Macrospondylus has historically been synonymized with Steneosaurus.[1] A 2005 phylogenetic analysis of Thalattosuchia, however, did not support the monophyly of Steneosaurus, as the genera Machimosaurus and Teleosaurus both fell within Steneosaurus.[2] 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.[3][4][5]
In 2016, its length was estimated at 5.5 m (18 ft), making it the largest known Early Jurassic crocodylomorph.[6] In 2020, the genus was formally revived.[7]
Palaeobiology
M. bollensis exhibited a regular, stable growth rate until reaching adulthood. It was adapted primarily for life in aquatic environments but also retained some adaptations for terrestrial locomotion.[8]
^Young, M. T.; Brusatte, S. L.; De Andrade, M. B.; Desojo, J. B.; Beatty, B. L.; Steel, L.; Fernández, M. S.; Sakamoto, M.; Ruiz-Omeñaca, J. I.; Schoch, R. R. (2012). Butler, Richard J, ed. "The Cranial Osteology and Feeding Ecology of the Metriorhynchid Crocodylomorph Genera Dakosaurus and Plesiosuchus from the Late Jurassic of Europe". PLoS ONE 7 (9): e44985. doi:10.1371/journal.pone.0044985. PMC3445579. PMID23028723. edit
^Ősi A, Young MT, Galácz A, Rabi M. 2018. A new large-bodied thalattosuchian crocodyliform from the Lower Jurassic (Toarcian) of Hungary, with further evidence of the mosaic acquisition of marine adaptations in Metriorhynchoidea. PeerJ 6:e4668 https://doi.org/10.7717/peerj.4668
^Eric W. Wilberg; Alan H. Turner; Christopher A. Brochu (2019). "Evolutionary structure and timing of major habitat shifts in Crocodylomorpha". Scientific Reports. 9 (1): Article number 514. doi:10.1038/s41598-018-36795-1. PMC 6346023. PMID30679529.