What is Antarctosauridae?

No official definition. Antarctosauridae was coined by George Olshevsky at a time when the validity of Titanosaurus indicus—the anchor of Titanosauria and Titanosauridae—was being questioned.

Although it's based on only a few tail bones and a thigh, many palaeontologists feel that Titanosaurus is perfectly valid and a more than capable name-bearer, though, if proven otherwise, then the tradirional "Titanosauridae" should be replaced with Antarctosauridae which was the first replacement name to be proposed for the same group of sauropd dinosaurs, despite never being officially defined.

Powell listed Antarctosauridae as a junior synonym of Titanosauridae in 2003, some palaeontologists unite Antarctosauridae/Titanosauridae and Saltasauridae in a group called Lithostrotia—"paved with stones"—in reference to the armoured backs of some members, some have adopted Lithostrotia as a replacement name for Antarctosauridae/Titanosauridae, and others refuse to accept Lithostrotia at all. Antarctosauridae is derived from the Greek "ant" (opposite), "arktos" (north), "sauros" (lizard) and "-idae" (family).