Papal cross Papal cross The papal cross is a Christian cross, which serves as an emblem for the office of the Pope in ecclesiastical heraldry. It is depicted as a staff with three horizontal bars near the top, in diminishing order of length as the top is approached. The cross is thus analogous to the two-barred archiepiscopal cross used in heraldry to indicate an archbishop, and seems to have been used precisely to indicate an ecclesiastical rank still higher than that of archbishop. In the past, this design of the cross was often used in ecclesiastical heraldry as a distinctive mark of
Horizontal gene transfer in evolution transferred. Although this may be rare, this possibility is forcing scrutiny of the validity of phylogenetic trees based on SSU rRNAs. Recent discoveries of "rampant" HGT in microorganisms, and the detection of horizontal movement of even genes for the small subunit of ribosomal RNA, have forced biologists to question the accuracy of at least the early branches in the tree, and even question the validity of trees as useful models of how early evolution occurs. <br> "Sequence comparisons suggest recent horizontal transfer of many genes among diverse species including across the boundaries of phylogenetic "domains". Thus determining the phylogenetic history