In my previous article (Maize in the hands of temple deities), I showed the image of the main deity (Mulavar) and the golden image of Lord Padmanabha Swamy of Trivandrum, in the context of discussing the features of the hand as per Iconography of the book of Vaastu sastra called Mayamatham, authored by Mayan.
While giving the features for sculpting "AnantasAyin", Vishnu in lying in cosmic sleep on the bed of Ananta, the snake, Mayamatham says that Vishnu's left hand holds a flower (Sanata manjari or perpetual flower) and his right hand holds the mace or supports his head. The main deity of Lord Padmanabha has an outstretched right hand but with the mace missing. Instead a Shiva linga is found below the hand. In the undated golden image found in the vault of the temple, the right hand holds a flower in a posture of doing puja to the Shiva linga.
I pointed out the probable role of the Cheran King Senkuttuvan in having made the changes in the posture of the main deity. Let me show here some images of AnantasAyin fitting well with iconographic rules of a flower in the left hand and out-stretched position of the right hand which must have supported a mace.
Mahabalipuram. Dated at 7th century