The issue focused by Australian scientist Simon Conway has raised fresh concerns over research conducted by Australia's CSIRO and international universities on ancient marine reptiles.About 90,000 specimens were recovered from Australia's lakes and oceans between 1976 and 2006.Only those marine reptiles whose skeletal remains could be excavated were examined.Prof Conway says there are concerns about how such specimens could have survived for millions of years."They're basically extinct because they've either gone extinct through habitat destruction or because they've died out through isolation," he told BBC