SSU rRNA secondary structure for Calcarea. Sequence is given as 90% consensus with variable positions in black boxes. Lower case indicates deletions at the site for some sequences, according to the consensus level. Differences in helices between Calcaronea and Calcinea are in frames (Calcaronea = black, Calcinea = grey). Synapomorphies for each subclass are shown in boxes with the same color code. Primer positions are bold at the 5' and 3' end, respectively. Open circles instead of dots mark positions where mismatches occur in some sequences. Inset: Shortening and elongations in the boxed part of Helix E10_1 for two calcaronean sequences and one calcinean sequence.