Eustreptospondylus

Phylogeny: Dinosauria > Saurischia > Theropoda > Neotheropoda > Tetanurae > Megalosauroidea (?) > Megalosauridae > Eustreptospondylinae

Overview: Only one fossil specimen of this carnivorous dinosaur has ever been described, consisting of portions of its skull, numerous vertebrae, its pelvis, and some limb bones. These remains came to light in 1870, discovered by workers in a clay pit in Oxfordshire, England. It was a significant find, as it would represent what is to this day one of the most completely known theropod skeletons ever found in the country. In the 1890’s, the fossils were attributed to the genus Megalosaurus, but later in 1905, the remains were instead referred to the poorly known genus Streptospondylus. Research in later decades would prove that the Oxfordshire fossils were actually from an entirely new, distinct genus. Eustreptospondylus was established as such in 1964 by the paleontologist Alick D. Walker. It was named in reference to Streptospondylus, being the “true Streptospondylus”, but the name also refers to the form of its vertebral spines, as it also translates as “well-curved vertebrae”. Studies since have usually placed the genus within the family Megalosauridae, within a subfamily referred to as the Eustreptospondylinae, but some see it as related to the spinosaurids in some way.

The type specimen was between four and five meters long at death, but it doesn’t appear to have been fully grown. Adults were possibly six or more meters in length, so decently large, but far from the largest of theropods. Still, Eustreptospondylus was likely among its region’s top land predators. It likely preyed on small to medium-sized herbivores as well as marine reptiles or fish that washed up along the coast. Eustreptospondylus is known from the Oxford Clay Formation, so it would’ve lived on islands in what was then a warm, shallow sea (much of Europe was submerged). Fossils of another, probably larger theropod called Metriacanthosaurus are also found in the Oxford Clay, as well as those of some sauropods and stegosaurs. Eustreptospondylus likely occupied a different niche than Metriacanthosaurus. The latter probably had relatively deep jaws, while those of this genus were rather narrow and pointed, which were good for snatching up quick and mostly small prey. Fossils of Eustreptospondylus are specifically known from marine deposits, which suggests to some it swam from island to island, but others maintain it was merely swept out to sea.