Thililua has 30 cervical vertebrae. Each cervical has a longitudinal ridge on its lateral surfaces, this is a convergent feature with elasmosaurids. The skull of Thililua is relatively large with a short postorbital region and elongate rostrum.
The type specimen (MHNGr.PA.11710) consists of a complete skull, entire cervical and pectoral series, and the first four dorsal vertebrae.
