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J. Paleont. Soc. Korea. Vol. 22, No. 1, (2006) : p. 173-193
NEW SPECIMENS, INCLUDING A GROWTH SERIES,
OF FUKUIRAPTOR (DINOSAURIA, THEROPODA)
FROM THE LOWER CRETACEOUS KITADANI
QUARRY OF JAPAN
Philip J. Currie1 and Yoichi Azuma2
1University of Alberta, Department of Biological Sciences, 11145 Saskatchewan Drive, Edmonton,
Alberta T6G 2E9, Canada, philip.currie@ualberta.ca
2Fukui Prefectural Dinosaur Museum, 5-11 Terao, Muroko, Katsuyama, Fukui 911-8601, Japan
Abstract: In addition to the holotype skeleton of Fukuiraptor kitadaniensis, isolated teeth and bones of the same
taxon have been collected from the Kitadani Quarry of the Lower Cretaceous (Barremian) strata in Fukui
Prefecture, Japan. These provide additional information that help determine its phylogenetic position, and also
represent a growth series. The holotype is an immature specimen, which was about 4.2 meters long. Other fossils
from the same quarry are all from smaller individuals. Some of the juvenile bones are less than a third the linear
length of equivalent bones in the holotype.
Key words: Fukuiraptor, growth series, Kitadani, Japan
INTRODUCTION
The Kitadani Quarry is on the Sugiyama River within the city limits of Katsuyama in Fukui
Prefecture, Japan. It is the largest dinosaur excavation that has been done in Japan, and is arguably one of
the largest dinosaur quarries in the world. Worked originally by the Fukui Prefectural Museum between
1988 and 1993, and from 1996 to 1998, the excavation is being continued by the Fukui Prefectural
Dinosaur Museum, which opened in 2000.
The excavation has produced bones, eggshell and footprints of theropods, sauropods and ornithischians.
Other fossils recovered from the site include plants, freshwater mollusks, fish, turtles, crocodiles and
birds (Azuma et al., 1995). The best specimens from the quarry include a nearly complete goniopholidid
crocodyliform (Kobayashi, 1998), the iguanodontians Fukuisaurus tetoriensis (Kobayashi and Azuma,
2003) and the carnosaurian theropod Fukuiraptor kitadaniensis (Azuma and Currie, 2000).
The type material of Fukuiraptor kitadaniensis represents an immature individual that was about 4.2
meters long at the time of death. Most of the other theropod teeth and bones from the same quarry are
from smaller individuals of the same taxon. Some of the juvenile bones are less than a third the linear
length of equivalent bones in the holotype. In this paper, we have focused on teeth, humeri and femora
because these are the most diagnostic elements that are well represented by multiple specimens. There
are additional bones from the quarry that probably represent Fukuiraptor. However, they lack diagnostic
Fukuiraptor characters, and/or they do not add significant information to the previous description
(Azuma and Currie, 2000), and/or they do not provide information about growth in this taxon.
SYSTEMATIC PALEONTOLOGY
DINOSAURIA Owen, 1842
THEROPODA Marsh, 1881
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J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
Tabl e 1 . Teeth of Fukuiraptor kitadaniensis. Abbreviations: AD1, number of anterior denticles
p
er 5 mm; AD2,
b
asal
width of posterior denticle as seen in labial or lingual view; BW, labial-lingual basal width of tooth; CH, crown height
;
FABL, fore-aft base length; d, dentary; mx, maxillary; pm, premaxillary; PD1, number of posterior denticles per 5 mm;
PD2, basal width of posterior denticle as seen in labial or lingual view; Pos, tooth position; TH, total height of crown
and root of tooth.
# Pos CH TH FABL AD1 AD2 PD1 PD2 BW
96080810 mx 50 xx 18.0 12.5 0.40 12.5 0.40 7.5
96081134 ? xx xx xx xx xx 12.5 0.40 xx
97080208 mx xx xx 9.5 20.0 0.25 20.0 0.25 xx
97081128
d
33.4 xx 17.4 16.5 0.30 16.5 0.30 7.5
97082330 mx 17 41.4 9.0 17.0 0.29 17.0 0.29 5.1
97082367 mx 23++ xx 14+ 17.0 0.29 14.0 0.36 6.5+
97082574 mx 33 xx 11.9 17.5 0.29 17.5 0.29 5.7
97082728 mx 41+ xx 15.6 15.0 0.33 12.5 0.40 7.4
9712201 mx 37+ Xx 14 19.0 0.26 16.1 0.31 5.5
9712203 mx 31.3 xx 15.4 14.0 0.36 14.0 0.36 6.1
9712204
d
34 xx 13.2 15.0 0.33 15.0 0.33 8.2
9712205
pm
17+ 31+ 8.2 15.0 0.33 16.5 0.30 6.0
9712206 mx 26 xx 14.6 20.0 0.25 16.5 0.30 xx
9712229 mx xx xx xx xx xx 17.0 0.30 xx
9712231 ?
9712232 ?
9712233
d
18.8 xx 11.5 19.0 0.26 16.0 0.30 5.6
9712234 mx 12.6 xx 10.4 16.5 0.30 16.5 0.30 4.6
9712235 mx 25 xx 13.0 17.0 0.29 14.0 0.36 xx
9712236
d
18.5 xx 12.0 19.0 0.26 16.0 0.31 5.0
9712237 ?
9712238 ?
9712239 ? 18+ xx 7.4 20.0 0.25 20.0 0.25 4.9
980721002
d
18 xx 9.9 19.5 0.26 18.0 0.28 4.2
980724112
d
xx xx 16.5 15.0 0.33 xx xx 7.8
980801101 ? xx xx xx 15.0 0.33 xx xx xx
980803001
pm
xx xx 8.0 20.0 0.25 19.0 0.26 5.5
980803120 mx 24+ xx 12.0 20.0 0.25 18.0 0.28 5.3
980803123 ? xx xx xx 17.0 0.29 15.0 0.33 xx
980804135 mx 17.6+ xx 8+ 17.5 0.29 16.0 0.32 4.9
980804144 ? xx xx xx xx xx 11.0 0.45 xx
980805101 mx 33+ xx xx 19.0 0.26 16.0 0.31 3.5+
980806009 ? 27+ xx xx 14.0 0.36 14.0 0.36 xx
980810141 mx 34 xx 15.9 14.0 0.36 13.0 0.38 5.6
980813008 mx 23 xx 10.5 16.0 0.31 16.0 0.31 5.6
980815020
d
27.5+ xx 12.0 16.0 0.31 15.0 0.33 9.5
980815176
d
25+ xx 13.4 17.5 0.29 17.5 0.29 6.5
98081540 mx 54.8 xx 22.0 14.0 0.36 12.5 0.40 7.5
980819055 mx 32+ xx 13.5 16.5 0.30 15.0 0.33 5.4
980819173 ? xx xx xx 15.0 0.33 xx xx xx
981200001
d
39+ xx 17.9 xx xx 15.0 0.33 9.4
981200012
d
6 xx 5.0 25.0 0.20 22.0 0.23 2.3
CARNOSAURIA von Huene, 1920
Fukuiraptor kitadaniensis Azuma and Currie, 2000
Specimens used in this study (Teeth are listed in Table 1)
FPDM-V97122 (holotype), associated skeleton (includes humeri and right femur)
FPDM-V97122BNA3, femur, right, individual 3 (size class 2)
FPDM-V97122BNA12, femur, right, individual 5 (size class 3)
Currie and Azuma - New Fukuiraptor with a growth series
175
FPDM-V970730003, femur, proximal two thirds of right,
FPDM-V97080623, femur, left (probably an ornithopod so do not include in measurements or on final of
this list)
FPDM-V97080937, femur, left (size class 1)
FPDM-V97081115, humerus, right
FPDM-V97081201, femur, right, individual 4 (size class 2)
FPDM-V97081317, tibia, right
FPDM-V97081330, femur, right, individual 1 (size class 1)
FPDM-V970813046, femur, right,
FPDM-V970814001, tibia, right
FPDM-V970820060, tibia, right
FPDM-V970821039, femur, right,
FPDM-V97082120, humerus, right
FPDM-V97082553, humerus, left
FPDM-V98072302, femur, left (size class 1)
FPDM-V980723005, humerus, right
FPDM-V980801141, manual ungual with proximodorsal lip
FPDM-V980805018, femur, right
FPDM-V9708102884, femur, right (shaft only)
FPDM-V980813017, femur, right, individual 2 (size class 1)
FPDM-V980815162, elongate, relatively straight manual ungual.
FPDM-V98082026, pedal phalanx III-2
FPDM-V990410001, manual phalanx I-1
FPDM-V99090901, femur, distal end of left,
FPDM-V9912141, tip of small manual ungual
FPDM-V97120001, femur, proximal head of left
FPDM-V98120001, femur, shaft only of left
FPDM-V98120002, femur, shaft only of left
FPDM-V9812638, femur, shaft only of right
Locality and Ag e
The Kitadani locality is on the Sugiyama River in the northern part of the city of Katsuyama, Fukui
Prefecture (Latitude 36o7'N, Longitude 136o33'E). Lower Cretaceous (Barremian) Kitadani Formation
(Akaiwa Subgroup, Tetori Group).
Institutional abbreviations
FPDM-V, Fukui Prefectural Dinosaur Museum, vertebrate collection, Katsuyama, Fukui.
DESCRIPTION
TEETH
Five teeth were associated with the holotype skeleton of Fukuiraptor kitadaniensis (Azuma and
Currie, 2000), including one in the socket of a dentary fragment. In addition to these, there is a tooth in
one of the sockets of a posterior fragment from a left maxilla (FPDM-V9712201) of the holotype. The
posterior left maxillary fragment figured by Azuma and Currie (2000, Figs. 3A-C) was incorrectly la-
beled as this specimen, but is actually that of a referred specimen (FPDM-V9712229).
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J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
Fi
g
. 1. Fukukiraptor kitadaniensis, left
p
remaxillary tooth of the holotype in
p
osterior (A, B), labial (C) and distal (D)
views. The plaster fills an impression in the rock of the missing part of the tooth, and includes a cast of the anterior carina.
1
,
midline of anterior surface
;
2
,
anterior carina
;
3
,
p
osterior carina.
Two premaxillary teeth are known for Fukuiraptor (Table 1), the best (Fig. 1) of which belongs to the
holotype. The distal tip of the tooth is missing, partly because of wear and partly because of minor
damage. The posterior carina forms the posterolateral edge of the tooth, and extends from below
gum-line at the beginning of the enameled crown to the broken tip of the tooth. The anterior carina is
posterolingual to the anterior longitudinal midline of the tooth, which gives the crown a J-shaped cross
section (Fig. 1D). The carina extends distally from the enamel-dentine contact at the base of the crown
(below gum-line) to the broken tip of the tooth. The first denticle is about 1.5 mm distal to the proximal
end of the anterior carina, and was probably just above gum-line. The anterior denticles are low and
rounded, but their basal diameters are the same or slightly more than those of posterior denticles at equiv-
alent heights in the tooth. The posterior denticles are about twice the height of the anterior denticles, even
though they have equivalent basal diameters, and are distally hooked (Fig. 1B). The root is incomplete,
but there was clearly no constriction between root and crown.
A maxillary crown from the holotype (Fig. 2A, and fig. 4 in Azuma and Currie, 2000) shows that
Fukuiraptor had narrow, blade-like cheek teeth. This crown is 31.3 mm high, and based on size compar-
isons with other teeth in the type, it is probably one of the last maxillary teeth. The denticulate anterior
Currie and Azuma - New Fukuiraptor with a growth series
177
Fi
g
. 2. Maxillary (A, B) and dentary (C, D) teeth of Fukuiraptor kitadaniensis. A, right maxillary tooth of holotype
(FPDM-V9712203) in anterior and lingual views; B, left maxillary tooth (FPDM-V98081540) in labial and anterior
aspects; C, left dentary tooth (FPDM-V98120001) in anterior and labial views; D, third right dentary tooth of holotype
(FPDM-V9712204) displayed in anterior and lingual aspects.
carina extends from just above gum-line to the tip of the tooth, whereas the denticulate posterior carina
starts just below gum-line at the enamel-dentine interface. Denticles are small near the tip, but went right
across the top of the pointed end. Anterior denticles are subequal with posterior denticles in terms of bas-
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J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
Fi
g
. 3. Bivariate scatter
p
lots comparing aspects of tooth dimensions with those of various theropods. A, FABL versus
BW of tooth crowns in Fukuiraptor (triangles), dromaeosaurids (X), carcharodontosaurids (squares) and tyrannosaurids
(diamonds). B,logarithms of FABL versus basal diameters of posterior serrations in Fukuiraptor (triangles), carchar-
odontosaurids (squares) and tyrannosaurids (diamonds).
al width, but are only about two-thirds the height. The posterior denticles are hooked towards the tip of
the tooth. Oblique blood grooves trail away from between the bases of almost all denticles (fig. 4 of
Azuma and Currie, 2000) on both labial and lingual sides.
The maxillary fragment from the holotype (FPDM-V9712201), which is coincidentally from the same
position in the left maxilla of the other, slightly smaller individual (FPDM-V9712229), has been pre-
pared to expose a germ tooth in the socket. Most of the crown (which is the second last maxillary tooth)
is preserved, and shows that the teeth of Fukuiraptor were anteroposteriorly long but labial-lingually
narrow. The crown lacks only the tip and is slightly more than 37 mm tall, with a basal cross-section of
14 x 5.5 mm. Most of the anterior carina is covered by bone so it is difficult to see how far it extends
down the tooth, but like the posterior carina, it is denticulate. Although the basal diameter of each ante-
Currie and Azuma - New Fukuiraptor with a growth series
179
Fi
g
. 4. Anterior maxillary tooth (FPDM-V97082728) of Fukuiraptorin anterior (A), lingual (B), labial (C) and
p
osterio
r
views.
rior serration is subequal to an equivalent posterior denticle, the anterior denticles are much shorter than
the posterior ones. In this tooth, the maximum basal diameter of a serration (as seen in lingual aspect) is
0.31 mm, which works out to be about 16 denticles per 5 mm (=5 mm/0.31; a standard metric for thero-
pod tooth comparison). There are problems with this measurement, however, because the carina in small-
er theropods may be less than 5 mm long, and because denticle sizes are smaller at the proximal and dis-
tal ends of a carina. The minimum number of denticles per millimeter would be a better standard for
comparison between theropods, although we recommend that the most useful measurement is probably
the average basal diameter of the largest denticles.
In the referred maxilla (FPDM-V9712229), there is a fragment of a germ tooth in the third last alveo-
lus, and it preserves a 13 millimeter section of the posterior carina. The maximum basal diameter for a
posterior denticle as seen in lingual view is 0.30. The third last alveolus is incomplete, but the second last
one is 15 x 7 mm, confirming that the basal cross-section of a posterior maxillary tooth of Fukuiraptor
was longer than wide. The last alveolus is smaller but has similar proportions (11.8 x 5.9).
Using the characteristics found in maxillary teeth of the holotype of Fukuiraptor kitadaniensis, iso-
lated maxillary teeth (Fig. 4) of other individuals can be identified. These characteristics include rela-
tively narrow, blade-like crowns in which the Fore-Aft Basal Length (FABL) is double the measurement
of the basal width perpendicular to the level where FABL is measured. The carinae are positioned along
the anterior and posterior vertical margins of the teeth, and the anterior carina is not significantly offset
lingually. Unlike coelurosaur teeth, the longitudinal axis of the tooth is sinuous when viewed anteriorly
(Fig. 4A) or posteriorly (Fig. 4D). The denticles are relatively small (Table 1, more than 12.5 denticles
per 5 mm), but like most coelurosaurian teeth, the posterior denticles are distally hooked. Although not
present on all teeth, blood grooves are another way to separate Fukuiraptor teeth from those of other
theropods in the Kitadani quarry.
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J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
The crown of one dentary tooth was recovered with the holotype, and it appears to be the third tooth
from the right side (Fig. 2D). The crown is 34 mm high, and like anterior dentary teeth in most theropods,
the base of the crown is relatively short (Table 1) anteroposteriorly compared to the basal width
(BW/FABL ratio is 0.62). The proximodistal basal widths of anterior denticles are the same as those of
equivalent posterior denticles. Although all of the anterior denticles are heavily worn, they were labiolin-
gually narrower and appear to have been much shorter than the posterior denticles. The serrations of the
dentary tooth are the same size as the anterior premaxillary denticles of the holotype, larger than the pos-
terior premaxillary ones, similar to most of the maxillary ones, but larger than those from teeth of the
posterior part of the maxilla (Table 1). The denticulate anterior carina only extends along the distal half
of the anterior surface of the tooth, whereas the denticulate posterior carina forms the entire posterior
margin of the tooth. Another tooth in the alveolus of a dentary fragment from the holotype was described
briefly by Azuma and Currie (2000).
Teeth of Fukuiraptor are similar to those of many other carnosaurs. The cheek teeth are compressed la-
bial-lingually, even more than the blade-like teeth of carcharodontosaurids (Fig. 3A, chart showing
FABL vs BW). Serrations are smaller in comparison with FABL (Fig. 3B, chart showing FABLvs basal
length of posterior denticle on a logarithmic scale) than in carcharodontosaurids and tyrannosaurids.
Posterior denticles are relatively elongate with distally hooked tips. An anterior denticle has a com-
parable basal width, but is less than half the length of a posterior serration on the same tooth. Similar to
tyrannosaurids, many Fukuiraptor cheek teeth have oblique blood grooves associated with the bases of
the serrations (Azuma and Currie, 2000). The grooves tend to be found on both labial and lingual surfa-
ces of the tooth, and are best-developed in association with the anterior denticles at the point of strongest
curvature of the anterior edge of the tooth, and with the posterior denticles. Like carcharodontosaurid
teeth (Sereno et al., 1996, Chure et al., 1999, Novas et al., 1999), the enamel on the labial and lingual
surfaces of the teeth can have broad arcuate wrinkles that sweep down towards the root and away from
the denticles. In some teeth, the anterior and posterior wrinkles extend right across the labial and/or lin-
gual surfaces of the tooth to connect with each other (as in Carcharodontosaurus and Giganotosaurus).
In anterior or posterior view, each cheek tooth has a flattened S-shaped curvature such as is also seen in
carcharodontosaurids like Giganotosaurus. At the base of the crown, the tooth initially curves labially to-
wards the outside of the jaw. This curve flattens, changes direction, and towards the tip of the tooth turns
lingually. The anterior and posterior carinae of a cheek tooth are positioned on the midline, and follow
the curvature of the tooth.
With the exception of five teeth (FPDM-V9812638, 96072901, 97082906, 980815181, 98092604) all of
the teeth from the Kitadani Formation can be referred to Fukuiraptor (Table 1). There are 42 Fukuiraptor
teeth, two of which are premaxillary, 19 are maxillary, 11 are dentary, and ten are too incomplete to
determine. The ratio of labial-lingual basal width to FABL is 0.71 for the premaxillary teeth, 0.43 for the
maxillary teeth, 0.64 for anterior dentary, and 0.46 for middle and posterior dentary teeth. This compares
well with alveolar dimensions in preserved fragments of the maxilla (0.48) and dentary (0.69 for the an-
terior fragment, 0.43 for the posterior) in the holotype of Fukuiraptor kitadaniensis.
Many of the teeth are maxillary, and show the same characteristics as the maxillary teeth of the
holotype. FPDM-V98081514 (Fig. 2B) is a large tooth that presumably occupied one of the third to fifth
maxillary tooth positions. Like other maxillary teeth of Fukuiraptor, the denticulate anterior and posteri-
or carinae extend from the gum-line to meet at the tip of the tooth. In addition to the presence of oblique
blood-grooves, there are shallow arcuate wrinkles that span the labial and lingual surfacesof the tooth as
in the holotype tooth FPDM-V9712206 (fig. 4 in Azuma and Currie, 2000), and in carcharodontosaurids
and some tyrannosauroids. These wrinkles are deeper and better defined close to the oblique blood
grooves that emerge from between the bases of adjacent denticles (both anterior and posterior). The
Currie and Azuma - New Fukuiraptor with a growth series
181
wrinkles are much broader and less numerous than the blood grooves, but may have a served similar pur-
pose in minimizing suction when the tooth was pulled out of flesh.
FPDM-V9712239 is a relatively small left, anterior dentary tooth with a BW/FABL ratio of 0.66. This
is the same ratio as the width versus anteroposterior length of the first alveolus of the anterior dentary
fragment (FPDM-V9712202) of the holotype. The anterior carina is lingual to the anterior longitudinal
midline of the tooth. These two facts suggest the tooth may represent the first tooth of a left dentary.
A left dentary tooth FPDM-V9812001 (Fig. 2C) is similar to the anterior dentary tooth of the holotype
(Fig. 2D) in most respects and can be assigned to Fukuiraptor. It is at least 15% larger than the holotype
tooth, and supports the idea that the described skeleton (Azuma and Currie, 2000) was not full grown
when it died. The posterior carina extends from the base of the crown to the tip, but the anterior carina is
restricted to the distal third of the front surface of the tooth. It is not clear whether this represents in-
dividual variation, variation between dentary teeth in different positions along the tooth row, or ontoge-
netic variation. Looking at what happens in other taxa suggests that the latter may be the correct
interpretation. As the teeth became larger in growing animals, the point of strongest anterior curvature
(as seen in lingual or lateral views) seems to migrate more distally in theropods. In most cases, the den-
ticulate anterior carina seems to extend from this inflection to the tip of the tooth, so it makes sense that
as the strongly curved portion of the tooth gets pushed relatively farther from the base, the relative length
of the denticulate anterior carina will also decrease.
A small (6 mm) tooth crown recovered from the Kitadani Quarry (Fig. 5) seems to be a posterior cheek
tooth of Fukuiraptor. The proportions are similar to juvenile tyrannosaurid teeth from North America
(Currie et al., 1990) and the broad, “plump” appearance would not be expected in the cheek tooth of a
small theropod species. Denticulation and faint crenulate wrinkles in the enamel are also consistent with
this identification. Because the anterior carina is limited to the distal half of the tooth, it is probably from
the dentary.
HUMERI
The holotype of Fukuiraptor included both humeri (Azuma and Currie, 2000). Four additional thero-
pod humeri have been recovered from the Kitadani Quarry, all of which are smaller than the holotype hu-
meri (Table 2, Fig. 6). Three are from the right side of the body, and one from the left. The deltopectoral
crest of FPDM-V97082553 is less prominent than that of the holotype (Fig. 7), but is morphologically
similar enough to tentatively identify this specimen as Fukuiraptor. The distal end of the crest is squared
off in lateral aspect, and is oriented anteroventrally. In lateral aspect, the distal margin of the deltopec-
toral crest is thickened where it borders a shallow proximal depression on the lateral surface.
FPDM-V9808115 (Fig. 8) is the largest, most complete humerus other than the holotype. It is an elon-
gate bone with a low deltopectoral crest that is intermediate in relative size between those of the holotype
and FPDM-V97082553. It is evident from growth series of other theropods (Raath 1990) that crest height
increases with positive allometry, so can only be used with caution for comparing humeri from in-
dividuals of different sizes. More significantly, FPDM-V98081115 has a more triangular deltopectoral
crest than either the holotype or FPDM-V97082553, and in lateral view the ridge between the head of the
humerus and the peak of the deltopectoral crest is straight rather than indented. The peak of the deltopec-
toral crest is 40% of the distance from the proximal to the distal end in the holotype of Fukuiraptor,
whereas it is only 25% of the distance in FPDM-V9808115. These differences strongly suggest that
FPDM-V98081115 represents a different taxon than Fukuiraptor kitadaniensis.
The remaining humeri (FPDM-V97082120, 980723005) are from small individuals (approximately
1.6 m long). The distal ends are similar to the holotype, to FPDM-V98081115, and to many other
theropods. At this time they cannot be assigned with confidence to any theropod taxon.
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J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
Fi
g
. 5. Posterior dentary tooth (FPDM-V98120002) of a juvenile Fukuiraptor in anterior (A),
p
osterior (D) and side
(E, F) views. B and C are enlargements of the anterior and posterior denticles.
Currie and Azuma - New Fukuiraptor with a growth series
183
Table 2. Measurements of theropod humeri from the Kitadani Quarry. Abbreviations: BL, estimated body length
b
y
comparison with the femora of other theropod taxa; DW, distal width; e, estimated; eL, estimated length of humerus
;
Femur, length of femur estimated from humerus length; PW, width of prox imal end; SW AP, anteroposterior shaft width
;
SW C, minimum shaft circumference; SW T, transverse shaft width.
# Type 97081115 97082120 97082553 980723005
L 242 144 Xx Xx Xx
PW 79.8 31.1 Xx 16+ Xx
SW T 27 12.5 9.9 8.5 11.2
SW AP 31.4 11.1 9.7 8.2 9.7
SW C89 42323139
DW 64 29 20 xx 24.1
eL 245 145 105 83 115
Femur 507 284e 197e 151e 218e
BL 4.2e 2.3e 1.6e 1.2e 1.8e
Fi
g
. 6. Theropod humeri (medial views) from the Kitadani Quarry. A, B, holotype of Fukuiraptor kitadaniensis. C,
FPDM-V97082553 (cf. Fukuiraptor). D, FPDM-V98081115, Dromaeosauridae incertae sedis. E, FPDM-V97082120.
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J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
Fi
g
.
7
. Isolated right theropod humerus (FPDM-V9808115) in dorsal (A), dorsolateral (B), lateral (C), ventral (D), medi
-
oventral (E), proximal (F) and distal (G) views.
Currie and Azuma - New Fukuiraptor with a growth series
185
Fi
g
. 8. Deltopectoral crests of right humerus (FPDM-V9808115) of unknown small theropod (A), and left humeri o
f
F
ukuiraptor kitadaniensis (B, FPDM-V97082553; C, holotype).
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J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
Tab le 3 . Minimum number of individuals of Fukuiraptor
b
ased on the femora from the Kitadani Quarry. Abbreviations:
Body, estimated snout to tip of tail length of body; Class, size class; Ind. #, individual number; L, length; DW, distal
width; eL, estimated length of femur; PW, proximal width; SW A-P, ante roposterior shaft width; SW Cir, circumferenc
e
of shaft; SW T, transverse shaft width. Note that the size class is an arbitrary designation.
#right or
left LPWSW A-
PSW T SW
Cir
DW Class Ind. # eL Body
980805018 righ
t
92.2 15.1 9.2 7.4 32 13.2 1 1 93 735
970813046 righ
t
116.3 17.4 11.7 6.6 35 17.5 2 2 116 925
970821039 righ
t
122.7 18 11.4 9.6 36 17 2 3 123 978
99090901 lef
t
xx xx xx 13.1 39 20.2 3 4 128 1021
980813017 righ
t
xx xx 10 12.3 40 xx 3 4 131 1046
98072302 lef
t
134.2 21 10 13.7 40 20.5 3 5 134 1072
9812638 righ
t
xx xx 13.8 11.3 41 xx 4 6 134 1070
97080937 lef
t
xx xx 13.4 11.4 42 21.4 4 6 137 1095
970730003 righ
t
xx 27.3 11.6 10.7 42 xx 4 7 137 1095
97120001 lef
t
xx 21.1 13.7 12.6 42 xx 4 7 137 1095
97081330 righ
t
134.9 20 xx xx 43 xx 4 8 135 1078
98081028 righ
t
xx xx 14.2 12.3 46 xx 5 9 149 1194
98120001 lef
t
xx xx 16.4 11.5 46 xx 5 9 149 1194
98120002 righ
t
xx xx 17.2 15.5 55 xx 6 10 176 1416
97122BNA3 righ
t
200 35 21.5 16.3 65 xx 7 12 204 1648
97081201 righ
t
196 35 xx xx 67 37.7 7 11 211 1707
97122BNA12 righ
t
244 xx 26.4 21.4 80 xx 8 13 248 2015
97122 righ
t
507 108.5 53 43 164 96.3 9 14 507 4200
FEMORA
Eighteen partial and complete theropod femora have been collected from the Kitadani Quarry (Figs. 9,
10, Table 3). Thirteen of these are from the right side of the body, and the other five are from the left. Two
of the incomplete left specimens (FPDM-97120001, 98120001) may be the same bone that became sepa-
rated during collection. Although they are in the same size range (from an animal just over a meter in
length), there is no good contact between the two pieces. No other possible connections exist between
other incomplete femora. The fact that there are thirteen right femora, ten of which are complete or al-
most complete, indicates that a minimum number of thirteen individual theropods are represented in the
collection. However, one left femur (FDM-V98072302) does not match the size of any right femur, so
the minimum number of individuals represented by femora is fourteen.
Theropod femora are rich in features and are therefore diagnostic at the family level. Many of the
Kitadani femora are incomplete, and show too few features to be identified more specifically than
Theropoda. The smallest femur (FPDM-V980805018) is 18% the length of the holotype of Fukuiraptor
kitadaniensis. However, like the femur of the holotype, it has a lateromedially elongate head (Fig. 10), an
alariform lesser trochanter separated from the shaft by a deep slot, a low moundlike process on the lateral
surface level with the base of the lesser trochanter, a distinct ridgelike fourth trochanter bounded ante-
romedially by a distinct oval muscle scar and posteriorly by a shallow depression, a gently curving shaft,
and a sharp mediodistal crest. This suite of features is characteristic of carnosaurs, and suggests that the
Currie and Azuma - New Fukuiraptor with a growth series
187
188
J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
Fig. 9. Femora of Fukuiraptor showing range in size.
A, FPDM-V97122
B, FPDM-V980805018
C, FPDM-V970813046
D, FPDM-V970821039
E, FPDM-V99090901
J, FPDM-V980813017
K, FPDM-V980723002
L, FPDM-V9812638
M,FPDM-V97080937
F, FPDM-V970730003
G, FPDM-V9712001
H, FPDM-V97081330
I, FPDM-V98081028
N
, FPDM-V98120001
O, FPDM-V98120002
P, FPDM-V97122BNA3
Q, FPDM-V97081201
R, FPDM-V97122BNA12
small femur is probably a juvenile Fukuiraptor. Five larger specimens (FPDM-V970813046, 970820039,
980723002, 97122BNA12, 97081201) show most of these characters, plus the presence of an accessory
wing on the lesser trochanter, a deep anterodorsal extensor groove andan adductor fossa on the distome-
dial surface of the femoral shaft. Together with the smallest specimen and the holotype, they represent a
growth series of Fukuiraptor femora. The remaining femoral specimens are not complete enough to be
certain of their affinities, although none show characters diagnostic of Dromaeosauridae or any other
coelurosaurian group.
DISCUSSSION
The theropod bones from the Kitadani Quarry can be assigned with confidence to two distinct taxa.
Most of the teeth and bones can conservatively be attributed to juvenile Fukuiraptor kitadaniensis.
Although this carnosaur has been the only theropod described so far from the Kitadani Quarry, there is at
least one undescribed small theropod, possibly a dromaeosaurid from the site (Azuma and Currie, 2000).
Manual unguals collected from the same quarry suggest that there may have been as many as three differ-
ent types of small theropods in the fauna. Nevertheless, none of the preserved femora have any of the
characteristic features of coelurosaurians. It can therefore be assumed that all of the better preserved fem-
ora in this collection are from Fukuiraptor.
Teeth that can be assigned to Fukuiraptor (based on tooth and denticle morphology, and positions of
carinae) from the Kitadani Quarry show considerable variation in size. Variation in tooth size is high
within most theropod individuals. However, identification of what jaw regions each of the teeth belong to
demonstrates that the Fukuiraptor teeth came from individuals of different sizes. Some of those in-
dividuals were much smaller than the holotype specimen (Azuma and Currie 2000), and one was clearly
larger.
Fukuiraptor teeth are distinctive amongst the teeth from the Kitadani Quarry. However, they are sim-
Currie and Azuma - New Fukuiraptor with a growth series
189
Fi
g
. 10. Right femora of Fukuiraptor kitadaniensis in
p
roximal
view. A) FPDM-V980805018. B) FPDM-V970813046. C) FPDM-
V970730003. D
)
FPDM-V97081201. E
)
Holot
yp
e
(
FPDM-V97122
)
.
190
J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
ilar to theropod teeth found in many localities in Japan and around the world. Like carcharodontosaurids
from Africa and South America, they are narrow and blade-like, have relatively small serrations, and
have arcuate wrinkles in the enamel on labial and lingual surfaces. Like carcharodontids as well, the in-
terdental plates are fused to each other and to the margins of the jaws.
Chure et al. (1999) described a tooth from the late Cretaceous Mifune Group of Japan that is very sim-
ilar in most respects (tooth size and shape, serration size, curved enamel wrinkles) to an anterior maxil-
lary tooth of Fukuiraptor. They concluded that the Mifune tooth compares more closely with carchar-
odontosaurid teeth than with any other type of theropod tooth described. However, when the ratio of
FABL is compared with BW (Fig. 3A) and posterior denticle size is compared with FABL (Fig. 3B), the
Mifune tooth falls on the regressions for Fukuiraptor rather than Carcharodontosauridae.
Although Fukuiraptor teeth have oblique blood grooves similar to those of tyrannosaur teeth, neither
they nor any of the other theropod teeth recovered from the Kitadani Quarry can be identified as
tyrannosaurid. The only premaxillary teeth recovered so far have J-shaped cross-sections, like the pre-
maxillary teeth of most theropod families (Currie et al., 1990). Manabe (1999) reported the discovery of
an isolated tyrannosauroid premaxillary tooth from a nearby area in Fukui Prefecture, but from the un-
derlying Jobu Formation (Itoshiro Subgroup, Tetori Group, Lower Cretaceous). The specimen was there-
fore recovered from an older formation, and represents a more ancient animal than Fukuiraptor.
Premaxillary teeth of tyrannosauroids have also been reported from the younger Mifune Group of Japan
(Anonymous, 1998), along with the carcharodontosaurid-like cheek teeth. Recent descriptions of tyran-
nosauroids from the Late Jurassic and Early Cretaceous of Europe and Asia (Hutt et al., 2001; Xu et al.,
2004; Xu et al., 2006) confirm the likelihood of the Japanese tyrannosauroid records.
The smallest individual of Fukuiraptorin the Kitadani Quarry is less than a quarter the size of the
holotype. A fourfold increase in size is reasonable for a growth series of an animal of this size, and prob-
ably does not represent a complete growth series. For example, Nile crocodiles grow to about the same
length as Fukuiraptor, but are only 0.25 m long at birth (Cott, 1961).
It is difficult to study ontogenetic changes in limb proportions when dealing with unassociated speci-
mens from bonebeds. However, using allometric equations developed for other theropods, such as tyran-
nosaurids (Currie, 2003), the approximate body lengths of each individual can be calculated (Table 3).
These were arranged into arbitrary size classes, with the smallest individual being assigned to Class 1,
and the largest to Class 9. Fukuiraptor size classes in the bonebed are nearly evenly distributed, with
peaks of four individuals each for size classes 4 and 7. There are not enough specimens for this bimodal
distribution curve to be statistically significant, but it provides weak evidence in support of this being an
attritional death assemblage (Voorhies, 1969).
Fukuiraptor remains in the Kitadani Quarry are common in comparison with the fossils of herbivorous
dinosaurs. Bonebeds dominated by theropods are very rare anywhere in the world, and the high number
of carnivores in the Kitadani Quarry suggests that there were some unusual circumstances involved in the
genesis of the site. Perhaps it was taphonomic, or perhaps it was more directly involved with the behav-
iour of Fukuiraptor itself. The concentration of juvenile Fukuiraptor teeth and bones may indicate that
this was close to where the theropods were nesting, perhaps similar to the scenario described by Bakker
and Bir (2004). There is a mixed faunal bonebed in Utah (USA) with a similar concentration of
theropods. The Upper Jurassic Cleveland-Lloyd quarry is dominated by more than seventy individuals
of Allosaurus fragilis, and has been interpreted as a predator trap (Madsen, 1976; Miller et al., 1996;
Richmond and Morris, 1996), or as a drought-induced mass death assemblage (Gates 2005). Coelophysis
(Colbert, 1989) and Syntarsus (Raath, 1990) are two examples of theropods that died en masse in Late
Triassic to Early Jurassic times, whereas trackway sites (Ostrom, 1972) suggest that coelophysoids may
have travelled in packs. The Coelophysis bonebed has also been interpreted as species-selectivity in
Currie and Azuma - New Fukuiraptor with a growth series
191
drought conditions (Schwartz and Gillette, 1994). In Late Cretaceous times, bonebeds dominated by ty-
rannosaurids (Larson, 1997; Currie, 2000; Currie et al., 2004), carcharodontosaurids (Coria and Currie,
1997, 2006), dromaeosaurids (Ostrom, 1969; Maxwell and Ostrom, 1995) and troodontids (Varricchio
and Currie, 1991) have been used to suggest that these animals hunted in packs. Unfortunately, there are
no strong taphonomic signals in the Kitadani Quarry to eliminate any of these scenarios as possible ex-
planations for the high concentration of Fukuiraptor specimens.
CONCLUSIONS
Most of the isolated theropod teeth and bones recovered from the Kitadani Quarry are from carno-
saurs, although some of the teeth, a humerus and several unguals seem to be dromaeosaurid. One me-
dium-sized carnosaur, Fukuiraptor kitadaniensis, has been described (Azuma and Currie, 2000) from the
quarry. The type specimen had an estimated length of 4.2 m when it was alive. Azuma and Currie (2000)
suggested that it was close to adult size when it died, and that the species never became as large as the
majority of known carnosaurs. Amongst the isolated teeth and bones from the Kitadani Quarry, only one
tooth is suggestive of a slightly larger individual, and the rest of the fossils are from much smaller
individuals. Because it is more parsimonious to assume that they represent only one species of carnosaur
from the Kitadani fauna, it is likely that they represent a growth series of Fukuiraptor. At least two other
theropod taxa can be recognized in the fauna from teeth and manual unguals, but in the Kitadani Quarry
these coelurosaurs are rare animals.
The theropod teeth and bones from the Kitadani Quarry represent a minimum number of 14 in-
dividuals based on femoral counts alone. The high concentration of juvenile carnosaurs at this one site
may represent a breeding or nesting area, a predator trap, or the catastrophic demise of a social group.
Taphonomic analysis of the bones in the quarry cannot resolve which of these three options (if any of
them) is correct.
ACKNOWLEDGMENTS
The first author would like to thank Eva Koppelhus (University of Alberta) and Yoshi Kobayashi
(Hokkaido University) for logistic support, without which it would have been impossible to do this paper.
All illustrations were done by the first author. Support for his trips to study the specimens came from
NSERC (Grant #203091-02) and the Fukui Prefectural Dinosaur Museum. The paper was improved by
careful reviews by Yoshi Kobayashi and Dale Winkler.
일본 전기 백악기 Kitadani 채석장에서 산출된 Fukuiraptor
(공룡, 수각류)의 개체발생을 포함한 새로운 표본들
Philip J. Currie1 and Yoichi Azuma2
1University of Alberta, Department of Biological Sciences, 11145 Saskatchewan Drive, Edmonton, Alberta
T6G 2E9, Canada
2Fukui Prefectural Dinosaur Museum, 5-11 Terao, Muroko, Katsuyama, Fukui 911-8601, Japan
192
J. Paleont. Soc. Korea. Vol. 22, No. 1, 2006
요 약: 모식표본 Fukuiraptor kitadaniensis 와 같은 종에 속하는 뼈와 이빨들이 일본 후쿠이현 전기 백악기(Albian)
지층인 Kitadani 화석지에서 발굴되었다. 이들 화석들은 계통발생학적 위치를 결정하는데 도움이 되는 여러 정보를
가지고 있을 뿐 아니라 일련의 개체발생을 나타내고 있다. 모식표본은 미성숙 표본이며 전체 길이는 4.2 m 였다. 같은
화석지에서 산출된 다른 화석들은 이 보다 더 작은 개체의 것이다. 새끼뼈의 일부는 모식표본의 것에 1/3 보다 작다.
주요어: Fukuiraptor, 성장단계, Kitadani, 일본
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