The fact that the only displayed Liliensternus I have ever seen lacks any ridges over the eyes is open to debate about the validity of that assertion, that it lacks a ridge. Originally Liliensternus was placed within the Ceratosaur family along with Ceratosaurus, Dilophosaurus, and Coelophysis. This has since been changed and now the coelophysids (Coelophysis, Liliensternus et al) and the dilophosaurids (Cryolophosaurus, Dilophosaurus et al) have been moved out of the Ceratosaur family and given their own separate families. If artists go by the old family lines, crests would certainly be expected as many of their fellow family members possessed crests (e.g. Dilophosaurus, Cryolophosaurus, Ceratosaurus). In the new family lines Liliensternus is a part of the coelophysids, Late Triassic dinosaurs who did not possess any cranial ornamentation that we have so far discerned. Therefore, in the modern familial organization, a skull crest makes little and almost no sense in Liliensternus, but it does remain.