What priesthood did the line of Adam from Seth to Melchizedek and Noah hold in LDS/Mormon teaching? In the summary of Noah on the lds.org site, it states that Noah was ordained to the priesthood at the age of 10 by Methuselah, his grandfather.  Furthermore, in D &amp; C 107:53, it indicates that the entire line of Adam from Seth to Methuselah were all high priests.

I understand that there are two priesthoods acknowledged by the LDS Church--the Aaronic Priesthood and the Melchizedek Priesthood.

The Aaronic Priesthood originated with Aaron during the Exodus.  Melchizedek was a contemporary of Abraham, who lived a few hundred years after the flood.  

Methuselah lived before the flood and apparently died the year of the flood, while Noah lived on both sides of the flood, of course, as did 7 other members of his family.

So, what specific priesthood did the line of Adam from Seth to Noah hold that would have to predate the other two priesthoods by at least four centuries?
The crux of this question seems to lie in the final paragraph:


  So, what specific priesthood did the line of Adam from Seth to Noah
  hold that would have to predate the other two priesthoods by at least
  four centuries?


The confusion leading to this question is cleared up in Doctrine and Covenants, section 107:


  2 Why the first [order of Priesthood] is called the Melchizedek Priesthood is because
  Melchizedek was such a great high priest.
  
  3 Before his day it was called the Holy Priesthood, after the Order
  of the Son of God.
  
  4 But out of respect or reverence to the name of the Supreme Being,
  to avoid the too frequent repetition of his name, they, the church, in
  ancient days, called that priesthood after Melchizedek, or the
  Melchizedek Priesthood.


Therefore, the Priesthood from the time of Adam to Noah was the Melchizedek Priesthood; it just wasn't called that yet.