Dear list members,
1) I've just gone through Dominik Haas's paper "Gayatri as a name for RgVeda 3.62.10". In it he notes: some manuscripts of the Northern recension [of the Mahabharata]  also add the line: ‘but if a non-Brahmin recites the sāvitrī, he perishes.’
Can this restriction of the RgVeda Gayatri 3.62.10 to Brahmin's explain the proliferation of the later Gayatri's .

2)I've done a quick search of GRETIL to see which texts the later Gayatri mantras are in. There is a very large number in Vaishnavite texts or authors/commentators with the later Gayatri mantras among these.  Any explanation. Is this also from the restriction of the original gayatri to brahmins.

The distribution of later Gayatri's by text (without diacriticals)

 agni purana 10

anandakanda 1

atharvavedapariśiṣṭa 1

Bhrgu-Samhita a text of the Vaikhanasa-tradition 1

Devigītā 1

Gauragovindarcanasmaranapaddhati by Dhyanacandra Gosvami 9

Garuda purana 3

Haribhaktivilasa by Gopalabhatta 1

linga-purana 30

Narada purana 3

Parasuramakalpasutra 1

Pasupatasutra 1

RgVedakhila 1

Sadhanadipika by Radhakrsnadasa Gosvami 5

Vaikhanasamantraprasna, Prasnas 5 - 8 71


Thanks,

Harry Spier