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''Suevoleviathan'' is an extinct genus of primitive
The genus was named in 1998 by Michael Maisch for ''Leptopterygius disinteger'' and ''Ichthyosaurus integer'', both found in the Toarcian-age
''Suevoleviathan'' was a large ichthyosaur about long. The skull is low, orbit medium-sized, dorsal profile of skull only weakly concave; premaxilla and dentary with well developed grooves extending in an alternating fashion from the fossa praemaxillaris and fossa dentalis; maxilla short anteriorly, not reaching far beyond external naris, taking part in the formation of external naris and ventral orbital margin, separating lacrimal and jugal; jugal robust and short, not extending beyond anterior orbital margin; squamosal large, forming most of the posterior margin of cheek region and reaching down to ventral margin of cheek, processus quadratus of quadratojugal thus apparently separated from main body of bone; prefrontal and postfrontal subequal in size; external naris large, of triangular shape; posterior maxillary dentition reduced; teeth robust and crenulated in typical fashion, without carinae; 44 presacral vertebrae, 88 preflexural vertebrae; postflexural segment of tail very long and flexible; neural arches of posterior thoracal region very low with expanded processus spinosi; rib articulations of thorax unicipital posteriorly; forefin with three primary digits, fourth digit postaxial, one accessory digit; third digit subdivided into 3 secondary rays; no notches in leading edge of forefin; digits of the forefin fanning out distally; most autopodial elements rounded and widely spaced; pelvis tripartite; ilium with anterior spine-like process; pubis slender and curved; ischium broad and subrectangular; hindfin tridactyl, most elements of first digit notched.
''Suevoleviathan'' was unique among ichthyosaurs in that it retained relatively large forefins. Other ichthyosaurs exhibit a trend of decreasing forefin size, reflecting its shift in function from paraxial propulsion during low velocity swimming to steering in basal
ichthyosaur
Ichthyosauria is an order of large extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides.
Ichthyosaurians thrived during much of the Mesozoic era; based on fo ...
found in 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 Holzmaden
Holzmaden is a town in Baden-Württemberg, Germany that lies between Stuttgart and Ulm.
Holzmaden is 4 km south-east from Kirchheim unter Teck and 19 km south-east of Esslingen am Neckar. The A 8 runs south from Holzmaden. The town a ...
, Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
.
Taxonomy
The genus was named in 1998 by Michael Maisch for ''Leptopterygius disinteger'' and ''Ichthyosaurus integer'', both found in the Toarcian-age 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 Holzmaden. The generic name means "Swabia
Swabia ; , colloquially ''Schwabenland'' or ''Ländle''; archaic English also Suabia or Svebia is a cultural, historic and linguistic region in southwestern Germany.
The name is ultimately derived from the medieval Duchy of Swabia, one of ...
n Leviathan
Leviathan ( ; ; ) is a sea serpent demon noted in theology and mythology. It is referenced in several books of the Hebrew Bible, including Psalms, the Book of Job, the Book of Isaiah, and the pseudepigraphical Book of Enoch. Leviathan is of ...
". The type species
In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
is ''Leptopterygius disinteger'' Huene 1926. ''Ichthyosaurus integer'' Bronn 1844 was also reassigned to the genus by Maisch to create the new combination ''Suevoleviathan integer''.
Based on the relocation of the holotype of ''Suevoleviathan integer'' and an updated description of the specimen, Maxwell (2018) concluded that the two ''Suevoleviathan'' species are growth stages of the same species, meaning that ''S. integer'' has priority and becomes the epithet of the ''Suevoleviathan'' type species. However, in 2020, Maisch disagreed after reassessing a specimen he tentatively assigned to ''S. integer''. This specimen differed from ''S. disinteger'' in multiple features, especially in the postcranial skeleton. While he resultingly treated ''S. integer'' as a valid, he nevertheless considered it a metaspecies due to the incompleteness of its holotype, which does not preserve important characters for specific assignment.
Description
''Suevoleviathan'' was a large ichthyosaur about long. The skull is low, orbit medium-sized, dorsal profile of skull only weakly concave; premaxilla and dentary with well developed grooves extending in an alternating fashion from the fossa praemaxillaris and fossa dentalis; maxilla short anteriorly, not reaching far beyond external naris, taking part in the formation of external naris and ventral orbital margin, separating lacrimal and jugal; jugal robust and short, not extending beyond anterior orbital margin; squamosal large, forming most of the posterior margin of cheek region and reaching down to ventral margin of cheek, processus quadratus of quadratojugal thus apparently separated from main body of bone; prefrontal and postfrontal subequal in size; external naris large, of triangular shape; posterior maxillary dentition reduced; teeth robust and crenulated in typical fashion, without carinae; 44 presacral vertebrae, 88 preflexural vertebrae; postflexural segment of tail very long and flexible; neural arches of posterior thoracal region very low with expanded processus spinosi; rib articulations of thorax unicipital posteriorly; forefin with three primary digits, fourth digit postaxial, one accessory digit; third digit subdivided into 3 secondary rays; no notches in leading edge of forefin; digits of the forefin fanning out distally; most autopodial elements rounded and widely spaced; pelvis tripartite; ilium with anterior spine-like process; pubis slender and curved; ischium broad and subrectangular; hindfin tridactyl, most elements of first digit notched.
''Suevoleviathan'' was unique among ichthyosaurs in that it retained relatively large forefins. Other ichthyosaurs exhibit a trend of decreasing forefin size, reflecting its shift in function from paraxial propulsion during low velocity swimming to steering in basal ichthyopterygia
Ichthyopterygia ("fish flippers") was a designation introduced by Richard Owen, Sir Richard Owen in 1840 to designate the Jurassic ichthyosaurs that were known at the time, but the term is now used more often for both true Ichthyosauria and their ...
and the more derived ichthyosaurs
Ichthyosauria is an taxonomy (biology), order of large extinction, extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides.
Ichthyosaurians thrived during much of ...
respectively. The large forefin of ''Suevoleviathan'' suggests it retained its plesiomorphic function in low velocity propulsion, although axial undulations of the caudal region were likely still the predominant locomotory mechanism at high velocities.
See also
*List of ichthyosaurs
This list of ichthyosauromorphs is a comprehensive listing of all Genus, genera that have ever been included in the clade Ichthyosauromorpha, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that ar ...
* Timeline of ichthyosaur research
This timeline of ichthyosaur research is a chronological listing of events in the History of paleontology, history of paleontology focused on the ichthyosauromorphs, a group of secondarily aquatic marine reptiles whose later members superficially ...
References
Ichthyosaurs of Europe Early Jurassic ichthyosaurs Early Jurassic reptiles of Europe Jurassic Germany Fossils of Germany Ichthyosauromorph genera {{Ichthyosaur-stub