Makarasana is a variation on Salabhasana. Iyengar cites Verse 40 of the second chapter of the Gheranda Samhita when describing the pose:
“Lie on the ground face down, the chest touching the earth and both legs stretched out: catch the head with the arms. This is the Crocodile Posture which increases bodily heat.”
The Gheranda Samhita is a 17th century, encyclopedic text on Hatha yoga. In addition to the Hatha Yoga Pradipika and the Shiva Samhita, the Gheranda Samhita describes the Hatha yoga practice. Many people speculate on when yoga came into existence. Some say hundreds of years ago, some say thousands. Regardless, the existence of an over 400 year-old text like the Gheranda Samhita speaks to the deep history of Hatha yoga. I am humbled to be a student of such a vast, inspiring tradition.