Fig. 90. Mollesaurus periallus, holotype (MOZ 2282 V). A) partial skull. B-C) basiocdpital in posterior and right lateral view. Redrawn
from FernAndez (1999). Scales equal 100 mm and 20 mm, respectively.
Occurrence: Chacaico Sur, 70 km southwest of Zapala,
Neuquen Province, Argentina.
Stratigraphic range: Los Molles Formation; Middle Jurassic
(lower Bajocian).
Remarks: Because of the incomplete nature of the holotype,
few comparisons can be made with Ophthalmosaurus.
There are no fins, or girdles, and the poorly preserved skull
has most of the snout missing. F ernAndez (1999: 677) commented
that the posterior portion of the snout is deep
dorsoventrally, but this could conceivably be due to postmortem
compression. She also referred to a prominent
ridge, lying immediately anterior to the orbit, which occupies
most of the anterodorsal quadrant. The basiocdpital,
with its prominent stapedial facets, is typically ophthalmo-
saurian, and compares closely with an Oxford Clay specimen
of Ophthalmosaurus icenicus (BMNH 474 3 0 ). Mollesaurus
may have occupied a position close to the ancestry of
Ophthalmosaurus. However, it would be premature to discuss
its affinities until more complete material becomes
available.
Genus Nannopterygius H u en e , 1922
Ichthyosaurus; Hulke, 1871A: 440 [partim]
Nannopterygius Huene, 1922: 98
Type species: Nannopterygius enthekiodon (Hulke, 1871A).
Diagnosis: Humerus with two distal facets, for radius and
ulna; forefin and hindfin greatly reduced in size. Coracoids
markedly elongate, being almost 70 percent longer than
wide. Snout long and slender; orbit not markedly large,
Fig. 91. Nannopterygius enthekiodon, holotype (BMNH 46497), redrawn from H u lk e (1871 A). Scale equals 500 mm.
orbital ratio probably <0.25. Teeth present.
Remarks: Huene (1922: 98) named this genus for the remarkably
small size of the fins, where both the fore- and
hindfins are considerably reduced in size.
Nannopterygius enthekiodon (Hulke, 1871 A)
Fig. 91
Ichthyosaurus enthekiodon H ulke, 1871 A: 4 40
Ichthyosaurus entheciodon; Lydekker, 1889A: 3 2 [unjustified
emendation]
Nannopterygius entheciodon; H uene, 1922: 98
Nannopterygius enthekiodon; McGowan, 1976: 671
Holotype: A nearly complete but rather poorly preserved
skeleton, BMNH 46497, on public display at the Natural
History Museum, London.
Diagnosis: As for genus.
Occurrence: Kimmeridge Bay, Dorset, England.
Stratigraphic range: Kimmeridge Clay; Upper Jurassic
(Kimmeridgian).
Remarks: Lydekker (1889A: 32) changed the spelling of
the name, substituting “ c” fo r “k”, on the grounds that
Hulke (1870) had previously used the name Enthekiodon in
a generic sense. Kirton (1983) considered this inappropriate,
and CM concurs. The fins, both pectoral and pelvic,
look inappropriately small for the size of the skeleton,
raising the question of whether they are correctly associated
with the rest of the skeleton. Hulke’s (1871 A: pi. 17)
illustration shows one of the partial forefins and the single
(partial) hindfin displaced from the rest of the skeleton
(Fig. 91). However, he explained that this is because they
got separated from the rest by the quarrymen, and were
only later affixed to the slab, below the skeleton. He describes
how the specimen was discovered by himself and
Mr. J. C. Mansel, who subsequently donated it to the Natural
History Museum. The involvement of a second party
suggests that the skeleton has not been modified, as have
others from the southwest of England (McGowan, 1990B),
and BMNH 46497 should probably be accepted as authentic.
Genus Undorosaurus E fimov, 1999B
Undorosaurus E fimov, 1999B: 51
Type species: Undorosaurus gorodischensis E fimov, 1999B.
Diagnosis: Humerus with three distal facets, the anterior
one, the smallest, articulating with a preaxial accessory
element; five digits; phalanges round. Teeth large (60 mm),