''Macrospondylus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of machimosaurid

teleosauroid Teleosauroidea is an extinct superfamily of thalattosuchian crocodyliforms living from the Early Jurassic to the Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostr ...

crocodyliform Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...

from the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

(

Toarcian The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian. The Toarcian ...

) of Europe. Fossils are known from the

Posidonia Shale The Posidonia Shale (german: Posidonienschiefer, also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation, is an Early Jurassic (Toarcian) geological formation of southwestern and northeast Germany, northern Swit ...

of Germany, the

Whitby Mudstone The Whitby Mudstone is a Toarcian (Early Jurassic; ''Falciferum''-''Bifrons'' in regional chronostratigraphy) geological formation in Yorkshire and Worcestershire, England.schistes bitumineux The "Schistes bitumineux" (French for Oil shale/Bituminous shale) is an Early Jurassic geologic formation in Luxembourg Luxembourg ( ; lb, Lëtzebuerg ; french: link=no, Luxembourg; german: link=no, Luxemburg), officially the Grand Duchy ...

"'' of Luxembourg.

Evolutionary relationships

''Macrospondylus'' has historically been synonymized with ''

Steneosaurus ''Steneosaurus'' (from el, στενός , 'narrow' and el, σαῦρος , 'lizard') is a dubious genus of teleosaurid crocodyliform from the Middle or Late Jurassic ( Callovian or early Oxfordian) of France. The genus has been used as a w ...

''. A 2005

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis of

Thalattosuchia Thalattosuchia is a clade of marine crocodylomorphs from the Early Jurassic to the Early Cretaceous that had a cosmopolitan distribution. They are colloquially referred to as marine crocodiles or sea crocodiles, though they are not members of Cro ...

, however, did not support the

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...

of ''Steneosaurus'', as the genera ''

Machimosaurus ''Machimosaurus'' is an extinct genus of machimosaurid crocodyliform from the Late Jurassic (Kimmeridgian and Tithonian) and Early Cretaceous. The type species, ''Machimosaurus hugii'', was found in Switzerland. Other fossils have been found ...

'' and ''

Teleosaurus ''Teleosaurus'' (from el, τέλειος , 'perfect' and el, σαῦρος , 'lizard') is an extinct genus of teleosaurid crocodyliform found in the Middle Jurassic Calcaire de Caen Formation of France. It was approximately in length and w ...

'' 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.

References

Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Early Jurassic crocodylomorphs Fossil taxa described in 1830 Early Jurassic reptiles of Europe Thalattosuchians {{jurassic-reptile-stub

Evolutionary relationships

See also

References