Remarks: This species lacks the apomorphies of the Shas-
tasaurinae, and thus cannot be assigned to Shastasaurus
(Motani, 1999B). Maisch & Matzke (2000B) recently proposed
a new generic name for the species, which is followed
here. It is possibly closely related to Besanosaurus or
Mikadocephalus (or Pessosaurus).
Family Guanlingsauridae Yin in
Yin et al., 2000
Genus Guanlingsaurus Yin in Yin et al., 2000
Guanlingsaurus Y in in Y in e t al., 2 000: 18
Type species: Guanlingsaurus liangae Y in in Yin e t a l., 2000
Diagnosis: About 80 presac ral vertebrae; extremely short
snout; poorly ossified forefins, with one o r two phalangeal
rows (about six rows including epipodials, mesopodials,
and metapodials).
Remarks: See the remarks for the type species.
Guanlingsaurus liangae Y in in Y in et al., 2000
Guanlingsaurus liangae Y in in Yin e t al., 2 000: 19
Holotype: GMR 014, a nearly complete skeleton.
Diagnosis: As for the genus.
Occurrence: Guarding region, Guizhou, China.
Stratigraphic range: Wayao Formation; Upper Triassic
(lower Camian).
Remarks: See the remarks for Guizhouichthyosaurus tangae.
Family Besanosauridae nov.
Remarks: A family comprising a single genus named sole-
ly for classificational convenience.
Genus Besanosaurus Dal Sasso et Pinna, 1996
Besanosaurus Dal Sasso & Pinna, 1996: 4
Type species: Besanosaurus leptorhynchus Dal Sasso et Pinna,
1996.
Diagnosis: Teeth small; four digits in limbs; circular manual
phalanges and metapodials (Dal Sasso & P inna, 1996).
Remarks: See the remarks for the genus Mikadocephalus.
Besanosaurus leptorhynchus Dal Sasso e t Pinna, 1996
Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996: 4
Holotype: MCSNM BES SC 999, a nearly complete skeleton.
Diagnosis: As for the genus.
Occurrence: Besano region, Lombardy, Italy.
Stratigraphic range: Grenzbitumen horizon; Middle Triassic
(Anisian-Ladinian boundary).
Remarks: See the remarks for Mikadocephalus gracilirostris.
(Unranked) Merriamosauria Motani, 1999b
Definition: The last common ancestor of Shastasaurus pa-
cificus and Ichthyosaurus communis, and all its descendants.
Diagnosis: Scapula and coracoid in contact, not only near
glenoid; radius with notch or largely reduced shaft anteriorly;
manual pisiform absent; metacarpal I not ossified
(hence digit I absent).
Infraorder Shastasauria Motani, 1999B
Definition: All merriamosaurians more closely related to
Shastasaurus pacificus than to Ichthyosaurus communis.
Diagnosis: Humerus nearly quadrangular even when disregarding
anterior flange; obturator foramen partially open
but mostly within pubis; presacral count more than 55.
Family Shastasauridae Merriam, 1902
Definition: The last common ancestor of Shastasaurus and
Shonisaurus, and all its descendants.
Diagnosis: Scapular longitudinal axis not parallel to glenoid,
forming angle of about 60 degrees with the latter
(humeral head directed proximodorsally in response); radius
without shaft anteriorly; radius twice as large as ulna.
Genus Himalayasaurus Dong, 1972
Himalayasaurus Dong, 1972:
Type species: Himalayasaurus tibetensis Dong, 1972.
Diagnosis: Large shastasaurine, probably exceeding 15 m
in total length; tooth crowns labiolingually flattened, with
prominent mesial and distal cutting edges giving swollen
outline in labiolingual view; radial shaft not reduced posteriorly
and absent anteriorly; cervical centra short, with
width/length ratio about 3.0.
Himalayasaurus tibetensis Dong, 1972
Himalayasaurus tibetensis Dong, 1972: 7
Holotype: IVPP V4003, partial jaws, radius, a fin element,
and some vertebrae.
Diagnosis: As for the genus.
Occurrence: Tulong area, Xizang, Tibet, People’s Republic
of China.
Stratigraphic range: Langjiexue Group; Upper Triassic
(Norian).
Remarks: This genus is tentatively referred to the Shasta-
saurinae based on the presence of an enlarged radius (Motani
et al., 1999).
Genus Shonisaurus Camp, 1976
Shonisaurus Camp, 1976: 128
Type species: Shonisaurus popularis Camp, 1976.
Diagnosis: Large shastasaurine, reaching 15 m in total
length; dorsal centra three times as high as long, very large.
Remarks: McGowan and Motani (1999) considered two
poorly known species of Shonisaurus, S. mulleri and S.
silberlingi, as nomina dubia.
Shonisaurus popularis Camp, 1976
Shonisaurus popularis Camp, 1976: 128
Holotype: UNLV FZVE-l, a partial skeleton.
Diagnosis: As for the genus.
Occurrence: Near Gabbs, Nye County, Nevada, USA.
Stratigraphic range: Luning Formation; Upper Triassic
(upper Camian).
Genus Shastasaurus M erriam, 1895
Shastasaurus Merriam, 1895: 5 7
Callawayia Maisch & Matzke, 2000B: 69
Metashastasaurus Nicholls & Manabe, 2 001: 985
Type species: Shastasaurus pacificus Merriam, 1895.
Diagnosis: Shastasaurines with preaxially notched radiale.
Shastasaurus pacificus Merriam, 1895
Shastasaurus pacificus Merriam, 1895: 5 7
Shastasaurus osmonti Merriam, 1902: 93
Shastasaurus alexandrae Merriam, 1902: 96
Shastasaurus altispinus Merriam, 1902: 99
Holotype: A neotype should be designated (see below).
Diagnosis: Shastasaurus with slightly asymmetrical coracoid.
Occurrence: Near Redding, Shasta County, California,
USA.
Stratigraphic range: Hosselkus Limestone; Upper Triassic
(upper Camian).
Remarks: There are two syntypes for Shastasaurus pacificus,
a pubis and a partial vertebral column. Both are very
poorly preserved. Shastasaurus is a widely used name, so it
is desirable to designate a better preserved specimen, such
as UCMP 9017, as the neotype under the Fourth Edition of
ICZN for nomenclatural stability. An appeal to the Commission
is in preparation. Motani (1999B) reassigned
Shastasaurus careyi to Shonisaurus sp.
Maisch (2000) published a reconstruction of the skull
of Shastasaurus alexandrae, by restoring the missing anterior
half of the skull using a specimen that Motani (1999B: 485)
had previously assigned to Shonisaurus sp. (see also the
section on tooth implantation in the Anatomical Diversification).
The reconstruction is, therefore, highly questionable.
There has been a series of skull reconstructions published
by the same author, based on incomplete, poorly
preserved, or poorly prepared specimens (e.g., Maisch,
2000, 2001; Maisch & Matzke, 1999). Although the intention
of trying to reconstruct the entire skull is plausible, its
cost (i.e., involvement of much speculation to fill the gap of
information) clearly exceeds its scientific value. Caution
should be taken when these figures are reproduced without
reference to the original material, as in Maisch &
Matzke (2000B).
Shastasaurus neoscapularis McGowan, 1994A
Shastasaurus neoscapularis McGowan, 1994A: 170
Callaway ia neoscapularis; Maisch & Matzke, 2000B: 69
Metashastasaurus neoscapularis; Nicholls & Manabe, 2001: 985
Holotype: ROM 41993, anterior half of the skeleton.
Diagnosis: Shastasaurus with symmetrical coracoid.
Occurrence: Williston Lake, NW British Columbia, Canada.
Stratigraphic range: Pardonet Formation; Upper Triassic
(Norian).
Discussion: Maisch & Matzke (2000B) argued that Shastasaurus
neoscapularis was more closely related to post-Trias-
sic ichthyosaurs than to Shastasaurus, and proposed a new
generic name Callawayia for this species. However, the
characters used by these authors are of doubtful taxonomic
significance. The scapula of the holotype of S. neoscapularis
is broken anteriorly, parallel to the crack present in the
slab. The straight scapular blade is the artifact of this break.
The median suture between coracoids is a matter of degree
of ossification and maturity. There is a possibility that the
species is more closely related to Shonisaurus than to
Shastasaurus pacificus, in which case the generic designation
may require reconsideration.