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The last last labyrinthodonts?
by
ANNE
WARREN,
THOMAS
H.
RICH
and
PATRICIA
VICKERS-
With 4 plates,
16
text-figures, 2 tables and 1 appendix
Zusammenfassung
Die aus der Umer-Kreide (Aptian) stammenden Schadel-
und
Postcranialiiberreste von Slidost-Australien scheinen die letzten Glieder
der Labyrothodomen (Amphibia) zu sein und zu def temnospondylen Superfamilie Brachyopoidea zu gehoren.
Koolasuchus
cleelandi gen.
et sp.
novo
lebte viel spater
als
die Labyrimhodomia in anderen Teilen der Welt und wurde vielleicht von einem polar "sicheren Gebiet«
geschutzt, das Mitbewerber wie die modernen Krokodile ausschloB. Diese spat-australischen Temnospondyli kommen in grobkornigen
Sedimemen vor.
Sch
I
us
sel
wo
ne
r:
Temnospondyli -Brachiopoidea -Kreide -Australien.
Summary
Cranial and postcranial remains from the Early Cretaceous (Aptian)
of
southeastern Australia appear
to
be
from the last known
members of the labyrimhodont Amphibia and to belong to the temnospondyl superfamily Brachyopoidea.
KoolasuchliS
cleelandi
n.
gen.
n.sp. lived well beyond the documented time
of
labyrinthodonts elsewhere in the world, perhaps protected by a polar "safe area" that
excluded such competitors
as
the modern crocodiles. These late occurring Australian temnospondyls are always associated with coarser
grained
facies.
Key
words:
Temnospondyli -Brachyopoidea Cretaceous -Australia.
Table
of
contents
Introduction
..
. . . . .
..
...............................
2 Ribs
...........................................
13
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
..
2 Clavicles . . . . . . . . . . . . . . . . . . . . . . .
..
......
........
14
Systematic Palaeontology
..............................
2 Interclavicles
..........................
. . . . . . .
..
14
Koolasuchus
cleelandi
n.
gen.
n.
sp. . . . . . . . . . . . . . . . . . . . . .
..
4 Cleithrum
......................................
14-
Other
material
.......................................
8 Fibula
..........................................
14
Temnospondyli
...................................
8 Taxonomic conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
..
14
Temnospondyli (?)
................................
9
Description of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
..
9
Mandible........................................
9
Skull
............................................
10
Distribution of post-Triassic temnospondyls
............
16
Remnant labyrinthodoms: a survival
scenario..
.
.........
16
Appendix
...............................
...........
19
References
..........................................
22
Neural arch
...
.
.................................
13
Explanation
of
plates
.................................
24
Intercentra
....................
. . . . . . . . . . . .
..
....
13
") Address of the authors: Dr.
A.
WARREN,
School of Zoology,
La
Trobe University, Bundoora, Victoria, Australia
3083,
Dr.
T.
RICH,
Museum of Victoria,
328
Swanston Street, Melbourne, Victoria 3000, Australia, and Dr.
P.
VrcKERs-RrcH, Department of Earth Sciences,
Monash University, Clayton, Victoria, Australia 3168.
0375-0442/97/0247/0001 $ 12.60
- 2 -
Introduction
The
first unequivocal evidence that labyrinthodont amphibians had survived the Triassic-Jurassic extinction
event was provided
by
WARREN
&
HUTCHINSON
(1983)
who
described Siderops kehli from the Early Jurassic
of
Queensland, Australia, in a paper titled
"The
last labyrinthodont".
The
challenge
thrown
out
by
that title was
met
almost immediately
by
DONG
(1985) with a Middle Jurassic temnospondyl, Sinobrachyops placenticephalus,
from
Sichuan, China, followed
by
ISHING
(1987)
who
named Superstogyrinus ultimus
from
the Middle Jurassic
of
Xinjiang, China,
NESSOV
(1988, 1990),
who
described temnospondyl remains from the Callovian of Central Asia
as
Ferganobatrachus riabinini, and
SHISHKIN
(1991)
with
Gobiops desertus
from
Late Jurassic sediments in
the
Gobi
Desert.
Much
earlier,
SUN
(1962) had recorded a series
of
small, neorhachitomous vertebrae from the Lufeng
Formation of Yunnan,
China
(Early Jurassic), while
LONGMAN
(1941) described
as
capitosaurid a section
of
mandible from the Early Jurassic Marburg Sandstone
of
southern
Queensland, Australia.
Other
isolated elements,
a stereospondylous intercentrum from the Callovian
(KAZNYSHKIN
1990), and a single
tooth
dated
as
Albian
or
Aptian-Albian
(NESSOV
1990) are also recorded from different regions
of
Fergana, Uzbekistan. A list of fauna
from the
upper
Elliot Formation (Early Jurassic)
of
South Africa also contains a brachyopoid amphibian
(KITCHING
&
RAATH
1984).
The
South African material, which
is
not
yet
prepared, includes the anterior half
of
a
mandible
of
similar size and shape to the post-Triassic Australian chigutisaurids,
and
a
number
of
vertebrae
(WARREN,
pers. obs. 1992).
Finally, the survival of temnospondyls into the Early Cretaceous, once again in Australia, was confirmed
by
WARREN
and others (1991) after the initial tentative identification
by
Jupp &
WARREN
(1986)
of
a partial mandible
from the Strzelecki
Group
of
south-central Victoria
as
a possible temnospondyl.
A moderately diverse biota from the Strzelecki
Group
and its more western equivalent, the
Otway
Group,
is
remarkable for the
number
of
its relict and endemic vertebrates, and also for its proximity to the Cretaceous
South
Pole (RICH et
al.
1988,
RICH
&
RICH
1989). Since the first crescentic intercentrum confirmed
without
doubt
the
presence of temnospondyls in the Strzelecki sediments, intensive collecting
by
Mike Cleeland, Lesley Kool
and
Andrew
Constantine has
shown
these relict amphibians to be more
common
in a restricted area than any
other
component
of the associated fauna. The nine kilometres
of
shore platform between the eastern limit
of
Westernport Bay and Kilcunda (Text-fig.
1)
have yielded over fifty temnospondyl bones
to
date, associated
with
a
single lungfish
tooth
plate and dinosaurs: hypsilophodontids, a single vertebra
of
an ornithomimosaur, and a claw
fragment of a carnosaur. Temnospondyls are
not
present in the Strzelecki sediments
to
the east of Kilcunda,
nor
are they found in the
Otway
Group
to the west.
While
no
well preserved skull material has been found to date we
now
have sufficient mandibular
and
postcranial remains to warrant their description.
Abbreviations
Institutional
NMV
P - Museum
of
Victoria, Palaeontology.
Anatomical
a,
angular; ac, anterior coronoid;
ag,
arcadian groove; asc, ascending column
of
the pterygoid;
ar,
articular;
c,
coronoid process;
cf,
clavicular facet; d, dentary; isr, infrastapedial ridge; mc, middle coronoid; ms, mandibular sulcus; p, truncated, unornamented, posterior
stem
of
interclavicle; pa, prearticular; pc, posterior coronoid; PGA, postglenoid area; pmf, posterior meckelian foramen; pr, palatal ramus
of
the
pterygoid; ps, postsplenial; qr, quadrate ramus of the pterygoid;
s,
splenial; sa, surangular; su, suture between the pterygoid and the
parasphenoid and exoccipital bones.
Systematic Palaeontology
Order
Temnospondyli sensu
ROMER,
1947
Superfamily
Brachyopoidea
SAVE-SODERBERGH,
1935
Family
Chigutisauridae
RUSCONI,
1951
San Remo
Back Beach
NMVP
186055
186101
186118
186205
186295
197908
-3
-
VICTORIA
. .
V
38°30'S
.San
Remo
TI,
I
RowellsBeach
NMV
P Dwyers Hill
NMV
P 156988
NMV
P
186040 186142 186182
186145 186155
186146
186213 186171
186214 186179
186237 186181
186239 186245
186249 186253
186277
186480
186481
186482
Melboume
1km
Tree Trunk Point
NMVP
186354
186355
..............
100km
Kilcunda
•
Text-fig.
1.
Localities from which labyrinthodom bones have been recovered from the early Cretaceous Strzelecki Group of Southern
Victoria, Australia.
- 4 -
Koolasuchus
n.
gen.
Know
Distribution:
Aptian (Early Cretaceous), Strzelecki Group, Southern Victoria, Australia.
Et
y m 0
log
y:
Named after Lesley Kool who found some
of
the material and prepared most of
it.
The
generic name also, fortuitously,
refers to the (presumed) cool climatic conditions present at the time of preservation. 'Souchos', Greek for crocodile,
is
commonly used in
naming temnospondyls because their bodies
are
similar in shape to those of crocodiles.
D i a g
nos
is:
A brachyopoid with a mandible distinguished from those
of
all
other temnospondyls in which
this area
of
the ramus
is
described except (possibly) Siderops kehli and Hadrokkosaurus bradyi in that the articular
is
excluded from the dorsal surface of the postglenoid area
by
a suture between the surangular and the prearticular
(Text-fig. 7). Among brachyopoids, distinguished from
S.
kehli and H. bradyi
by
the absence
of
coronoid teeth.
c
o
Text-fig.
2.
Koolasuchus
cleelandi
n.
gen.
n.
sp., holotype, NMV P186213: right mandible in
A,
dorsal;
B,
ventral; C, lateral; D, medial; views.
The mandible appears foreshortened
in
C and D
as
these views are drawn at right angles to the midline of the animal's body.
c
D
Text-fig.
3.
Tracing of Fig.
2.
- 5 -
Koolasuchus
cleelandi n. sp.
Text-figs.
2,
4-6, 7C; Plates 1-3
Et
y m 0
log
y:
Named after Mike Cleeland who found the Holotype mandible and who, with students from Newhaven College,
has
spent several years searching the coastal rock platforms of the Strzelecki Group.
D i a g
nos
is:
As for the genus until further species are described.
H
010
typ
e: NMV P186213, a right mandibular ramus, complete except for an approximate two centimetre section at the level of the
posterior coronoid, and the posterior half of a left ramus. These were found together and are assumed to be from the same individual.
Referred
material:
Mandible. NMV P156988, posterior half
of
a right ramus
(WARREN
et
aL
1991). NMV P186277, posterior
half of a left ramus. Although
all
four mandibles are determinable only to
family,
we
place them in the Family Chigutisauridae by association
with the pterygoids (below).
Skull
fragments.
NMV P186145, an almost complete left pterygoid (Text-fig.
8).
NMV P186055, the body of a left pterygoid.
NMV P186182: skull roofing bone containing one quarter
of
an
orbit; probably a right prefrontal (Text-fig.
10).
Interclavicle.
NMV P186480, the posterior three quarters of an interclavicle (Text-fig.
9).
- 6 -
Text-fig.
4.
Koolasuchus
cleelandi
n.
gen.
n.
sp., holotype,
NMV
P 186113: left mandible in A, dorsal;
B,
ventral;
C,
lateral;
D,
medial; views.
-
7-
po
so
on
pa
an
Text-fig.
5.
Tracing
of
Fig.
4.
B
c
8 -
10 cm
H
po
'V
an
ps
Text-fig. 6.
Koolasuchus
cleelandi
n.
gen. n.sp., holo-
type,
NMV
P186213: composite restoration of man-
dibles
in
A, medial;
B,
dorsal; C, ventral; D, lateral
views.
E-H,
transverse sections where indicated.
Clavicles.
NMV P186237: right,
NMV
P186144: left (Text-fig.
11
H,}; Fig. 4A),
NMV
P186155a, right, (all complete);
NMV P186214: right, incomplete.
Type
locality
and
stratigraphic
position:
West end
of
Rowell's Beach, east
of
Potter's Hill Road (38°32' 16"S,
145°23'
15.5"
E), Kilcunda, Victoria. Strzclecki Group (Aptian).
Other
Material
Temnospondyli
-Skull fragments NMV
P186101:
frontal, parietal
or
supratemporal bone
(WARREN
et
al.
1991),
NMV
P186205,
NMV
P186181: skull roof fragments with ornament. NMV P186171: part
of
right ectopterygoid bone with tooth sockets.
Neural
arch.
NMV
P186179 (Text-fig.
!lA).
In
te
rc
e n
tra
(Text-fig.
11
B-E). NMV P186040: crescemic (rhachitomous)
WARREN
et
al.
(1991); NMV P186146,
NMV
P186238,
NMV P186207: stereospondylous; NMV P197908,
NMV
P186142,
NMV
P186253,
NMV
P186354,
NMV
P186355: stereospondylous and
notochordal.
- 9
Ribs.
NMV
P186481,
NMV
P186482: anterior presacral ribs;
NMV
P18615Sb,
NMV
P186245: posterior, presacral ribs.
Clavicle.
NMVP186167: partial blade
of
small specimen,
Cleithrum.
NMV
P1861S8: almost
complete?
right c1eithrum (Text-fig.
llF;
PI.
3C).
In
t
er
cl
a v i
cl
e.
NMV
P186295: anterior half
of
interclavicle.
Fibula.
NMV
P186239: left fibula (Text-fig.
llG,
PI.
3D).
Temnospondyli
(?) -Centrum.
NMV
P186249 (Text-fig. 11E),
NMV
P186118: elongate, dorso-ventrally compressed, stereo-
spondylous and notochordal.
L 0 c a
lit
y:
All
of
the temnospondyl material was recovered from sediments
of
an unnamed unit
of
the Strzelecki
Group
exposed
on
the coastal platform between the San Remo 'back' beach (38032' 10"S, 145"22' 9"E) and Dwyer's Hill (38° 32' 44"S, 145°25'
21"
E)
(CONSTANTINE
&
WAGSTAFF,
this volume). Localities for the separate specimens are
shown
in Text-fig.
1.
Description
of
material
Mandible
Four mandibular rami have been recovered: the original specimen described
by
WARREN
and others (1991)
(NMV P156988), the holotype rami
(NMV
P186213), and
NMV
P186277. All are in an excellent state
of
preservation although variously distorted post mortem. This distortion
is
so severe in the holotype that the left
and right mandibles are quite dissimilar in profile, the right being rounded (in parts almost dorsoventrally
flattened) in transverse section, while the left
is
crushed from lingual and labial aspects, so that its transverse
section
is
tall and thin. The different distortions are readily explained by the different orientation
of
the two jaws
in the sediments, the right being preserved in a natural position, while the left had fallen sideways so that its labial
side was uppermost. The overlying sediments have compressed the left mandible from above and the right
from
its side.
NMV
P156988
is
compressed from above in a similar manner to the right mandible of the holotype, while
NMV
P186277
is
even more laterally compressed than the left mandible
of
the holotype.
Despite their different shapes, neither holotype jaw
is
noticeably broken, the implication being that their
change in shape occurred
as
plastic flow over a long period.
On
the other hand,
NMV
P186277
is
obviously
crushed.
Our
reconstruction
of
the holotype (Text-fig.
6)
is
nearer in cross-sectional shape to the right mandible,
but
we have increased its depth and decreased its width, especially in the posterior half
of
the jaw.
Although the holotype jaws are much larger than the referred jaws, when corrected for distortion
all
four
have similar proportions and sutural arrangements, and we consider them to be conspecific.
Holotype mandible
NMV
P186213.
Only
those features in which the mandible
of
Koolasuchus cleelandi
differs from the usual temnospondyl pattern
(J
UPP
&
WARREN
1986) and those features considered taxonomically
significant, are described.
The postglenoid area (PGA), that
is,
the area posterior to the region which articulated with the skull,
is
Type
II (Jupp &
WARREN
1986). This means that
both
the prearticular and angular bones extend
onto
the PGA, the
posterior extremity
of
the articular does
not
form a distinct retroarticular process, there
is
no arcadian groove
(Jupp &
WARREN
1986) incised
on
the posterior end
of
the
PGA
between the articular and the surangular, and the
oral sulcus
is
the only sensory canal present.
Of
particular interest
is
the suture on the dorsal surface
of
the
PGA
between the surangular and the
prearticular so that the posterior extension of the artieular
onto
the
PGA
is
restricted to a broad triangle
immediately posterior to the glenoid fossa (Text-figs.
6,
7).
It
is
possible that a similar sutural arrangement was
present in Siderops kehli
(WARREN
& H
UTCHINSON
1983) since the surangular-articular and prearticular-articular
sutures are beginning to converge
on
that part
of
the
PGA
preserved, and also in Hadrokkosaurus bradyi
(WELLES
1947).
In
other Mesozoic temnospondyls the articular
is
exposed dorsally, and sometimes lingually, for
the whole length
of
the
PGA
(Text-fig.
7).
Another feature rarely developed in temnospondyls,
b'ut
present in
several brachyopoids, including Siderops kehli,
is
the presence
of
a small coronoid process
on
the posterior
coronoid. Significantly, the presence
of
this process and also the absence
of
coronoid teeth are shared with one
of
the Indian chigutisaurs
(SENGUPTA
1991).
The
absence
of
coronoid teeth
is
also a feature of the metoposaurids.
The posterior Meckelian foramen
is
small and it and the angular-surangular suture are positioned close to the
ventral border
of
the ramus, that foramen usually referred to
as
the chorda tympanic
(e.
g.
J
UPP
&
WARREN
1986)
10
po
7.
Dorsal views of the three main types of post glenoid
area.
A,
Type
I,
found in most temnospondyls;
B,
Type
II,
found in the
families Brachyopidae, Chigutisauridae, Metoposauridae and Pla-
giosauridae;
C,
Type II with the prearticular forming a suture with
the surangular
as
in
Koolasuchus cleelandi
n.
gen.
n.
sp.
is
absent from its usual position below the posterior margin
of
the glenoid fossa (although there
is
a small foramen
in the prearticular anterior to the glenoid), and there
is
no prearcicular process. A well developed lateral line
system consisting
of
an oral sulcus, but no mandibular sulcus,
is
present. All the above features are characteristic
of brachyopoids.
The dentition consists of a dentary
tooth
row of approximately 40 marginal teeth and a symphyseal tusk,
with no postsymphyseal tooth
row
and no teeth
on
any
of
the coronoids. All teeth
in
which the tips are preserved
are curved inwards with lance-shaped tips bearing mesial and distal keels, a structure similar to that found
in
the
teeth of Siderops kehli
(WARREN
&
HUTCHINSON
1983), although in K cleelandi these keels are
not
serrated
as
they are
in
S.
kehli. A tooth broken near its base shows the extremely convoluted, labyrinthine pattern
to
be
expected
in
a tooth of this diameter: approximately
15
mm, measured at the base
(WARREN
&
DAVEY
1992).
Taxonomic position. Their Type II post glenoid area allies these mandibles with those
of
the Brachyopidae,
Chigutisauridae, Plagiosauridae
or
Metoposauridae
(J
UPP
&
WARREN
1986). The mandibles of metoposaurids are
easily distinguished
by
the following characters: their articular
is
distinctly convex, their
PGA
is
short, the
posterior coronoid borders the posterior Meckelian fenestra (whereas in K cleelandi the posterior coronoid
is
separated from the Meckelian foramen
by
the prearticular), and their symphyseal tusks are formed from an
enlarged marginal tooth (personal observation by A.
A.
W.
of metoposaurs
in
the Texas Memorial Museum,
University
of
Texas, Austin, and The Museum
of
Paleontology, University of California, Berkeley).
None
of
these
metoposaurid characters are present in
K.
cleelandi. Although Jupp &
WARREN
(1986) earlier suggested that
NMV
P156988 could be a member of the Plagiosauridae, largely because of its extreme dorso-ventral flattening, that
assignation
is
now
discounted because the flattening
of
two
of
the mandibles has been shown above to be
due
to
post mortem distortion.
In
addition, plagiosaurs lack a symphyseal tusk (with one possible exception,
MICHAEL
SHISHKIN,
pers. corn. 1991), and commonly have teeth
on
all three coronoid bones, whereas K cleelandi has a
symphyseal tusk and lacks coronoid teeth.
Based largely
on
Xenobrachyops
alios,
WARREN
(1981a) described the mandible
of
the family Brachyopidae
as
follows: retroarticular process [= postglenoid area (PGA) of Jupp &
WARREN
(1986)J elongate, posterior
Meckelian foramen and angular-prearticular suture exposed
on
ventral surface
or
only very low on lingual surface
(COSGRIFF
1974), articular exposed
on
the dorsal surface of the retroarticular process between surangular and
prearticular, angular extending posteriorly far along the undersurface of the retroarticular process [Type II
PGA
(J
UPI'
&
WARREN
1986
)J,
dentition characterised
by
relatively
few,
large teeth which are curved inwards. This
definition was extended to include the mandible of the Chigutisauridae
(WARREN
1981
b), although
in
that paper
the chigutisaur jaw was thought to be deeper anteriorly than that of brachyopids, to have a lingual exposure
of
the
articular on the retroarticular process (PGA), and to have smaller, more plentiful teeth.
We
now think that these
last characters distinguish Keratobrachyops australis and possibly some South American chigutisaurs only, so that
the original definition of the brachyopid jaw
(WARREN
1981a) now applies to the whole of the superfamily
Brachyopoidea (families Brachyopidae and Chigutisauridae). Although we can find no derived character to
distinguish the mandibles
of
these two families, we will show below that the Cretaceous mandibles can
be
assigned,
by
probable association with other material,
to
the Chigutisauridae.
S k u
11.
Of
the two pterygoids recovered, one
(NMV
P186145), consists
of
almost complete palatal and
ascending rami and the proximal part of the quadrate ramus which turns downward in the characteristic
brachyopoid manner. The ascending ramus of this specimen and also
of
the less complete pterygoid
(NMV
-
11
-
isr
Text-fig.
8.
NMV P186145: left pterygoid
of
a chigutisaurid temnospondyl
in
A,
medial;
B,
dorsal; C, posterior views.
In
A and B, anterior
is
to
the right.
,
,
,
,
,
,
,
,
,
'LCxt-fig.
9.
NMV
P186480: interclavicle, ventral
view.
Text-fig.
10.
NMV
P186182: brachyopoid right
prefrontal bone.
P186145) has an enlarged medial
border
forming an ascending column (Text-fig. 8). This feature was said
by
WARREN
&
HUTCHINSON
(1983) to be a derived character of chigutisaurs, being present in Siderops kehli
and
Keratobrachyops australis. South American chigutisaurs are
not
normally well preserved in the region of the
ascending column
but
it
is
present in at least one of them
(CLAUDIA
MARSICANO,
pers. comm. 1991).
The
condition in the Indian chigutisaur described by
SENGUPTA
(1991)
is
indeterminable.
The more complete
of
the Victorian pterygoids also has a well defined infrastapedial
(=
substapedial) ridge, a
feature found
only
in chigutisaurs
(WARREN
&
HUTCHINSON
1983).
Aside from the pterygoids, the
only
cranial material of taxonomic importance
is
the (?) right prefrontal
(NMV
P186182) which contains a large part
of
the orbital margin. In
our
opinion, the size of the
orbit
in relation
to the rest
of
the bone, the position
of
the one suture preserved, the orientation
of
the sculpture ridges, the
position
of
a possible sensory canal,
and
the absence
of
curvature
of
the whole element, together indicate that
the
-
12
-
bone
could belong
to
a brachyopoid,
or
a plagiosaur, although this area
is
poorly
known
in
the latter taxon.
We
refer the pterygoids and prefrontal,
with
caution,
to
K
cleelandi.
The
other
cranial fragments are indeterminate;
NMV
P186171, a right ectopterygoid,
is
unlikely to belong to
the Brachyopidae, as members
of
the family
do
not
have a
continuous
row
of
ectopterygoid teeth.
It
could belong
to the Chigutisauridae
or
to
most
of
the
other
families
of
Triassic temnospondyls.
B c o E
A
I cm
11.
Postcranial materiaL
A,
NMV P186179: neural arch
in
anterior (top) and right lateral views.
B,
NMV P186040: imercentrum
in
posterior (top) and left lateral views. C, NMV P197908, D, NMV P186142: intercentra;
E,
NMV P186249: probable intercentrum,
in
posterior (top) and right lateral views.
NMV P186158: cleithrum in lateral (left) and posterior views. G, NMV P186239: left fibula.
H,J,
NMV P186144: left clavicle in posterior (H) and lateral m views. The scale bar beside J applies
to
B-J.
-13-
Neural
arch.
The single neural arch,
NMV
P186179 (Text-fig. 1lA),
is
poorly ossified having a low
neural spine which
is
displaced posteriorly and somewhat expanded
on
its
dorsal surface. An extremely truncated
transverse process
is
directed slightly dorsally. In the posterior displacement and dorsal expansion this neural arch
most resembles those
of
the family Rhytidosteidae,
but
is
also similar to plagiosaur neural arches although lacking
the clearly defined anteroventral and posteroventral facets for articulation between adjacent centra typical
of
the
latter family. Too few brachyopid neural arches are known for them to be characterised, while neural arches in the
two chigutisaurs in which they have been described are much more extensively ossified than
NMV
P186179. This
lack
of
ossification in
NMV
P186179 would not preclude it belonging to the Chigutisauridae
as
the degree of
ossification
is
variable, even within a single vertebral column, but the dorsal expansion and posterior displacement
of the neural spine have not been described in that
family.
Intercentra
(Text-fig.
llB-E).
Of
the twelve centra in the collection, one
(NMV
P186040),
is
without
doubt a crescentic intercentrum from a rhachitomous temnospondyl
(WARREN
et
al.
1991) and could belong to
any Mesozoic family except the Plagiosauridae. Its position in the vertebral column
is
probably posterior
presacral.
It
lacks the ventral flattening characteristic of caudal intercentra.
NMV
P186146 and
NMV
P186238 are typically stereospondylous intercentra bearing rib facets (diapo-
physes). Such stereospondylous intercentra are commonly present in the Metoposauridae and have been found in
the Mastodonsauridae and Capitosauridae, especially in the anterior part of the vertebral column
(WARREN
&
SNELL
1991). A spool-shaped
axis
was described by
CHERNIN
(1977) in the brachyopid, Batrachosuchus
while
both
stereospondylous and crescentic intercentra were found associated with the Late Jurassic brachyopid
Gobiops desertus
(SHISHKIN
1991)
but
otherwise stereospondylous intercentra are unknown in the
Brachyopoidea. It should be noted here that the enigmatic Triassic brachyopoid Tupilakosaurus heilmanni
(SHISHKIN
1961)
was
associated with spool-shaped embolomerous centra.
We
would
not
consider these Victorian
specimens
out
of place in any family of Mesozoic temnospondyls except the Plagiosauridae.
In
that family, the
centra are somewhat anteroposteriorly elongate and late surviving plagiosaurs have
both
anterodorsal and
posterodorsal facets for the intervertebral neural arches. They also have both anterior and posterior facets for rib
articulation
(WARREN
&
SNELL
1991).
Centra
NMV
P186207,
NMV
P186142,
NMV
197908,
NMV
P186253 and
NMV
P186354 are stereo-
spondylous, amphicoelous, notochordal, and a little more anteroposteriorly elongate than
is
usual among
temnospondyls. While notochordal centra are rare among temnospondyls, they are not unexpected, and are
present in Gobiops desertus
(SHISHKIN
1991). Although
NMV
P186207 bears rib facets typical of temnospondyls
(triangular and posterodorsal), the facets are different in the other specimens.
NMV
P186142 has a small
posteroventral rib facet which projects laterally so that the centrum
is
wider posteriorly than anteriorly, a
morphology found also
in
NMV
P197908 and
NMV
P186355 where the rib facets apparently have been lost
through weathering. Although
less
surely affiliated with the temnospondyls than
NMV
P186238,
NMV
P186146
and
NMV
P186040 (above) we nevertheless consider
all
of these centra to belong to that group.
NMV
P186354 and
NMV
P186253 are smaller than the other centra,
but
are similarly stereospondylous,
amphicoelous and notochordaL The better preserved specimen (NMV P186354) has rib facets midway
down
its
posterolateral margins
but
is
not markedly wider posteriorly than anteriorly. These centra look different from the
larger ones
but
still appear to belong to the temnospondyls.
The centra (NMV P186118,
NMV
P186249, Text-fig.
llB-E)
are also stereospondylous and amphicoelous,
but
are extremely elongate and a little dorsoventrally compressed. They may be notochordal
but
it
is
not
possible
to follow the notochordal canal for the length of the centrum. A single pair of rib facets are placed low
on
the
presumed posterolateral border of the larger specimen (NMV P166249) which
is
widened in this region in a
similar manner to NMV P186142. These elements are unlike any described temnospondyl centrum, yet the lack
of any evidence
of
an attached neural arch makes them more likely to be temnospondyl than reptile
or
fish.
They
are probably anterior caudals because of their dorsoventral flattening and the presence
of
rib facets which are lost
in more posterior caudals.
Because of the variety of form seen
in
centra of late surviving temnospondyls, especially the Jurassic
temnospondyls from Asia, we consider
all
of the above centra to be temnospondyl. Some of the Victorian
specimens are particularly close to the notochordal centra of the brachyopid Gobiops desertus
(SHISHKIN
1991)
which are also more anteroposteriorly elongate than
is
usual among temnospondyls.
Ri
b s (Plate 2A). The four well preserved ribs (NMV P186245,
NMV
P186155,
NMV
P186481,
NMV
14 -
P186482) are
of
two main types. The former two are narrow distally
but
with well preserved, although poorly
ossified, proximal ends divided
by
a thinning of the bone into capitulum and tuberculum. Neither has an uncinate
process and this together with their narrow distal ends, places them
as
posterior presacral ribs. The latter two ribs
have a more robust capitulum and tuberculum, are expanded distally, and bear distinct, triangular uncinate
processes so that their position was probably anterior presacral. Such ribs can be assigned
to
the Temnospondyli
on
the basis of their incompletely divided proximal ends.
CIa
v i
cl
e
s.
Of
the
five
clavicles one,
NMV
P186167, lacks the dorsal process and
is
not taxonomically
determinable.
The
other four, from much larger animals, are
all
fairly similar in size and shape. Two
(NMV P186214 and
NMV
P186144) have coarser ornament than the others, and one
of
these,
NMV
P186144
(Text-figs.
lIH,];
Plate 4A) has the medial border of its ventral plate indented. The shape
of
the ventral plate
is
not determinable in
NMV
P186214,
but
the two clavicles with finer ornament (NMV P186155a,
NMV
P186237)
have ventral plates which do not show the medial indentation. All four dorsal (cleithral) processes consist of a
rod
of bone with a posterodorsal slope, not drawn
out
anteriorly and not having a sigmoid shape.
In
cross section the
dorsal process
is
crescent-shaped in its distal half. Such a process
is
characteristic of the Brachyopoidea
(WARREN
&
SNELL
1991) and
is
especially reminiscent of Siderops kehli
(WARREN
&
HUTCHINSON
1983), and the Indian
chigutisaur material. These clavicles could not belong to the Plagiosauridae, the Metoposauridae
or
the
Capitosauridae, because in those temnospondyls
is
the base
of
the dorsal process
is
markedly drawn
out
anteriorly and usually carries muscle scars, and the process itself has a sigmoid curve
(WARREN
&
SNELL
1991).
We
refer these clavicles
to
K.
cleelandi because they are demonstrably brachyopoid, and, within that family, most
resemble those of
S.
kehli and the Indian chigutisaur material.
In
t e r
cl
a v i
cl
e
s.
Interclavicle
NMV
P186295
is
typically temnospondyl, with its centre of ossification
situated immediately posterior
to
its maximum width. A single ridge of ornament
on
the anterior stem
of
the
interclavicle separates the clavicular facets except at the anterior end, where the facets merge.
It
is
not determinable
to family.
NMV
P186480
is
similar to
NMV
P186295 in the anterior areas preserved, but its posterior stem
is
unique in being relatively longer than it
is
in other temnospondyls, and
is
unusual in being sharply truncated
rather than pointed. Outstanding also
is
the lack of ornamentation on the posteroventral and posterolateral
surfaces
of
the posterior stem. This truncation
of
the posterior stem and lack of ornament
is
found elsewhere
among Mesozoic temnospondyls only in Siderops
(WARREN
&
HUTCHINSON
1983) and for this reason
we
consider
NMV
P186480 to be from
K.
cleelandi.
Cleithrum.
NMV
P186158 (Text-fig.
11F,
Plate 3C)
is
incomplete distally
but
otherwise well preserved.
Its head
is
not greatly expanded and
is
unornamented.
Of
the few temnospondyl cleithra described, only the
plagiosaurs are distinctive, having an expanded, ornamented cleithral head and, usually, a ventral suture with the
dorsal process
of
the clavicle
(WARREN
&
SNELL
1991). Among brachyopoids, Siderops kehli alone has a cleithrum
preserved, and it
is
dorsally incomplete.
NMV
P166158 could belong to any temnospondyl family except the
Plagiosauridae.
Fib
u I a. The single fibula,
NMV
P186239 (Text-fig.
11
G, Plate 3D),
is
slightly weathered at
both
ends
but
has the characteristic temnospondyl shape
(WARREN
&
SNELL
1991), being laterally flattened, expanded at
both
ends and having a marked groove across the anterodistal end
of
the lateral surface.
Taxonomic conclusions
Of
all the specimens from the Strzelecki Group described above, only the neural arch (NMV PI86179), and
the unusual (for temnospondyls) centra (NMV P186249,
NMV
P186142) are unlike described elements from the
superfamily Brachyopoidea.
It
is
possible that
NMV
P186179,
NMV
P186249 and
NMV
P186142 are
brachyopoid and, if so, could
be
from the caudal region of the vertebral column. Morphologically, the
mandibles, clavicles, and the skull roofing bone
(NMV
P186182) are of a type only found in the superfamily
Brachyopoidea, while the pterygoids are characteristic of the brachyopoid family Chigutisauridae, and the
interclavicle (NMV P186295)
is
similar only to one found in Siderops, also a chigutisaur.
AFRICA AUSTRALIA ASIA
Millions Tashkumyr
Orange Free State of Kirgizia Sichuan Xinjang Southwestern
South Africa Queensland Victoria years Russia China China
Early Aptian I Unnamed
130' Cretaceou
Koolasuchus I
140
1
Berriasian j
Late
.....
V1
..
CaJ/gyian U
,'"
:M"
'(,
Middle
" I , Superstogyrinus
Jurassic I \
",'8"
I r
Gobiops
Ferganobatrachus
Early
Austropelor I Sinobrachyops
Brachyopoid I
I, z
,j
I I I Unnamed
Siderops 7
00 1
Text-fig.
12.
Stratigraphic occurrences of the post-Triassic labyrimhodollts.
-16 -
Distribution
of
post-Triassic temnospondyls
At present there
is
no evidence that temnospondyls other than members of the superfamily Brachyopoidea
survived beyond the end
of
the Triassic (Text-fig.
12).
Among late survivors, neither Superstogyrinus ultimus
(DONG
1992), nor the neorhachitomous vertebrae from Yunnan
(SUN
1962) are determinable to family
(DONG,
pers. comm. 1992). Those fragments from the late Middle Jurassic (Callovian)
of
Uzbekistan originally described
by
NESSOV
(1990)
as
Ferganobatrachus riabinini, a capitosauroid, have
now
been shown to be brachyopoid
(SHISHKIN
1991). Among pre-Jurassic brachyopoids, members
of
the family Brachyopidae have a cosmopolitan
distribution (apart from South America), while the Chigutisauridae are confined to Gondwana where their
distribution
is
further restricted to South America, Australia and India (Table
1).
Table
1.
Distribution
of
Mesozoic members of the families Brachyopidae and Chigutisauridae in time and space.
C:
Chigutisauridae;
B:
Brachyopidae. The specimens represented by symbols
in
the table are
as
follows.
Aus SAm
lnd
SAf
Ant
NA
Eu Ru
Ch
Mon
Early Cretaceo
r>
I
Late J u rassic B
Middle Jurassic B B
Early Jurassic C
C?
Late Triassic C C
Middle Triassic B B B
Early Triassic CB B B
B?
B
I
Early
Cretaceous.
Koolasuchus
cleelandi n.gen. n.sp., Strzelecki Group, Victoria, Australia (Aptian). Chigutisauridae (?).
Late
Jurassic.
Gobiop>
deSe1"tl£5
SHlSHKIN,
1991; Shara-Teg, southern Mongolia. Brachyopidae.
!
Mid
die
J u r
ass
i
c.
Sinobrachyops
placenticephalus
DONG,
1985;
Lower Shaximiao Formation, Sichuan Province, China. Fagano-
batrachus riabinini
NESSOV,
1990;
Balobansay Formation, Fergana, Uzbekistan (Callovian). Both Brachyopidae.
Earl
y J u r
ass
i
c.
Siderops
kehli
WARREN
&
HUTCHINSON,
1983;
Evergreen Formation, Queensland, Australia (Pliensbachian).
Chigutisauridae. Attstropelor wadleyi
LONGMAN,
1941;
Marburg Sandstone, Queensland, Australia (Pliensbachian). Probable brachyopoid.
Brachyopoid amphibian
(KlTCHING
& RMTH, 1984); upper part
of
the Elliot Formation, Orange Free State, South Africa.
Late
Triassic.
Pelorocephalus
mendozensis
CABRERA,
1944;
Cacheuta Formation, Mendoza, Argentina (Carnian -Norian).
Chigutisauridae. Chigutisaur
(SENGUPTA
1991); Maleri Formation, Pranhita Godavari
Valley,
Deccan, India.
Middle
Triassic.
Notobrachyopspicketti
COSGRll'l',
1973, and an unnamed fragment
of
large brachyopid
(WATSON
1958);
Wianamatta Shale, Sydney, Australia.
Batrachosttchus
concordi
CHERNIN,
1977;
N'tawere Formation, Zambia. Hadrokkosaurtts bMdyi
(WELLES,
1947); Moenkopi Formation, Arizona, U.S.A. Brachyopidae.
Ear
I y T r i
ass
i
c.
Keratobrachyops
attstralis
WARREN,
1981
b;
Arcadia Formation, Queensland. Chigutisauridae. Xenobrachyops
alios
(HoWIE, 1972); Arcadia Formation, Queensland.
Blinasattrus
henwoodi
COSGRIFF,
1969;
Blina Shale, Western Australia.
B.
wilkinsoni
(STEPHENS,
1887); Gosford Formation,
N.s.W
B.
townrowi
COSGRIFF,
1974; Knocklofty Formation, Tasmania.
The
last four are Australian.
Brachyops
faticeps
OWEN,
1855;
Mangli Beds, central India.
Batrachosttchus
browni
BROOM
1903 and B.watsoni
HAUGHTON,
1925; both
Cynognathus Zone, South Africa. Austrobrachyops jenseni
COLSERT
&
COSGRIFF,
1974; Fremouw Formation, Antarctica. Batrachostt-
choides
facer
SHlSHKIN,
1966;
Baskunchakskaia Series, European Russia. The last nine are described
as
Brachyopidae, although
A.
jenseni
is
not determinable and B.lacer
is
probably brachyopoid but not determinable to family.
Available evidence suggests that while the Brachyopidae survived in the
Northern
Hemisphere, in Gondwana
the brachyopids were outlived
by
the Chigutisauridae, the only possible exception being the brachyopoid from
South Africa. Also
of
interest are the disparate sizes
of
members of the two surviving families, those from Laurasia
being relatively smaller (estimated skull midline lengths: Gobiops,
90
mm; Sinobrachyops,
120
mm) than their
Gondwanan counterparts (Siderops,
600
mm; Koolasuchus, 650 mm).
Remnant labyrinthodonts: a survival scenario
In the older Cretaceous rocks from Victoria where temnospondyls have been found, they are confined
to
the
coarser facies, namely grits. These fades may not,
of
course, reflect the habitat favoured
by
the temnospondyls,
Millions
of years
100
110
120
130
140
Early
Cretaceous
-
17
Victoria, Australia
Albian
Aptian
Barremian
Hauterivian
Valanginian
Berriasian
Unnamed
crocodilian
Koolasuchus
Text-fig.
13.
Stratigraphic ranges of labyrinthodonts and crocodilians
in
the early Cretaceous Strzelecki and Otway groups of Victoria,
Australia. Note the non-overlap of the two groups.
but merely the energetics of the environment in which they were fossilised. Such coarser, fossil-bearing fades are
rare,
but
not
unknown, higher in the section,
e.
g.
at Point Lewis, Victoria, which
is
latest Aptian-earliest Albian
and
is
as
coarse
as
any
of
the older, Victorian temnospondyl sites.
Thus
there
is
evidence to suggest that the
disappearance
of
temnospondyls from Victoria
by
the Albian may in fact have been owing to their extinction in
the area and
not
to lack of the
proper
facies for the preservation
of
a younger record.
The
restriction
of
the formerly widespread temnospondyl labyrinthodonts to Asia and Australia after the
Triassic and their subsequent demise there may have been, at least in Australia, owing
to
the extremely high
latitude at that time accompanied
by
low temperatures.
In
this scenario, a temnospondyl dominated fresh water
fauna persisted along the high latitude margin
of
peninsular Australia-Antarctica, protected
by
cold, until the
climate changed.
Other
relicts such as the conservative palaeoniscoid,
Cocolepis
(W
ALDMAN
1971) and ceratodont
lungfish, also survived,
as
well
as
the terrestrial theropod, Allosaurus. Subsequently, an increase in temperature in
the Albian allowed a
warm
water fauna, including early members
of
the Crocodylia,
to
invade the region. Similar
to
modern crocodilians in their overall morphology, it
is
not
unreasonable to assume that temnospondyls might
have competed with
them
for resources. Alternatively, crocodiles may have preyed
upon
the temnospondyls,
or
their larvae may have succumbed to suction-feeding actinopterygians.
Some modern amphibians such
as
frogs and salamanders are active at temperatures near the freezing
point
of
water
(BRATISTROM
1970) while crocodilians are
not
active below water temperatures
of
10°C. This difference in
water temperature tolerance would explain the pattern seen in the Jurassic and Cretaceous occurrences of
temnospondyls in Australia. Estimates
of
the prevailing water temperatures based
on
016
/0
18 ratio have been
made for the early Cretaceous (Aptian) deposits where temnospondyls occur and nearby (Albian) deposits where,
instead, crocodilian remains are
known
(Text-fig. 13).
They
indicate
that
where temnospondyl remains are found
the water temperatures were coIder than prevailed where crocodilians are known. Victorian temnospondyls are
restricted to the deposits
of
Aptian age in the Strzelecki Group.
It
appears that temnospondyIs and crocodiles may
be indicator taxa for a major faunal changeover which followed the change
to
a warmer climate in the Albian.
The situation in Asia
is
more complex. There, in the Jurassic
of
south
western Russia, Mongolia and China,
crocodilians are reported together
with
temnospondyls (Text-fig. 14). Unfortunately, where these
joint
-
18
-
DISTRIBUTION
OF
POST -TRIASSIC LABYRINTHODONT AMPHIBIANS
J -
Jurassic
K -
Cretaceous
c -
Labyrinthodonts
with
crocodilians
associated
Equator
Jc
TropiC
of
Capricorn
...
J
Tropic
of
Cancer
14.
Geographic occurrences of the post-Triassic labyrinthodonts. Unlike the situation in Australia, crocodilians are
also
found in
most Asian localities where labyrinthodonts have been recovered.
occurrences have been reported, the crocodilians have not yet been identified below the ordinal
level
and,
according to
BENTON
&
CLARK
(1988), none of these are crocodilians in the strictly phylogenetic sense.
In
the
Jurassic of all of Asia, three families
of
mesosuchian crocodilians have been recognised to date.
None
are
particularly similar to the mode.rn crocodilians
nor
the temnospondyls.
If
the
as
yet undetermined, mesosuchian
remains associated with temnospondyls belong to these three families, then it
is
quite conceivable that, although
they occurred together, they did
not
compete.
In
India, particularly in the Maleri Formation, the long snouted, and hence crocodile-like, metoposaurid
temnospondyls were replaced by the short snouted chigutisaurid temnospondyls at the end
of
the Carnian, and
the chigutisaurids survived with advanced phytosaurs to the end of the early Norian. Phytosaurs continued into
the overlying Dharmaram Formation, and in the upper part
of
that formation sphenosuchid crocodiles appeared
without the phytosaurs
(SENGUPTA,
pers. comm. 1993).
It
seems that in this
case
the sphenosuchids may have
displaced the phytosaurs from a similar ecological niche,
as
the chigutisaurs displaced the metoposaurs. That the
chigutisaurs coexisted with phytosaurs suggests ecological separation.
NESSOV
(1990)
has
already proposed that
Asian Jurassic temnospondyls and crocodilians found at the same site may have occupied quite different
ecological niches.
-19 -
The ultimate demise of the labyrinthodont temnospondyls may have been owing to the appearance
of
a
whole warmer aquatic fauna, perhaps dominated by advanced crocodilians, the eusuchians, in the late Early
Cretaceous. Whether their extinction was hastened by the crocodilians,
or
another factor such
as
loss of their
tadpoles to another component
of
the fauna, for example, advanced holostean
or
early teleostean fish, cannot be
determined.
If
this scenario
is
true, it can be expected that temnospondyl remains will never be found in deposits
of Albian age in Victoria although they are
known
from Aptian ones in that State, the Albian being the time
of
the
thermal maximum.
Acknowledgements
We
would like to thank
all
those who assisted with field work, especially Mike Cleeland, Graham Hird, Lesley Kool, and Natalie
Schroeder. D.
P.
Sengupta and
C.
Marsicano generously provided information about undescribed chigutisaurs. Organisations that supported
the project, either financially,
or
in other ways, include the National Geographic Society, Australian Research Council, Atlas Copco,
Department of Conservation and Natural Resources, and the State Emergency Service. Lesley Kool and Natalie Schroeder prepared the
material, Natalie drew Text-figs.
7,
9 and
11,
while Frank Coffa and the La Trobe University Reprography Service took the photographs.
The manuscript was improved by valuable comments
on
an earlier version by Andrew Milner, Hans-Dieter
Sues
and Dhurjati Sengupta.
We
also wish to thank Draga Gelt for her assistance
in
graphics and Steve Morton and Adrian Dyer for their photographic skills.
Appendix
Palynological
dating
of Strzelecki
Group
sediments associated
with
Lower Cretaceous
labyrinthodont
fossils, Victoria, Australia
by
BARBARA
E.
WAGSTAFF,
ANDREW
E.
CONSTANTINE,
JENNIFER
R.
C. McEwEN
MASON'})
Introduction
In a previous paper
(WAGSTAFF
& McEwEN
MASON
1989) the palynological zonation of a number
of
localities associated with Lower Cretaceous vertebrate faunas in the Strze!ecki and
Otway
groups was discussed.
Following
on
from this, palynological effort has been concentrated
on
the Strzelecki Group, with the main aim
of
the study to provide time control for the localities that are currently yielding vertebrate fossils.
It
was also hoped
that a palynological zonation of the entire Early Cretaceous coastal section
of
the Strzelecki Group could be
determined, with the aim
of
allowing the vertebrate palaeontologists to know the age of bone collected in the
future. To this end, rather than the piecemeal method that had been used in the past,
i.
e.
spot samples taken from
the bone sites, a more methodical approach was required.
New
palynological
work
was undertaken after the coast
had been mapped by a sedimentologist/stratigrapher
(ANDREw
CONSTANTINE),
who then selected sites for the
collection of palynological samples. This appendix deals with the
age
determination of the section of the
cOast
that
has yielded labyrinthodont fossils.
Sample
preparation
and
storage
The new samples in this study were prepared, using standard palynological techniques,
by
Laola Pty. Ltd.,
Perth, Western Australia. For the methods used in the preparation of the samples from Punch Bowl (97214,
99954-7) and near Kilcunda (80396-80433) see
WAGSTAFF
& McEwEN
MASON
(1989). All rock samples, residues
and slides referred to are stored in the collection of the Department of Earth Sciences, Monash University. Sample
P22588 discussed
by
DETTMANN
(1963)
is
in the collection of the Museum
of
Victoria.
,;.
Address of the authors: Dr.
B.
E.
WAGSTAFF,
Dr.
A.
E.
CONSTANTINE
and Dr.
R.
C.
McEwAN
MASON,
Department of Earth Sciences,
Monash University, Clayton, Victoria, 3168, Australia.
-
P22588
99778-80
-San
Ramo
99782-84
?--
99774-76
38°30'S
145°25'E
97214
99954-57
• Age detemlined by palynology
-
20
-
VICTORIA
Melbourne
99806-08
99810-12
El
Age determined by strati graphic relationship
? Age indeterminate
--.....
100km
1km
99906-08 Kilcunda
99935-37 / •
80396-80433
99794-96
Black Head
Text-fig.
15.
Palynological sample sites associated with labyrinthodont fossil sites in the Strzelecki Group. Those marked with a solid square
have ages determined by palynology. Those marked with an open square have ages based
on
their stratigraphic relationship with
palynologically dated sites. Those marked with a ?
have
indeterminate
ages.
Palynological sampling techniques
Samples for palynology were taken from each mudstone dominated lithofacies, in stratigraphic order.
For
most sites only one sample was taken from each stratigraphic unit selected
i.
e.
one from each identifiable
mudstone section. Twelve new samples were taken from the section
of
the coast that has yielded labyrinthodont
fossils.
Other
samples included in this study (80396-80433, 97214, 99954-57) were previously discussed in
WAGSTAFF
&
Mc
EVEN
MASON
(1989). Also included
is
one sample (P22588) from near
San
Remo, the species list
for which
was
determined
by
DETTMANN
(1963).
The
location of
all
samples
is
shown
in
Text-fig. 15. For each
palynological sample, in this study, at least two slides were examined to determine the species list for a site.
-
21
-
GEOLOGIC TIME SCALE SPORE -POLLEN
(Harland et al. 1990) DATUM EVENTS
m.y.
110-
ALBIAN
-f.a. Crybelosporites striatus
(f)
APTIAN
:J
120 -0
W
0
.....
f.a . Dictyotosporites
fHosus
........
La . Foraminisporis asymmetricus
IJJ
f.a. Pilosisporites notensis
[
0 BARREMIAN
130 -
>-
..J
a:
<{
HAUTERIVIAN
W
VALANGINIAN
140 -
........
f.a. Foraminisporis wonthaggiensis
BERRIASIAN
ta
. Cicatricosporites spp.
ta.
Cyclospontes hughesl/
Text-fig.
16.
Spore-pollen first appearance datums tied to the geologic time scale
of
HARLAND
et
al.
(1989).
........
..
Age
of
the
labyrinthodont
localities
The samples used in this study were, where possible, assigned an age based
on
the presence
of
key indicator
species. The order of first appearance
of
species, in this region, has been determined based
on
the combined
work
of
a large number
of
authors
(DETTMANN
1963, 1986,
DETTMANN
&
PLAYFORD
1969,
DETTMANN
&
DOUGLAS
1976,
HELBY
et
aL
1987,
MORGAN
1987).
The
reasons for selecting the spore-pollen first appearance datums
that
have been used in this study
is
due
to
their reliable presence in the samples.
The
first appearance datums have been
tied to the geologic time scale based
on
the assumption that the selected datum events used are time equivalent
Australia-wide, although, it
is
recognised that some species show variation in their time ranges across the
continent
(HELBY
et
a\.
1987). The order
of
the selected first appearance datums
is
shown in Text-fig. 16.
The
occurrence
of
these species in the samples
is
shown in Table 2.
The
location of palynological samples sites along the section
of
the coast that has yielded labyrinthodont
fossils
is
illustrated in Text-fig. 15. The presence
of
Foraminisporis
asymmetricus
and/or
Pilosisporites
notensis in a
spore-pollen sample indicates the sample site
is
Aptian in age. As can be seen from Table 2, these age indicative
-
22
-
species are not always present in some samples due to factors such
as
poor
recovery and low diversity. Therefore,
the age of some labyrinthodont sites cannot be confirmed
by
palynology alone due
to
the absence
of
these
two
age-indicator species. However, these samples can be correlated laterally with,
or
stratigraphically overlie,
other
spore-pollen sites which contain
F.
asymmetricus and/or
P.
notensis. This indicates the majority of labyrinthodont
sites are Aptian in
age.
Table 2.
The
distribution
of
spore-pollen index species in the samples associated with
the
Iabyrinthodont fossil sites
in
the Strzelecki
Group.
0
"""
rJJ
cb
to
SAMPLE .
"""
'V
(")
"""
to
(")
NUMBERS 0'> 0'> o
'iT
..
SPECIES
Cicatricosisporites spp. Potonie & Gelletich 1933 •
• • •
• • • • i'
••
Crybelosporites striatus (Cookson & Dettmann) Dettmann 1963
Cyclosporites hughesii (Cookson & Dettmann) Cookson & Dettmann 1959 ? •
••
• • • • •
•
• •
Dictyotosporites filosus Dettmann 1963 • •
Foraminisporis asymmetricus (Cookson & Dettmann) Dettmann 1963 • 0 • • •
•
Foraminisporis wonthaggiensis (Cookson & Dettmann) Dettmann 1963 0 •
••
0 • • • •
••
••
•
•
Pilosisporites notensis Cookson & Dettmann 1958 •
• •
• ••
•
•
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-24 -
Explanation
of
plates
Plate 1
Koolasuchus
cleelandi n.gen. n.sp., holotype,
NMV
P186213: right mandible in stereo,
A,
dorsal and
B,
ventral. X 0.25.
Plate 2
A,
NMV
P186480, presacral rib. X .65.
B,
C,
Koolasuchus
cleelandi n.gen. n.sp., holotype,
NMV
P186213, right mandible.
B,
lateral; C,
medial. Stereo pairs. X 0.25.
Plate 3
A,
B,
Koolasuchus
cleelandi n.gen. n.sp., holotype,
NMV
P186213: left mandible.
A,
dorsal;
B,
ventral. X 0.25. C,
NMV
P186158:
cleithrum. X 0.60. D,
NMV
P186239: left fibula. X 0.60. Stereo pairs.
Plate 4
A,
NMV
P186144: left clavicle from below. X 0.50. B,
C,
Koolasuchus cleelandi n.gen. n.sp., holotype,
NMV
P186213: left mandible.
B,
lateral;
C,
medial. X 0.25. Stereo pairs.
Palaeontographica Abt. A Band 247, Tafel 1
lA
WARREN
et al., Plate 1
Ann
e
War
r
en,
T h 0 m
asH.
Ri
c
hand
Pat
r i
cia
Vie
k e r s -
Ri
ch:
The
last last
labyrinthodonts?
Palaeontographica Abt. A Band 247, Tafel 2
WARREN
et al., Plate 2
2A
28
Anne
Warren,
Thomas
H.
Rich
and
Patricia
Vickers-Rich:
The
last last labyrinthodonts?
Palaeontographica Abt. A
Band
247, Tafel 3
WARREN
et al., Plate 3
3D
Ann
e
Wa
rr
en,
T h 0 m
asH.
Ri
c
hand
Pat
r i
cia
Vie
k e r s -R i
ch:
The
last last
labyrinthodonts?
Palaeontographica
Abt.
A
Band
247, Tafel 4
WARREN
et al., Plate 4
4A
Ann
e
\"XI
a r r
en,
T h 0 m
asH.
Ri
c
hand
Pat
r i
cia
Vie
k e r s -
Ri
ch:
The
last
la
(
la.
-
--=...=::
- - -
--:
