Dinosaur 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 Memoirsofthe Queensland Museum Nature • 2010 • 55(1) • www.qm.qld.gov.au 135 | 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. 136 MemoirsoftheQueensland Museum Nature • 2010 • 55(1) | 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 Memoirs ofthe Queensland Museum Nature • 2010 • 55(1) 137 | 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 138 Memoirsofthe Queensland Museum Nature • 2010 • 55(1) | Dinosaurfootprintsfrom Queensland FIG. 4. A-C, Anomoepus from the Fireclay Caverns, Mount Morgan; D, Isolated partial pes and possible manus print,Anomoepus. Memoirsofthe Queensland Museum Nature • 2010 • 55(1) 139 | 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). 140 Memoirsofthe Queensland Museum Nature • 2010 • 55(1) | 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. Memoirsofthe Queensland Museum Nature • 2010 • 55(1) 141 | Cook, Saini & Hocknull FIG. 7. Large indeterminate, weathered theropod prints. 142 MemoirsoftheQueensland Museum Nature • 2010 • 55(1) | 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" MemoirsoftheQueensland Museum Nature • 2010 • 55(1) 143 | 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. 144 Memoirsofthe Queensland Museum Nature • 2010 • 55(1) |