Table Of ContentDinosaur footprints from the lower Jurassic
of Mount Morgan, Queensland
Alex G. COOK
Queensland Museum Geosciences, 122 Gerler Rd, Hendra, Qld 4011, Australia. Email: alex.cook@
qm.qld.gov.au
Nupur SAINI
School of Earth and Environmental Sciences, UniversityofWollongong, NSW 2522, Australia.
Scott A. HOCKNULL
Queensland Museum Geosciences, 122 Gerler Rd, Hendra, Qld 4011, Australia.
Citation: Cook, A.G., Saini, N. & Hocknull, S.A. 2010 03 15. Dinosaur footprints from the Lower
Jurassic of Mount Morgan, Queensland. Memoirs ofthe Queensland Museum — Nature 55(1):
135-146. Brisbane. ISSN 0079-8835.Accepted: 5 May2009.
ABSTRACT
Over 190 partial and completedinosaur printswhich includesixtrackwaysare preserved
in the ceilings ofa disused clay mine near Mount Morgan central eastern Queensland,
Australia. These representthe best record of EarlyJurassic dinosaur footprints thus far
discovered within Australia. Anomoepus dominates with other morphologies present
including, Grallator, cf. Eubrontes, and Skartopus and several indeterminate prints. Only
one possible manus print was observed. All preserved tracks are short walking tracks.
LowerJurassic, dinosaur trackways, ornithopod, theropod, dinosaur footprints,
Razorback Beds, Mount Morgan.
EarlyJurassicrecordsofdinosaursin Australia but only isolated prints and no trackways
arescantwith no EarlyJurassic dinosaurskeletal were figured. This work concerns the dinosaur
material known, and only isolated occurrences footprintsprintsexposed inthe'Fireclay Caverns'
of dinosaur prints known in Queensland mine at Mount Morgan and the few trackways
(Bartholomai 1966; Bartholomai in Hill, Playford preserved in the ichnological assemblage.
& Woods, 1966; Thulborn 1994). Dinosaur prints Mount Morgan gold and copper deposit was
and trackways are known in Australia from the exploited between 1882and 1990. In supportof
mid-Triassic onwards into the Late Cretaceous mining operations, were a series of clay mines
(Thulborn & Wade 1984; Thulborn 1998) and supplying raw material with which to make
have proved essential in delimiting the diversity bricks for the smelting furnaces. These 'fireclay
and evolutionary importance of otherwise caverns' operated spasmodically between 1886
unknown elements of the dinosaurian faunas and 1925. Activity in the mine and subsequent
of the continent. Dinosaur footprints have been chemical weathering exposed the lowermost
recognised near Mount Morgan for over fifty surfaces of at least three layers of dinosaur
years, but there has not been any documentation footprints. A prime reason for the delay in
of their occurrence, composition and inferred investigating these occurrences of trackways
palaeobiological information. Reconnaissance was that they are exposed on the ceiling of
m
reportsofthisichnofauna weremadebyStaines the mine, 10-12 above the mine floor. This
(1954), Bartholomai (1966) and Molnar (1991), rendered replication, photography or removal
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Cook, Saini & Hocknull
difficult. One small area of footprints was commonly called the Razorback Beds (Playford
exposed in a suspended drive and was within & Cornelius 1967, Day et al., 1983). Studies
4-5 metresof the mine floor. It was these prints by Playford & Cornelius (1967) of these units
that Staines (1954) photographed. indicatea lowermostJurassicageandcorrelated
theRazorbackBedswiththeEvergreenFormation
STRATIGRAPHIC AND of the Precipice Sandstone within the Great
SEDIMENTOLOGICALSETTING Artesian Basin to the west and south west.
m
Nearly 65 ofJurassic sediments are exposed
Mount Morgan is located 38 km SW of the near the Mount Morgan Mine. Detailed logging
regionalcentreofRockhampton, central eastern of this section has been interpreted to represent
Queensland (Fig. 1). A ~65 m thick succession three distinct facies groups; (1) Basal pebbly
non-marineJurassic sediments unconformably sandstone; (2) siltstone and (3) cross-bedded
overliesDevonianbasement(Fig.2)andhasbeen coarse sandstone.
FIG. 1. Locality and general geology ofMt Morganwith map ofFireclay caverns afterStaines (1954). Main
footprintsites marked A-E.
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Dinosaurfootprints from Queensland
Basal Pebbly sandstone facies. This facies lies
unconformably atop Devonian porphyry and is
m
approximately20 thick. Coarsemassivequartz
and sublithic sandstones, minor polymict con-
glomerates medium grained quartz sandstone
m
units 0.6-2.2 thick are intercalated with Coarsequartzoseplanar
sporadic mudstone and siltstone units. Minor cross-bedded sandstones.
trough cross bedding and planar laminations Minorconglomeraticlenses,
minorsandysiltstones.
are present in the coarser units. Scour bases and Alluvial fan setting.
lithic breccia lensesare present in the lower parts
ofcoarseunits.Generallythefaciesfinesupwards
and isdirectlyoverlainbythethicksiltstonefacies
described below. The sequence is interpreted
as an alluvial fan deposit with sporadic channel
and limited floodplaindeposition.
sSitlotnsteoniesfoavcieersl.aTinwobymmetorneostmoofnofiunse-fimneed-igurmaisniletd- 10m sLLaaacnmuidsnytarstiienldetsstseoitnltetissn.tgo.neand fine
laminated siltstone, over 16 thick which domi-
nates the middle of the sequence. Sedimentary
structuresinclude planarand parallel ripplecross
laminations, isolated outsize quartz pebbles
and subangular clay clasts. Significant pyrite
crystals are distributed throughout which are Basal pebblysandstones and
conglomerates, sandysiltstones
considered secondary given the nature of the and coarsesandstones.
proximalorebody. Dinosaurprintsarepreserved Riverine and alluvialfan setting.
in theuppermostonemetreofthisfacies.Theunit
is interpreted as a lacustrine system which in
uppermost parts shallows to form a regressive
lacustrine system onto which footprints were
impressed.
Cross beddedsandstonefacies. In mthe study area FIG. 2. Stratigraphic column for Razorback Beds in
this forms the uppermost 25 of exposed thevicinity orthe Fireclay Caverns, Mount Morgan.
section andisdominated bymassiveand planar
and trough cross bedded coarse quartz and of the clay caverns mine (Fig. 1). They are
m
sublithicsandstones. Beddingsets are up to 2 preserved in several layers of the uppermost
thick and have common basal pebble lags. The 1 m of siltstone facies within the sequence.
m
facies is interpreted as part of a small braided Their preservation mostly >10 above the
river system which built out over a restricted mine floor was a major impediment to earlier
lacustrine environment. study. In addition the small area in which
m
the prints are less than 5 above the mine
PRESERVATION floor could not be cast as the prints were too
fragile. This was exacerbated by pyrite growth
Footprints are preserved as hyporelief and throughout the siltstone producing large areas
transmitted hyporelief prints throughout most of friable and extremely fragile rock. Finally in
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Cook, Saini & Hocknull
2007,usingmajorscaffolding,asmallsection of the caverns and the ceiling, approximately 10
footprints was moulded. The mould is lodged m, all measurements are approximate.
with theQueensland Museum (QMF54079).
Calculations of hip height follow Alexander
METHODS (1976) and Thulborn (1990).
Initial work which formed part of reconnai- DISTRIBUTION
ssance studies (Cook et a]., 2002) simply photo-
graphed the major footprint-bearing panels. The prints are present in many parts of the
These were then assembled as a photo mosaic mineceiling.Areaswithmoreconcentrated prints
foranalysis. Twolaserdevices10cm apartwere sets weregiven informal namesforconvenience.
used to provide a scale for further work with Trackways are preserved in 'Bat Cave', 'Main
photo mosaics. Individual images were either Entrance', 'Mezzanine Hall', 'North Bat Cave'
solarised or embossed in Adobe ™Photoshop and 'Ladder hall' (Fig. 3).
7.0. Rectified images were imported into No preferred overall orientation of prints
ArcMAP™ 9.0 for further measurement. was observed within the caverns (Fig. 3). Two
Becauseofthe largedistancebetween thefloorof areaswith slighWt pSrWeferencWe NforWtrends ofprints
directed to the and for 'Bat Cave'
and the 'Main Entrance' where there was an
EW-NW
bipolar orientation.
PRINTS
Only one possiblemanusprintwasobserved
in the caverns despite the observations of
Bartholomai (1966) reported in Molnar (1991).
Most prints were tridactyl pes prints. Largest
printswerethatofcf.Eubronteshad FootLength
(FL)=40cm and thesmallest, that ofAttomoepus
FL=5 cm. Seven print morphologies were
identified, but only three can be confidently
assigned to ichnotaxa. Many printsare eroded,
with many of their features distorted by
erosion. An equally large number of prints are
transmitted prints or partial transmitted prints
with digit'breakthrough' fromoverlyinglayers.
All prints are preserved in hyporelief.
Attomoepus (Fig. 4)
This is the dominant print present within
the caverns represented by 69 full prints and
61 partial prints which can be confidently
assigned. FLvariesfrom5cm to27cm with most
prints rangingin FL from 10-15cm. Divaricance
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Dinosaurfootprintsfrom Queensland
FIG. 4. A-C, Anomoepus from the Fireclay Caverns, Mount Morgan; D, Isolated partial pes and possible
manus print,Anomoepus.
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Cook, Saini & Hocknull
One print is associated with an additional
manus impression (Fig.4D),consistingofthree
short stubby digits, approximately 7 cm long,
with a divaricanceofapproximately85°. These
lie just anterior to a distinct partial Anomoepus
pes print.
Four short trackways are attributable to
Anomoepus. Anomoepus has been recorded in
the Precipice Sandstone of Queensland by
Thulborn (1994), but the specimens lodged
in the Queensland Museum by Thulborn are
generally smaller and have slightly narrower
digits. Moyenisauropus has been used by many
authors for prints similar in morphology to
Anomoepus, but larger than 20cm FL. A number
of authors however assert that the forms are
indistinguishable (Lockley & Meyer 2000;
Olsen & Rainforth 2003; Olsen & Gatton 1984;
Thulborn 1994). For the purposes of this work
we regard them as sizevariants.
cf. Eubrontes (Fig. 6)
Fourteen individual prints and one trackway
are assigned to this ichnotaxon. FL is between
16-40 cm. The prints assigned to cf. Eubrontes
differ from Grallator in both size and that Dili
isreduced incomparison toDII and DIV. In the
MountMorgan prints, the DII-IV divarification
FIG.5.A,Largetransmittedtheropodprint;B,Stubby- is between 50°and 70°. Claw marksare present
toedomithopodprintNotetracksaretransmittedwith inthreeofthe14printsobserved.Theserepresent
breakthroughsondeeperdistal digits,especially III.
the largest ofthe prints at Mount Morgan.
is between 85-105°. Digits are relatively broad Skartopus (Fig. 8C)
and a semiclaw is present in some specimens.
Digits are long and tapered with digit (D) III Thisisrepresented bya singlesmall tridactyl
longerand more tapered than DII orDIV.Slight print with FL of 5 cm, interdigital angles <40°.
medialswellingispresentonDill,howeverthere Digit III slightly longer than others. The single
isa pronounced swelling distallyon DIV. Distal print is distinctive and unlike any other in the
ends tapered more sharply on Dill, but are Fireclay Caverns. Skartopus is known from the
subrounded on theother two digits. Interdigital medial Cretaceous of western Queensland
angle is greater on DII-III than DIII-IV. (Thulborn & Wade 1984).
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Dinosaurfootprintsfrom Queensland
FIG. 6. cf. Eubrontes prints forminga short trackway near theentrance toFireclay Caverns
Grallator (Fig. 5) five prints from the mid-Triassic (Carnian)
of Queensland. Grallator and its synonyms
Tridactyl print, digit III is longer than DII
and DIV, which are nearly equal in length. (Thulborn 1998) arecommon printswithin Early
Divarification is between 85-95°. No hallux Jurassic assemblages worldwide (Ellenberger
impression is present. Most prints are between 1974; Olsen &Galton 1984; Rainforth 2001).
42-818cmcmloinngFLisbuptreasesnitn.gleT,himsucmhorlpahrgoetr,ypperinits INDETERMINATE PRINT1 (Fig 7A-C)
represented by 16completeand 8 partial prints. Large tridactyl prints, up to 24 cm FL, with a
One short trackway is attributable to Grallator. divaricanceof70-100°. Digitsare longand taper
Thedivarificationishighincomparison totypes to a point. Rear of the print is crescent-shaped.
of Grallator (Olsen, Smith & McDonald 1998) DII-III angle is less than DIII-IV. Dill deep has
and other described footprints, but the general a medial swelling. Two examples of this print
foot morphology isconsistent. Lack ofdetail in haveaprobablehalluximpressionwhichextends
the phalangial pad marks makes discrimination approximately one quarter the distance behind
ofindividual phalangial swellings difficult. the proximal part of the print. The sharp distal
Theearliestrecord in Australiaofgrallatoroid ends of the digit and the size suggest that these
tracks is thatofThulborn (1998) who described printsareattributabletoatheropod.
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Cook, Saini & Hocknull
FIG. 7. Large indeterminate, weathered theropod prints.
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Dinosaurfootprintsfrom Queensland
INDETERMINATE PRINT2 (FIG. 8A)
FL approximately 8 cm, consisting of three
widely divaricant digits with an overall
divaricance of 95°. Digits are short and blunt
v/ith rounded distal ends. Dill is slightly longer
than D1V and has a slightswelling approaching
the distal margin. DIV deep. DII shallowerwith
less pronounced swelling at the distal end.
This print differs from Indeterminate print 3
by its widerdivaricanceand theconnectedness
ofthedigits.Thebluntnatureoftheprintssuggest
an ornithopod origin.
INDETERMINATE PRINT 3 (Fig. 8B)
Foot length is approximately 12 cm. Print
consistsof three blunt digits with a divaricance
of50°. Dill longerand deeperthan DIIand DIV,
with DIV longer than DII. Slight swellingatthe
proximalendofDill.Thethreedigitsarealmost
unconnected on theprint. Theblunt toed nature
of this print suggests an ornithopod origin
SIZES OF PRINTMAKERS
Thulbom (1990)suggestedthattheapproximate
relationship of FL to hip height and his
formulae and conversion factors are followed
here. Anoinoepus prints suggest most animals
with a hip height of 25-131 cm. One example
suggested an animal witha hip heightof161 cm,
but thissingleprint isaberrant. Prints ascribed to
cf. Eubrontes suggest animals in the range 70-
180 cm at the hip and those assigned to Grallator
indicate hip heights ofbetween 20-120 cm.
ASSEMBLAGE
Thevarietyoftheprintswithintheassemblage
is skewed by our decision to lump ichnotaxa.
Nevertheless what is striking about this fauna
is the high percentage of anomoepid prints
in relation to theropod prints (Fig. 9). Prints
attributable to ornithopods constitute just
over two-thirds of the assemblage. This is in pFrIiGn.ts8.. AA,,B.disgmiatlsls,hboluwntw-itdoeeddpirvoarbiacbalneceo;rnBi,thDiipgoidt
contrast to other Triassic-Jurassic assemblages impressionsonlywithmoderatedivaricance;C,Isolated
worldwide which show greater percentages of Skartopus print"
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Cook, Saini & Hocknull
grallatoroid and other theropod prints (Lockley
& Hunt,1995; Lockley & Meyer, 2000,Gierlinski
& Sawicki, 1998; Gierlinski & Niedzwiedzki,
2002; Niedzwiedzki & Pienkowski, 2004). A
possibility is that the ecological setting for the
site, essentially at lakes edge could account for
the greater numbers of ornithopods, utilising
the lake asa regular watering hole.
TRACKWAYS
Six trackways (Fig. 10) are present in the clay
caverns, the longest of which is represented
by 6 successive prints. Three are attributed to
Anomeopusandoftheremainingoneto?Eubrontes
and two to Grallator. Pace lengths and other
data are summarised in Table 1. Stride length
mAnomeopus bGrallator acf Eubrontes to hip height ratios (Alexander 1976, Thulborn
hindettheropod indetomithopod 1990) are all less than 1.3 indicating cursorial
gaitsforall theshort trackways present. Data is
FIG. 9. Pie chart of proportions of prints found too incomplete to make any other meaningful
wpriitnhtinintchleuFdierdecilnaIynCdaevteerrnmsi.nant=e19t2h.erSoipnogdleprSiknatrst.opus comment on speeds, however it is clear all the
trackways represent walking tracks.
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