Milleretta

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Milleretta is an extinct, lizard‑like reptile from the Late Permian of what is now South Africa. Fossils come from the Balfour Formation, and the only widely recognized species is Milleretta rubidgei, though several historically named species have been merged into this genus.

Discovery and naming
Milleretta was first described in 1938 as Millerina rubidgei, but the name Millerina was already in use for a fly genus, so the reptile was renamed Milleretta rubidgei. For a long time only a juvenile specimen was known, labeled BP/1/3821. An adult was found in 1950 at Wildgebosch farm, in the Dicynodon Assemblage Zone (BP/1/2040), confirming adult features and extending its known range in the area.

What Milleretta looked like
About 60 cm (24 inches) long, Milleretta was a medium-sized, reptile‑like animal. The skull and inner ear are known from modern imaging techniques (micro-CT scans). Its vertebrae have wide neural arches with spines, horizontally oriented zygapophyses, and strong transverse processes. The ribs are thick and dorsally expanded, providing body protection but reducing flexibility. In adults, parts of the skull and skeleton show fusion, such as the centrum and neural arch coming together.

A distinctive feature
Milleretta is unusual among Paleozoic stem reptiles for secondarily closing both the upper and lower temporal openings as it grew. It also has a single row of teeth on the palate.

Habitat and lifestyle
Fossils come from a forested environment in the Karoo Basin, suggesting Milleretta lived among forest floor litter. Later in the Permian, climate trends became drier, a change that may relate to broader extinction events, though details are still studied.

Taxonomy and relationships
Millerettidae is the family named in 1956 for reptiles close to Milleretta. For many years it was viewed as a very primitive parareptile group, but Milleretta is now seen as more derived within Millerettidae. Some studies place Millerettidae near the base of Neodiapsida, with Milleretta close to Millerosaurus; recent research continues to refine these relationships.