Fig. 71. Suevoleviathan disinteger (SMNS 15390). A) skull, depicting only the right side. B) forefin, depicted as a right, in dorsal view.
C) hindfin, depicted as a right, in dorsal view. D) pelvic girdle. Revised from M a is c h (1998A); for discussion of correct orientation see
p. 56. Scales each equal 100 mm.
Pelvic girdle tripartite; pubis slender and curved; ischium
subrectangular; ilium with anterior process. Preflexural
vertebrae >80; postflexural segment long and seemingly
flexible. Maxilla short, premaxillary ratio >0.42; orbital
ratio <0.22. Teeth robust, posterior maxillary teeth reduced
in number.
Suevoleviathan disinteger (Huene, 1926)
Fig. 71
Leptopterygius disinteger H uene, 1926: 66
Leptopterygius disinteger; Huene, 1931: 369
Leptopterygius integer dissidens H uene, 1931A: 369
Leptopterygius disinteger, H uene, 1931B: 319
Leptopterygius disinteger; H uene, 1952: 56
Leptopterygius disinteger, H auff, 1953: 16
Leptopterygius disinteger, Huene, 1956: fig. 174g
Stenopterygius disinteger; McGowan, 1972A: 5
Stenopterygius disinteger; McGowan, 1972B: 6
Leptopterygius disinteger; McGowan, 1979B: 122
Temnodontosaurus disinteger; Godefroit, 1994: 67
Suevoleviathan disinteger; Maisch, 1998A
Holotype: SMNS 15390, a complete skeleton.
Diagnosis: As for genus.
Occurrence: Holzmaden, southern Germany.
Stratigraphic range: Upper Lias; Lower Jurassic (Toarcian).
Remarks: Bronn’s (1844) brief description of Ichthyosaurus
integer was based on a complete skeleton, which appears to
have been lost or destroyed (McGowan, 1979B: 132). Fraas
(1891) gave a more complete description, figuring a skeleton
(SMNS 4692) that Maisch (1998A) believed represented
the same taxon as Bronn’s type specimen. The forefins
of this specimen have splayed digits, as in Suevoleviathan
disinteger, suggesting that Leptopterygius disinteger H uene
might be a subjective junior synonym of I. integer Bronn.
However, there are some differences, and both McGowan
(1979B) and Maisch (1998A) considered it prudent to keep
the two species distinct. Given the apparent loss of Bronn’s
(1844) type material and that the specimens that have since
been referred to L. disinteger are generally not well preserved,
I. integer should be regarded as a species inquiren-
da. Huene (1931A: 369 and pi. 2, fig. 6) described a variant
of the species, which he named I. integer mut dissidens
(treated here as a subspecies) distinguished by a more
square coracoid with a small notch on the anterior border.
This is considered here as a minor difference and the subspecies
designation is unnecessary.
Suprafamily Leptonectoidea nov.
Remarks: A superfamily comprising a single family named
solely for classificational convenience.
Family Leptonectidae Maisch, 1998A
Definition: The last common ancestor of Eurhinosaurus
longirostris and Leptonectes tenuirostris, and all its descendants.
Diagnosis: Temporal region facing posterolaterally, appearing
narrow in lateral view; extremely slender snout,
tooth size relative to the skull width small (<0.05); tibia and
fibula separated.
Remarks: Motani (1999C) used the name Eurhinosauria
for this group. However, Maisch (1998A) already used the
name Leptonectidae for a group containing Eurhinosaurus
and Leptonectes. Although without a definition, the latter
name stands.
Genus Leptonectes McGowan, 1996A
Leptopterygius Huene, 1922: 11 [preoccupied]
Leptonectes McGowan, 1996A: 441
Type species: Leptonectes tenuirostris (Conybeare, 1822).
Diagnosis: Humerus with constricted shaft, widely expanded
distally with leading edge facet that is usually
prominent. Forefin with less than five digits; phalanges
large, probably well spaced distally. Rostrum and mandible
slender; snout commonly long; large orbit, occupying
most of post-rostral segment of skull. Teeth often slender
and may be relatively small, especially in large individuals.
Pubis-and ischium separate, but may be partially
fused; presacral vertebrae probably >44 and possibly >50;
preflexural vertebrae >79. Moderate-sized to large ichthyosaurs,
but skull length probably <1 m.
Remarks: Leptopterygius Huene, 1922 has served as a
catch-all genus for a wide variety of species that have little
or nothing in common. These species included L. tenuirostris
(type species), L. platyodon (now referred to Temnodontosaurus),
and L. acutirostris (now referred to Temnodontosaurus).
Leptonectes tenuirostris (Conybeare, 1822)
Fig. 72; PI. 1
Ichthyosaurus tenuirostris Conybeare, 1822: 108
Ichthyosaurus chirostrongulostinus H awkins, 1834: 29
Strongylostinus H awkins, 1840: 13
Ichthyosaurus tenuirostris; Owen, 1840: 117
Ichthyosaurus tenuirostris; Owen, 1881: 122
Ichthyosaurus longirostris Owen, 1881: 124 [preoccupied]
Ichthyosaurus tenuirostris; L ydekker, 1889A: 83, fig. 25
Ichthyosaurus latifrons Konig, 1825 [nomen nudum]; L ydekker,
1889A: 89 [partim]
Stenopterygius tenuirostris; A bel, 1919: fig. 379
Leptopterygius tenuirostris; H uene, 1922: 11
Ichthyosaurus tenuirostris; McGowan, 1974B: 25
Leptopterygius tenuirostris; A ppleby, 1979: 943
Leptopterygius tenuirostris; McGowan, 1989A: 413
Leptonectes tenuirostris; McGowan, 1996A: 441
[non] Temnodontosaurus longirostris (Mantell); McGowan,
1974A: 22
Holotype: A tooth, formerly in the collection of the Geological
Society of London (Woodward & Sherborn, 1890:
240) but now apparently lost (Delair, 1960: 70). McGowan
(1974B: 25) designated BGS 51236, a complete skeleton,
currently on display at the Natural History Museum, London,
as the neotype (Fig. 72A).
Diagnosis: Forefin with 4 digits; phalanges large and dis-
coidal, probably well spaced distally; humerus with constricted
shaft, widely expanded distally, but distal width is
less than length, leading edge facet is usually prominent;
radius notched; occlusal edges of radius and ulna usually
enclosing a small foramen. Snout long and slender, snout
ratio >0.70; prenarial ratio >0.56; premaxillary ratio >0.48;
orbit appears to be large, occupying most of post-rostral
skull, but orbital ratio <0.25 and may be <0.20. External
naris may not be simple petaloid shape; snout may extend
beyond mandible, giving small overbite. Teeth predominantly
slender and may be relatively small. Tailbend may
not be prominent; preflexural vertebrae >80; presacral vertebrae
>40, but probably <50. Tibia notched, probably also