Specimens at different developmental stages, found in the same type of sediment at the same locality, also support an ovoviviparous reproduction model. However, fossils have been found of female Keichousaurus with fetuses within the lower portion of the thoracic cavity.
Specimens at various developmental stages, found in the same type of sediment and location, support an ovoviviparous reproduction model. Conversely, fossils reveal that female Keichousaurus sometimes carried embryos within their thoracic cavities.