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Pal~iontologische Zeitschrifl I 72 (1/2) 179-189 8 Abb., 1 Tab. Stuttgart, April 1998
Small theropod teeth from the Upper Jurassic coal mine
of Guimarota (Portugal)
JENS ZINKE, Berlin
With 8 figures and 1 table
Kurzfassung: Isolierte Z~ihne theropoder Dinosaurier aus dem
Oberen Jura der Kohlengrube Guimarota (bei Leiria, Portugal)
werden beschrieben und abgebildet. Die h~tufigsten Zahnfunde
~ihneln morphologisch den Bezahnungen der oberjurassischen
Theropoden
Archaeopteryx
und
Compsognathus.
Ein Morpho-
typ deutet auf das Vorhandensein eines Allosauriden hin. Sechs
weitere Morphotypen von Theropoden-Z~ihnen zeigen grol3e
Ahnlichkeiten mit kreidezeitlichen Formen, wie Dromaeosau-
riden, Troodontiden, Tyrannosauriden,
Richardoestesia
und
Paronychodon.
Fiir diese Gruppen wird ein spatjurassischer
Ursprung diskutiert, wie er von einigen Autoren bereits ver-
mutet wurde.
Abstract: Isolated teeth of small theropod dinosaurs from the
Upper Jurassic lignite coal mine of Guimarota (near Leiria,
Portugal) are described and illustrated. The well known Upper
Jurassic theropods from Europe,
Archaeopteryx
and
Compso-
gnathus,
are the most common taxa in the Guimarota assem-
blage. One morphotype is closely related to an allosaurid
theropod. Six further morphotypes of theropod teeth are also
described, which are closely related to Cretaceous theropods
such as dromaeosaurids, troodontids, tyrannosaurids,
Richar-
doestesia
and
Paronychodon.
A Late Jurassic origin of these
groups of theropods, which is very often postulated, is dis-
cussed.
Introduction
The screen washing activities of the Free University of
Berlin, searching for early mammals in many parts of
Europe, also yielded dinosaur material, which has been
briefly described (THULBORN 1973; ZINKE & RAUHUT
1994). The coal mine of Guimarota (near Leiria, Portu-
gal, Fig. 1) is one of the most important Upper Jurassic
microvertebrate localities, being especially famous for
early mammals (detailed publication list in KREBS 1991).
Dinosaur remains, mainly teeth, are also quite common.
The locality was dated as early Kimmeridgian by HELM-
DACH (1971) and this was confirmed by SCHUDACK
(1993) on the basis of ostracods. The vertebrate-bearing
strata are two lignite coal layers within marly limestone.
The lower coal layer yielded more vertebrate remains,
and was the subject of a systematic dig from 1972-1982.
Of the dinosaur fauna, only the Ornithischians were ex-
Fig. 1. Geographical position of the coal mine Guimarota, near
Leiria (from SCHtJDACK 1993).
amined by THULBORN (1973), who described a new hyp-
silophodontid ornithopod,
Phyllodon henkeli,
on the ba-
sis of isolated teeth. Further studies in the collection of
the Free University Berlin will provide new information
about the Ornithischians in Guimarota (RAUHUT in prep.).
MmNER & EVANS (1991) described a maxilla of
Lisboa-
saurus estesi
as a maniraptoran theropod, which was re-
examinated and interpreted as a notosuchian crocodile by
BUSCALIONI et al. (1996). Teeth and a fragmentary den-
tary of a small theropod dinosaur were described by
ZINKE & RAUHUT (1994). WEIGERT (1995)
described iso-
lated teeth of cf.
Archaeopteryx
sp.
Since new research in the Upper Jurassic Morrison
Formation (USA) has revealed small dinosaur teeth, as
well (CHURE et al. 1993; CHURE 1994, 1995), the descrip-
tion of the small theropod teeth from the coal mine of
Guimarota in this paper will give new information about
the diversity of tooth morphologies in Upper Jurassic
theropod dinosaurs for a comparison with the American
forms.
Address of the author: JENS ZINKE, Institut ftir Palaontologie, Freie Universit~it Berlin, MalteserstraBe 74-100, Haus D, D-12249
Berlin, Germany.
0031-0220/98/0072--0179 $ 3.00
9 1998 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart
180 JENS ZINKE
Fig. 2. cf.
Compsognathus
sp.; A: lingual view, B: labial view, C: posterior denticles; IPFUB GUI D 64. - D: lingual view, E:
labial view, F: posterior denticles, G: anterior denticles; IPFUB GUI D 65.
Tab. 1. Mean value of measurements taken from all Guimarota-specimens referred to known genera and variation range of DSDI.
Guimarota genera
cf.
Compsognathus
sp.
velociraptorine dromaeosaurids
cf.
Dromaeosaurus
sp.
cf. Paronychodon
sp.
cf. Richardoestesia
sp.
probable troodontids
large morphotaxa
probable allosaurids
probable tyrannosaurids
number of
teeth
49
28
29
40
14
13
TCH
(mm)
1.71
2.26
8.05
1.67
3.42
1.02
10.15
8.75
6.19
FABL
(nun)
1.01
1.65
4.47
1.12
2.08
0.92
3.71
5.12
3.02
BW (mm)
0.75
0.79
4.05
0.65
1.02
0.51
2.5
2.75
2.99
anterior
denticles
per 1 mm
10-17
8-16
(18)
8-14
8-16
6-8.5
6-10
5-7
posterior
denticles
per 1 mm
10-15
5-10
6-13
9-14
6-14
5.5-8
5.5-8
5-7
DSDI
0.79-1.33
1.0-2.4
1.0
(1.63)
0.8-1.33
0.8-1.5
1.09-1.33
1.0-1.18
1.0
Small theropod teeth from the Upper Jurassic coal mine of Guimarota (Portugal) 181
Materials and methods
From the first two years of screen washing (05.06.1974-
30.04.1976), the author recognized 440 isolated theropod
teeth, which are described in this paper. 296 of these
theropod teeth were identified and measured (Tab. 1) us-
ing SEM (Cambridge Stereoscan 360) or a Leitz-Micro-
scope.
The theropod teeth are characterized by the following
features: TCH = tooth-crown-height; FABL = fore-aft-
basal-length; BW = basal width (these terms have been
defined by CURRIE et al. 1990 and FARLOW et al. 1991);
number of denticles per 1 mm on the anterior and poste-
rior carina; DSDI = denticle size difference index (de-
fined by RAUHUT & WERNER 1995); cross-section of the
base. All systematic terms are used following HOLTZ
(1994).
The abbreviation IPFUB GUI D (Number) means:
IPFUB = Institute for Paleontology of the Freie Uni-
versit~t Berlin, GUI = Guimarota, D = Dinosauria.
Description
Class Dinosauria OWEN 1841
Superorder S aurischia SEELEY 1888
Order Theropoda MARSH 1881
Suborder Coelurosauria (sensu HOLTZ 1994)
Family Compsognathidae
cf. Compsognathus sp.
Fig. 2 A-G
Referred material: 49 isolated teeth; IPFUB GUI D 28-65,
98, 103, 105-110, 112-113.
D e s c rip tio n : These teeth are represented by three mor-
photypes which correspond with different positions in the
jaw. The first morphotype is characterised by very slen-
der, cone-shaped crowns, which are only recurved at the
apex and lack serrations, approximately from the ante-
rior part of the jaw. The second morphotype is less
recurved apically, and the posterior carina is only slightly
concave and shows serrations (Fig. 2A-C). The anterior
carina lacks serrations, but is sharp-edged. These teeth
are from a middle position of the jaw. The third morpho-
type shows nearly the same TCH as FABL, which results
in a compact shape (Fig. 2D-E). Usually both carinae are
serrated, with the anterior denticles smaller and more
strongly hooked apically than the posterior ones (Fig. 2F-
G). The anterior denticles are found only at the very tip
of the crown (Fig. 2D). Like the teeth of the second
morphotype these teeth show a slight constriction be-
tween crown and root. The DSDI varies from 0.79-1.33.
Discussion: The three morphotypes described above
can be correlated very well with different tooth positions
in the jaw of the Upper Jurassic genus Compsognathus,
which have been described and illustrated by STROMER
(1934). In Compsognathus there are cone-shaped teeth
Fig. 3. Premaxillary tooth from cf. Dromaeosaurus sp.; A: lin-
gual view, B: enlargement of posterior denticles, C: cross-sec-
tion of the base; IPFUB GUI D 77. -A premaxillary tooth of a
probable tyrannosaurid; D: lingual view, E: anterior view, F:
cross-section of the base; IPFUB GUI D 89.
from the anterior part of the dentary, slightly recurred
teeth with only posterior serrations from the middle of
the dentary and compact-shaped teeth with fine serrations
on the posterior carina from the back of the mouth. The
variation of TCH and FABL in the Guimarota specimens
is nearly the same as in Compsognathus. Since some
Guimarota specimens show serrations on both carinae,
the teeth from Guimarota belong to a closely related
form, but not to Compsognathus itself.
Family Dromaeosauridae
Subfamily Dromaeosaurinae
cf. Dromaeosaurus sp.
Fig. 3A-C
Referred material: 1 premaxillary tooth; IPFUB GUI D 77.
Description: The tooth IPFUB GUI D 77 shows the
typical crown shape of a premaxillary tooth (Fig. 3A).
The serrated anterior carina appears on the upper half of
the crown and bends inward to the lingual surface at its
lower part (Fig. 3 A). All denticles are heavily worn
down. The posterior carina is also serrated and the den-
ticles, which are well preserved, are orientated perpen-
dicularly to the edge and only slightly hooked apically
182 JENS ZINKE
Fig. 4. A velociraptorine dromaeo-
saurid; A: labial view, B: lingual
view, C: anterior denticle, D: poste-
rior denticles; IPFUB GUI D 75.-
A probable tyrannosaurid premaxil-
lary tooth; E- posterior denticles, F:
anterior denticles; IPFUB GUI D
89.
(Fig. 3B). The blood grooves do not reach the surface of
the tooth. The cross-section appears rounded and not D-
shaped, because of the appearance of the carinae (Fig.
3C).
D i s c u s s i o n : IPFUB GUI D 77 is closely related to the
premaxillary teeth of the Late Cretaceous genus
Dro-
maeosaurus
for the following reasons: 1. The anterior
and posterior carinae are on the lingual side of the tooth;
2. the cross-section of the base is rounded and not D-
shaped; and 3. the DSDI is 1.0 and lies within the range
for
Dromaeosaurus
(RAUHUT & WERNER 1995). The pos-
terior denticles may have been longer than those from the
anterior carina, as proposed for
Dromaeosaurus
(CuRRm
et al. 1990), but due to intensive wear this cannot be de-
termined.
Subfamily Velociraptorinae
Gen. et spec. indet.
Fig. 4A-D
Referred material: 28 isolated teeth; IPFUB GUI D 66-88,
99, 101,157, 158, 170.
Description: These teeth are strongly laterally com-
pressed and recurved (Fig. 4A-B). The serrated carinae
show a significant difference in denticle size on the ante-
rior and posterior serrations. The posterior denticles are
twice as high as those from the anterior carina (Fig. 4C-
D). The posterior serrations are slightly hooked apically,
while those from the anterior carina are orientated per-
pendicularly to the edge (Fig. 4C-D). The cross-section
of the base is rectangular. The DSDI varies from 1.0-2.4.
Small theropod teeth from the Upper Jurassic coal mine of Guimarota (Portugal) 183
Fig. 5. A possible troodontid; A:
labial view, B: lingual view, C:
posterior denticles, D: anterior
denticles; IPFUB GUI D 94.
Di s c u s s ion : A significant difference in the size of den-
ticles from the anterior and posterior serrations, in com-
bination with the tooth shape described above, is only
found in velociraptorine dromaeosaurids (CtJRRm et al.
1990; RAUHUT • WERNER 1995). Usually the denticles
of velociraptorine dromaeosaurids are strongly hooked
toward the tip of the crown, but the Guimarota specimens
differ in this character. Since strongly hooked denticles
are the advanced character, the Guimarota specimens
may belong to a primitive velociraptorine dromaeosaur.
The variation range of the DSDI in the Guimarota speci-
mens lies within the range of the Cretaceous velocirap-
torines
Saurornitholestes, Deinonychus
and
Velociraptor
(RAUHUT 8Z WERNER 1995).
Family Tyrannosauridae
Gen. et spec. indet.
Figs. 3D-F, Figs. 4E-F
Referred material : 3 premaxillary teeth; IPFUB GUI D 89-
91.
Description: These teeth show a D-shaped, basal
cross-section with the anterior and posterior carina situ-
ated on the lingual side of the tooth (Fig. 3D-F). Both
carinae are serrated, but the denticles are heavily worn
down (Fig. 4E-F). Blood grooves between adjacent den-
ticles extend onto the surface of the tooth (Fig. 4E). Both
carinae bend inwards to the lingual surface antapically
(Fig. 3D). A well defined median ridge is found on the
lingual surface of the tooth near the posterior carina,
which becomes more shallow and less pronounced api-
cally. Smaller ridges can be found on both sides of the
median ridge (Fig. 3D). IPFUB GUI D 90 possesses a
broken lingual surface which has been worn down to a
smooth surface probably through mastication. IPFUB
GUI D 89 and D 91 have a DSDI of 1.0.
Dis c u s s i o n: The occurrence of two characteristic fea-
tures of tyrannosaurids - a D-shaped cross-section at the
base, and a typical wear surface - means that it is likely
that these teeth represent a closely related form. A well
developed median ridge on the lingual surface of D-
shaped teeth is found only in the Upper Cretaceous ge-
184 JENS ZINKE
nus Aublysodon, which could represent a juvenile morph
of a tyrannosaurid (MOLNA~ & CARPENTER 1989; CURRIE
et al. 1990). The variation of the DSDI lies within the
range of Tyrannosaurus and Aublysodon (RAUHUT &
WERNER 1995).
Family Troodontidae
Gen. et spec. indet.
Fig. 5A-D
Referred material: 14 isolated teeth; IPFUB GUI D 93-97,
100, 102, 104, 111,114-116, 156, 190.
D e s c r i p t i o n: These teeth are laterally compressed with
a triangular cross-section at the base (Fig. 5A-B). In the
majority of specimens, both carinae are serrated, with the
anterior denticles being broader and less high than those
of the posterior carina, which are strongly hooked
apically (this is also true for teeth with only posterior ser-
rations). The anterior denticles (where they exist), and
posterior denticles are very large in relation to the TCH;
therefore they are reduced to a number of 8-9 denticles
per 1 mm (Fig. 5C-D). The blood grooves between adja-
cent denticles do not reach the surface of the crown. In
some of the Guimarota specimens the anterior denticles
are found only at the apex. A constriction between crown
and root is found in all the Guimarota specimens. The
DSDI varies from 0.8-1.5.
Dis c u s s i o n : These Guimarota specimens are closely
related to the Upper Cretaceous troodontids on the basis
of the following features: 1. constriction between crown
and root is found in all teeth; 2. the triangular cross-sec-
tion of the base; 3. they possess large denticles in rela-
tion to the TCH. Usually these features are seen as
autapomorphies of troodontids (BARSBOLD 1974; CURRm
1987; CURRIE et al. 1990). Besides these features, the
number of denticles per 1 mm is nearly the same as that
in troodontids, but this feature is not very useful for diag-
nostic purposes (FAI~LOW et al. 1991). The arrangement
of the denticles, and the difference in the shape of the
anterior and posterior denticles in the Guimarota speci-
mens is very similar to the pattern known in troodontids.
The variation range of the DSDI in the Guimarota speci-
mens is higher than in troodontids, but this may be due to
a position within the jaw.
Theropoda incertae sedis
cf. Richardoestesia sp.
Fig. 6A-E
Referred material: 40 isolated teeth; IPFUB GUI D 118-
155.
Description: These teeth are laterally compressed,
strongly elongated and recurred only toward the apex
(Fig. 6A-B). Both carinae are serrated, but the denticles
are very small in relation to tooth size. There is only a
slight difference in the size of the denticles on the ante-
rior and posterior carina; therefore the variation range of
the DSDI is rather low and varies from 0.8-1.33 (Fig. 6C-
D). On both the lingual and labial sides of the teeth, a
longitudinal groove is found. This groove, which be-
comes more shallow and narrow toward the tip of the
crown, is more pronounced on the lingual side (Fig. 6A).
The cross-section of the base is rectangular (Fig. 6E).
D i s c u s s i o n: The teeth of
Richardoestesia gilmori from
the Upper Cretaceous deposits of the Judith River For-
mation (USA) are the only well described theropod teeth
which also show a lanceolate shape, very small denticles
in relation to tooth size and a longitudinal groove on the
sides (CURRIE et al. 1990). The teeth of the type species
Richardoestesia show a greater difference in the size of
the denticles of the anterior and posterior serrations than
the specimens from Guimarota, but our specimens are
nearly the same as Richardoestesia-like teeth from the
Lower Cretaceous Spanish locality Ufia (RAUHUT &
ZINKE 1995). Similarities with the teeth of the Upper
Triassic theropod Coelophysis (COLBERT 1989) and the
temporal distance to Richardoestesia might indicate that
the combination of characters found in the specimens
from Guimarota is a result of convergent development.
The variation of the DSDI in the specimens from Gui-
marota lies within the range of Richardoestesia and
Coelophysis (RAUHUT & WERNER 1995).
Fig. 6. cf. Richardoestesia sp.; A: lingual view, B: labial view,
C: enlargement of posterior denticles, D: enlargement of ante-
rior denticles, E: cross-section of the base; IPFUB GUI D 128.
cf. Paronychodon sp.
Referred material: A fragmentary left dentary and 29 iso-
lated teeth; IPFUB GUI D 1-27.
Description: The dentary fragment and the isolated
teeth are described in detail by ZINRE & RAUHUT (1994).
So far, the most interesting feature on the teeth in the jaw
and the isolated teeth are the longitudinal grooves and
ridges found on both sides of the tooth. All Parony-
Small theropod teeth from the Upper Jurassic coal mine of Guimarota (Portugal) 185
Fig. 7. A peculiar theropod tooth;
A: labial view, B: lingual view,
C: posterior view, D: posterior
denticles in occlusal view; IPFUB
GUI D 159.
chodon-like
teeth from Guimarota show serrations on the
posterior carina, and sometimes on both carinae.
Discussion: Since the holotype of
Paronychodon
(COPE 1876) is known from the Upper Cretaceous, again
the temporal distance might suggest, that the reference
of the specimens from Guimarota to the same genus is
wrong. It is very difficult to do systematic work with the
teeth of
Paronychodon,
as the holotype has only been
described tentatively and a lot of teeth bearing longitudi-
nal grooves on their faces, from different localities and
of different times, have been ascribed to this genus, but
their taxonomic position is still uncertain. As mentioned
by CURRIE et al. (1990), the name
Paronychodon lacu-
stris
should be restricted to non-serrate forms. For the
specimens from Guimarota it is important to mention that
similar teeth have been found in the Lower Cretaceous
Spanish locality Galve (RAUHUT & ZINKE 1995). So far,
the occurrence of this tooth morphotype is certain on the
Iberian Peninsula from the Upper Jurassic until the
Lower Cretaceous. Since the Iberian Peninsula was a
consolidated landmass during these periods, the speci-
mens from Spain and Portugal may belong to closely re-
lated forms. The exact taxonomic position is difficult to
determine, but a few features of the dentary fragment and
the isolated teeth indicate a relationship to the mani-
raptorans, and above all to the troodontids (ZINKE &
RAUHUT 1994).
186 JENS ZINKE
Indeterminate small theropod teeth
Fig. 7A-D
Referred material: 11 isolated teeth; IPFUB GUI D 159-
169.
Description: These teeth are slightly recurved with a
rounded cross-section at the base. The arrangement of the
serrated posterior carina is very peculiar, because they are
mostly in a labial position (Fig. 7A-B). Four teeth show
serrations, which are chisel-like in appearence. Serrations
are missing from the other teeth, but on most of them a
row of rounded pits can be found, which represents the
remains of worn denticles. The shape of the denticles on
the posterior carina is very peculiar too, since they are
asymmetric. The lingual side of each denticle is higher
and more oblique than the labial side (Fig. 7C-D). The
posterior carina bends antapically toward the labial side.
A deep groove is developed labially to the entire serra-
tion.
Discussion: This morphotype has never been de-
scribed before, and its taxonomic position remains un-
certain. The only comparison could be to a peculiar tooth
morphotype mentioned by MOLNAR & CARPENTER (1989)
in their description
ofAublysodon mirandus.
Since asym-
metrical carinae are known from tyrannosaurid teeth, it
is possible that our teeth may represent a member of this
family. However, as such teeth have not been described
in detail, this is only a conjecture. Some of the larger teeth
from Guimarota (TCH more than 1 cm) show asymmetri-
cal carinae, as well as a rounded basal cross-section, and
it is possible that these large teeth are closely related to
the teeth described above.
Larger theropod teeth with a rounded cross-section
Fig. 8A-D
Referred material: 13 isolated teeth; IPFUB GUI D 174-
186.
Description: These teeth are strongly elongated and
recurved only apically (Fig. 8A). In half of the sample,
both carinae are serrated with denticles orientated per-
pendicularly to the edges. The posterior denticles are
higher than the anterior ones (Fig. 8B-C). The denticles
are relatively small in relation to tooth size. Blood
grooves between adjacent denticles reach the surface of
the tooth, but they are not orientated toward the base of
the crown. The posterior carina shows a twist toward the
labial side of the tooth in the middle of the crown. The
most striking feature is the nearly rounded cross-section
of the base, which gives these teeth a compact basal shape
(Fig. 8D), whereas apically these teeth show a lenticular
cross-section. The DSDI is rather low and varies from
1.0-1.33.
D i s c u s si o n: Strongly elongated teeth with a rounded,
basal cross-section have been described and illustrated
for maxillary and dentary teeth of
Aublysodon mirandus
(MOLNAR & CARPENTER 1989). The rounded sockets of
the alveoli known in tyrannosaurid jaws, which were il-
lustrated for
Gorgosaurus
(LAMBE 1917), suggest that
tyrannosaurid lateral teeth possessed a rounded cross-
section at the base, above all the anterior teeth (CURRIE
pers. com. 1996). However, this has not been described
before. The Guimarota specimens differ from tyranno-
saurid teeth in the appearance of the blood grooves,
which are not orientated toward the base (F~ORmLO &
CURRm 1994), and also in the slightly higher variation
range of DSDI (RAUHUT & WERNER 1995).
Probable allosaurid teeth
Fig. 8E-I
Referred material: 4 lateral teeth; IPFUB GUI D 191-194.
Description: The lateral teeth are laterally compressed
and recurved at the apex (Fig. 8E). They show a FABL/
BW ratio of two to one, which gives them a very broad
appearance in anterior-posterior direction (Fig. 81). On
three of these teeth both carinae are serrated. The basal
length of the anterior and posterior denticles is the same,
but the posterior denticles tend to be longer than those
from the anterior carina (Fig. 8F-G). The blood grooves
extend onto the surface of the tooth, but they are not ori-
entated toward the base of the tooth. On the lingual side a
well developed median ridge follows the midline of the
crown, becoming narrower toward the tip (Fig. 8E). This
ridge shows the appearance of two longitudinal grooves
between the carinae and the median ridge, mainly in the
upper half of the tooth (Fig. BE). The cross-section of the
base is rectangular, while apically the cross-section is
rather lenticular (Fig. 81). The DSDI varies from 1.0-
1.18.
D i s c u s s io n: Lateral teeth of
Allosaurus are
character-
ised by a middle FABL/BW ratio of two to one (pers.
obs.), which is found in all the Guimarota specimens. A
well-pronounced median ridge on the lingual side of the
tooth, showing the appearance of two longitudinal
grooves between the carinae and the median ridge, is also
developed in these lateral teeth
ofAllosaurus
(pers. obs.).
The anterior and posterior denticles
of Allosaurus
lateral
teeth show the same basal length apically-antapically, but
the posterior denticles tend to be longer than those from
the anterior carina (pers. obs.). The same is found in all
the Guimarota specimens. Therefore the variation range
of the DSDI in
Allosaurus
(1.0) and in the Guimarota
specimens is rather small. While downpointing blood
grooves have been found in
AUosaurus
lateral teeth, the
Guimarota specimens differ in this respect (pers. obs.).
However, this may be due to the ontogenetic stage of the
Guimarota teeth and so cannot be stated for certain.
Distribution of isolated teeth
440 theropod teeth were collected from the screen wash-
ing between the years 1972-1974 (including the isolated
Small theropod teeth from the Upper Jurassic coal mine of Guimarota (Portugal) 187
Since Archaeopteryx shows the smallest number of
tooth positions of all theropods described in this paper,
this taxon may represent the most common theropod in
this locality. The teeth of cf. Compsognathus sp. and cf.
Richardoestesia sp. are represented by nearly the same
number in the Guimarota fauna, which can be correlated
with their similar number of tooth positions. The velo-
ciraptorine theropods are more common than the prob-
able troodontids and tyrannosaurids, although the latter
usually show a larger number of tooth positions.
In relation to the distribution of herbivore dinosaurs in
Guimarota, which are represented by 45 isolated teeth
(39 hypsilophodontid teeth [THULBORN 1973], 4 sauro-
pod teeth [pers. obs.], 2 iguanodontid teeth [pers. obs.]),
theropod teeth form the dominant component.
Fig. 8. A side tooth from a larger theropod with a rounded
cross-section; A- labial view, B: enlargement of anterior
denticles, C: enlargement of posterior denticles, D: cross-sec-
tion of the base; IPFUB GUI D 178. - A side tooth of a prob-
able allosaurid; E: lingual view, F: enlargement of anterior
denticles, G: enlargement of posterior denticles, H: labial view,
I: cross-section of the base; IPFUB GUI D 191.
teeth of cf. Archaeopteryx sp. described by WEIGERT
1995). 67.3 % of these have been identified, and the rest
remains unidentified, because they lack taxonomically-
valid features. The most common theropod teeth at
Guimarota are those of cf. Archaeopteryx sp. (23.4 %),
followed by cf. Compsognathus sp. (11.1%), cf. Richar-
doestesia sp. (9.1%), cf. Paronychodon sp. (6.6 %), velo-
ciraptorine dromaeosaurids (6.4 %), probable troodontids
(3.2 %), larger theropod teeth (2.9 %), the small indeter-
minate theropod teeth (2.5 %), probable allosaurids (1.1
%), probable tyrannosaurids (0.7 %) and cf. Dromaeo-
saurus sp. (0.2 %).
The significance of the number of tooth positions
in
the mouth of theropod dinosaurs in relation to their dis-
tribution in the Guimarota coal mine is extremely hard to
determine. FIORILLO & CURRm (1994) argued that the
relative abundance of teeth can only give a rough idea of
the relative abundance of the animals from which they
are derived. Also taphonomic sorting may have occurred.
In that case, the following palaeoecological informations
about the Guimarota specimens cannot be given without
difficulties and inaccuracies.
Systematic and paleobiogeographic
significance
From the theropod teeth described in this paper, only two
genera are well known from Upper Jurassic localities of
Europe: Compsognathus (Solnhofen, Germany [STRO-
MER 1934; OSTROM 1978], Canjuers, France [BIDAR et al.
1972]) and Archaeopteryx (Solnhofen, Germany
[WELLNHOFER 1993]). These genera are also the most
common theropods in the Guimarota assemblage, form-
ing 34.5 % of the teeth studied. With their proposed pa-
laeoecological habits as small predators perhaps special-
izing on a diet of insects and tiny vertebrates, they would
have been perfectly adapted for the swampy environment
proposed for Guimarota
(SCHUDACK
1993). So far, the
occurrence of these theropods in the fauna is supported
by morphological, paleobiogeographical and temporal
aspects.
The occurrence of allosaurid teeth is also not surpris-
ing, since Allosaurus has been found in the Upper Juras-
sic Morrison Formation (USA; MADSEN 1976).
According to the systematic studies of HOLTZ (1994)
Archaeopteryx is proposed as a sister taxon of the Dro-
maeosauridae. If this is correct, the occurrence of dro-
maeosaurids at Guimarota is not surprising. 'Dromaeo-
saur'-like teeth were also found in Middle Jurassic
deposits of England (METCALF & WALKER 1994). Since
teeth similar to dromaeosaurids, troodontids, tyranno-
saurids and ornithomimids have also been found in the
Upper Jurassic beds of the Morrison Formation, a Mid-
dle to Late Jurassic origin of these theropods may be as-
sumed (CHURE & MADSEN 1993; CHURE 1995). This
argument is especially supported by the worldwide
diversification of dromaeosaurids in the Lower Creta-
ceous (OSTROM 1969; Km~:LAND et al. 1993; AZUMA 8,:
CURRIE 1995; RAUHUT t~ WERNER 1995), and from their
presence in the Barremian of the Iberian Peninsula
(ZINKE • RAUHUT 1994; RAUHUT t~ ZINKE 1995). Since
the Iberian Peninsula was more or less a consolidated
landmass during Late Jurassic and Lower Cretaceous
times, and as there is good evidence for a faunal inter-
188 JENS ZINKE
change between Europe, North America and Africa in the
Late Jurassic (ZIEGLER 1988; GALTON 1972; GALTON
TAQUET 1982), the dispersal of early dromaeosaurids and
other maniraptorans could have taken place during this
period.
Besides dromaeosaurids, isolated teeth from cf.
Ri-
chardoestesia
sp. and cf.
Paronychodon
sp. are also
known from the Barremian of Spain (ZINKE ff,~ RAUHUT
1994; RAUHUT & ZINKE 1995) and the Lower Cretaceous
of Utah (K/RKLAND & PARRISH 1995). The temporal dis-
tance to the Upper Cretaceous finds of
Richardoestesia
and
Paronychodon
(CuRRIE et al. 1990) and slight mor-
phological differences, may indicate that the teeth from
Guimarota, as well as those from Spain and Utah, belong
to closely-related forms, but not to
Richardoestesia
and
Paronychodon
themselves, or that they are a result of
convergent development.
Finally, the significance of theropod teeth to system-
atic and paleobiogeographic studies is always question-
able, because the morphology of teeth underlies func-
tional aspects, and convergent development could have
taken place at many points in the evolutionary history of
the Theropoda. However, in poorly-known dinosaur lo-
calities, theropod teeth can show an approximate insight
into the composition of the theropod fauna, especially if
they show a large morphological diversity like those at
Guimarota. Hopefully, the comparison of the teeth stud-
ied in this paper with other Middle and Upper Jurassic
localities, like Hornsleasow Quarry in the British Mid-
lands and the Morrison Formation (USA), will help to
settle the problems surrounding the early origin of mani-
raptoran theropods during Jurassic times.
Acknowledgements
I would like to thank SARA J.
METCALF,
ANTHONY R. FIORILLO
and PHILIPP J. CURRIE for reviewing this manuscript and OLIVER
RAUHUT for useful discussions while this paper was written. I
also thank Prof. Dr. BERNHARD
KREBS,
who gave me the oppor-
tunity to study this material.
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Eingang des Manuskriptes am 10. September 1996;
Annahme durch die Schriftleitung am 3. Juni 1997.
