Poekilopleuron is a difficult taxon to classify, as its original material is lost, and few casts are known.
Poekilopleuron has a history of being renamed under different species and genera, most of which are now its
junior synonyms. Eudes-Deslongchamps' choice caused problems however, when
Friedrich von Huene in 1923 concluded it was part of
Megalosaurus but as a separate species within that genus. As both species carried the same epithet
bucklandii, they could no longer be distinguished. Von Huene therefore renamed the species into
Megalosaurus poekilopleuron. Most later authors continued using the generic name
Poekilopleuron. Another problem was caused by the fact that the name was only partially Latinised. In correct Greek it would have been "poikilopleuron", in Latin "poecilopleurum". This induced later writers to improve the spelling, leading to such variants as
Poecilopleuron and
Poikilopleuron (still used as late as 2006). However, the original name has priority and is valid. Five other species would be named in the genus. In 1869
Edward Drinker Cope renamed
Laelaps gallicus into
Poekilopleuron gallicum. In 1870
Joseph Leidy created a
Poicilopleuron valens based on a fossil probably belonging to
Allosaurus. In 1876
Richard Owen named a
Poikilopleuron pusillus, in 1879 renamed by Cope to
Poekilopleuron minor; in 1887
Harry Govier Seeley made it a separate genus:
Aristosuchus. In 1883 W.A. Kiprijanow created a
Poekilopleuron schmidti, of which the specific name honours
Friedrich Schmidt, based on some indeterminate ribs and a
sauropod metatarsal. This
chimaera is a
nomen dubium. A much later named species is
Poekilopleuron valesdunensis created by
Ronan Allain in 2002. In 2005 it was renamed
Dubreuillosaurus. Because the original fossil was destroyed and no other remains of
Poekilopleuron have since been found, and also because of its name change, there is much controversy surrounding its classification that cannot be resolved. Traditionally it has been assigned to the
Megalosauridae, but some recent analyses showed a position in the
Sinraptoridae; others had as result it was a member of
Megalosauroidea, in a basal position or in the
Eustreptospondylinae. Benson
et al. (2010) found it and
Lourinhanosaurus to belong to
Sinraptoridae. An earlier study found that it was a primitive
allosauroid outside Sinraptoridae. However, a recent analysis by Carrano et al. (2012), also used in subsequent studies of
tetanuran theropods, recovered it as a Megalosauroid closely related to
Afrovenator. However, the authors of that study state that this position is uncertain since "with a single additional
step it can be recovered as a piatnitzkysaurid, elsewhere within Megalosauridae, or at several possible positions within Allosauria." In recent studies,
Poekilopleuron was recovered within different positions of
Allosauroidea. Cau (2024) recovered
Poekilopleuron within
Metriacanthosauridae, ==Paleobiology==