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405
Sullivan et al., eds., 2011, Fossil Record 3. New Mexico Museum of Natural History and Science, Bulletin 53.
THE FIRST LAMBEOSAURIN (DINOSAURIA, HADROSAURIDAE,
LAMBEOSAURINAE) FROM THE UPPER CRETACEOUS OJO ALAMO FORMATION
(NAASHOIBITO MEMBER), SAN JUAN BASIN, NEW MEXICO
ROBERT M. SULLIVAN
1
, STEVEN E. JASINSKI
1
, MERRILEE GUENTHER
2
AND SPENCER G. LUCAS
3
1
Section of Paleontology and Geology, The State Museum of Pennsylvania, 300 North Street Harrisburg, PA 17120-0024;
2
Elmhurst College, 190 Prospect Ave., Elmhurst, IL 60126;
3
New Mexico Museum of Natural History and Science, 1801 Mountain Rd NW, Albuquerque, NM 87104
Abstract—A nearly complete robust left humerus (SMP VP-2263) and right jugal (SMP VP-1534) belonging to a
lambeosaurin lambeosaurine (= Lambeosaurus + (Corythosaurus + Hypacrosaurus)) dinosaur have been recov-
ered from two separate localities in the Naashoibito Member (Ojo Alamo Formation), San Juan Basin, New
Mexico. Measurements of the humerus are: length = 550 mm; deltopectoral crest length = 260 mm; deltopectoral
width = 135 mm. The robust morphology and measurements of the humerus confirm it pertains to a member of the
lambeosaurin clade, which we formally establish. The jugal has a maximum rostrocaudal length of 255 mm and a
shape that is inconsistent with the jugals of all species of Parasaurolophus. These specimens, which are very
similar to the humerus and jugal of Corythosaurus and Hypacrosaurus, constitute definite records of lambeosaurines
from the Naashoibito Member, despite previous erroneous reports of the occurrence of Parasaurolophus tubicen
from this horizon. The putative hadrosaurine, NMMNH P-19147, is re-interpreted as a lambeosaurin lambeosaurine,
based primarily on the morphology of the pubis. Recovery of additional lambeosaurine material in the Naashoibito
Member lends further support to a pre-Lancian age for this interval and for the Alamo Wash local fauna.
INTRODUCTION
Hadrosaurid dinosaurs from the Ojo Alamo Formation (Sand-
stone) have been known for a century. Many of the early records cite the
hadrosaurids, and other dinosaurs, as coming from the Ojo Alamos beds
(Brown, 1910; Gilmore, 1916; Lehman, 1981, 1985). Only four
hadrosaurid genera have been recognized in the Upper Cretaceous de-
posits of the San Juan Basin (Anasazisaurus, Kritosaurus,
Naashoibitosaurus and Parasaurolophus). Two of these taxa are still
regarded by some to be of questionable validity (Anasazisaurus and
Naashoibitosaurus), and all four genera are from the Kirtland Formation
(Williamson, 2000). To complicate matters, two of the San Juan Basin
hadrosaurids (Naashoibitosaurus and Parasaurolophus) were originally
reported as coming from the Naashoibito Member, but are now known
to be restricted to the De-na-zin Member of the Kirtland Formation
(Williamson, 1998; Williamson and Sullivan, 1998; Sullivan and
Williamson, 1999; Sullivan et al., 2005a, b). The Naashoibito Member
was previously included in the Kirtland Formation, but is now consid-
ered to be part of the overlying Ojo Alamo Formation (Lucas and Sullivan,
2000; Sullivan et al., 2005b).
Recently, a number of new lambeosaurines from North America
and Asia have been documented, and phylogenetically assessed (Godefroit
et al., 2001, 2004, 2008; Gates et al., 2007; Prieto-Márquez, 2010a, b).
Other studies, most notably that of Guenther (2009), have developed
methods to recognized ontogenetic development of postcranial elements
within hadrosaurid taxa that help to discriminate lambeosaurine from
hadrosaurine taxa.
In Asia, lambeosaurines are now known from Maastrichtian units
of Russia (Amurosaurus riabinini [Udurchukan Formation]) (Godefroit
et al., 2004; Van Itterbeeck et al., 2005) and northeastern China
(Charonosaurus jiayinensis and Sahaliyania elunchunorum [Yuliangze
Formation]) (Godefroit et al., 2001, 2008). Although some of these oc-
currences are considered late Maastrichtian (~69.2 to 65.5 Ma, as de-
fined by Ogg et al., 2004), based on correlation using palynozones, we
consider these correlations to lack precision. Recently, in Europe, a new
lambeosaurine Arenysaurus ardevoli, from the lower part of the upper
Maastrichtian (normal polarity Chron 30) Tremp Formation of Spain,
has been described based on an incomplete skull roof and braincase
(Pereda-Suberbiola et al., 2009). In North America, lambeosaurines are
unknown from strata younger than 67 Ma (the base of the Lancian LVA,
see below). Although a putative lambeosaurine has been reported from
the Hell Creek Formation, lambeosaurines are not known from either the
Lance or upper part of the Hell Creek formations (latest Maastrichtian/
Lancian) of the Western Interior. Moreover, lambeosaurine dinosaurs are
not considered a faunal component of the Lancian LVA, which spans
65.8-67.61 Ma (latest Maastrichtian). The youngest known North Ameri-
can lambeosaurin, Hypacrosaurus altispinus, is from the Horseshoe Can-
yon Formation of Alberta, and it comes from the upper part of the
formation (unit 4), which is dated at 69-68 Ma. Unit 4 of the Horseshoe
Canyon Formation correlates with the Naashoibito Member – both are
~ 69 Ma.
Here, we document a humerus (SMP VP-2263) and jugal (SMP
VP-1534) of a lambeosaurin lambeosaurine from separate localities in the
Naashoibito Member and discuss their biostratigraphic significance. We
also re-assess the taxonomic assignment of NMNNH P-19147, from the
Naashoibito Member, originally interpreted as representing a
lambeosaurine dinosaur close to either Lambeosaurus or Corythosaurus
(Hunt and Lucas, 1991) based on the morphology of the pubis, and, to a
lesser extent, the scapula. The identity of NMMNH P-19147 had been
dismissed by Williamson (2000), who considered it to be an indetermi-
nate hadrosaurine.
Institutional abbreviations: NMMNH = New Mexico Mu-
seum of Natural History and Science, Albuquerque; SMP = The State
Museum of Pennsylvania, Harrisburg.
TAXONONOMIC NOTE
We note here that the terms “corythosaur clade” and
“parasauroloph clade” were introduced by Chapman and Brett-Surman
(1990) as informal clades. The “corythosaur clade” included
Corythosaurus, Hypacrosaurus, Lambeosaurus, and Nipponosaurus.
Juvenile specimens of “Procheneosaurus” were also assumed to be mem-
bers of this clade. The “parasauroloph clade” included Parasaurolophus,
Bactrosaurus and Tsintaosaurus. The taxonomic composition of these
two informal clades was changed by Godefroit (2004), who united
Parasaurolophus with Charonosaurus in the “parasauroloph clade”
406
and Lambeosaurus with Corythosaurus, Hypacrosaurus and Olorotitan
in the “corythosaur clade.” This later clade was elevated to formal usage
(“Corythosaurini”) by Evans and Reisz (2007, p. 388), and named the
other clade “Parasaurolophini.”
According to Article 37.1 of the International Code of Zoological
Nomenclature (1999) “When a family-group taxon is subdivided, the
subordinate name that contains the taxon that contains the type genus of
the superior taxon is denoted by the same name the nominotypical name.”
Thus, given that “Corythosaurini” is a subdivision (tribe) of
Lambeosaurinae coordinate with Parasaurolophini, the proper name of
the tribe should be Lambeosaurini, not “Corythosaurini.” The following
formal subdivisions of the Lambeosaurinae encompass two clades:
Lambeosaurini clade (included taxa are Lambeosaurus, Hypacrosaurus,
Olorotitan, Corythosaurus and Velafrons) and the Parasaurolophini clade
(included taxa are Parasaurolophus cyrtocristatus, P. walkeri, P. tubicen
and Charonosaurus jianyinensis).
MATERIALS AND METHODS
Hadrosaurid postcranial material (jugals, humeri and scapulae) in
the collections of the New Mexico Museum of Natural History and
Science in Albuquerque and the State Museum of Pennsylvania were
examined and compared. Studies characterizing the morphologies of these
elements by Sullivan and Williamson (1999) Sullivan and Bennett (2000),
Godefroit et al. (2001, 2004, 2008), Evans and Reisz (2007), Guenther
(2009), and Prieto-Márquez (2010a,b) were also used. The characters
and data matrix used herein (Appendix 1) are from Evans and Reisz
(2007) along with four new additional jugal characters identified by Sullivan
et al. (2009).
SYSTEMATIC PALEONTOLOGY
DINOSAURIA Owen, 1842
ORNITHSCHIA Seeley, 1888
HADROSAURIDAE Cope, 1869
LAMBEOSAURINAE Parks, 1923
LAMBEOSAURINI, new tribe
Lambeosaurini indeterminate
Referred material: SMP VP-2263, nearly complete left humerus
(Fig. 1), SMP loc. 403b, De-na-zin Microsite (SE); SMP VP- 1534 (Fig.
3), nearly complete right jugal (badly weathered), SMP loc. 392b, De-na-
zin Wash (SE).
Horizon and Age: Naashoibito Member (Ojo Alamo Formation),
early Maastrichtian.
Description of Humerus: The left humerus (SMP VP-2263) is
nearly complete (Fig. 1). In caudal view, the articular (humeral) head and
the proximal edges of the medial side are eroded. Though eroded, the
humeral head constitutes one third of the width of the proximal articular
margin. It bears a complete and prominent deltopectoral crest; its lateral
margin has a strong, well-developed edge for the attachment of the M.
deltoideus clavicularis and M. scapulohumeralis rostral (Dilkes, 2000;
Evans and Reisz, 2007). The muscle scar of the latissimus dorsi is weakly
developed. The degree of angulation of the ventral margin of the
deltopectoral crest is strong (character 221 of Prieto-Márquez, 2010a).
In cranial view, the bicipital sulcus is also well-developed and widens
proximally, expanding to almost the full width of the element. The caudal
surface of the shaft is damaged, and it is highly fractured in a region
immediately adjacent to the midpoint of the shaft; however, an accurate
reflection of the proportions of the element is not compromised by this
damage. The radial and ulnar condyles are complete, with the ulnar condyle
slightly larger than the radial condyle. The olecranon fossa is well-devel-
oped and deeper than the coronoid fossa. Measurements of the humerus
are: length = 550 mm; deltopectoral crest length = 260 mm; deltopectoral
width = 135 mm; width of the shaft = 68 mm. Ratio of deltopectoral
width to the shaft width = 0.5037. The ratio of the length of the
deltopectoral crest to the proximodistal length of the humerus = 0.47
(character 219 of Prieto-Márquez, 2010a). The ratio between the total
length and the width of the lateral surface of the proximal end of the
humerus is 3.6 (character 222 of Prieto-Márquez, 2010a).
Remarks: The robust morphology and measurements of the hu-
merus confirm it pertains to a member of the “lambeosaurin” clade based
on a bivariate plot analysis of hadrosaurid taxa, including average mea-
surements for hadrosaurid humeri of various genera (Fig. 2). The length
of the deltopectoral crest of this specimen is more than twice the width
of the humeral shaft, characteristic of a lambeosaurine humerus. Note
that we calculated a ratio of 1.78 for the lateroventral expansion of the
deltopectoral crest of the humerus (character 220 of Prieto-Márquez,
2010a), which is nearly the mean for the expanded deltopectoral crest.
Thus, SMP VP-2263 lacks the wide deltopectoral crest seen in
Parasaurolophus, but has a narrower shaft, like Corythosaurus and
Hypacrosaurus. Shafts of Hypacrosaurus tend to be proportionally
longer than those of Corythosaurus, so we believe that SMP VP-2263 is
more like Corythosaurus than Hypacrosaurus. This specimen also lacks
the rotated orientation of the deltopectoral crest observed in some speci-
mens of Hypacrosaurus.
Description of Jugal: SMP VP-1534 (Fig. 3) is a badly weath-
ered, but nearly complete, right jugal. Despite its poor condition, enough
of the element is preserved to allow comparison to other hadrosaurines.
The jugal has a maximum rostrocaudal length of 255 mm. The shape of
the jugal conforms to that of lambeosaurines, but it has a morphology
that is inconsistent with jugals of all species of Parasaurolophus (see
Sullivan and Bennett, 2000). Specifically, SMP VP-1534 is characterized
by: 1) having an inferior infratemporal border that is wider than the
inferior orbital border; 2) lacking a short dorsal caudal process; 3) having
a fan-shaped caudal process border; and 4) lacking the distinctive
“W”-shaped articulation between the rostral process of the jugal and the
lacrimal, a feature seen only in species of Parasaurolophus. These are
new characters for the jugal (see Appendix 1, below). In addition, in SMP
VP-1534 the jugal is also expanded dorsoventrally and forms the lower
part of the orbital rim; the borders of the infratemporal fenestra form an
acute angle between the jugal and postorbital bars; the jugal is dorsoven-
trally constricted beneath the infratemporal fenestra; and the ventral
flange of the jugal is rounded. The shape of the rostral process is uncer-
tain due to breakage.
Remarks: As noted above, based on the characters of the jugal,
SMP VP-1534 clearly pertains to a lambeosaurine. Moreover, the lack of
the distinctive “W”-shaped articulation between the superior border of
the rostral jugal process, and the inferior border of the lacrimal, indicates
that the jugal is not from Parasaurolophus. Prieto-Márquez (2010a)
identified 13 jugal characters (103 through 115), but only a few can be
assessed due to the incomplete nature of SMP VP-1534. These charac-
ters include: strong inclination of the bony rim that bounds the medial
articulation surface of the jugal rostral process (character 108 of Prieto-
Márquez, 2010a); auricular shape of the quadratojugal flange (character
111 of Prieto-Márquez, 2010a); relatively wide and pronounced concav-
ity of the ventral margin located between the caudoventral and
quadratojugal flanges, despite the fact that the medial section of the
ventral margin is broken and missing in SMP VP-1534 (character 112 of
Prieto-Márquez, 2010a); and wider orbital margin and relatively con-
stricted ventral margin of the infratemporal fenestra (character 112 of
Prieto-Márquez, 2010a).
PHYLOGENETIC ANALYSIS
We scored both the humerus (SMP VP-2263) and jugal (SMP VP-
1534) using the data matrix of Evans and Reisz (2007) and added four
more (new) characters (32-35) identified by Sullivan et al. (2009) for the
jugal (see Appendix 1). We ran two analyses: 1) for the jugal; and 2) for
the jugal and humerus combined. The later scenario assumes that the two
elements are from a single taxon. The data analyses were run using PAUP
4.0b10 (Swofford, 2002).
407
FIGURE 1. Indeterminate lambeosaurin, SMP VP-2263, nearly complete left humerus, from the Naashoibito Member (Ojo Alamo Formation), San Juan
Basin, NM. A, caudal view; B, cranial view. Abbreviations: hh, humeral head; ms(lb), muscle scar on the lateral border of the humerus; and ms(ld),
muscle scar of the latissimus dorsi. Bar scale = 10 cm.
408
Both analyses produced 470 trees, a tree length of 125, and a
consistency index = 0.8400; retention index = 0.8330 and rescaled con-
sistency index = 0.7418. A strict consensus tree and 50% majority-rule
consensus tree are presented in Figure 4 for both the jugal alone and for
the jugal + humerus combined.
DISCUSSION
Based on our analyses, both SMP VP-1534 and VP-2263 clearly
fall within the Lambeosaurinae and cluster with the Corythosaurus-like
taxa. The strict consensus tree suggests they are distinct from both
Lambeosaurus and Parasaurolophus (Fig. 4C), whereas the 50% major-
ity rule consensus tree (Fig. 4D) shows both forming a polytomy with
Corythosaurus, Velafrons, Olorotitan and Amurosaurus, with
Lambeosaurus + Hypacrosaurus as a sister group. Based on these analy-
ses and our personal observation, we conclude that both these elements
are from a Corythosaurus-like lambeosaurine that appears to be closer to
Corythosaurus than to Hypacrosaurus. We consider both to be indeter-
minate lambeosaurin [“corythinosaurin”] lambeosaurines.
The presence of a Corythosaurus-like hadrosaur in the
Naashoibioto Member, based on these two specimens, reopens the ques-
tion of the identity of NMMNH P-19147 (Fig 5). This specimen, which
was first described by Hunt and Lucas (1991), consists of an incomplete
right scapula, parts of both pubes, two dorsal vertebrae, five neural
spines and 22 ribs and/or partial ribs. Williamson (2000) later noted that
the specimen also included the distal end of the left tibia.
In their taxonomic assessment of this specimen, Hunt and Lucas
(1991) noted that the pubes and scapula were the most (potentially)
diagnostic elements of this specimen. Unfortunately, the scapula offered
little help in actually determining the generic identity of the hadrosaurid.
The right pubis, on the other hand, was complete enough to compare to
other hadrosaurids and had features that suggested relationships to known
taxa. Hunt and Lucas (1981) noted that the right pubis (Fig. 5A, B) was
relatively short and broad, as in most lambeosaurines. They also noted
that the shape of the scapula was variable in Corythosaurus, so it is
inferred that the parallel dorsal and ventral morphology of the scapular
blade described by them was considered to be too ambiguous to allow for
any taxonomic identification. They concluded that NMMNH P-19147
represented a lambeosaurine that was related to either Corythosaurus or
Lambeosaurus (Hunt and Lucas, 1991).
Williamson (2000, p. 205) reinterpreted NMMNH P-19147, based
on the morphology of the pubis, and stated that “the neck of the pubis is
narrow rather than broad as in lambeosaurines” and that the scapula
blade is long with sub-parallel margins, despite the fact that Hunt and
Lucas (1991) stated that variation in blade morphology is dubious among
Corythosaurus specimens. Williamson (2000) reinterpreted NMMNH
P-19147 as a hadrosaurine rather than a lambeosaurine.
A re-evaluation of the morphology of the right pubis (Fig. 5A-B)
clearly shows that NMMNH P-19147 is, in fact, a lambeosaurine that is
close to Corythosaurus. Prieto-Márquez (2010a) identified a number of
characters of the pubis, most of which we can use to determine the
affinities of NMMNH P-19147. We have presented a reconstruction of
the prepubic process of the pubis based on the directions of the pre-
served dorsal, ventral and cranial margins. Our reconstruction suggests
that the ventral region is more expanded than the dorsal region (character
252 of Prieto-Márquez, 2010a). Despite its broken condition, it is evi-
dent that the geometry of the dorsoventral expansion of the prepubic
process of the pubis of NMMNH P-19147 is oval shaped (Fig. 5B),
being dorsoventrally taller than craniocaudally long (character 253 of
FIGURE 2. Bivariate plot of the width of the humeral shafts versus the width of the deltopectoral crest among selected hadrosaurids. Note that SMP VP-
2263, falls within the lambeosaurines, having closest affinities to Corythosaurus and Hypacrosaurus.
409
FIGURE 3. Indeterminate lambeosaurin, SMP VP-1534, badly weather right jugal, from the Naashoibito Member (Ojo Alamo Formation), San Juan Basin,
NM. A, lateral view; B, medial view. Bar scale = 10 cm.
410
FIGURE 4. Cladograms. A, strict consensus tree (jugal only); B, 50% majority rule consensus tree (jugal only); C, strict consensus tree (jugal + humerus);
D, 50% majority rule consensus tree (jugal + humerus); black dot is the node for the Lambeosaurini The inclusion of Amurosaurus is equivocal based on
analyses of Godefroit (2004, 2008), Evans and Reisz (2007) and Evans (2010). Amurosaurus and Sahaliyania form a clade within Lambeosaurini in the
analysis presented by Prieto-Márquez (2010a, b). The taxon Sahaliyania elunchunorum is considered to be a lambeosaurine, but was not included in our
data set (see Appendix 2).
411
FIGURE 5. NMMNH P-19147, lambeosaurin indeterminate. Incomplete right pubis, A, medial view; B, lateral view. Incomplete right scapula, C, lateral
view; D, medial view. Dotted line is the restored prepubic blade based on dorsal, ventral and distal margins of the pubis. Asterisk and black dot indicate
position of maximum concavity for the dorsal and ventral margins (B), after Prieto-Márquez (2010a). Abbreviations: ap, acromion process; p, depth
of proximal end of scapula; sb, maximum distal depth of scapula blade; and sn, minimum depth of scapula neck. Bar scales = 10 cm.
412
Prieto-Márquez, 2010a). We are unable to determine the ratio between
the dorsoventral expansion of the prepubic process relative to the width
of the acetabular margin (character 254 of Prieto-Márquez, 2010a) be-
cause the acetabular region in NMMNH P-19147 is largely missing. The
craniocaudal length of the proximal constriction of the prepubic process
is longer than the dorsoventral expansion (character 255 of Prieto-
Márquez, 2010a). The relative position of the maximum concavity of the
dorsal margin is located distally relative to the point of maximum convex-
ity along the ventral margin (character 256 of Prieto-Márquez, 2010a).
The morphology of the acetabular margin (character 257 of Prieto-
Márquez, 2010a) is unknown because the region is not preserved in
NMMNH P-19147. The obturator foramen as well as the iliac and is-
chial peduncles (characters 258 through 261 of Prieto-Márquez, 2010a)
are also not preserved, so their morphologies and related measurements
cannot be assessed. Finally, the total length of the pubis (character 262 of
Prieto-Márquez, 2010a) is not known due to the incomplete nature of
the pubis.
Our examination of the scapula also confirms that its morphology
is consistent with that of Corythosaurus based on the recent analyses of
Prieto-Márquez (2010a). The dorsal margin of the scapula is curved
(character 211 of Prieto-Márquez, 2010a). The ratio of the craniocaudal
length and the dorsoventral depth is 5.0, a little less than C. casuarius
and C. intermedius (character 212 of Prieto-Márquez, 2010a). Dors-
oventral expansion of the distal region (character 213 of Prieto-Márquez,
2010a) appears slight, but the scapula’s dorsal and ventral margins are
broken. Nevertheless, we calculated a ratio of 1.0+ for this character that
would support its lambeosaurine affinities. The ratio between the dors-
oventral length of the proximal constriction and the dorsoventral depth
of the cranial end of the scapula is 0.75, a value that is nearly the same as
those for Corythosaurus (0.70 to 0.72) (character 214 of Prieto-Márquez,
2010a). The acromion process is directed dorsally and is slightly re-
curved (characters 215 and 216 of Prieto-Márquez, 2010a). The deltoid
ridge is weakly developed and is confined to the proximal region of the
scapula (character 218 of Prieto-Márquez, 2010a), a situation similar to
Hypacrasaurus stebingeri. Therefore, we reject Williamson’s (2000) in-
terpretation and conclude that the specimen is a Corythosaurus-like
hadrosaurid and is not a hadrosaurine.
BIOSTRATIGRAPHIC SIGNIFICANCE
Hunt and Lucas (1991) considered NMMNH P-19147 to repre-
sent a possible range extension for lambeosaurines (Corythosaurus or
Lambeosaurus) because the Naashoibito Member was considered to be
late Maastrichtian age (equivalent to the Lancian) and because there were
no lambeosaurine hadrosaurs known from Lancian age deposits in North
America. The Naashoibito Member is regarded by us to be pre-Lancian
(early Maastrichtian) and has been dated at 69 Ma based on the occur-
rence of Alamosaurus sanjuanensis, which is restricted to the Naashoibito
Member in the San Juan Basin (Sullivan and Lucas, 2003, 2006). None-
theless, NMMNH P-19147, and the jugal and humerus described above,
each from separate localities, are among the youngest known
lambeosaurines (Hypacrosaurus altispinus being the other) in North
America. More importantly, these specimens may represent the young-
est known Corythosaurus-like genus.
ACKNOWLEDGMENTS
We thank Michael Brett-Surman (United States National Mu-
seum) for discussions regarding hadrosaurid postcrania. We also thank
David Evans (Royal Ontario Museum, Toronto) for earlier discussions
regarding lambeosaurines and issues regarding the PAUP analyses. Spe-
cial thanks are extended to Peter Dodson (University of Pennsylvania)
and Pascal Godefroit (Royal Institute of Natural Sciences of Belgium,
Brussels) for their respective critiques and suggestions that improved
the manuscript. Thanks are extended to the Bureau of Land Management
for issuing the Paleontological Resource Use permits SMP-8270-RS-01-
C and SMP-827 RS-04-D and their continuing support in the field.
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11.
APPENDIX 1
Characters and data matrix used in cladistic analysis (modified from Evans and Reisz, 2007).
Skull
1. Premaxilla, oral margin with a “double layer” morphology consisting
of an external denticle-bearing layer seen externally and an internal
palatal layer of thickened bone set back slightly from the oral margin
and separated from the denticulate layer by a deep sulcus bearing
vascular foramina: absent (0); present (1) (Horner et al., 2004, charac-
ter 25).
2. Premaxillary rostral bill margin shape: horseshoe-shaped, forms a
continuous semicircle that curves smoothly to postoral constriction
(0); broadly arcuate across rostral margin, constricts abruptly behind
the oral margin (1) (Horner et al., 2004, character 22).
3. Premaxillary caudal processes (PM1, PM2) and construction of nasal
passages: caudodorsal premaxillary process short, caudodorsal and
caudoventral processes do not meet caudal to external nares, nasal
passages not enclosed ventrally, external nares exposed in lateral view
(0); caudoventral and caudodorsal processes elongate and join behind
external opening of narial passages to exclude nasals, nasal vestibule
completely enclosed by tubular premaxillae, left nasal passage di-
vided from right passage, homologue of hadrosaurine external naris
not exposed in lateral view (1) (Horner et al., 2004, character 27,
modified).
4. Premaxilla, external naris shape: bony external naris formed by pre-
maxilla and nasal (0); naris defined entirely by premaxilla, naris elon-
gate (1); lacriform in shape, naris constricted caudally, primarily by
lateroventral expansion of caudodorsal premaxillary process (2);
lacriform in shape, naris constricted caudally primarily by dorsal
expansion of caudolateral premaxillary process (3) (Morris, 1978).
5. Premaxilla, vertical groove on the caudolateral process rostral to the
maxillary dorsal process that extends ventrally from a small lateral
opening between the premaxillary caudal processes: absent (0); present
(1).
6. Premaxilla, elongation of the caudolateral process above the prefron-
tal: absent (0); present (1) (Suzuki et al., 2004, character 4, modified).
7. Position of nasal cavity: nasals flat caudodorsally and restricted to
area rostral to braincase, nasal cavity rostromedial to orbits (0); pre-
maxilla extended caudally and nasals retracted to lie over braincase in
adults, resulting in a convoluted, complex narial passage and hollow
crest that extend supraorbitally (1) (Horner et al., 2004, character 33,
modified).
8. Nasal vestibule morphology, s-loop in the enclosed premaxillary pas-
sages rostral to dorsal process of maxilla: absent (0); s-loop present
(1) (Weishampel, 1981).
414
9. Hollow nasal crest tubular, elongate, and extends caudally well beyond
the occiput: absent (0); present (1) (Horner et al., 2004, character 36,
in part).
10. Hollow nasal crest shape, solid plate-like extension of premaxilla, or
“cockscomb,” above the nasal passages in the rostral region of the
crest (i.e., crest raised into a large vertical fan): absent (0); present (1)
(Hopson, 1975; Horner et al., 2004, character 36, in part; Suzuki et
al., 2004, character 11).
11. Hollow nasal crest shape, helmet-shaped crest with apex above orbit
and nasal forms a large, plate-like portion of the caudal external crest
surface: absent (0); present (1) (Norman, 2002, character 9, modified;
Godefroit et al., 2004, character 14, modified).
12. Hollow nasal crest, length: crest absent or extends beyond occiput
less than basal skull length (0); extends posterior to occiput more
than basal skull length (1) (Sullivan and Williamson, 1999).
13. Hollow nasal crest, crest-snout angle along dorsal margin of premax-
illa in lateral view: absent (0); less than 110 degrees, crest procumbent
(1); present, angle between 110 and 155 degrees (2); facial profile
shallowly concave in lateral view, angle between 155 and 180 degrees
(Suzuki et al., 2004, character 12, modified).
14. Hollow nasal crest, relative shape of the two lobes of caudoventral
process of premaxilla (PM2): absent (0); present, rostral lobe ap-
proximately level with or higher than caudal lobe (1); present, caudal
lobe higher than rostral lobe (2) (Horner et al., 2004, character 35).
15. Hollow nasal crest, enclosure of the nasal passages on lateral crest
surface between the caudolateral process of the premaxilla and nasal:
absent (0); premaxilla nasal-fontanellae persist into late ontogenetic
stages (1), crest fontanellae completely closed in subadult individuals
(2). (Norman, 2002, character 5, modified).
16. Hollow nasal crest, composition of caudal margin of fan-shaped
crest: absent (0); present, composed of largely of the premaxilla
caudodorsal process (PM1), nasal contributes to the lateroventral
portion of a solid caudal process only (1); present, composed of
nasal, nasals have long external internasal joint along caudal and
caudoventral margin of crest (2) (Horner et al., 2004, character 37,
modified).
17. Hollow nasal crest, rostral nasal-caudodorsal process of premaxilla
(PM1) contact: absent (0); present, rostral end of nasal fits along
ventral edge of premaxilla (1); present, premaxilla and nasal meet in a
complex W-shaped interfingering suture in which a long, finger-like
process of the nasal has an extensive overlapping joint with caudodorsal
process of the premaxilla in the rostral region of the crest (2) (Horner
et al., 2004, character 34, modified).
18. Hollow nasal crest, premaxilla caudodorsal process with accessory
rostroventral flange that overlaps the lateral surface of the nasal in the
rostral region of the crest: absent (0); present (1) (Evans and Reisz,
2007, character 18).
19. Maxilla, rostrodorsal process: has a separate rostral process that
extends medial to the caudoventral process of premaxilla to form part
of medial floor of external naris (0); rostral process absent, rostrodorsal
margin of maxilla forms a sloping shelf that underlies the premaxilla
(1) (Horner et al., 2004, character 42).
20. Maxilla, dorsal process shape in lateral view: low and gently rounded
(0); tall and sharply peaked (1) (Horner et al., 2004, character 48,
modified).
21. Maxilla, position of apex in lateral view: well caudal to center (0); at
or rostral to center (1) (Horner et al., 2004, character 47).
22. Maxilla, location of large rostral maxillary foramen: opens on
rostrolateral body of maxilla, exposed in lateral view (0); opens on
dorsal surface of maxilla along maxilla-premaxilla suture (1) (Horner
et al., 2004, character 44, modified).
23. Maxilla-lacrimal contact: present externally (0); largely covered ex-
ternally by a jugal-premaxilla contact (1) (Horner et al., 2004, charac-
ter 45, modified).
24. Maxilla, ectopterygoid ridge: poorly developed (0); strongly devel-
oped, thickened horizontal ridge on lateral surface of maxilla (1)
(Godefroit et al., 2004, character 24).
25. Ectopterygoid-jugal contact: present (0); absent, palatine-jugal con-
tact enhanced (1) (Horner et al., 2004, character 51).
26. Lacrimal-nasal contact: present (0); absent (1) (Norman, 2002, char-
acter 12).
27. Jugal, expansion of rostral end below lacrimal: dorsoventrally nar-
row, forms little of the rostral orbital rim (0); expanded dorsoven-
trally in front of orbit, lacrimal pushed dorsally to lie completely
above the level of the maxilla, jugal forms lower portion of orbital rim
(1) (Horner et al., 2004, character 52).
28. Jugal, rostral process shape: asymmetrical with a pointed process
between the maxilla and lacrimal (0); truncated and symmetrical (1)
(Horner et al., 2004, characters 53 and 54, modified).
29. Jugal contribution to infratemporal fenestra, acute angle between
postorbital bar and jugular bar: absent (0); present (1) (Horner et al.,
2004, character 71).
30. Jugal, development of free ventral flange: absent, jugal expands gradu-
ally below intrafenestra to meet the quadratojugal-quadrate (0); present,
jugal dorsoventrally constricted beneath infratemporal fenestra to set
off flange rostral to constriction (1) (Horner et al., 2004, character
55).
31. Jugal, ventral flange shape: rounded or lobate (0); angular (1) (Suzuki
et al., 2004, character 21).
32. Jugal, inferior infratemporal border wider then inferior orbit border:
present (0); not present (1) (NEW, Sullivan et al., 2009).
33. Jugal, dorsal portion of caudal process shorter then ventral portion of
caudal process: present (0); not present (1) (NEW, Sullivan et al.,
2009).
34. Jugal, border of caudal jugal process fan-shaped rather then sub-
rectangular: present (0); not present (1) (NEW, Sullivan et al., 2009).
35. Jugal-lacrimal contact of dorsal border of anterior jugal process “W”-
shaped: present (0); not present (1) (NEW, Sullivan et al., 2009).
36. Prefrontal, medial margin forms a thin vertical flange that laps onto
the base of the crest: absent (0); present (1) (Godefroit et al., 2004,
character 16).
37. Prefrontal, medial flange extends caudally over the dorsal surface of
the frontal and above the prefrontal-postorbital joint in lateral view
(in adults): absent (0); present (1).
38. Supraorbital articulation: freely articulate on orbit rim (0); fused to
orbit rim or absent (1) (Horner et al., 2004, character 59).
39. Postorbital, bifurcation of the caudal process: absent (0); present (1).
40. Postorbital, caudal process: elongate above of infratemporal fenestra
(0); short and deep, resulting in a constricted dorsal region of the
infratemporal fenestra (1).
41. Postorbital, dorsal ‘promontorium’: absent (0); present in adults (1)
(Godefroit et al., 2004, character 17).
42. Frontal, upward doming over braincase in adults: absent (0); present
(1) (Horner et al., 2004, character 58).
43. Frontal, exposed along dorsal margin of orbit: present (0); excluded
from orbital rim by an extensive prefrontal-postorbital joint (1) (Horner
et al., 2004, character 57).
44. Frontal, platform for nasal articulation: absent (0); present, com-
prised of two thin, rostroventrally curved tongues that form a median
cleft (1); or thickened and steeply angled, with median cleft absent (2)
(Evans and Reisz, 2007, character 40).
45. Frontal, nasal articulation surface extends posterodorsally to over-
hang the parietal in adults: absent (0); present (1) (Godefroit et al.,
2004, character 4, in part).
46. Frontal, shape of ectocranial surface: elongate with an ectocranial
length/width > 0.8 (0); relatively short, with a length/width < 0.8 (1);
415
greatly shortened length/width ratio <0.4) (2) (Godefroit, 2004, char-
acter 6, modified).
47. Frontal, shape of the ventral annular ridge that defines the rostral
extent of the cerebral fossa: long, low and gently rounded in medial
view (0); annular ridge sharp (1) (Evans and Reisz, 2007).
48. Parietal midline crest: straight and level with skull roof or slightly
down-warped along length (0); sagittal crest deepens caudally (strongly
down-warped) (1) (Horner et al., 2004, character 69, modified).
49. Parietal midline crest, length: long, parietal narrows quickly to form
the crest, crest more than half the length of supratemporal fenestrae
(0); short, parietal crest narrows gradually caudally, crest less than
half the length of the supratemporal fenestrae (1) (Horner et al., 2004,
character 70).
50. Parietal, shape: long, length/width ratio greater than 2 (0); less than 2
(1) (Godefroit et al., 2004, character 2).
51. Squamosal, separation of squamosals in caudal view: completely
separated by the parietal (0); extensive intersquamosal joint present
at the midline (1) (Suzuki et al., 2004, character 33, modified).
52. Squamosal, shape of caudoventral surface: shallowly exposed in
caudal view (0); form a deep, near vertical, well-exposed face in cau-
dal view (1) (Horner et al., 2004, character 64).
53. Squamosal, height above quadrate cotylus: lateral side relatively low
(0); markedly expanded dorsally above the cotylus (1) (Godefroit et
al., 2004, character 18).
54. Quadrate, shape of mandibular condyle: mediolaterally broad, lateral
and medial condyles subequal in size (0); lateral condyle expanded
rostrocaudally so that condyles appear subtriangular in distal view,
lateral condyle longer than medial one (1) (Horner et al., 2004, charac-
ter 60).
55. Laterosphenoid, complete enclosure of ophthalmic sulcus by bone
laterally: absent (0); present (1) (Ostrom, 1961).
56. Supraoccipital, ventral margin: bowed or expanded ventrally along
midline (0); horizontal, strong ridge developed along supraoccipital-
exoccipital suture (1) (Horner et al., 2004, character 30).
57. Transverse width of the cranium in the postorbital region in dorsal
view: broad, width maintained from orbit to quadrate head (0); dis-
tinctly narrowed at quadrate heads (1) (Horner et al., 2004, character
67).
Lower Jaw and Dentition
58. Predentary shape: deep and robust, arcuate rostral margin, neurovas-
cular foramina large and located near midline of predentary body,
dorsally directed spike-like denticles on rostral margin that fit into
slots on underside of premaxilla (0); gracile and shovel-shaped, straight
to gently rounded rostral margin, numerous nutrient foramina across
entire rostral margin, rounded, triangular denticles project rostrally
and fit into a continuous transverse slot on underside of premaxilla
(1) (Horner et al., 2004, character 13, modified).
59. Dentary, orientation of ramus rostral to tooth row in lateral view:
approximately straight or moderately down-turned (0); or strongly
deflected (1) (Horner et al., 2004, character 11, modified).
60. Dentary, coronoid process inclination: oriented roughly perpendicu-
lar to the dentary ramus (0); inclined rostrally (1) (Suzuki et al., 2004,
character 39).
61. Coronoid process configuration: apex only slightly expanded ros-
trally, surangular large and forms much of caudal margin of coronoid
process (0); dentary forms nearly all of greatly rostrocaudally ex-
panded apex, surangular reduced to thin sliver along caudal margin
and does not reach to the distal end of the coronoid process (1)
(Horner et al., 2004, character 17).
62. Dentary, length of diastema between first dentary tooth and
predentary: short, less than one-fifth the length of the tooth row (0);
long, greater than one-fifth of the length of the tooth row (1) (Horner
et al., 2004, character 9, modified).
63. Dentary, number of replacement teeth per position: two or less (0);
three or more (1) (Horner et al., 2004, character 2).
64. Dentition, number of tooth rows: 32 or less (0); greater than 32 (1)
(Horner et al. 2004, character 1; Suzuki et al., 2004, character 46,
modified).
65. Dentary crown shape (middle of tooth row): diamond-shaped with a
height/width ratio less than 3.0 (0); elongate lanceolate-shaped with a
height/width ratio greater than 3.1 (1) (Horner et al., 2004, character
5, modified).
66. Dentary teeth, number of accessory ridges: two or more prominent
ridges (0); tooth crown dominated by one primary ridge, secondary
ridges are faint when present (1) (Godefroit et al., 2004, character
30).
67. Dentary teeth, position of apex: offset to either mesial or distal side,
or some teeth curved distally (0); apex central, tooth straight and
nearly symmetrical (1) (Horner et al., 2004, character 8, modified).
68. Surangular foramen: present (0); absent (1) (Horner et al., 2004,
character 19).
69. Angular, position on lower jaw: large and deep, exposed laterally (0);
dorsoventrally narrow and not visible in lateral view (1) (Weishampel
et al., 1993, character 26).
Postcranial Skeleton
70. Cervical vertebrae, number: 13 or fewer (0); greater than 13 (1)
(Horner et al., 2004, character 72, modified).
71. Mid-dorsal vertebrae (~D10), neural spine height greater than 4 times
centrum height: absent (0); present (1) (Suzuki et al., 2004, character
51, modified).
72. Dorsal (caudal) and sacral neural spines: short, less than three times
centrum height (0); elongate, approximately three times centrum height
or greater (1) (Horner et al., 2004, character 76, modified).
73. Sacrum, number of sacral vertebrae: seven or fewer (0), eight or more
(1) (Horner et al., 2005, character 75).
74. Scapula, shape of proximal end: dorsoventrally deep, acromion pro-
cess directed dorsally, articulation extensive (0); dorsoventrally nar-
row (no wider than distal scapula), acromion process projects hori-
zontally, cranioventral corner notched, articulation restricted (1)
(Horner et al., 2004, character 80).
75. Scapula, dorsal border: straight (0); curved rostroventrally (1)
(Norman, 2002, character 43).
76. Scapula, orientation of borders of distal blade: divergent (0); subparallel
to one another (1) (Horner et al., 2005, character 81).
77. Coracoid, biceps tubercle size: tubercle small (0); large, laterally
projecting biceps tubercle (1) (Horner et al., 2004, character 78, modi-
fied).
78. Coracoid, cranioventral process (cranioventral hook): short and weakly
developed (0); long, extends well below the glenoid (1) (Horner et al.,
2004, character 79).
79. Coracoid size: large, coracoid: scapula lengths more than 0.2, length
of articular surface greater than length of glenoid (0); coracoid reduced
in length relative to scapula, glenoid equal to or longer than articula-
tion (1) (Horner et al., 2004, character 77, modified).
80. Humerus, deltopectoral crest length: short, much less than half the
length of the humerus (0); extends at least to midshaft or longer (1)
(Horner et al., 2004, character 83).
81. Humerus, deltopectoral crest shape: relatively low (0); angular and
enlarged (1) (Suzuki et al., 2004, character 59, modified).
82. Humeral distal condyles: compressed mediolaterally, flares little from
shaft of humerus (0); mediolaterally broad, flare moderately from
shaft of humerus (1) (Horner et al., 2004, character 84, modified).
83. Antebrachium length: humerus subequal to or longer than radius (0);
radius significantly longer than humerus (1) (Horner et al., 2004,
character 85).
416
84. Carpus: robust, with more than two small bones present and proxi-
mal ends of the metacarpals aligned (0); reduced to no more than two
small carpals with MCIII offset distally with respect to MCII and IV
(1) (Horner et al., 2004, characters 86 and 88, modified; Suzuki et al.,
2004, character 57, modified).
85. Manus, digit 1: metacarpal and one phalanx present (0); entire digit
absent (1) (Horner et al., 2004, character 87).
86. Manus, Digit III-1: longer than wide (0); as wide or wider than long
(1) (Suzuki et al., 2004, character 66, modified).
87. Ilium, size of supracetabular process: small, projects only as a lateral
swelling (0); large, broadly overhangs the lateral side of the ilium and
usually extends at least half way down the side of ilium (1) (Horner et
al., 2004, character 91).
88. Ilium, shape of dorsal margin: nearly straight (0); distinctly depressed
over supracetabular process and dorsally bowed over base of
preacetabular process (1) (Horner et al., 2004, character 100).
89. Ilium, postacetabular process: short and triangular in lateral view
with a large brevis shelf (0); rectangular in outline, brevis shelf absent
(1) (Horner et al., 2004, character 93).
90. Pubis, iliac peduncle: relatively small (0); has the form of a large and
dorsally directed process (1) (Horner et al., 2004, character 92, modi-
fied).
91. Pubis, height of prepubic process: maximum depth of prepubic blade
less than twice the height the minimum constriction (0); expanded,
greater than twice height of minimum constriction (1) (Horner et al.,
2004, character 95, modified).
92. Pubis, length of prepubic process constriction: long, dorsoventral
expansion restricted to distal process (0); shaft short, dorsoventral
expansion begins at base of process, repubic neck relatively tall (1)
(Horner et al., 2004, character 96, modified).
93. Ischium, shape of distal end: small knoblike foot (0); large and pen-
dent foot (1) (Horner et al., 2004, character 99).
94. Ischium, expansion of terminal foot: less than 25 percent the length
of the ischium (0); greater than 25 percent the ischium length (1)
(Suzuki et al., 2004, character 73, modified).
95. Femur, development of intercondylar extensor groove: moderately
deep, groove fully open (0); deep, edges of groove meet or nearly
meet cranially to enclose an extensor tunnel (1) (Horner et al., 2004,
character 101).
96. Tarsus, modified with cranial ascending process of astragalus equilat-
eral in shape and expanded distal fibular head: absent (0); present (1)
(Godefroit et al., 2004, characters 39 and 40).
97. Pes, distal phalanges of pedal digits II through IV: axially shortened
to disclike elements with width at least three times length (0); greatly
shortened, width at least four times length (1) (Horner et al., 2004,
character 104).
98. Pes, shape of unguals: taper evenly distally, clawlike (0); dorsoven-
trally flattened and broadened, hoof-like (1) (Horner et al., 2004,
character 105).
APPENDIX 2
SYSTEMATIC PALEONTOLOGY
FAMILY Hadrosauridae
SUBFAMILY Lambeosaurinae
TRIBE Lambeosaurini, new tribe
Type species: Lambeosaurus lambei Parks, 1923.
Included species (following Evans and Reisz [2007] and with
the additional characters included herein): Corythosaurus casuarius,
Hypacrosaurus altispinus, Hypacrosaurus stebingeri, Lambeosaurus
lambei, Lambeosaurus magnicristatus, Olorotitan arharensis, and
Velafrons coahuilensis.
Equivocal taxa: Amurosaurus riabinini and Sahaliyania
elunchunorum (see Prieto-Márquez, 2010a, b).
Diagnosis: Lambeosaurines distinguished from parasaurolophines
by the following features: premaxilla has a vertical groove on the
caudolateral process rostral to the maxillary dorsal process that extends
vertically from a small lateral opening between the premaxillary caudal
processes; nasal vestibule morphology consists of an S-loop in the en-
closed premaxillary passages rostral to the dorsal process of the maxilla;
and 13 or fewer cervical vertebrae present (characters 5, 8, and 66, re-
spectively, of Evans and Reisz, 2007).
Comments: Previously the Lambeosaurini consisted of four gen-
era: Lambeosaurus, Corythosaurus, Hypacrosaurus, and Nipponosaurus;
but later the clade was revised to include Olorotitan (Evans et al., 2007).
Recent work by Prieto-Márquez (2010a, b) included the following taxa
in this clade: (1) Corythosaurus intermedius, which we consider to be a
subjective junior synonym of C. casuarius, and (2) ?Lambeosaurus
417
laticaudus, a taxon that has been recognized as having a suite of charac-
ters similar to those of Hypacrosaurus stebingeri (see Evans and Reisz,
2007), but as currently recognized, is paraphyletic to both Lambeosaurus
and Hypacrosaurus, based on the recent phylogenetic analyses pre-
sented by Prieto-Márquez (2010a, b). His analysis suggests that “H.”
stebingeri belongs to a genus other than Hypacrosaurus or Lambeosaurus
as “H.” stebingeri is nested within the “corythosaurs” (which includes
Lambeosaurus) whereas ?L. laticaudus is nested within the
“hypacrosaurs,” but it is excluded from the “corythosaur” clade, which
includes Lambeosaurus (see Prieto-Márquez, 2010a, b). A recent study
of Hypacrosaurus stebingeri (Brink et al., 2010) concluded that it was
more closely related to Corythosaurus than to Lambeosaurus, while
another study (Evans, 2010) concluded that H. stebingeri is a metaspecies
and that it may be the ancestor of H. altispinus. Godefroit (2004, 2008),
Evans and Reisz (2007) and Evans (2010) considered Amurosaurus
rabinini to be a basal lambeosaurine. However, our analysis Amurosaurus
forms a polytomy with Olorotitan, Corythosaurus, Velafrons and the
jugal and humerus specimens (SMP VP-1534 and VP-2263, resectively).
The newly named taxon Sahaliyania elunchunorum formed a polytomy
with the Lambeosaurini and Parasaurolophini based on the phyloge-
netic analysis presented by Godefroit et al. (2008, fig. 18), yet it is
nested within the “hypacrosaur” clade ((Sahaliyania + Amurosaurus)
(Hypacrosaurus (Lambeosaurus + Velafrons))) according to Prieto-
Márquez (2010a, b). Velafrons coahuilensis was part of the polytomic
lambeosaurin clade recognized by Gates et al. (2007). Both Sahaliyania
and Velafrons are herein included in our modified data set of Evans and
Reisz (2007) and are considered to be lambeosaurins. We note that
Charonosaurus jiayinensis fell well outside the Lambeosaurini in the
modified analysis of Evans and Reisz (2007), which is contrary to its
position in the analyses of Prieto-Márquez (2010a, b). Nipponosaurus
sachalinensis was omitted by Prieto-Márquez (2010a, b) but it was
included in the definition of the clade and analysis of Evans and Reisz
(2007) despite the fact that the taxon is based on a juvenile and incom-
plete individual. Evans and Reisz (2007) noted that the topology of their
cladogram did not change with the omission of Nipponosaurus. There-
fore, following Prieto-Márquez (2010a, b) we do not recognize Nippono-
saurus as belonging to the Lambeosaurini. Our definition of the
Lambeosaurini would be equivalent to node 38 of Prieto-Márquez (2010a:
fig. 9), with the exception that we include Olorotitan, which may be
equivocal. The taxa Amurosaurus riabinini and Sahaliyania elunchunorum
are members of the Lambeosaurini based on the recent analysis of Prieto-
Márquez (2010a, b), but their phylogenetic position is equivocal based
on the analysis of Evans and Reisz (2007) and Evans (2010).
