Plate 14
Stenopterygius cuneiceps, holotype, NMC 8161. Scale measures 1000 mm.
Plate 15
Stenopterygius cuneiceps, skull of holotype, NMC 8161. Scale measures 100 mm.
Stratigraphic range: Upper Lias; Lower Jurassic (Toar-
cian).
Remarks: Like S. hauffianus, this is a short-snouted species,
with a tendency toward tooth reduction. However, it
differs in having long slender forefins with a high aspect
ratio, often exceeding 3.0^ a smaller orbit, and more pre-
flexural vertebrae.
McGowan (1979B: 115) listed five referred specimens,
ranking them in order of decreasing levels of confidence in
their identity. Stenopterygius cuneiceps is likely the least well
supported of the species referred to Stenopterygius.
Maisch (1998B: 410-412) synonymized S. cuneiceps with
S. megalorhinus, arguing that the skull of the holotype was
clearly compressed anteroposteriorly, giving an illusion of
its having a short snout. It is difficult to visualize how an
ichthyosaur skeleton could become embedded in the strata
such that its, skull became anteroposteriorly compressed.
Notwithstanding this problem, if the skull had become
compressed, shortening the snout, why did the orbit not
also become anteroposteriorly distorted so that its major
axis were vertical rather than horizontal?
Stenopterygius longifrons (Owen, 1881)
Ichthyosaurus longifrons Owen, 1881: 118
Ichthyosaurus zetlandicus Seeley; Lydekker, 1889A: 76 [par-
tim]
Stenopterygius acutirostris; McGowan, 1974A: 27, 32
Holotype: BMNH 33157, a well-preserved, three-dimensional
skull, incomplete much beyond the external naris.
Diagnosis: Maxilla reaches ventral border of external!
naris; no contact between frontals and postfrontals.
Occurrence: The holotype, and a second, less complete
skull (BMNH 32681), are from Curcy, Normandy, France.
Other specimens come from Luxembourg.
Stratigraphic range: Upper Lias; Lower Jurassic (Toar-
cian).
Remarks: Owen’s (1881: 118) description of I. longifrons
comprised a brief reference to some figures of an incomplete
but well-preserved three-dimensional skull from the
Upper Lias of Curcy. The skull was figured by L ydekker
(1889A: 79, fig. 29) who drew attention to its similarity to
that of Seeley’s (1880) holotype of I. zetlandicus. L ydekker
(1889A) synonymized I. longifrons with I. zetlandicus, a
course followed by most other authors (see W oodward &
Sherborn [1890]). However, Godefroit (1993B) considered
S. longifrons to be a separate species, and gave an emended
diagnosis, based in part upon additional material. Some of
his diagnostic features also apply to other taxa. Thus the
feature “frontals narrow, widely covered by nasals and
parietals” (Godefroit, 1993B: 70) also applies to Ichthyosaurus
(McGowan, 1973B), and “snout and mandible long ...
and slender” applies to many taxa. Furthermore, the feature
“medial suture of the frontals forms a narrow and
especially deep hollow”, which presumably refers to the
furrow formed between the contact edges of the dorsally
arched frontals, applies to Ichthyosaurus (McGowan, 1973B).
However, his remaining diagnostic features appear applicable,
and the species is provisionally considered valid.
Family Ophthalmosauridae Baur 1887
Definition: The last common ancestor of Brachypterygius
extremus and Ophthalmosaurus icenicus, and all its descendants.
Diagnosis: Extracondylar area of basioccipital reduced;
angular largely exposed laterally, reaching as far anteriorly
as the surangular; extra zeugopodial element anterior to
radius, and digit distal to it.
Remarks: Baur (1987B), in the English version of Baur
(1987A), used the name Baptanodontidae instead of Ophthalmosauridae.
Motani (1999) was unaware of this dual
naming, and erroneously attributed the name Ophthalmosauridae
to Appleby (1956).
Genus M o lle sa u ru s FernAndez, 1999
Mollesaurus F ernAndez, 1999: 6 7 7
Type species: Mollesaurus periallus F ernAndez, 1999.
Diagnosis: Teeth reduced. Orbit large; scleral ring occupies
only about half of orbit. Postorbital region broad.
Basioccipital with slightly convex anterior surface, extracondylar
area less extensive than condyle, from which it is
not clearly set off, and is largely occupied by an extensive
pair of stapedial facets.
Remarks: This genus is similar to Ophthalmosaurus, with
which it was shown to share a sister-group relationship
(FernAndez, 1999: fig. 5). Unfortunately, the single specimen
upon which the type species is based is fragmentary,
so only few comparisons can be made. Obvious differences
from Ophthalmosaurus are the relatively small scleral ring,
the wide postorbital region, and in the basioccipital condyle
not being clearly set off from the (reduced) extracondylar
area.
Mollesaurus periallus F ernAndez, 1999
Fig. 90
Mollesaurus periallus F ernAndez, 1999: 677
Holotype: MOZ 2282 V, a partial skull, missing most of
the rostrum, together with 39 articulated vertebrae and ribs.
Diagnosis: As for genus.