Macrospondylus Bollensis
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''Macrospondylus'' is an
extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of machimosaurid teleosauroid
crocodyliform Crocodyliformes is a clade of Crurotarsi, 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 ...
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 Triassicâ ...
(
Toarcian The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...
) of Europe. Fossils are known from the
Posidonia Shale The Posidonia Shale (, also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation, is an Early Jurassic (Early to Late Toarcian) geological formation in Germany, northern Switzerland, northwestern Austria, souther ...
of Germany, the Whitby Mudstone of the United Kingdom, and the "'' schistes bitumineux"'' of Luxembourg.


Evolutionary relationships

''Macrospondylus'' has historically been synonymized with ''
Steneosaurus ''Steneosaurus'' (from , 'narrow' and , '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 wastebasket taxon for thalattosuchian ...
''. A 2005
phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analysis of
Thalattosuchia Thalattosuchia is a clade of mostly 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 member ...
, however, did not support the
monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...
of ''Steneosaurus'', as the genera '' Machimosaurus'' and ''
Teleosaurus ''Teleosaurus'' (from , 'perfect' and , 'lizard') is an extinct genus of teleosaurid crocodyliform found in the Middle Jurassic Calcaire de Caen Formation of France. It was approximately in length. The holotype is MNHN AC 8746, a quarter of ...
'' both fell within ''Steneosaurus''. Reinforcing the paraphyly of ''Steneosaurus'', Young et al. (2012), Åsi 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.


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.


See also

*
List of marine reptiles Following is a list of marine reptiles, reptiles which are adapted to life in marine or brackish environments. Extant The following marine reptiles are species which are currently extant or recently extinct. Crocodiles :*'' Crocodylus'' ::'' ...


References

{{Taxonbar, from=Q61963367 Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Early Jurassic crocodylomorphs Fossil taxa described in 1830 Early Jurassic reptiles of Europe Thalattosuchia