Pessosaurus polaris (Hulke, 1873)
Ichthyosaurus polaris H ulke, 1873: 3
Shastasaurus polaris (Hulke, 1873); Yakowlew, 1902: 194
Cymbospondylus (?) polaris (Hulke, 1873); Merriam, 1908:
149
Syntypes: Two series of vertebrae, one with eight and the
other with three, and some assodated rib fragments.
Diagnosis: Medium-sized ichthyosaur; humerus wider
than long, with very short posterior shaft; humeral outline
almost symmetrical proximo-distally; coracoid with large
scapular facet; coracoid highly asymmetrical, with dear
notch on one side; radius short, yet retaining short shaft;
round fin elements present.
Locality: Sassenbay and Middlehook of Isfjord, Spitsbergen.
Stratigraphic range: Upper Sticky Keep Formation; Middle
Triassic (Ladinian).
Remarks: Pessosaurus polaris is a widely used name, recognized
by all major reviews of Triassic ichthyosaurs since its
publication (Huene, 1916; Kuhn, 1934; Callaway & M as-
sare, 1989B; M otani, 1999A). Sander & Faber (1998), followed
by Motani (1999B), considered it a nomen dubium.
In the present contribution, RM's previous acceptance of
the argument by Sander & Faber (1998) is withdrawn, and
the spedes is placed as a species inquirenda for the reasons
given below.
Sander & Faber (1998) made the following points to
invalidate Pessosaurus polaris: (1) the syntypes are nondiagnostic;
(2) there may have been more than one large
ichthyosaur represented in the referred specimens; (3) the
referred humerus seems distinctive but it is not wise to
erect a new spedes based on the humerus alone. The
syntypes of Pessosaurus polaris may not be diagnostic as
Sander & Faber (1998) argued. However, the referred humerus
(PMU R176) is indeed distinctive among ichthyosaurs
(Motani, 1999A), as Sander & Faber (1998) admitted.
Furthermore, this humerus is assodated with other
elements, including a coracoid and radius (Wiman, 1910:
pi. 7, fig. 2; a partial ulna, which is present on the same slab,
is missing from the figure), both of which are also distinctive
among ichthyosaurs. There is an undescribed iehthyo-
saurian skeleton in the Ziirich collection that has a humerus,
radius, and coracoid whose outlines dosely resemble
those of PMU R176 (referred to as Zürich 4 by McGowan
[1976], and reported as an unnamed new genus by Cook
[1994]). This skeleton is smaller and slightly older (Ani-
sian-Ladinian rather than late Ladinian) than the material
referred to P. polaris, so it could represent a distinctive
spedes within the same genus. This specimen has a femur
that is very similar to the one referred to P. polaris (Wiman,
1910: pi. 7, fig. 3), suggesting that the femur and shoulder
girdle from the Upper Saurian Niveau were indeed derived
from a single taxon, as suspected by Wiman (1910).
Unlike in the case of the Lower Saurian Niveau, where
several taxa of ichthyosaurs and non-ichthyosaurian tetra-
pods are dearly recognizable (Motani, 2000B), there is no
evidence to suggest that the presence of two or more large
ichthyosaurian spedes in the Upper Saurian Niveau of
Spitsbergen. Therefore, it seems reasonable to accept that
the majority of the referred specimens of P. polaris actually
belongs to a single taxon.
Several ichthyosaurs have recently been reported from
the lower Carnian of China (Yin et al., 2000), Judging from
published photographs, three of them (Guizhouichthyosau-
rus tangae, Guanlingsaurus liangae, and Typicusichthyosaurus
tsaihuae) may be similar to Pessosaurus polaris. Given that
the articulated skeletons from China and Switzerland are
not yet well described, it is not possible to assess with
confidence whether PMU R176rs suffidently diagnostic to
be the neotype of P. polaris. Therefore, judgement on the
validity of P. polaris is postponed until the better preserved
specimens are described.
Sander & Faber (1998: 157) stated that there was no
specimen of Pessosaurus polaris in the PMU collection that
was not figured by Wiman (1910). However, RM’s search
found several specimens referable to Pessosaurus from the
expeditions in 1909 (e.g., PMU R179) and 1913 (e.g., PMU
R621, R644 and R646).
Typicusichthyosaurus tsaihuae Yu in Yin, et al., 2000
Typicusichthyosaurus tsaihuae Yin et al., 2000: 17
Holotype: GMR 015, a nearly complete skeleton with
poorly exposed forefins.
Diagnosis: To be clarified.
Locality: Guarding, Guizhou, China.
Stratigraphic range: Wayao Formation; Upper Triassic
(lower Carnian).'
Remarks: See the remarks for, Guizhouichthyosaurus tan-
gae.
Wimanius odontopalatus Maisch et M atzke, 1998A
Wimanius odontopalatus M aisch et M atzke, 1998A: 27
Holotype: GPIT 1797, a partial skull.
Diagnosis: Pterygoid(?) teeth (modified from Maisch &
M atzke, 1998A).
Locality: Monte San Giorgio, Switzerland.
Stratigraphic range: Grenzbitumen horizon; Middle Triassic
(Anisian-I adinian boundary).
Remarks: See the remarks for the genus Mikadocephalus
graciliroslris.
3. Nomina dubia
Genera
Genus Ekbainacanthus Y akowlew, 1902 '
This genus is invalid because the type and only known
species, Ekbainacanthus tschemyschewi, is based on nondiagnostic
material.
Genus Macropterygius H uene, 1922
This genus was erected for reception of several Jurassic
species, including Ichthyosaurus bodenbenderi I. dilatatus, I.
leucopetraeus, I. ovalis and I. trigonus, treated below. Given
that these species are indeterminate, Macropterygius is also
rejected as a nomen dubium.
Genus Pachygonosaurus H uene, 1916
Huene (1916) erected the genus Pachygonosaurus upon isolated
vertebrae. He recognized three types within the genus,
two of which are from the Lower Muschelkalk (Middle
Triassic: Anisian) of Gomy Slask (formerly Upper Silesia),
Poland (.Pachygonosaurus sp. and sp. II). The third
type was based on two vertebrae described by Wiman
(1910). The genus is' considered invalid here, following
Maztn (1986) and Callaway & Massare (1989). However,
it should be noted that the lack of type species itself does
not invalidate generic names proposed prior to 1931 (ICZN
Article 11c).
Genus Perrinosaurus Merriam, 1938
Merriam (1938) proposed a generic name Perrinosaurus to
replace Delphinosaurus Merriam, 1905 [preoccupied]. The
name is unavailable because Kuhn (1934) earlier proposed
the va lid replacement name Californosaurus.'
Genus Pessopteryx W iman, 1910
This genus is invalid because the type and only known
species, Pessopteryx nisseri, is based on non-diagnostic
material.
Genus Rotundopteryx M aisch et M atzke, 2000B
This genus should be treated as an objective junior synonym
of Pessopteryx. See Rotundopteryx hulkei details.
Genus Spitsbergenosaurus M azin, 1981B
This genus is a nomen dubium because the type and only
known species, Spitsbergenosaurus crassidens, is based on
non-diagnostic material.
Species
lAncanamunia espinacitense Rusconi, 1949
Rusconi (1949: 9 1, fig. 3 ) based this species on a dorsal
vertebra from the Lower Jurassic of the Quebrada Honda,
San Juan, Argentina. There was some doubt as to the appropriate
generic designation. The material is indeterminate.
Cymbospondylus germanicus H uene, 1916
This species was erected upon a vertebral centrum from
the Wellen-Dolomit (lower Muschelkalk; Middle Triassic:
Anisian) of Germany, together with other isolated vertebral
material, and a basioccipital from the same horizon
(Huene, 1916). As H uene (1916: fig. 39) pointed out, die
basioccipital resembles that of Cymbospondylus piscosus
(UCMP 9950, referred to by him as C. petrinus). However,
the material is too poorly preserved to be of diagnostic
value, as Callaway & M assare (1989) and Sander (1989)
concluded.
Cymbospondylus parvus H uene, 1916
The holotype is a partial vertebral centrum probably being
from the anterior dorsal region (Huene, 1916: 28, fig. 46).
H uene (1916: fig. 47) also assigned a complete mid-dorsal
vertebral centrum to this species. Both specimens are from
the Wellen-Dolomit (lower Muschelkalk; Middle Triassic:
Anisian) of Laufenburg, Germany. Callaway & Massare
(1989b) considered the material non-diagnostic, and and
this view is followed here. Sander (1989), who reviewed
the genus Cymbospondylus, considered C. parvus valid.
Cymbospondylus (?) natans Merriam, 1908
This species was erected upon an isolated humerus (UCMP
9873) from the Middle Triassic (Anisian) of the West Humboldt
Range, Nevada. Merriam (1908) also tentatively referred
a partial forefin and a series of caudal vertebrae to
this species. Wiman (1916: fig. 1) recognized Mixosaurus-
like features in the humerus, and called it Mixosaurus (?)
natans. He also pointed out the possibility that the humerus
belongs to Mixosaurus fraasi (then identified as Phalar-
odonfraasi). Mazin (1983B) formerly transferred the species
to Mixosaurus. These authors are correct in that the specimen
belongs to Mixosaurus, but the material is probably
too incomplete for erection of a species.
It is not possible to judge the specific identification of
UCMP 9873. UCMP 9873 is smaller than a typical humerus
of Mixosaurus nordenskioeldii from Spitsbergen, from which
it differs slightly in shape. However, there is a humerus