Elachistosuchus is an extinct genus of neodiapsid reptile, most likely basal archosauromorph, known from the Late Triassic Arnstadt Formation of Saxony-Anhalt, central Germany.

More recently however, a non-invasive μCT scanning was performed to resolve its placement within Reptilia, and found it to represent a more basal reptile, potentially closely related to several early archosauromorph clades.

The specific name huenei honors the German paleontologist Friedrich von Huene who greatly contributed to the study of various vertebrate groups, especially extinct reptiles.

4520, which consists of six small blocks (I–VI) of bone-bearing rock currently housed at the fossil reptile collection of the Berlin's Natural History Museum, in Germany.

[1] Using the Ezcurra et al. (2014)[3] data set, Sobral, Sues and Müller (2015) found Elachistosuchus with Coelurosauravus just outside Sauria using parsimony, or alternatively as the basalmost archosauromorph (out of the included taxa), using the Bayesian approach.

[1] Araeoscelidia Orovenator Lanthanolania Youngina Thadeosaurus Acerosodontosaurus Hovasaurus Tangasaurus Claudiosaurus typical archosauromorphs Thalattosauria Wumengosaurus Hupehsuchia Ichthyopterygia Helveticosaurus Saurosphargidae Sauropterygia Elachistosuchus Choristodera Coelurosauravus Pamelina Kuehneosauridae Sophineta Lepidosauria Araeoscelis Petrolacosaurus Acerosodontosaurus Youngina Coelurosauravus Lepidosauromorpha Elachistosuchus Aenigmastropheus Protorosaurus Macrocnemus Tanystropheus Trilophosaurus Mesosuchus Noteosuchus Howesia Prolacerta Archosaurus Proterosuchus Eorasaurus Erythrosuchus Euparkeria