The Marcianosuchus holotype specimen, SMNS 91318, was discovered in 1972 by Rupert Wild in talus deposits of the retired Kössig quarry, representing outcrops of the Röt Formation (Buntsandstein Group) near Ebhausen in Calw district of Baden-Württemberg, Germany.

The generic name, Marcianosuchus, combines a reference to the Black Forest near the type locality (its Latin name, used by historian Ammianus Marcellinus in the 4th century, is "Marciana silva", meaning "border forest") with the Greek σοῦχος ("suchus"), after Sobek, the crocodile-headed ancient Egyptian deity.

With the euparkeriid-like Dorosuchus from Russia, Marcianosuchus presents a generally skeletal morphology comparable to the archosaur plesiomorphic condition.

[1] In their phylogenetic analysis, Sues, Spiekman & Schoch (2024) recovered Marcianosuchus as a basal member of the archosauriform clade Eucrocopoda, in a polytomy with Dorosuchus outside of the Euparkeriidae.

Their results are displayed in the cladogram below:[1] Vancleavea Koilamasuchus Archeopelta Doswellia Jaxtasuchus Proterochampsa Chanaresuchus Tropidosuchus Dorosuchus Marcianosuchus Euparkeria "Turfanosuchus" shageduensis Halazhaisuchus Osmolskina Phytosauria Pseudosuchia Avemetatarsalia Marcianosuchus is known from the Röt Formation of Germany, which dates to Anisian age of the beginning of the Middle Triassic period.