Backwards oriented is a sign, presumably indicating things are ending here. There is a kind of similarity between this glyph and Aa7-1.

And Aa7-1 seems to be connected to the preceeding glyph Aa6-84. And that glyph resembles - as if to mark something - even earlier glyphs:

Aa6-39 (455) Aa6-40 (416 + 40) Aa6-49 (465) Aa6-62 (416 + 62)
Evidently these two belong together. This kind of glyph is found in more places, though nowhere with the 'root'.
Aa6-84 (500) Aa7-1 Aa7-6
These two belong together because one ends line a6 and the other is at the beginning of line a7. Is a tail a sign of end?

... The Maya New Year started with 1 Pop, the next day being 2 Pop, etc. The final day of the month, however, carried not the coefficient 20, but a sign indicating the 'seating' of the month to follow, in line with the Maya philosophy that the influence of any particular span of time is felt before it actually begins and persists somewhat beyond its apparent termination ...

Looking forwards instead we will find:

Aa7-22 Aa7-32 (532) Aa7-38 Aa7-59 (559) Aa8-8 (593)

The sign of an open hand from the person reminds me of the Sun in the afternoon, when his force is abating. Notice how the string to the Fish is broken in Aa7-32 (→ 2 * 266).

If we read increasing Sun in the sign of kai, i.e. with hand towards the mouth or inwards towards the person, then logically the sign of an open hand oriented away from a person means the opposite: that he is on the decline.