[3] In 1984, the premaxilla specimens MNHN GDF 365 and 366 were first described in detail by Taquet, where he referred them to an unnamed new theropod within the family Spinosauridae, because of shared characteristics with the holotype dentary of Spinosaurus aegyptiacus.

This was later proven incorrect in 1996 by Brazilian paleontologists Alexander Kellner and Diogenes Campos, in light of the discoveries of other spinosaurids preserving upper jaw tips with over five teeth.

[1][4] In a 1986 publication, British paleontologists Alan Charig and Angela Milner considered Taquet's jaw elements nearly indistinguishable from those of the spinosaurid Baryonyx walkeri; which they were describing on the basis of a partial skeleton from the Barremian of the Weald Clay Formation, England.

Its describers, the American paleontologist Paul Sereno and colleagues, agreed with Charig and Milner in that there was no distinction between the skull fossils of Baryonyx and Cristatusaurus; concluding that the latter was a nomen dubium.

[8] The same year, Hans-Dieter Sues and colleagues regarded both Cristatusaurus and Suchomimus as junior synonyms of Baryonyx, stating that there is no fossil evidence indicating more than one spinosaur lived in the Elrhaz Formation.

[11][16] In 2016, Christophe Hendrickx, Octávio Mateus, and Buffetaut noted that Taquet and Russel might have interpreted Cristatusaurus as having a shorter snout than Baryonyx by mistaking the notch where the maxillae articulated with the premaxillae for the nostril openings.

However, Cristatusaurus's convex secondary palate is clearly visible in side view (situated under the premaxillary teeth), whereas in Suchomimus it is discernible only through cracks on the fossil snout.

The researchers concluded that further study is needed to determine whether these differences are possible autapomorphies (distinguishing features) between the taxa, or if they are the result of ontogenetic (developmental) changes, given that the Cristatusaurus holotype represents a younger individual.

[4] The holotype's smaller size, smoother surface, and lack of co-ossified (fused) sutures all indicate that it belongs to a juvenile individual; while MNHN GDF 365 probably represents an adult.

[4] The tip of Cristatusaurus's premaxilla was short and expanded, while the rear end was narrowed near the suture with the maxilla; this rosette-like snout shape was characteristic of spinosaurids.

[2][4][22] A thin sagittal crest ran lengthwise on top of the premaxillae, a condition present in Baryonyx and Suchomimus, and very prominent in Angaturama (a possible synonym of Irritator).

[13] Baryonyx The Elrhaz Formation, part of the Tegama Group, consists mainly of fluvial sandstones with low relief, much of which is obscured by sand dunes.

[27][28] The sediment layers of the formation have been interpreted as an inland habitat of extensive freshwater floodplains and fast-moving rivers, with a tropical climate that likely experienced seasonal dry periods.

Crocodylomorphs were abundant; represented by the giant pholidosaur species Sarcosuchus imperator, as well as small notosuchians like Anatosuchus minor, Araripesuchus wegeneri, and Stolokrosuchus lapparenti.

Cristatusaurus's teeth would have likely been used for piercing and gripping prey items, rather than slicing flesh, as indicated by their subcircular cross section and reduced serrations.

The retracted nostrils would have allowed it to submerge its snout further underwater than most theropods, while still being able to breathe; and the bony secondary palate is theorized to have reinforced the skull against bending stresses when feeding.

The use of the giant recurved manual unguals of spinosaurs is still under debate; suggested functions have ranged from gaffing aquatic prey out of the water, to scavenging carcasses or digging.