Macrospondylus is an extinct genus of machimosaurid teleosauroid crocodyliform from the Early Jurassic (Toarcian) of Europe. Fossils are known from the Posidonia Shale of Germany, the Whitby Mudstone of the United Kingdom, and the "schistes bitumineux" of Luxembourg.
Evolutionary relationships
Macrospondylus has historically been synonymized with Steneosaurus. A 2005 phylogenetic analysis of Thalattosuchia, however, did not support the monophyly of Steneosaurus, as the genera Machimosaurus and Teleosaurus both fell within Steneosaurus. Reinforcing the paraphyly of Steneosaurus, Young et al. (2012), Ősi et al. (2018), and Wilberg et al. (2019) recovered Steneosaurus bollensis and other Steneosaurus species in disparate positions within Teleosauridae.
In 2016, its length was estimated at , making it the largest known Early Jurassic crocodylomorph. In 2020, the genus was formally revived.