Preprismatoolithus is a Late Jurassic oogenus. The species P. coloradensis is described by John Foster as being "of the prismatic basic type," with subspherical eggs about 10 cm (4 inches) in diameter. This oospecies has been initially attributed to "hypsilophodontid" dinosaurs, although a lack of associated embryo material currently makes confirming the egg-layer's identity impossible, but now is known to be theropod after the finding in Portugal, associated with the embryos.