AmericaFebruary 2nd, 2009 - 1:01 pm ICT by ANI
Washington, Feb 2 (ANI): In a new research, scientists have found a surprise fossil of a tropical, freshwater, Asian turtle in Arctic Canada, which suggests that the ancient animal migrated from Asia to North America directly across a freshwater sea floating atop the warm, salty Arctic Ocean.
The find, by a team of geologists from the University of Rochester in the US, rebuffs an earlier theory that said animals migrated from Asia to North America around Alaska.
Weve known theres been an interchange of animals between Asia and North America in the late Cretaceous period, but this is the first example we have of a fossil in the High Arctic region showing how this migration may have taken place, said John Tarduno, professor of geophysics at the University of Rochester and leader of the Arctic expedition.
The finding also suggests that a rapid influx of carbon dioxide (CO2) some 90 million years ago was the likely cause of a super-greenhouse effect that created extraordinary polar heat.
Were talking about extremely warm, ice-free conditions in the Arctic region, allowing migrations across the pole, said Tarduno.
In 2006, Tarduno led an expedition to the Arctic to study paleomagnetism, which incidentally led to the discovery of the well-preserved shell of a turtle.
Together with collaborator Donald Brinkman of the Royal Tyrrell Museum of Canada, they later named the fossil Aurorachelys, or aurora turtle.
The turtle strongly resembles a freshwater Mongolian species, which raised obvious questions about how it came to be in the marine waters of the North American Arctic.
Tardunos paleomagnetic expertise, which allows him to ascertain when points on Earths crust were at specific locations, allows him to rule out the possibility that millions of years of tectonic activity had brought the fossil from southern climes.
The turtle was clearly a native of the area.
As to how a freshwater turtle migrated across a salty ocean; Tarduno points to the results of drilling by the Integrated Ocean Drilling Programs ACEX expedition that demonstrated episodes of unusually fresh surface waters in the past Arctic Ocean.
At the time the aurora turtle lived, the Arctic Ocean was probably even more separated from the global oceanic circulation system than it is today. Numerous rivers from the adjacent continents would have poured fresh water into the ancient Arctic sea.
Since fresh water is lighter than marine water, Tarduno thinks it may have rested on top of the salty ocean water, allowing a freshwater animal such as the aurora turtle to migrate with relative ease. (ANI)
- Asiatic turtle migrated to America over a tropical Arctic - Feb 02, 2009
- Scientists find car-sized turtle fossil - May 18, 2012
- Study On Deep Sea Turtles Show Interesting Results - Jan 20, 2011
- China to conduct Arctic expedition - Mar 12, 2012
- Gigantic new turtle fossil discovered - Jul 12, 2012
- Warming oceans drive largest movement of marine species - Jun 26, 2011
- 25 endangered turtles seized in Odisha, one held - Dec 16, 2011
- Rising temperatures could render some species homeless - Nov 07, 2011
- Sea ice formed in the Arctic before it did in Antarctica - Jul 16, 2009
- Arctic Ocean water is 'warmest it's been for more than 2,000 years' - Feb 01, 2011
- How young migrating turtles find their way back home - Feb 25, 2011
- Sudden temperature drop, not comet strike, behind extinction of dinos - Apr 24, 2010
- Earth's weak magnetic field helped Sun to steal water from planet's early atmosphere - Mar 05, 2010
- A turtle fest in golden sands of Maharashtra (Feature, With Images) - Feb 17, 2012
- Pew Environment Group excited about Obama's expected suspension of oil-drilling - May 27, 2010
Tags: ancient animal, arctic canada, arctic expedition, arctic ocean, arctic region, brinkman, collaborator, freshwater turtle, geologists, geophysics, greenhouse effect, late cretaceous period, marine waters, paleomagnetism, rapid influx, research scientists, royal tyrrell museum, southern climes, university of rochester, warm ice