The
phylogenetic position of
Deltadromeus is complicated by the fragmentary nature of the holotype, though others have found it to be more primitive, possibly related to the more ancestral ceratosaurs
Elaphrosaurus and
Limusaurus. A more comprehensive study of noasaurid relationships published in 2016 effectively agreed with both of these interpretations, with
Deltadromeus,
Limusaurus and
Elaphrosaurus all found to be within the Noasauridae. A 2017 paper describing ontogenetic changes in
Limusaurus and the effect of juvenile taxa on phylogenetic analyses placed
Deltadromeus as a noasaurid in every analysis regardless of which
Limusaurus specimen was used, although the analyses did not include
Gualicho or
Aoniraptor. According to the authors, resolving the phylogenetic positions of
Gualicho, Aoniraptor, Deltadromeus and megaraptorans is a critical issue facing theropod systematics.
Deltadromeus was also considered a noasaurid in a 2020 review of the Kem Kem Group geology and fauna. Since then, some studies find
Deltadromeus as a ceratosaur, The
cladogram below follows the 2016
Gualicho analysis by Sebastián Apesteguía, Nathan D. Smith, Rubén Juarez Valieri and Peter J. Makovicky. In 2020, Ibrahim and colleagues acknowledged similarities between the two genera, but considered it unlikely that
Deltadromeus represents a specimen of
Bahariasaurus due to perceived differences in the pelvic bones. They further regarded
Bahariasaurus as a
nomen dubium. The following year, Cau and Paterna used an updated version of this dataset to reanalyze the relationships of
Bahariasaurus,
Deltadromeus, and other Cretaceous theropods from Africa. They determined that the variation observed between specimens of
Deltadromeus and
Bahariasaurus was the result of individual and
ontogenetic variation, as the former is known from immature remains. They further reidentified specimen SNSB-BSPG1912VIII82—recognized as a indeterminate theropod pubis by Stromer in his 1934 description of
Bahariasaurus—as a complete ischium. The authors observed anatomical characters that the bone shares with the less complete ischia of the holotypes of both
Bahariasaurus and
Deltadromeus, which they used to strengthen their argument. They concluded that
Deltadromeus should be regarded as a junior synonym of
Bahariasaurus. The results of their phylogenetic analysis are displayed in the cladogram below, with
Bahariasaurus (including
Deltadromeus) indicated in the so-called "abelisauroid clade 1". |label1=
Abelisauroidea}} In a paper analyzing the relationships of
Mirischia and
Santanaraptor, two coelurosaurs from the Cretaceous of Brazil, Brazilian paleontologist Rafael Delcourt and colleagues found
Deltadromeus and
Gualicho to be early-branching ornithomimosaurs in their phylogenetic analysis. Delcourt and colleagues (2025) noted that
Deltadromeus' femur lacks a crest seen in many other theropods, a condition observed in ornithomimids like
Struthiomimus and
Gallimimus. Additionally, the medial
condyle of the tibia of
Deltadromeus bears a large process found in the tibiae of ornithomimosaurs like
Mirischia. Although several African theropods from Gondwana have been theorized to be ornithomimosaurs, many of these taxa have since been reclassified as noasaurids, which too have edentulousness, gracile limbs, and elongated (neck) vertebrae like the ornithomimosaurs. However, Delcourt and colleagues as well as a conference abstract recovered
Deltadromeus and
Gualicho within Ornithomimosauria in their phylogenetic analyses, with the former paper stating that the classification of the two needs further study. == Paleoenvironment ==