"I found that the Indus Valley script signs matched the star constellations along the ecliptic. "
I am very sympathetic to his approach since it mirrors some of my own views about the common astronomical origin of many symbols in disparate cultures. I do not however agree with many of his individual interpretations, but I think he is definitely on the right track in seeing symbols of the Indus Valley script to be astronomical signs for the Nakshatras (ancient Vedic Sanskrit moon stations of the sky). In other words, he is very right in seeing the astronomical connection. I then saw it as my responsibility, based on my experience with ancient astronomical scripts, to identify those symbols that I can.
Below, I compare one of the seals that Daniel Salas shows on his website with my decipherment 26 years ago of a wooden tablet from Easter Island known as "Honolulu Tablet No. B. 3622", which I showed to be an ancient zodiac, as published in the year 1981 in An Astrological Zodiac in the Script of Easter Island. That there is a clear connection between that Easter Island script and the Indus Valley seal pictured by Daniel Salas is beyond doubt, and I interpret the Indus Valley seal accordingly below.
At the bottom of the graphic below, to the right (and reproduced backwards next to it left), is the Indus Valley seal pictured by Salas:
To our eye, the second line appears merely to be a variant writing of the same symbols.
In the middle of the page below is found the Easter Island Zodiac deciphered by me in the year 1981:
If we now directly compare the Indus Valley seal with the Easter Island tablet we get the following comparison and identification of astronomical signs:
The second row of symbols on the seal appears to be a variant form of the same group of symbols - or - perhaps this lower group of symbols applies to the southern heavens, which would support the ancient Vedic Sanskrit legends that the ancient seafarers mapped the southern heavens so as to be nearly identical to their northern counterparts. Richard Hinckley Allen in Star Names, Dover Publications, N.Y. 1997, reports of ancient legends that the southern stars were initially created by ancient seafarers to approximate the shape of Northern constellations in similar positions. Allen writes in Star Names (p. 436) as follows:
"Before the observations of the navigators of the 15th and 16th centuries the singular belief prevailed that the southern heavens contained a constellation near the pole similar to our Bear or Wain; indeed it is said to have been represented on an early map or globe. Manilus wrote:
The lower Pole resemblance bears
To this Above, and shines with equal stars;
With Bears averse, round which the Draco twines;'
and Al Biruni repeated the Sanskrit legend that at one time in the history of the Creation an attempt was made by Visvamitra to form a southern heavenly home for the body of the dead king, the pious Somadatta; and this work was not abandoned till a southern pole and another Bear had been located in positions corresponding to the northern, this pole passing through the island Lunka, or Vadavamukha (Ceylon). The Anglo-Saxon Manual made distinct mention of this duplicate constellation 'which we can never see.'..."
Footnote: The name Rongorongo for Easter Island is an unfortunately erroneous rendering by misled scholars and their equally detoured followers. The ancients doubled their symbols and names to form plurals and the term rongo is cognate with Indo-European e.g. Latvian runas "talks, stories" of which runa is the singular. To form the plural, the ancients doubled the rongo "runa" symbol. The Latvian term RUNA "talk" viz. RUNAS "talks" explains why the carved messages found on ancient megaliths are called RUNES in the Scandinavian pantheon.