Ichthyosaurus strombecki Meyer, 1862
Meyer (1862: 83, pi. 11) erected this species on an indeterminate
rostral segment, from the L ow e r Cretaceous of
northern Germany.
Ichthyosaurus thyreospondylus Owen, 1840
Owen’s (1840: 12 4 ) very brief description of this species,
erected upon five vertebrae which were not figured, did
not refer to the horizon. Phillips (1871: 337, fig. 129) gave
some small and not very detailed figures of a cervical
vertebra from the Kimmeridge Clay, which he referred to
this species. The material is indeterminate.
Ichthyosaurus torrei Torre e t Cuervo, 1939
The one-sentence description of this species drew attention
to the conduction of the dental nerves to the tooth
alveoli in the maxilla and premaxilla (TORRE & Cuervo,
1939: 9). No holotype was designated, nor were figures
provided for this indeterminate Jurassic material.
Ichthyosaurus torulosi Quenstedt, 1885
Quenstedt (1856:317, pi. 43, fig. 39) made a brief reference
to Ichthyosaurus from the torulosi bed of southern Germany,
figuring a single vertebral centrum. In his later work,
Quenstedt (1885: 207), following a tradition for naming
fossils from their bed, proposed the name Ichthyosaurus
torulosi. Kuhn (1934:36) gave the authority for this name as
Quenstedt, 1858 (meaning 1856), but it should be Quenstedt,
1885. In any event, this Early Jurassic species is
indeterminate.
Ichthyosaurus trigonus Owen, 1840
Owen (1840: 124) gave a brief description of a vertebral
centrum, from the Kimmeridge Clay, which interested him
because of its triangular profile, being widest dorsally and
narrowing ventrally. However, as discussed earlier, in the
descriptive section (Fig. 19A), such vertebrae occur in the
cervical region of Ophthalmosaurus. This could be considered
grounds for synonymizing Ophthalmosaurus icenicus
with Ichthyosaurus trigonus. However, that would not serve
nomenclatural stability because the name Ophthalmosaurus
has been in active use for over a century, whereas the older
name is seldom ever used. Given that the diagnostic features
are generic rather than specific, the species name can
be regarded as a nomen dubium.
Ichthyosaurus volgensis Kasansky, 1903
K asansky (1903: 29, pis. 1-2) described and figured a
number of individual ichthyosaurian bones including vertebrae,
cranial elements, and rib fragments, from the Lower
Cretaceous of the Ul’yanovsk Region of Russia. All the
material lacks diagnostic features.
Ichthyosaurus walkeri Seeley, 1869
Seeley (1869: 64-65) erected this species upon the cast of a
femur from the Upper Greensand (Albian) of Cambridgeshire,
England. It was said to differ from other femora
“chiefly through the suppression of the trochanteroid processes
at the proximal end ... .’’ No consideration was
given to the likelihood that this appearance was due to
compressional distortion. The material is quite inadequate
for the erection of a new species.
Ichthyosaurus zollerianus Quenstedt, 1856
Quenstedt (1856: 371) erected this species on a vertebral
centrum from the Middle Jurassic of Germany. Such material
is indeterminate.
Ichthyoterus [sic] fischeri Rouillier, 1847
This species was erected upon some teeth and vertebral
centra (Rouillier, 1847:25). The generic name is seemingly
a misspelling of Ichthyosaurus. The material is apparently
Late Jurassic in age, and is indeterminate.
Leptopterygius margaritatus H uene, 1922
The holotype is a tooth, and 10 large vertebrae (SMNS
4147) from the Upper Lias, which H uene (1922: 21, pi. 14,
figs. 3-8) briefly described. The material, which is too fragmentary
for the erection of a new taxon, is probably referable
to Temnodontosaurus trigonodon.
IMacropterygius incongnitus Rusconi, 1948
Rusconi (1948:148) erected this species on a dorsal vertebra
from the Upper Jurassic of Neuquen, Argentina. The
material is indeterminate.
Mixosaurus helveticus Huene, 1916
Huene (1916) erected this species upon vertebrae from the
Wellen-Dolomit of Laufenburg (lower Muschelkalk; Middle
Triassic: Anisian). Huene (1916) distinguished this species
from the similar-sized Mixosaurus intermedius on subtle
features of the vertebral margins and rib facets. Given
that the shape of vertebrae differs remarkably within a
single individual of ichthyosaur, it is not well established
whether these differences are taxonomically significant.
M. helveticus is a nomen dubium, as Mazin (1983B) and
Callaway & Massare (1989B) already concluded.
Mixosaurus intermedius Huene, 1916
Huene (1916: 19) based this species on some of the vertebrae
described by Fraas (1891) as Mixosaurus atavus var.
minor from the Wellen-Dolomit of Rohrdorf and Niedere-
schach (lower Muschelkalk; Middle Triassic: Anisian). He
stated that the difference between this species and M. atavus
was size (Huene, 1916:19). Mazin (1983B) considered
this species a nomen dubium, which was followed by
Callaway & Massare (1989B). As these authors argued,
the material is insufficient for diagnosing a species.
Mixosaurus major F raas, 1891 (as M. atavus var. major)
Fraas (1891: 37) recognized two varieties of Mixosaurus
atavus (Quenstedt, 1852), and named the larger one Mixosaurus
atavus var. major, based on two vertebral centra from
the Wellen-Dolomit of Niedereschach (lower Muschelkalk;
Middle Triassic: Anisian). Huene (1916) argued that one of
the two centra, when combined with additional material,
warranted species rank as Mixosaurus(?) major, whereas the
other belonged to Cymbospondylus germanicus. Because of
Huene’s (1916) action, the name major is considered to
have been a subspecies name since its first establishment
by Fraas (1891), according to ICZN Article 45g. Therefore,
the authorship of Mixosaurus(?) major belongs to Fraas,
1891. Some papers incorrectly cite Huene (1916) as the
author of the species (e.g., Maisch & M atzke, 2001). Huene
(1916:20) also removed the larger specimens of what Fraas
(1981) termed Mixosaurus atavus var. minor to M.(?) major.
Even with these additions, Mazin (1983B) found that the
material of Mixosaurus(?) major was non-diagnostic. Mazin
(1983B) is followed here, and the species is considered a
nomen dubium. At least one tooth (Huene, 1916: fig. 33a)
has a characteristic of Mixosaurus nordenskioeldii, as H uene
(1916) himself noticed, but the taxonomy of the other material
cannot be established with confidence.
M aisch & M atzke (2001), in an attempt to re-establish
the species as Phalarodon major, designated a lectotype.
However, this specimen (jaw fragments) was not among
the original material of Mixosaurus atavus major Fraas,
1891, but was listed among the hypodigm for Mixosaurus
atavus atavus Fraas, 1891 (see Mixosaurus atavus for the
discussion of this name). Therefore, it cannot become a
lectotype, and therefore the designation is invalid. There is
much doubt as to whether this material belongs to the
same species as the syntype vertebrae, which are probably
too fragmentary for diagnosing a species.
Mixosaurus maotaiensis Y oung, 1965
Young (1965) erected this species of Mixosaurus based on
a slab containing two coracoids, a humerus, some ribs,
vertebral centra, and gastralia (IVPP V2468). The specimen
is from the Kaunling Formation (Middle Triassic: Anisian)
of China. The specimen is small and resembles M. cornali-
anus, but lacks diagnostic features. Motani (1999B) considered
it a nomen dubium, and this view is upheld here.
Mixosaurus timorensis Broili, 1931
Broili (1 9 3 1 :1 0 ) named this species based on a basioccip-
ital and nine vertebrae, four of which were fragmentary
and one incomplete, from Timor. The horizon was indeterminate,
although it was possibly Triassic (Broili, 1931).
The basioccipital has a concave condyle, as in Cymbospondylus
piscosus (UCMP 9950) and a specimen from Germany
(C. germanicus Huene, 1916 [nomen dubium]). Mazin (1983B)
considered Mixosaurus timorensis a nomen dubium, and
this view is followed here. The basioccipital may belong to
Cymbospondylus, but the concave basioccipital condyle is
probably plesiomorphic for ichthyopterygians (Motani,
1999B).
Myobradypterygius mollensis Rusconi, 1938
Rusconi (1938: 2, figs. 1-4) founded this species on some
vertebrae and ribs from the. Upper Jurassic of Los Molles,
Mendoza, Argentina. The material is indeterminate.
Pessopteryx arctica W m a n , 1910
W iman (1910) erected Pessopteryx arctica based on a broken
humerus from the upper Sticky Keep Formation (Lower
Saurian Niveau; Lower Triassic: Olenekian) of Spitsbergen,
Svalbard. This humerus is non-diagnostic, and Motani
(1999b) considered the species a nomen dubium.
Pessopteryx nisseri W iman, 1910
W iman (1910) assigned every specimen found in the upper
Sticky Keep Formation (Lower Saurian Niveau; Lower
Triassic: Olenekian) exposed at the Middlehook of Isfjord,
Spitsbergen (Svalbard), to this species, with the exception
of three humeri. These humeri were different from the
typical humerus found in the same horizon, and W iman
(1910) considered them as three referred species of Pessopteryx.
Motani (1999B, 2000B) recognized the composite
nature of the hypodigm for P. nisseri, but decided to tentatively
retain the name. After a careful examination, RM
found that it is more confusing to retain the name than to
reject it, and herein considers the name a nomen dubium.
At least two types of ichthyosaurs are provisionally recognized
in the original material of Pessopteryx nisseri, apart
from an omphalosaur, to which only the dental material
can be referred with confidence (Motani, 2000B). The
majority of the postcranial material can be identified as
ichthyopterygian, probably belonging to Besanosaurus and
Isfjordosaurus. Most postcranial specimens are referable to
Besanosaurus, including femora (Wiman, 1910: pi. 9, figs.
1-3), tibiae (pi. 9, figs. 9-10), a humerus (pi. 8, fig. 3), a
radius (pi. 8, fig. 9), and numerous autopodial elements
(pi. 8, figs. 20-34). The femur of this genus is characteristic
for having a well-developed anterior facet next to the tibial
facet, being almost parallel to the femoral shaft (Dal Sasso
& P inna, 1996: fig. 17D). This anterior facet faces posteriorly
as preserved in the holotype, thus appearing as if it
were the articular facet for the fibula (Dal Sasso & Pinna,
1996: fig. 17D). However, there are three reasons to infer