[7] Milleretta had plesiomorphic vertebrae and made its ribs wider by growing its bone out the shaft to airfoil-like section.

In contrast, Eunotosaurus’ trunk vertebrae are stretched and it has T-shaped ribs with double articulations.

The femur becoming fully ossified, complete formation of articular ends at the limbs, and expanding ribs occur as Milleretta become adults.

[3] Something attributed to this family is the creation of the lateral temporal opening, which adult Milleretta managed to close completely.

Eunotosaurus, which was also discovered in the Balfour Formation and lived around the same time as Milleretta, has sometimes been considered the sister taxon to Millerettidae.

[3] Brazilosaurus sanpauloensis Mesosaurus tenuidens Stereosternum tumidum Eunotosaurus africanus Milleretta (rubidgei) Broomia perplexa "Millerosaurus" nuffieldi Milleropsis pricei Millerosaurus ornatus Australothyris smithi Microleter mckinzieorum Ankyramorpha The two specimens of Milleretta both lived at the end of the Late-Permian (Changsingian).

[5] The vast range of sharp teeth helped make it possible to chew the insects present at the time.

Milleretta probably lived in a forest-like environment due to the preserved forest-floor litter from the Karoo Basin located in South Africa.

[12] A recent examination of soil profiles shows that the environment in which Milleretta lived became more dry as time moved on.