The remains were acquired by the local bookseller James Parker, who brought them to the attention of Oxford Professor John Phillips.

In 1890, the skeleton was bought by Oxford University, and Arthur Smith Woodward examined it and referred it to Megalosaurus bucklandii.

In 1905 and 1906 Baron Franz Nopcsa reassigned the skeleton to the species, Streptospondylus cuvieri, which had been first described by Sir Richard Owen in 1842, based on a now lost vertebra from the Bathonian stage of the Jurassic period.

[6] In 1964, Alick Donald Walker clarified matters by erecting a separate genus and species for the Oxford specimen: Eustreptospondylus oxoniensis.

[8] The holotype, OUM J13558, was recovered by W. Parker from claystone in a marine layer of the Stewartby Member of the Oxford Clay Formation, which dates to the Callovian stage of the Jurassic period, approximately 162 million years ago.

In 2000, Oliver Walter Mischa Rauhut found that only minor differences in the hip bones — a more upward extending fusion of the "feet" of the pubic bones — make Eustreptospondylus different from a previously known megalosaurid called Magnosaurus,[9] and in 2003 he proposed that they should be the same genus, which would make the full species name Magnosaurus oxoniensis.

The main specimen of Eustreptospondylus was not fully grown, and according to an estimate by Paul in 1988 was about 4.63 metres (15.2 ft) long and weighed about 218 kilograms (481 lb).

[14] Sadleir also found additional traits proving that Eustreptospondylus differed from Magnosaurus nethercombensis in more than a single detail.

The interdental plates reinforcing the back of the teeth are longer from front to rear than they are tall; with M. nethercombensis the opposite is true.

Seen from above, the pubic bone forms transversely a more narrow part of the lower rim of the hip joint.

[12] In 1964, Walker assigned Eustreptrospondylus to the Megalosauridae, which was historically included in a paraphyletic "Carnosauria", though sometimes a separate Eustreptospondylidae was recognised.

In 2000, David Martill and Darren Naish pointed out that the portrayal of the animal as an island-dwelling dwarf species was caused by not realizing that the holotype specimen represented a subadult.