E-f*u PROCEEDINGSOFTHE YORKSHIREGEOLOGICAL SOCIETY, ^l,' Jurassicdinosaur tracks and trackwaysof the Cleveland Basin,Yorkshire: preservation, diversity and distributio

M. Rorr,reNoland M. A.Wuyrr,

' ( Presidentíaladdresses ileliyered at York,4th December1999, and 2nd December,2000) ' Depatunent oÍ Geogruphy Dainton Building, Btookhill, University of Shefield" Shefield 33 7HF (e-mail: m.romano@ shefield. ac. uk; m.o. w hyte@sheffiel d.ac.uk)

SUMMARY:Dinosaur tracks are abundantin the Middle Jurassicrocks of Yorkshire and indeed characterizethe non-marine sequencesdeveloped vr'ithin the ClevelandBasin. These tracks and associatedtrackways provide valuableevidence of the possible diversity of the dinosaur communities,their potential makers and behaviour and useful insightsinto the habitats and palaeo- environmentduring the time of deposition.The uneven historical developmentof researchinto Yorkshire dinosaur tracks is reviewedand the Middle Jurassiclithostratigaphy, biostratigraphyand chronostratigraphyof the region is outlined. Next, the probablepalaeoenvironment of the Middle JurassicCleveland Basin, generally regarded as a coastalplain and fluvial complex,is briefly summarized.The terminologyused to descdbethe dominantpreservational types ofdinosaur tracks,such as surface, trans- mitted and underprints,is clearly defined,$,ith examplesfrom the Yorkshire sequences.Thè Yorkshire tracksshow considerable moryhologicaldiversity ard at pr€sent29 different morphotypeshave been recognized,which possiblyrepresent at least 15 ich- notaxa.These morphotypes include both quadrupedaland bipedal forms, as well as a distinctivesuite of raking prints resulting from swimmingactiyity, The distribution and abundanceof the known dinosaurtuacks within the Middle Jurassicrocks of York- shireis described.For the flrst time, a range cha of dinosaurtuacks is presentedthat illustratesthe persistenceof somemorpho- tlpes throughout the RavenscarGroup (Middle Jurassic)of the ClevelandBasin. Track distribution and diversity data allow reconstuuctionof the Yorkshiredinosaur communities that Ìveremade up ofbetween7-10 commontypes, belonging to sauropods, 'megatracksite' stegosaurids,ornithopods and theropods.The area is a of global importance.

Dinosaur remainsfrom the Middle Jurassicof Yorkshire are the tacks. These persorlneland their contributions will be very rare (\{illiamson 1837;Fox-Strangways 1904; Benton identifiedbelow. 1996)and reflect the poor global record of the group at this Folìowinga brief historicalreview, an outline of the Middle time, pa icularly in the Aalenian (Romer 1966;Weishampel Jurassiclithostratigraphy, biostratigraphy and chronostratig- et al. 1990;Benton 1993).The singlereported find of bone raphy of the region will be presented;after which the Middle assignedto the sauropodCetiosaurus îrom the marine Scar- Jurassicpalaeoenvironment will be desqibed.Thenfollows an boroughFormation (Williamson 1837;Fox-Strangways 1904) account of the terminology used to describethe dominant still remainsthe only publishedoccurrence of dinosaurskele- preservationaltypes of dinosaurtracks encountered.Finally, tal elementsftom the Middle Jurassicof this area.However, three aspectsof the dinosaurtracks of Yorkshirewill be inves- dinosaurtracks and trackwaysarevery commonand thesecan tigated;track diversity,track distribution and àbundanceand provide valuable evidence of the possible diversity of the possibledinosaur divenity. Although in this review relatively dinosaurcommunities, their potential makersand behaviour, few of the tracks are named,this is not meant to signify an and ùseful ínsìghtsinto the palaeoenvironmentduring the aversionto this practice.Indeed, the naming of tracks allows time of deposition(Thulborn 1990;Lockley 1991r). easyleference tO any previouslynamed ichnite in the litera- Recent work on dinosaurprinls by the authorshas shown ture (McAllister 1989, p. a) and, by using the cu[ently that thereis a v/iderange ofprint morphotypesfrom the York- adopted'binomen' system based on the Linneanclassification, shire Middle Jurassicsuccession, which indicatesthe former may indicate close morphologicalsimilarity or dissimila ty. presenceof varied dinosaurcommunities (Whyte & Romano Howeyer, at this stage of these studies,in particular \ryith 798I,1993,1995,2Co1,2002;Romano & Whyte 1996;Romano referenceto the t dactyl hacks, it is preferential to identify el al 1999).As regular visitorsto the eastcoast over the past different unnamedmorphotypes that may, with more rrork, 15 yearswe,have produced a comprehensivedatabase on the becomethe basisof more formal ichnotaxa.This work on the variety and occurrenceof these ichnites.Extended detailed behaviourpatterns of thesedinosaurs, as deduced ftom track suryeysof th€ coastalexposures with volunteersftom Earth- morphology,configuralion of the trackwaysand habitats,\ryill watch Intemational started in 1996. These, together with be addressedat a later date. numerousgeological field excursionsand individual contri- butions ftom colleaguesand co-workers too numetous to mention, have also added to theserecords. More specifically, 1. HISTORICAL REVIEW OF TR-ÀCK RESEARCH a Dinosaur Track Research Group (DTRG) has been estabishedat the University of Sheffreld,which has overseen It is now nearly 100 yearssince definite dinosaurtracks were a number of PhD projects on field and laboratory stùdiesof first describedftom the Middle Júrassicrocks of Yorkshire (Brodrick 1907), the 'true staúing-point of British Jurassíc O Yorkshire GeologicalSociety, 2003 palaeoichnology'(Sarjeart in Casamiquelaet al. 1987, p. 5).I\ t.-i

186 M. ROMANO& M. A.'WHYIE fact they had probably been observedaround 1895,sinca it is accounts.Certainly dinosaurshad not become significantly reported (Hargeaves 1913, p. 92) that a 'Mr. Rowntree less fashionable,nor Ìvas there any lack of active Ìvork on obtained a lootprinr frcm Cayton Bay [south oî Scaúorcugh], dinosaurtracks elsewhere in the Ìvorld,since this was the tirne which Mr Lamplugh prcnouncedto beprobably crocodílían'. (between1939-1954) that Roland T. Bird publisheda seriesof Despite their early recognitionin this area,thoùgh consider- popular articleson the subsequentlyîamous sauropod track- ably later than the first findsof Triassicprintselselvhere in the way at the PaluxyRiver site in Texas,USA (descriptionsand country (Sarjeant1974), there has not been a consistentflow referencesin Farlow & Lockley 1989;Farlow et al, 7989; of publicationson theseemotive yet enigmatictlace fossils. Lockley & Hunt 1995).So why did British workers not fully Paperspublished on Yorkshire dinosaurtracks over the last exploit the ch pickingsof dinosaurhacks on the eastcoast? 100 years show a strongly bimodal production rate (Fig. 1). Part of the reasonmay havebeen that trackswere regarded as Following an initial rush in the earlypart of the 20th century, rare and,indeed, when the presentauthors started work on the that coincidedlvith H. C. Beasley'sinvestigations in the Tri- Middle Jurassic dinosaur t acks of Yorkshire (Whyte & assicoî Cheshire(Sarjeant 1974), numbers of papersdeclined Romano 1981),there waslittle indication as to the wealth of until the znd World War and did not increaseasain until thc material that vr'ouldcome to light, However, it soon became mid-1970s. apparentto us that dinosaurtracks, far ftom being just scat- tered or relativelylocalized occurrences, actually characterize This dearth of pape$ between1920-1970 on the Yorkshire many of the non-marinerock sequencesof this area. They dinosaurtracks is recognizedin two comprehensiveaccounts occur throughout the Middle Jurassic,often in considerable by Sa{eant (1974)and Delair & Sarjeant(1985) on the history numbersand in a variety of facies.Thus the earlyrecords that of the stùdy of fossil vertebratefootp nts in the British Isles. gavethe impressionthat prints tendedto occu at particular In these\ryorks, Jurassic Yorkshire dinosaurp nts occupy a horizonsor beds,such as the'footprint bed'at Bùmiston combined total of just over four pagesof text and 13 refer- (Hargreaves1914) and the'Unio bed' at Whitby (KendalÌ ences,whereas the TriassicCheshire/lancashire prints merit 1908),are noìv known to be rather biasedviews and do not over 21 pagesof text and in excessof 100referelces (aÌthough, reflectthe true picture. admittedly,Beasley contdbuted 19 of the latter!). It is diff,cult to pinpoint why, following the initial recognitionand subse- Anolher reasonfor their unpopularity(though certainly not quent publications,the interest in theseYorkshire dinosaur peculiarto Yorkshire)may bave beenthat the full potential of tracks was not sustained,at least with regardsto published the trackswas not appreciated.Hence the early paperson the tracks of the east coasL(Brodrick 1907,1908, 1909a, 1909b; Kenda[ 1908; Hargreaves 1913, 1914; Fox-Strang\a,ays& Barrow 1915;Black et at. 1934)dealt mainly with print shape and assignmentto particulardinosaur groups. Yet, apart from possiblyenabling the maker to be identified (though in fact this is probablyrather rare),the tracksalso may provideinfor- mation on the sizeof the animal (hip height,gleno-acetabular 0) distance)and its behaviour(mode oflocomotion, gait,speed). Also tracksmay supplyevidence on abundance,diversity, and ecology (gregariousnature, migratory pathways,prefe[ed o habitat),as well asyielding information on the stateof the sub- strate during footprint fomation. Pioneering work by = _o Alexander (1976,1985) also showed that the speedof loco- l motion could be deducedfrom their trackways. A further reason for the apparent unpopularity of the (D pdlts may stem from their occurrence.They afe most com- 22 monly found on the coastalexposures, often on loose boul- 5 ders close to the steepunstable cliffs; specimenscommonly z fail to survive the winter storms:access to someof the beach localities is difncult, or at least unpopular to the casualday visitor; the lure of Early Jurassicammonites, belemnites, bivalvesand marine reptilesis too distracting.Whatever the raason(s),interest ce ainly did declineduring the middle of 'cuftent 1900 '1950 2000 the 20th century, and it was not until the dinosaur Year truck rcnaissance'(Lockley 19914,1991b, 1998; Lockley & Meyer 2000,p. xii) that it hasreturned again.Papers became Fig, 1. Bar chartshowing numbeft of publicationson dinosaurtracks more numerousin the early 1990s(\ryhyte & Romano 1993, ofthe Middle Jurassicrocks ofthe ClevelandBasin,Yorkshire 1994,7995) including a very useful publication by Ivens & perdecadeover the lastcentury (Refeaencesused to construct Watson (1994) that listed and describedmany of the pub- bar charr Broddck 1907,1908,1909a, 1909b; Sheppard 1908; lished (and unpublished)finds from the Yorkshirecoast. It is & Kendall 1908; Hargreaves 19'13,791,4:Fox-Strangways hoped that the encouragingpresent upsurge in publications Barrow 1915; Kèndall & Wroot 1924; Black et al. 1934i will continue and producefurther revelaùonson thesemost Saieanl1970, 19?4;Delair & Sarjeant1985; Ivens & \Matson fossils, since we believe that 1994;Whyte & Romano 1993,1994,1995,2001,2002; Romano appealing of studies of the & Whyte 1996,present papeq Romanoetol 1999;Rawson & dinosaurtracks in the Yorkshirearea are particularly import- wright 2000). Papers published or in press after 2000 ate ant owing to the scarce records of skeletal remains of , shownulomamented. dinosaursftom the Middle Jurassic. JURASSICDINOSAUR TRACKSAND TRACK\#AYSOF THE CLEVELAND BASIN, YORKSHIRE 187

2. STRATIGRAPIIY unconformably.The Middle Jurassicrocks, depositingunder fluctùating non-rnarine and marine conditions, were sub- TheJurassicrocks ofYorkshire sharesufficiently disùnct char- dividedby Fox-Strangways(e.g.1880, p.3) into Lower,Middle acteÉ to warrant recognitionas a singledepocenter. This area and Upper Estuarineseries separated by marine units.These wasgenerally known as the Yorkshire Basin(Fox-Strangways subdivisionswere later renamedand modifiedby Hemingway 1.892,p.388), although more recently the term Cleveland (1949),who introduced the terms Lower, Middle and Upper Basin (Dingle 1971;Heminway 7974:Bradshaw et aL 1992) Deltaic series which are underlain by the madne Dogger. has been adopted to restrict the region to north of the Someyears later Hemingway& Knox (1973)applied a more Coxwold-FlamboroughFault line. The Middle Jùrassicrocks formal lithostratigraphicalterminology to the Middle Jurassic are well exposedalong most of the coastftom just south of sequenceof the ClevelandBasin and it is this (Fig. 3) that has YonsNab to around Port Mulgrave in the north, a distanceof essentiallybeen adoptedand usedby subsequentauthors. approximately55 km (Fig. 2), whereasinland exposurestend The dominantly non-marine RavenscarGroup (c.240 m to be uncommon. thick) overliesthe Dogger Formation (or marine Lias where the latter is absent) and consistsin the main of shaly rnud- 2.1. Lifhostratigaphy stones, sandstones,siltstones, rare impure coals and iron- The Lower Jurassicrocks of the ClevelandBasin were folded stones that constitute three major non-rnarine units, the during late Early Jurassic(Toarcian) times into a seriesof low- Saltwick, Cloughton and Scalbyformations, which are 57 m, amplitude basinsand domes (Herningway1974). This event 85 m and 60 m thick respectively.Separating these units are wasfollowed by a period of widespreaderosion to producea two main madne units, the Eller Beck and Scarboroùgh nearly level surface on which Middle Jurassic rocks lie formations, together with a locally developed marine unit

Pott Mulgrave N UpperJurassic tl MiddleJurassic % LowerJurassic Saltwick Bay E Dinosaurprint locality *lTt-\ Hawsker N \

Robin Hood's Bav \'Iqavenscar 05 km Fylingdales Moor I ú ù ùù It I tt$Hayburn Wyke I Cloughton Wyke Spauntoò \' Moor \ Wyke ù \ Scalby Bay SCARBOROUGH

Rocks White Nab CornelianBay Yons Nab

fig' 2" Simplified geological map of eastern Yorkshte between Port Mulgrave and Gristhorpe, showing localities mentioned in the text and ptuciPal , siteswhere dinosaur pdnts havebeen recorded. 188 M. ROMANO& M. A. 1VHYTE

on the basisofoshacods (Bate 1978)and foraminifera (Morris & Coleman1990) is assignedto fhe Hyperliocerasdiscites to BATHONIAN Witchellia laevíusculabiozones (lower Baj ocian) (Cope et al. 1980à).The topmostmaririe unit of the RavenscarGroup, the ScarboroughFormation, has yielded ammonites indicating the presence of all three sub-biozonesof the Stephanoceras BAJOCIAN humphriesianwn Biozone (Parsons 7917; Cope et aL 7980b). Bate (1978),ftom his studyofthe oshacods,suggested thatthe lower part of the ScarboroughFormation was deposited during the previous-Emileis. (Otoites) sauzei Biozone. AALENIAN The marine CornbrashLimestone Formation (Rawson & Wright 2000;=Abbotsbury CornbrashFormation of Rawson& Wright 1995)of the upper Middle Jurassicoverlies the Scalby Fig.3. Lithostratigraphyand chronostratigraphyof the Middle Formation.Diagnostic ammonite faunas from the Conbrash Jurassicrocks of theCleveland Basin (modified from Rawson LimestoneFormation on the coastindicate the presenceofthe stippled.Note that & Wright 2000).Marine units are Macrccephalites (Kamtokepfulites) kcnzpras Sub-biozone of îhicknessesof units are not drawnto scale. the M. (M.) macrccephalusBiozote (Wright 1968). Thus the ScalbyFormationcould span at least11 ammonite biozones, i.e. (Lebberston Member) in the Cloughton Formation in the a durationof c 8-10 Ma. Altematively,rapid depositionand a southof the area,Hemingway & Krox (1973)did notformally break below the CornbrashLimestone Formation could indi- namesubdivisions in the ScalbyFormation ('Upper Estuaine/ cate that significantlyfewer ammonite biozonesare present Deltaic Series'), although Black (1929) had earlier docu- (Leeder& Nami 1979).A palynologicalanalysis by Riding & 'Level 'Wrigh menteda lower 'CuÍent BeddedSedes' and an upper t (1989)concluded thatthe depositionaltime spanfor the BeddedSeries', the former being further subdividedinto tbe ScalbyFormation was ir the order of 11 ammonite biozones, 'Moor Crit'and overlyingCurrent Bedded Sandstone' (see althoùgh sedimentation was probably not continuous. also Hemingway194). Nami & Leeder (1978)and Leeder & However,a more recentpalynological study (Hogg 1993)sug- Nami (1979)recognized a lower Moor Gdt Member of the gestedthat there is a major stratigaphical break betweenthe ScalbyFormation and an overlying Long Nab Member, the Scarboroughand Scalbyformations, and that the ScalbyFor- latterbeingequatedwithBlack's'CurrentBedded Sandstone' mation may only encompasstwo or three ammonitebiozones and 'Level BeddedSeries'. The marineCombrash Limestone (Hesselbo& Jenkyns1995, fig. 3). Formation restson a burrowed (pers.obs; Riding & Wdght eroded Formation (Rawson & 1989), surfaceof the Scalby 2,3. Chronostratigraphy Wright 2000,p.9) and in turn is overlain by further marine units of Middle Jurassicage. Knox et al- (1991) recognized Basedon the chronostratigaphyin Cope et al. (1980a,b), the three major hansgressive-regressivecycles \'r'ithin the Middle Dogger Formation-RavenscarGroup of the ClevelandBasin Jurassiclithostratigraphy ofthe ClevelandBasin, each starting ranges in age from the early Aalenian to late Bathonian with a marine ùnit ('upper' Dogger,Eller Beck, Scarborough (Fig. 3). The Aalenian/Bajocianboundary is not well denned, formations)and passingup into paralic mudrocksand sand- but the aboveauthors assigned the Saltwick (=Hayburn) and stones. Elìer Beck formations to the Aalenian, and the base of the Bajocian is tentatively placed at the Eller Beck/Cloughton Formation junction. rùhile the ScarboroughFormation is 2.2. Biostratigraphy firmly datedas early Bajocian (I àlagdeaiSub-biozone of the The paucityof ammonitesin the Middle Jurassicof the Cleve- S. humph esíanumBiozone; Cope et al 1980à)the possible land Basinrenders the applicationof a detailedzonal scheme stratigraphicalbreak between the Scarboroughand Scalby basedon thesefossils virtually impossible.The marineDogger formations makeslocating the boundary between the lower Formation probably belongs to the Leiocerus opalinum and upper Bajocianproblematical. Biozone (Riding 1984;Knox et al. 199LiPatliani & Riding The Bajocian-Bathonianboundary is alsodifficult to locate. 2000) and the Ludwígia haugi S.rb'biozone of the succeeding Riding & Wright (1989)showed that the palynoflorasftom Ludwigia murchísonae BiozoÍe (Cope et ol. 19804, fig. 4a, the loìvermostLong Nab Member of the Scalby Formation column 4838, p.20). The next marine ùnit, the Eller Beck indicateda late Bajocianto Bathonianage, while thosefrom Formation,has not yielded any ammonitefaunas (Sylvester- the uppermostLong Nab Member were dominatedby terres- Bradley 1953)but it was tentatively assignedby Cope et al. trially-derivedspores and pollen and indicated a Bathonian (1980à,frg. 4a, column AB38) to Lhetop part of the Grupho- age.Consequently, the Bajociarì/Bathonianboundary is pro- cerusconcavutn Biozone (top Aalenian) ard in Knox e, al visionallyplaced at the baseof the Long Nab Member. The (1991) questionably to the younger Hyperliocerasdiscites overlying Cornbrash Limestone Formation is assignedan (basal that the Saltwick Biozone Bajocian). This indicates early Callovianage (Wright 1977). Formation waslaid down dudng the duration of between1-2 ammonite biozones,i.e. between 0,7-1.8Ma depending on different estimatesof averagebiozone durafion (Cope et al. 3. PALAEOGEOGRAPIIY AND 1980a). ENVIRONMENTAL MODEL The LebberstonMember (=C6y1e11Bay Beds of Richard- son 1912 and Cayton Bay Formation of Cope et al. 1980b) oÎ The rocksofthe RavenscarGrOupare now generallyreearded plain and fluvial the CloughtonFormation has rÌot yieldedany ammonites,but asbeing a caastal comptex(Alexa;de; i9g9) JURASSICDINOSAUR TRACKS AND TRACKIVAYSOF THE CLEVELANDBASIN. YORKSHIRE 189

with occasionalmatine intercalatiors. Howeyer, as pointed verticalfacies changcs also occur in the Cloughtol Formation. out by Eschard et al. (7991) and Rawson & Wright (2000, To the southof Scarborough,the marine LebberstonMember pp, 8-9), somesedimentological features may also suggesta ofthe CloughtonFormation consists of a lower Millepore Bed deltaic origin for parts of the sequence.From approximately and upper Yons Nab Beds.North of Scarborough,where the late Aalenian (c. 177Ma) to late Bathonian(c. 160Ma) times marine influencehas diminished,the fully marine Yons Nab this coastalplain complexoccupied a large areaovet present Beds have given way to the basal,quasi-marine part of the day Yorkshire and extended easti,ard into the North Sea GristhorpeMernber (Rawson & Wright 2000,p.52). Also the (Kîox et al. 1991;Bradshaw €/ al 1992).The depocenterwas Gristhorpe Member (the upper member of the Cloughton boundedto the north and westby the Mid North SeaHigh and Formation) hasfew lenticularchannel sandstones (Knox er4l Pennine l,andmassrespectively (Fig. 4). Theseupland areas 1991).In the youngestnon-marine Scalby Formation, latge- were probably the major sourcefor the siliciclasticmaterial scale cross-beddedsheet sandstonescharacterize the lorÀ,er (Alexander 1986) that accumulatedto a thicknessof over Moor Grit Member.The upper Long Nab Member consistsof 200m during this time interyal. The generally southìvard medium-scalecross-bedded sandstones with subordinateshaly sloping coastal plain (Alexander 1986) maintained connec- mudstones,overlain by generallylaterally persistent mudrock tions with the open sea to the south and SE, allowing the and sand-dominatedheterolithic units, which may be traced periodic marine incu$ions to flood the area. for long distances(\'r'ith minor changes)within the confinesof a single bay, such as Buniston Bay (=Burniston Within the non-marine units of the RavenscarGroup Wyke). Yet where the sequenceis interrupted (Saltwick, Cloughton and Scalby formations), mudrocks by downcuttingsandstone lensesor landslipareas it is generally generallydominate volumetrically, whereas medium- to fine- difficult to correlatethe lithostratigraphyin detail either sideoî the break grainedsandstoles are locally common;the latter occurringas in exposure. sheets,l€nses and ir heterolithic packageswith mudrocks. Plant remains are extremely common and diverse dark grey-black Thin, carbonaceousshaly mudstore units (Konijnenburg-VanCittert & Morgans 1999) and occur as commonly form prominent and laterally persistentbeds and isoÌateddífted leaves(pteridophytes, pte dospe.ms,cycads, sphaerosidedticmudrocks and sandstonesare ubiquitous. bennettitales,ginkgoales and conifers) transported logs, rootlets Despite their historical importance (Hemingway & Owen andin rira erectstem s (Equisetum).Invertebrate body fossils, on 1975)coals are not particularlycommon. The lithotypesofthe the otherhand,arevery sparse; only bivalvesand insectremains three non-marineunits are essentiallythe same,though vary togetherwith a singleexample ofafish (Hemingway1974) have proportion. in For example,a feature of the lowestSaltwick beenrecorded.The non-marinebivalve Unio hasbeen recolded Formationis the markedlateral faciesvariation in the Whitby ftom the Saltwick and Scalby formations, although bivalve area (Alexander & Gawthorpe 1993).To the eastof Whitby escapestuctures (Lockeía) arc much mote comrnon,wide- the formation is dominated by mudrocks \vith intermittent spreadand locally prolific. Other invertebratetrace fossils, such bbon sandstonebodies, whereas immediatelywest of the as Cochlichnus, Protovítgulnria, Beaconites (?= Taenídium) (on town the other side of the Whitby Fault) the formation is (Goldring & Pollard 1995),Selenichnites (Romano & Whyte made up almost entirely of sandstone.Significant lateral and 1987, 1990), Kouphichnium (Romano & Whyte in press), 'Díplocraterion' andsimple buÍo\rys are locally common.

The thick (up to a few metres)mudtocks may haveaccumu- lated in flood plains,shallow lakes and marshes, or abandoned ver channels,Ìvhereas the coaIser arenaceousrocks \{ere deposited as sand bodies within river channels,levee and creyassesplay deposits(Hemingway 1974;Nami & Leeder 1978;Liven & Leeder 1981;Hancock & Fisher 1981;Knox et al. 7991;Alexander 1986,1987, 1989, 1992i Eschard er cl. 1991;Alexander & Gawthorpe1993; MjOs & Prestholm1993; W4s et al. 1993;Whyte & Romano 2002).Rootlet bedsbear testimony to soils capable of supportiog luxu ant plant growth,and palaeosolswith abundantsphaerosiderite indicate swampyconditions (Kantorowicz 1990). The generalabsence of coarse-grainedsandstones and siliciclasticclasts suggests that, on the whole. the Middle Jurassicrocks of the Cleveland Basin, exposedalong the Yorkshire coast,\,vere deposited in an areaof lo\ryavailable relief and relativelylow flow regimes. The largest and most common clasts are carbonizedplant fragments,mud flakes and reworked sideritizedsedimentary pebbles,typically found as lag depositsat the baseof channel sandstones;whereas at the base of scouredunits within the Moor Grit Member, quartz pebblesoccur (Nami & Leeder 1978).Bone ftagmentsin excessof 25 cm in length are very 'Fig.4. rare clastcomponents. We haverecotded large tlee trunks up Palaeogeographicalmap of northem Englandduring Middle to 4.7 m in length ftom the Long Nab Member. Jurassictimes, showing extent of coastal plain complex, generalized sedimentary environments and dir€ctions of The bighestand most pe$istent flow phasespresent during sediment derivation (after Knox et al. lggll Br^dshaw et al. the depositionof thesesedimentary sequences gave rise to the 1992). large-scaleqoss-bedded units in the Moor Grit Member, the 190 M. ROMANO& M. A. WHYTE downcuttingof the channelsystems that pùnctuateall three substratesfor p nt preservation.Although the sporadicinter- non-madneunits, and the stackedsandstone channels of the tidal .ock platforms of horizortally beddedstrata potentially Saltwick Formation to the west of Whitby (Alexander & allow extendedtrackways to be identified,coastal erosioo and Gawthorpe1993). Shorterliyed, high energyregimes resulted marine biota normally modify and mask the bedding plane in the eventbeds that correspondto crevasse-splayand sheet- sudaces.The seasonalmovement ofbeach sandand gravelcan flood deposits.The cross-beddedsandstones Ìvithin the Moor also affectthe amount of rock exposedand the availabilityof Grit ('a complexsandstone sheet' of Alexander 1986,p. 302, prints. The common occurrenceof prints on loose blocks is or 'a valley-flllcomplex' of Escharder al 1991)and the lower particularly valuable,though they rnay be limited in sizeand l,ong Nab Member appear to be major channelinfills \flithin ephemeralin nature. The relatively rare inland exposures, braided ver systemsand lateralaccretion ,rithin meande ng mainly in streamsections though also includingnatural crags channef deposits(Nami & Leeder 1978;Knox et al. 1991). and quaÍies, may yield more long-lasting,but generallymor€ Nami & Leeder (1978)proposed an upward changefor the weathered,priflts. from low sinuosityto high sinuositychan- ScalbyFormation In recording p nts we \vere initially much influencedby a reductionin discharge. nels.accompanied by previousdesc ptive terminology(e.9. Thulborn 1990;see also Severalauthors (Alexander 1986,p.299,1987,p. 316;Knox below), which emphasizedp nts seenpredominantly in plan eral 1991,p. 60; Rawson& Wright 2000,p. 9) haveremarked view and which distinguishedthree principal presentational on the abundanceand intensity of localized soft-sediment varianls.These, and our terminoÌogyare: deformationwithin the Long Nab Member,particularly in the (a) surfaceprints: in which the rock splits cleanly along the sandstonesof the meanderbelt. Theseauthors commonly link surfaceon which the animalmoved, to revealthe original the formation of thesestructures to water-escapeprocesses footpdnt-bea ng substrateand the infill aspart and coun- ('dewatering We believethat someof thesestruc- structures'). terpart (Fig. 5, A3); tures,which exhibit downward drag of beds,may more satis- (b) underprints:in which the rock splitsalong a surfaceinter- factorily be explainedby 'diDoturbation',the deformationof sectingwith the prilt so that part of the original substrate sedimentbrought about by the emplacementof a foot- Such adheres to the innll Gig.5, B4), or part of the infill action may have initiated more rapid dewateringof the an adheresto the substrate(Fig. 5, B5), or both; sediment(section 4.5). (c) transmittedprints: in which the rock splitsalong a surface The generallack of coalsìvithin the non-ma ne units of the which is entirelybelow the p nt and print-bearingsurface RayenscarGroup, together with a considerationof the sedi- so that both part and counterparLreveal only transmitted mentology,fossil floras,growth ring analysisand presenceof features(Fig. 5, C3, C4). charcoal,has led Morgans(1999) and Morganset al (1999)to A fourth variant, overprints, can occur where bedding suggostthat the region was charactedzedby climatic season- 'greater featuresìrithin the infilling sedimentare influencedby and, ality and,during late Bajocian-Bathoniantimes, by a thus,preserve aspects of the footprint (Thulborn 1990,p. 28) aridity' than during the Pliensbachian-midBajocian. and where the rock subsequentlyspÌits at such a level and entirely within the infilling material. However, this has been 4. TRACK PRESERVATION recordedrarely, if ever,in the Yorkshireprints and is not dis- cussedhere. It has also become increasinglyapparent that A footprint is madewhen an animal'sfoot is impressedinto a manyYorkshire prints are displayedin verticalor obliquesec- yielding substrate.It might appearthat this impressionwould tions, which show important aspects of the relationships effectively be a mould of the foot (foot mould) but, as the betìdeenthe surfaceprint, the transmittedfeatures and the resultingfootp nt usuallyalso embodies evidence both of the moulding sedimentyet do not fit easilyinto any of the three motion of the foot and of the physicalstate of the sediment, categorieslisted above.Furthermore there are a number of sucha simpleconcept is rarely,if ever,applicable. As the sub- prints, which do not fit with, and are more complexthan, the strateyields and deforms,evidence oî the passageof the foot very simplepreservational paradigm outlined above. will also be transmitt€d to sedimentaround and below the The three groupings and the other preservationaland dewateringaod grain footp nt through compaction,shearing, presentationalstyles are further discussedbelow. In this and rearrangement.In for the footp nt and associatedtrans- order elsewherein this paper we have followed the following con- mitted structuresto be preseryed,they must be covered by 'track' yentions.The terms'p nt' and are usedsynonymously later sediment,which will cover the surface on which the in a geologicalsense, in that they refer to the biogenicmark- animal walked and infill the footp nt. Lithified prirts then ings preservedin rocks, irrespectiveof preservationaltypes. becomeavailable for study wben îhe rock splits or erodesto The term 'impriot' is restricted to particular anatomically discloseaspects of the original structure and its infill. The related aspectsof the p nt (track) morphologysuch as digit, in which this exhumationhappens and in which the 'Footprint' manner claw, heel or pad imp nt. is reserved for the print becomesdisplayed has in the literature often been con- impressionmade in soft sedimentby an animal'sfoot during foundedwith preservation,though the distinctionbetween the locomotion (but see usageby other aùthors such as Farlow two should be recognized.The exposureor presentatiolal & Chapman 1997;Thulborn 1990; Lockley & Hunt 1995). print affectsthe information that stylein which the is revealed 'Trackway' is preferred to tracks or trails when refeÍing to can be deducedfrorn it. two or more consecutivep nts made by a particular animal, n( tr The diverse charactedstics of the Yorkshire coastal asthe word trackwayisso entrenched in vertebratettacefossil 'track' tI enable nùmerous pdnts to be viewed and literature (and d€spite the more suitable term as exposures the il studiedjn a variety of ways.Thus, the prints may be exposed deflned in the Oxford English Dictionary). Although the on bedding planes or oo vertical surfaces(commonly both) terms'hypichniaY'epichnia' (Martinsson 1970; Hàntzschel 'hyporelief'/'epirelief' and the heterolithicand homolithic sequencesprovide varied 1975) and (Seilacher1964) are more ruRASSIC DINOSAUR TRACKSAND TRACKWAYSOF THE CLEVELAND BASIN. YORKSHIRE

Sulace print Underprint

B1 A1

AE B2

=t= i];

:

Flg. 5. Schematic diagrams illustrating the mode of formation and preservation of $rrface pdnts (A), underprints (B) and transmitt€d pritts (C). Dashed lines represent homogeneoùs mudrock; horizontal lines represert laminated or thinly bedded sediments. ,Exploded, diagrams it the base of each type show possible preservational variants depending or level of splitting. normally used to describe the preservationof invertebrate 4.L Surface print (track) (Fig. 5, A-A3) traces,they provide useful additional terminologyto irdicate the position of the track with reference to the block on which When Thulborn (1990, frg. 2.1) presented his 'simplified rt occnrs.Leonardi in Casamiquelaet al. (1987)presented a model' to explain the preservation of dinosaur tracks, he full discussionof the terms and methodsused in describins essentially described atype that \ve I'ould refer to as a 'surface vertebtatetracks. print (or trac9'. Fu her to the statement above, a surface & M. A. WHYTE 192 M. ROMANO

clawsand fleshysheaths (Fig. ?). In a felv sauropodPrints, a print may be deflnedas a Prinl that isprcserved as a positiveor transmittedshear cone of sedimentadheres to the underside correspinding negativefeature on the bedding sulace on which of the pdnt (Fig. 7). thefoot wasimpressed duing îootpriht foftnation

et aL (!999), who compared footpdnts of modern I-ockley& Meyer (2000,fig. 1.9). Gatesy srounà-dwellingbirds with Triassic theropod tracks Asdigits Surfaceprints accoldmost closely with the sort of footprínts irove forward their clawsmay pull through the sediment other soft that peoplà are usedto seeingin beachsands and surface leaving claw drag marks, which exaggeratetheir print will substrates.It is commonly assumedthat a surface length. record most accuratelythe foot shape and other morpho- Ms Ruth Hughes(an undergraduaterecipient of a Nuffield logicalinîormation on the producer,and indeedexamples are Foundation Research Bursary, University of Sheffield) known from the fossilrecord where details of skin impressions

marksat the tips oÎ digits. able outline (Fig. 8A, B). The chancesof either tlace being However, the movementof the foot, the nature of the sub- presewedin the natural state as a sudaceprint is very low- surface strate and the subsequenthistory of the print-bealing àn accountof the minimal reworking necessaryto destoy all of striae yet also affectthe surfaceprint characters.The plesence surface traces, In intermediatg moisture conditions the the (ca on the sidesof the pri;t during footptint formation reflect imprints of cla\r,sand claw drag marks, and even palts or all may 198 mechanicsof Îoot emplacementand withdrawal and so digits, may close entirely or partially after the foot has of exa be usedto reconsfiuctthe foot and even the limb dynamics Thesemay be recognizedby lines of closureand -on"d on. fea of the maker. The examplesof stuiaeobserved in the York- stft be def

SW Britain. The phenomenaof collapseof the margins of MA\ry of foot emplacementor withdrawal.Observations by digit imp.ints has beer observedby one of us (MAW) while ng emu locómotionshowed that similar striaeYvere made du recording surfacefootpdnts of emus at Chester Zoological (Fig' 6)' foot entry. On one specírnet oÎ Deltapodus brodricki Gardens. two sets of cross-cuttingstriae are plesent that apPear to pdnt-bearingsurface may also show the surfaceexpres- record both foot perÌetration and withdrawal movements The effects.As remarked by Thulborn (1990' Foot insefiion in this specimen,as deducedftom the striae' is sion oftransmitted estimated to have been at c. 4M4' to the horizontal' {'hereas foot withdrawal\a,as at a higher angle (53-55')' Both sets of striae slope towards the anterior end of the track and the steepera;gled striaecut the eallier, more gently-dippingset' This would suggestthat, during this gait, the maker's foot in the sedimentrim (Fig. 9) in a few cases'The enteredthe sedimentat a lower angle than at its Ìvithdrawal' micro faúlts the feature and actual meansof sedimentdisplace- Evidenceof foot rotation is seenin deep sauropodpnnts tn shaDeof r"ry accordingto the grain size and water contelt lt which imDressionsof the anterior digits sho$' both terminal ."nt

Ftg.6. Lateral view of pdnt of Deltapodus showing two sets of cross-cutting striae. Antenol the Drint is to the left. SDecimenis f;om me Nab Member, Scalby Formation, northem end E'c. ScaìbyBay. Scale bar is 10 cm long. JURASSIC DINOSAUR TRACKS AND TRACKWAYS OF THE CLEVELAND BASIN, YORKSHIRE 193

Fig. 7. Anterolateralview oflarge sauropodtrack showing imprints of curved digits with terminal claws and fleshysheaths. Note th€ conicàlbulge ofsedÌment on the undersideof the track. Specimenis ftom the Long Nab Member, Scalby Formation, Comelian Bay.Scale bar is 10 cm long. wouldbe imaginedthat sedimentrims are rarelypreserved, sedimentaround the print. Allen (1997)also showed that mar- yet suchstructures have been recorded from the fossil record ginal ridgesdecrease in amplitude downwards;implying that (Casamiquelaer at.798'/,pl. XIX, fig. B; Thulborn& ÌVade well developed/high-amplitudemarginal ridges are more 1989,p. 53,fig. 6.3;Thulborn 1990. fig 2 2). However,in these Ìikely to represenl surface(or near-surface)features. If this examples,the preservation of scdiment rims as a surface wasthe case,the prominentmarginal rims aroundlarge sauro- featureis impljedrather than proven.Allen (1997)demon- pod tracks (Fig. 10) near the baseof the Long Nab Member, strated that surfacemarginal ridges(rims) of sedimentcould south of Scarborough,may be good indicatorsfor thesebeing be produced experimentallyand resulted from subsurface surfacetracks. Howeyer, the inwardly dipping malginsof the deformation (marginal fold) forming a positive ridge of rims indicate a transmittedeffect (see below) and these are,

ExPerimentalsurface prints of a model foot impressedrnto damp (A) and satùrated(B) sand. 794 M. ROMANO & M. A. \ryHYIE

'a occosíons be partly thus, more likely to be near-surface prints. Tucker & 513) remarked, shafi may on several 'pushed-aside' ìE upPer erosively Buchette (19?7) have described sediment frtted panly or wholly emptíed and Port ' from presurned surlace preseryations of Triassic dinosaur modifed before final buriat is achíeved' prints ftom South Wales. (Fig 5, B-B5) Although surface pdnts are perhaps the easiest to under- 4.2, Urderpdnt (Unilertrack) recogmze stand in terms of formation, tlley can be diffrcult to An underprint may b e defiied as theprint that is rcvealed by a of pdnt-bearing surfaces is, unequivocally. The recognition bedding-parallel or sub-parallel lracture, which does not it identifres tlle actual surface on howèver, important since exactly coincide wíth the Prínî and pùnt-beaing suÚace but accurate recon- which the footprint was made and, thus, allox's which inîersectswith it in such a way that pon and/or counler- moved structions of the palaeosurfaceson which the animals paft shov,)both the original substrate bnd the sediment WL The initiation and the palaeoenvironmentsin which they lived. Underprints are a particularly common a[d very vafiable way qacks and the presence of mud radiating out from the track in which prints may be exposed and many of the Yorkshire may provide of rain imprints on the hack and adjacent surface dinosaur tracks are displayed as underpdnts. Because of the HoweYer, it co[firmatory evidence of the original surface. common marked lithological contrast betxTeen the original may have must be bome in mind that the print and surface substrate and the infill, they can be very striking in appearance prior to their being been modified by other erosive events though, itr some examples,difficult to interpret. coveredby the inf,lling sediment.Indeed as Allen (1997' p' In someunderpriots, splitting may coincideat leastpartially with the surfaceof the print (Fig. 5, 84) so that someaspects of the print morphology, such as pads and nodes and the Dresenceor absenceof claws,can still be observed'However, iince some parts of the Print will still be obscured, measured dimensions may be different from the true dimensions of the surfaceprint,In other cases,the ftacturemay transectthe infrll ofthe print (Fig.5, 85) and the print surfacewill be seenonly in section,Again, dependingon the level of the closs-sectron, it will be difficult to record reliable dimensional data from such underp nts and the amount of morphological information that canbe recoveredwill alsobereduced. However, the char- acter of the infill sediment,as discussedbelow (section4.4), may be observed. Features of the Pdnt-bearing surface will also be obscwed,though its position rnay usually be distin- guished to one side of the ftacture. Underp nts were descdbedby Thulbom (1990'p' 26) on the basisof printsthat hadbeen made and preservedin a lami- nated sediment.As he noîed, splitting along the laminae at successivelydeeper levels \ryouldreveal progessively lessof the infill, In extreme cases,\ryhere the ftacture surface meets only the deeper parts of the print, the underprint may be reduced to showing only a single digit (usually digit III) or eveD just the tip of that. Where the print has been made in laminated or heterolithic sediment, this may show hansmitted effects of the types discussedbelow (sections 43 & 4.4) and is a common associateof Yorkshire underprints (Fig 11)' Fig,9. Footprint of a dog made itr damp sand on a beach Note the this can, howevet, also be observed in homo- raised iú of satrd with surface dacking alound the Posterior Underprinting nargin of îhe footprint. Scale bar is 10 cm long. geneoùssubstrates (Fig. 12)

fìg.10. Raisedrims arourid large (sauropod) tracks ftom Îhe Long Nab MeÉber, Scalby Fomiatiotr, Cometian Bay. Length of hammer 30 cm. Tbese Íacks were frsî Doi[ted oùt to tbe authors by Mr Paul EDsom ruRASSIC DINOSAUR TRACKSAND TRACI

4.3. fransmifteal pdnt (tr8cù) (Fie. 5, C-C5) A transmitted print may be defned as a print thot dísploys the dÍstortion of sedimmts and bedding plnrcs below the surfdce on h'hìch the lootprint was impressed (after Ensom 19E2,p- 1.41i 19't13,p. 201 a.nd 1995, p.78i Thulbom 1990, p. 27). Synonyms for this preservational type include'ghost tracks', 'undertacks' oî 'subtrace' of Sarjeart (1975), Mossmatr & Sadeant (1983), Irckley (1991ú, fig. 3.1), Lockley & Hunt (1995, fig. 1.11) and Lockley & Meyer (2000, fig. 1.9). Transmitted prints are most connonly observed in heterolithic/lamioated sediments and the ftequ€ncy of this character in the non-marino sedimetrts of the Ravenscar Group provides numerous examples of trarsmitted prints. These are revealed as localized disturbances resultiDg from soft-sediment deformation and reflerting the outline of a print (Figs 13, 14). Such prints generally become more shallow and ill-defned with depth belon, the print surface. The character of the traDsmitted features may be indicative of the state and nature of the substrate (section 4.4).

Tridactyl underprirt (moryhotype Bir, Fig. 20) showing fansúitted effecîs from the Long NÈb Member, Scalby Formation, Black Rocks, Scsrborougtl Figured by Whyte & RoEano (1981, frgs 3, 4) (udveEity of Sheffield specimen number F0076ó). Priùt is 14 cm long.

Tridactyl (morphotype Bú, Fig. 20) atrd other incoEplete Ftg.13 Tracing of laninae of a trarsEitted priùî, shoúing (fude priÍt underpritrts showing claw oa*s. Gisthorpe Member, oùdire and irdicaîioDs of digit impritrts. Saltwick Forúation, Cloughton ForEation, YoDs Nab. Scalebal is 10 co. I-ong Bight, a 500 m east of East Pier, Whitby, 796 M. ROMANO& M. A. WHYTE

^i:A E g=

Fir

aI oÌ io ol Fig,15. Cut vertical sectiori of print in rock showingiúdisîinctly cl beddedin6[ of middledigit, and transmitted effects. Uppet part of sectionis extensivelydinoturbated. Long Nab nl Member, ScalbyFormatiotr, Bùmi$on Bay. Thicknessof br Fig.14. Transmittedpnrt îrom the Saltwick Formation,Port sectionis 9.5crn. (Univenity of Sheffieldspecirtren rumber Mùlgrave.Scale bar is markedin cenlimetres. F00861). d,

Although common, the value of transmitted prinîs in assess- particular the morphologicalinformation that \yould haye a ing the morphology of the foot and the possible maker is bea ng on the possibleprint maker,it Ìyill usuallyclearly show ratber Iimited, since the margins of the digits are normally not therelationshipbetweel the print and thc sedimentinto which d, clearly defiled. Although general characters of the foot such it has been impressed.Where the sodimentis heterolithic or o' asnumber and divarif,cationof digitsmay be determined,it is laminatedit may be possibleto distinguishwhether the foot normally impossibleto obtain accuratemeasuements of digit baspunctured (or rupturedsensu Ensom 1995)through layers p, imp nr length and width. Despite these limitatio$ in ichno- or whether it has dragged layers down and deformed/com- p, taxonomic studies, transmitted prints provide information on pressedthem as the footprint Ìvasmade. In section,deformed sl track abundance, occuÍence and, to a more limited extent, laminae commonly sho,r, charactedstic downward U or V- diversity. Trackways composed of transmitted prints will still shaped deflections where a digit has depressed and/or dis- 3. allow crude estimations of locomotion speed and gleno- rupted the sedimentary laminae. Sectional views will also acetabularlength (distancebetween shoulder joint and hip allow the extent and character of other transmitted effects, r1 joint), although the inevitably vagueprint length (or width) including marginal folds, shears and microfaults to be exam- ci obtained probably will intoduce significant sources of error. ined and described. These features will be a function both of u the movement of the foot, size of the animal and of the state tl of the substuate.Allen (199, p. 483) suggestedthat it may be ri 4.'1, Oblique and veÉical seclions necessaryto have two nomenclatures in order to describe and rl In explaini[g the nature of surface pdnts, underprints and differentiate the anatomical (track-specific) charactedstics d transmittedprints, it has been convenient,paradodcally, to from the sedimentary deformation features causedby the foot a illustate these with diagams (Fig. 5) showing prints in emplacement. The condition of the substrate may be deter- tl section. However, in natual exposuresr oblique or veficaì mined from the deformational features (plastic and brittle) in d sectionscan be extremely important in understandingpriot the sediment, \,vhich thus may provide information on the tl formation since they can sho$, clearly the relationships water content, tenacity and shear strength. Transmitted effects between the original substrate, the print and print-beadng nay range frorn a few cantimetres in depth (Fig. 11) (\ryhyte a surface and the infilling sediment. Serial vertical sectioning of & Romano 1981) down to over 0.5 m belolv the surface on si pdnts in the laboratory 15)has helped to shedimportaot \trhich the footpdnt was made (Fig. 16,4, B). @ig. r| light on aspectsof print preservatiotr (c., Avanzini 1998). The characteÉ of the infilling material may also be inshuc- si In oblique and vertìcal yìo.ws,the print and print-bearing tively displayed in sections. It is commonly a.ssumedthat a F surface are usua.llyentirely, or almost entirely, seenin section. phase of drying out and hardening is necessary before sedi- ir Although this may obscure cefain aspectsof the print and in ment infill (Thulborn 1990), but in many prints the infill ruRASSIC DINOSAUR TRACKSAND TRACK\VAYSOF THE CLEVELAND BASIN YORKSHIRE 197

--..t'-*-

- ---t-=--

Fig. 16. Field photograph (A), and drawing (B), oI a vetical section throùgh a print ir sitt, showing transmitted effect dow! to c. 0.5 m below the print-beadng surface. I-ong Nab Member, Scalby Formation, near Lofig Nab, nofh oî Bumiston Bay. Scalebar in photograph is 10 qri.

appea$ to have been inìtiated with an i[flux oI sedimentat, closer to underprints, they lack any innll within the digit or very soon after, foot withdrawal. This may be virtually imprints and there is no simple term for this case.We suggest 'collapsed instantaneousftom the slumpingof unconsolidatedsediment that a term such as print' might be used for this type on the sides of the footprint or from the surface, resulting in of print. chaoticallybedded structuresforming the fill (Fig. 15; also Allen 1997,frg. V$. At other times, the infill appearsmore homogeneous,yetalsopoints to a rapidfill, sincethe print may 4.5. Dinoturbation be up to 0.5 m deep (Fig. 16.4,B) and with vertical sides.It is We include this type asa sepatatecategory, although the sedi- very unlikely that sedimentwhich wassaturated enough to be mentary fcatures present may include some of the types deformed to a depth of 0.5 m was able to maintain vertical describedabove. The Ìyord lvasfust coinedby Dodson er a/. facesfor any length of time and indeed,as earlier indicated (7980, p. 229), with reference to dinosaur trampling of the (section4.1), collapseof digit walls and partial or complete substrateand was defired by Lockley (7991b,p- 215) as a closure of digit and claw imprints can take place and be 'tramplíng and dísturbance of soils and substrates by detectedin unusuaìlynarrow and/or irregular infills and by dìnosaurs'.In the senseof the term used by Dodson ef 4l overhangson the digit walls. (1980),extensively dinotùrbated beds are a relativelycommon Less rapid infilling may come from sedimentbeing trans- featurc in the non-madne rocks of the Saltwick, Cloughton ported over the substratesurface. Theoretically, it should be and Scalby formations, The typically sandstonebeds com- 'loaded' possibleto identify this processsince sedimeritary structures mooly show planar tops and very uneven, bases such as qoss-lamination, parallel or low-angle lamination (Fig. 18). Thicknessof individual units vary considerablyand would be presentin the infill (e.g.Whyte & Romano 1995,flg. dinoturbatedbeds interbedded between thick mudstoneunits 3). Intraclasts,if present,may result from suctionas the toot in the Long Nab Member, in Gdsthorpe Bay, may vary in waswithdrawn, caving in of footprint walls or later erosionof thicknessbetlveen 1 m and 0.5m within a very shol distance. the print-bearingsùrface (Whyte & Romano 1995).In a few The intemal structue of these beds is also variable and in cases,the infill sedimentsho\À,s indistinct laminaethat teflect some instancescomposite. Thg tlvo extremes are illustrated by the filling of the print, yet are commonìytoo vagueto identify beds that still retain taces of disturbed bedding but also the process.In its qudestform, this maybe indicatedby indis- contain underpdnted backs (Fig. 194, B) $,ith or without digit tinct and $'ayywisps of carbonaceouslaminae. In somecases, drag mark, to completely homogenized beds with only rarely the larninaeare more complote and may show a distinctiYe recognizable tracks and digit imprints. A few dinoturbated downwardcurve. This feature is more readily seenin section beds have been colonized by pla[ts and the deformation struc- and may be better observed by vertical serial sectioning tures are cut by sub-vertical rootlets, indicating colonization throughthe specimen;the exampleillùstrated (Fig. 15) shows after the bedshave been [ampled. Lockley & Conrad (1989) digit III with downward-curvedlaminae within the infill and irhoduced a'Dinoturbation Index'that could be used to transmitted effect adjacent to this digit imprint. denote light, medium afld heavy kamplirg of the subsftate surface.This index emphasizesareal distribution rather thaD A number of prints seenin sectionshow complexdisturb- depth of disturbance and the limited areal extent of bedding ances within which there is evidence of deep digital impres- surfaces withiq the Yorkshire sequences do not permit a sions that have completely closed up 17A, B). The @ig. detailed assessmentof this Dinoturbation Index. However resulting surfaceprint is a shallow depression,like those of some relatively small exposures indicate that in places the simulated prints made in saturated sediment (section 4.1; 'heavy'. index would certainly qualify as Fig. 8B), Plan viewsof levelsbelow the surfaceand intersect- 'localized ing with the digit traces would appear similar to, alld could The soft-sediment deformation' within the sand- 'meander easily be confused with, transmitted prints. Though perhaps stones of the basal Long Nab Member b€lt' (section M. ROMANO & M, A. WITYTE

I

.i

-'i

.J

lì'

at

?ì Fig. 17. se Fietd phoîograph (A), ard drawing (B), of a vertical tu sectioú through a collapsed print, showing af transmitted effect and micro-faulring down to neaÌly in 0.5 m below the print-bearing surface. Loose block, Saltwick Formation, Long Bight, c. 500D east of East Pier, Whitby. Scale bar in photograph is 10 cm. trr pr ul

th R 'n pr re di

m bj

sa di

dt th fi& 1& th Ditrotubated bed, showing planat tOp and deepty di 'loaded' base. LoDg Nab Member. Sca.lbv rh Formation, Cometiatr Bay, Note person for sc€le. n( ruR-A.SSICDINOSAUR TRACKSAND TRACKWAYSOF TIIE CLEVEI-AND BASIN' YORKSHIRE 799

rig. 19. Field photograph (A), and drawing (B), of dinoturbated bed with utrderprinted tracks and disturbed bedding. Loose block, Long Nab Member, Scalby Formation, Gristho.pe Bay. Scale bar in photographis 10 cm.

3) may result fÍom trampling by dinosaursin watet-saturated periods herald the rise of sea level (and presumablyhigher sediments.These featùres are distinctfrom the typesof dino- ìeater table) prior to the Eller Beck aud Scarborough marine turbation descdbedabove and, though they rarely preserve incursions respectively. Therefore, the sediments of the any details of foot morphology, are important in providing coa-stal plain complex of the Cleveland Basin may have information on dinosaurhabitat. becomemore saturatedwith ìvaterjust pdol to inundation by the seaand thùsmore susceptibleto p€netrationand reìvork- In the slightìy broader unde$tanding of the term dinoturba- ing by the feet of dinosaurs. tion usedby Lockley (1991à),included are somebeds that are particularly characteristic of the Saltlvick Formation. In these units,bedding surfaces may be coveredwith subparallel,elon- 4.ó. Trackwap gate grooves or corresponding ridges that record the raking of Since the prints of a trackway have been made by a single of swimming dinosaurs (Whyte & the substrate by the îeet aDimal, they can be of use in helping to unde$tand aspectsof surfacesmay be so Romano m02). At times the bedding pdnt preservation. In particular, anatomical characters may be completely distwbed by raking prints as to be classined as distinguished ftom other sourcesof va ation. This may be ot 'heavy'in Lockley's(1991b) Dinoturbation Index.The raking importance in ichnotaxonomic studies. Whyte & Romano p nts are commonly aligned (Whyte & Romano 20OZ) at)d (2002), for instance, ascribed differences in print morphology record the unidirectionalmoyement of numerousswimming in a pair of pdnts to substuatedifferences. Trackways can also dinosaurs. This type of dinoturbation contrasts with those indicate whethor the maker was moving bipedally or equally surfaces that may record the heavily diloturbated quadrupedally, though in the latter case it must be borne in rnore curvilinear (?random) trackways produced for exarnple mind that fore and hind appendagesmay be imptessed into the by a single animal while drinking or foraging for food. It is sediment to different depths. With certain gaits, animals Ìyofih noting that though the Dinoturbation Index may be the moving quadrupedallymay also superimposeol registel hind sameon both swimmingand tramplingsurfaces the depth of footprints on top of fore footprints with potentially confusing disturbance is usually very small (<5 cm) in the former case. consequences for print morphology and ichnotaxonomy Locktey & Hunt (1995, ftg. 7.\ attempted to quantify the (Whyte & Romano 2001). degree of trampling, ircluding dinotùrbation, throughout the Phanerozoic, but it is difficult to equate our records with the tends they suggest.However, it was noticed that heavÙ 5. TRACK DIVERSITY dinohubated beds are particularly common towards the top of the Saltwick and Scalby îormations. The reasons for this ate Firstly, it is important to state clearly the aùthors' approach to rlot apparent, but it is interesting to speculate that these the identification and ultimate naming of fossil tracks and 200 M, ROMANO& M. ,\, W}TYIE

ichnotaxa BrontopodLs, trackways.The aulhors believethat tracks (vrith their corle- represent at least three distinct

believelhis to be the most easilyapplicable and leastcontre may be explainedby morphologicaldiffelences in the lateral versialmethod of ichnotaxonomy.This approachis also con- digitsofthe foot ofthe maker (differentlengths, divarification sistentwith that adopted by workers on invertebratetraces or curvature),while in othere\amPles the asymmetry may be (e.g.Hàntzschel 1975; Pickerilt 1994).However, it is import- better explainedby preservationaldifferences Thus, although ant to distinguish preservational v4ri-4.4s'-trg9k!-l!l3!-!gl9 the lateral digit imprints in the figued specimenof Bir (Fig. been interDretedas havingbeen modifiedby sedimenlary 20) showsignificanldifferences, these are consideredto reflect processes dewatering.distortion or cLosureof digit lscouring, real differencesin the foot, sinceeach digit ímprint is termi- imprinfs, etc.) and to excludethese from any JQ!n!4-!omen-- natedby a clawprint and independentcu ature-However, it clature. would be unwiseto assumemorphological differences in the For descriptivepurposes the tracksftom the Middle Juras- lateral digils for specimensBvii, Bx-xiv, where the distortion sic rocks of Yorkshire have been convenientlyarranged into and incompletenessof the digits (pafiicularly in Bxii) may be (Fig.20, B andC) lhal arebased on morpho- by prese ation- Finally, morphotypesBvii -ÉiìóGnathreeeroups A, better explained inferredbehavìoural characterisúcs. All the oul- and Bxiii show similar featuressuch as rounded heel margin lines are taken from aatualprints recordedin the field by the and quite divergent lateral digit impdnts. Yet they differ in authors.Thus, thosetracks that have been made-byhabitual that the central digit is longer in the former and naÍows quadrupeds(Fig. 20, A'i-v) are distinguishedfrom thosethat anteriorly in the latter. It is conceivablethat the central digit 'aie the result of locomotion by tridactyl bipeds (Fig 20, impressionof Bvii may havebeen produced by the dragof the Bi xyi). The finalgroup (Fig.20. Ci vii) includean arrayof middle digit in the sediment, but at this stage this is not tracksand track$aysthat are characteriledby havingindi- regarded as the most likely explanation.Since the ngured vidual tracks consisting of parallel to subparallel digit morphotypes of BYii and Bxiii differ by more than one impdnts, \ryhichare interpreted as having been made by character.it is prelerentialto leavethem as separate lyPes for animalsduring swirnming. The majority ofthe morphotypesin now. To summarize,for the prints in Group B, thesestudies all threegoups representpes (hind foot) prints.Malus (iore- have not yet clearly distinguishedin all casesbetween rue foot) prints are known for two morphotypeswithin Group A morphotypesthat me t ichnospecificstatus ('track-specific' (Fig.20, Aiii and -4.v)(Romano et al 1999;Whyte & Romano and 'behaviouraÌtypes') and preservationalvariants. Yet it is 2001), while only one unambiguousmanus-pes couple is believedthat of the 17 morphotypesf,gured under this group, figured(Av). MorphotyPeBxvii is a ratherenigmalic race and at leasthalf may representdislinct ichnolaxa.Some of the tri- may rgPresenteither a manusol a pes prllll dactylmorphotypes may be closelycompared with previousÌy describedand f,gured ichnotaxa. For example,a Pdnt from the The morphotypes(Fig.20) wereselected Îrom our database Saltwick Formation described and identified by Sarjeant as representingdistinct types that may be distinguishedfrom (7910)as Sampliasaurusdsocenídzei Gabouniya, 1951, could one anotherby at leasttwo characteristics,such as lengt! and be assignedto morphotype Biii, whereastypes Bv and DÉii shapeof digit impdnts, divarificationof digit imp nts, pres- showfeatures in commonwith'Grallator' and'Eùbrcntes' ènceoî claw marks and phalangeaVdigitalpads. As such,they respectively(Lockley & Hunt 1995,fig- 4.6).The naming of arereasonably well-defined tyPes to which mostofthe present someor all of thesemorphotlpes will be addressedin subse- database and, hopefully, newly collected prints may be quentpapers when the morphotypeshave been fully analysed. assignedwith a good level of confidence(see Appendix) So In the meantime,the Appendix (seealso section7) indicates thal a workabletaxonomy and nomenclatureof prints may be thosemorphotypes already assigned to ne\ryor existingichno- established,the validity of these morphotypes in terms of taxa. ichnotaxaneeds to be resolved.In other words, do the 29 morphotypesrecognized lepres€nt 29 ichnospecies? The tracks and trackwaysincluded in Group C are dom! behavioural pattern The morphotyPesincluded withir Group A (Fig. 20) have nated by morphotypes that reflect a of the foot. The alr€adybeen studiedby the authors(Whyte & Romano 1993, rather than the anatomicalcharactedstics and' although this 1995,2001; Romano er aL 1999) ar'd the reasonsgiven for behaviouralpattern is one of swimming to the nùmber of func- recognizingfive morphotyPeswill not be repeatedhere Thus activity may still yield infolmation as (and manus), the true in this group it is believed that the different morphotypes tional digits in the pes occasionally

so far from the non_marinefocks Fig. 20. (opposite)Diagrams, taken from actualspectmens, showing the fangeof track mofphotypeslecognized of the morphotypes,details o[ the RavenscarGroup. l he rreegroups of morphotypes(A, B, c) aredefined in the text.Brief descriPtions detefminedor suggestedhere) are of their geographicallócation, st.at-igraphicaì position and raxonornicassignation (where.previously C, t]?es Civ--Cviare assignedto given inìhe Alpenrli*. All types inlroups A and B are regardedas dinosaurianin origin ln Group , to Group B and GroÙPC' crocodìliansand Cvi to chelomans.líorc the scalebar for Group A is differentfrom that conrnon JI'RASSIC DINOSAUR TRACKS AND TRACKWAYSOF TIIE CIIVEI.AND BASIN. YORKSHIRE

6

Bi

Bxii Bxiii Bxiv Bxv Bxvi Bxvii A- !\ A A UUYy -.Jtt :Pz r' w R Cv

r\,I oèà N 04 c

l0 ":Guó \\ Cvii (:J 2m M. ROMANO& M. A. WHYTE

generally sParse shapeof the foot and angleof divarificationof the digits are communitiesis to be obtained.Data are on in not recorded.The sevenmorPhotypes figured are considered the gowth rate of dinosaursand the same is tfue the probably to representas many ichnotaxa, but at this stageonly dinosaurtrack record.Olsen's (1980) growth series model (see Anchkauripus one (Fig. 20, Ci) has been formally named as-Charrcichnos discussionon Olsen'smodel of the Gtallator' 1995,pp trídrctytus (Whyte & Romano 2002). ln view of the approach arrdEubrontes $owth series in Lockley & Hunt gowth hind ìthztve-adopted in naming these vedebrate ichnites (see 120-121)appears to illustrate allomet c in the Lockley above).it is conceivablethat the sameanimal (or species)rnay foot (basedon tracks)ofsome Jurassictheropods, but havebeen responsible for making tracksnow includedin both & Hunt (1995) disputed this conclusion.The ody definite groùps B and C (for exampte morphotyPes Bxi and Ci; see morphotype from the Jurassicrocks oÎ Yorkshire that this (38) investi- section7). Includedwithil this group are tuacksconsidered to studyhas found insufflcientnumbers tobe ableto possiblegrowth es..is have been made by qocodilians (Civ-Cvi) and chelonians gare se \3,.?f*l!!p,t!E-!2!!# (Cvii). Thesewill be describedin later publications. Whyte& Romano(1993, 1995.2001). The rangein morPho- typesassigned to Deltapodusbrodrícki is quite varied (Fig.20, been provisionally Thus, 29 different morphotlpes haYe Av, andFig, 21), but all showthe diagnosric fealures ìisted by possiblyrepresent , identified that, the autho$ believe,could Wtyre a Romano(1995, p.24). The lengthand widtho[ pes to be true it i approximately15 disLinctichnotaxa. For this of D. brod.ríòEíaerc-plottedon a scatter diagram to we-re fprints would need tb be cqú#Red that rhe morPhotyÈe! growthseries of this ichnotaxon(Fig.22). Although vqr:arE- (see {recordthe';inconclusive, Jìeithererected on the basis of preseryeliolal in view of the paucity of small p nts, the distd- part an ònto- iÈ-oie) n6i thui i*o oJ more may represent ,o-f trution of points indicatesa linear relationship and not the morpho{ypesmay geneticgrowth serieswhereby prints of two allomet c growthsuggested by Olsen(1980). The rarity of pes (seebelow). These gradeimperceptibty ovel a givensize range príîfs of Deltapodus brodicki smaller than 20 cm in length the full extent of the studiesso far have not frflally resolved and the apparentabsence (or non-recognition)of suchprints tridactyl tracks, importanceof preservationin the Yorkshire under 8 cm in length, is rather enigmatic. Four possible play important role io deter- but it is clear that habitat will an reasonsfof the absenceof very smallprints are that: (a) such ìvork that the mining final pdrt types. Laboratory simulation prints have not been recognized;(b) they have not been ple- and continued by a authors initiated for Ms Ruth Hughes served;(c) juvenilesof ft'e Deltapodusbrodrícki maker lived clearly demonstrated former student, Dr Phil Manning, has in anotherhabitat, outside the study area;and (d) on birth the pdnt pleservation.Current the influenceof substratet)?e in Deltapodusbrodricki maker was alreadyof a sizeto produce authols' postgraduatestudents work being undertakenby the prints oi the minimum sizeobserved. The lack of Preservation and Simon Jackson Danny Elvidge (morphometric anatysis) of the p nts is difficùlt to prove,but smaller (lighter) animals of tracks) at the Uni- (experimentallaboratory simulation will not producesuch deeply impressed footp nts and so their directed versity of Sheffield,is extendingthese studies and is presewationalpotential is low. However, tridactyl pdnts, less classificationof tridactyl to\vardsa better understandingand than 10 cm in length,are not uncommonin similar lithofacies morphotypes. and despite their different shapesuggest tt'at smaller Deltapo- preserved.The possibility that The recognitionof $owJ! seriesis alsopertinent if a formal d,,J prints should have been ichnolosic nomenclatureis to be erected and a full under- juveniles lived outside the present area exposed along the standini of the true diversityof the Yorkshiredinosaur Yorkshire coastcannot yet be proven.The final possibilityis ,6J

,\/ \_-_-,' c "-[.

1995ftom the Saltv.'ickFormation (A-I) aíd Scalby Fomation Iìg.21.' Range of morphotypes of tracks of D eÈapodus brodrickí V.t:ntle& Romano, (2001,frg- 1; note that this print is coúposiîe, and is (fy. [a-O, f-g ."" Wnyt" & no*uno (2001,fig.3). (E) seeWh]te & Romano just ùierpreted as i registered track ìthere the manus and pes tracks are superimposed). (J) from soùth of Cromer Point, Scalby Bay lower ' part oî Long Nab Member,Scalby Formation. ruRASSIC DINOSAUR TRACKSAND TRACKWAYSOF THE CLEVELAND BASIN' YORKSHIRE 2.43

Delapodus brodrickí

aao

st'o atk a ota* * a pes o a a 7zo

il Scalby Formation CloughtonFormation FiC./2. Scatter diagraú showing plots of pes length against a Formation Saltwick pes width for 38 speciEelJ.sof Deltapod.usbrcdricki 0 Whyte & Romano, 1995. SpecimeDscollected from the Saltr{ick, Clotrghton and Scalby forhations as L (cm) iddicaîed.

that on birth (either ftom an egg or by a viviparous mode of gacite than the print of the other dimorph. Some authors (see reproduction) the juvenile Delmpodus maker $,as of a size Sampson199, p. 390) have suggestedthat in dinosaursthe where the pes was approximately this minimum observed larger, more robust,skeletal form representsthe female but, lorgth. If this was the casethen the longost (c. 48 cm) recorded when Tresise (1996) rccogllizedlhat Chirotherium úacks com- Delnpodus príú was six times as long as that oî the hatched monly fell into two categories,slender and stout, he tentatively juvenile. If the gov/th series of Olsen (1980) is correct attributed the former to the female and the latter to the male. (Lockley & Hunt 1995,flg. 4.6), then the length of an adult As Iockley & Meyer (2000,p. 59) stated, the subject remains bipedal tridactyl pes track may be over 25 times as long as that conkoyersial. While the autho$ are not in any position to be of a juvenile. This is a considerably larger ratio than that able to suggest possible sexually dimorphic variarts in the presently sho},n fot Deltapodus and suggeststhat we would tlack record irom Yorkshire, the possibility that among the expect to find smaller pes prints of the Yorkshire ichnotaxon. morphotypes recognized (Fig. 20) there may exist at least one Comparisom with other dinosaus (Chure et al. 1994; C-atper:. sexualdimorph shouldnot be dismissed. ter 1999)also indicatethat juvenilesshould have existedthat A final consideration of dinosaur tuack dive$ity from the were of a size potentially able to produce considerably smaller rocks of the Cleveland Basin concerns the apparent absence prints than the single observed 8 cm long example. Thus, it of tail drag marks. There are no convincing records of grooves would have been expected that more and smzllet Deltapodus associated\a,ith isolated Íacks or hackways that may be inter- prints have if the young had lived in the would been found preted as disturbances resulting from the contact of the tail of same area and habitat as the adùlts. It is noteworthy that a dinosaur rvith the sodiment surface, Tail marks were briefly Deltapodus priris are relatively rare until they reach a length discussedby Thulbom (1990,p. 89) and l-ockley (1991b),who c.28 cm (Fig. 22\. Above this length, they are much more oî pointed out the radty of sùch traces. The reasons for their abundant, This may indicate either that tho preservational rarity, or absence, may be due either to animals generally potential significantly improves after footprints (and associ- lifting their tails clear of the gound, or that any tail contact increase in body reach a critical size, or that ated weight) with the substrate was rarely sufficient to disturb more than mature juyeniles are joining the adult populations living on the the sudace of the sediment and thus anY tlace would have a coastalplain. At this questioncannot be conclusively Fesent, low preservationpotential. resolved. A potentially important aspect of track dive$ity concerns the possibility of sexual dimorphism. ComparisoN u'ith extant 6. TRACK DISTRIBUTION AND ABI]NDANCE vertebrates suggest that it is probable that some dinosaurs exhibited sexual dimorphism (Sampson1997, p.389). Such Vertebrate tracks are arguably the most characteristic feature dirnorphism may have resulted either in characteristic orna- oi the Ravenscar Group. Far ftom being confined to a few 'footprint ments,for defeDceor weaponry or sexual display, as suggested restricted horizons, such as the Burniston bed', they 'non-marirc' for the bom-faced dinosaws (Dodson 1996,p. 23), or may are found within the lithostratigraphical udts at have expressed itsolf itr body size and shape. If this was the almost every level wherc there are suitable lithological con- case,then it might be exp€ctod to show up in the icbnologic trasts. Indeed bedding surfaces which lack any evidence of reco{d where the print of one sex is smaller and possibly more vertebrate activity are in their own way noteu,orthy. Tracks m4 M. ROMANO & M. A. \ry}TYTE

'marine' eyen occur within parts of some units, thus empha- the rocks alone ('Whyte & Romano 2002). Swimming and td- sizing the sùbtle and intimate inter-finge ng of different dactyl tracks are also found on the upper surface of the unit. facies.However, becaùse of the restrictionsof the exposures, The 'swimming bed' of the logged section can be traced the faciesvariations and the problemsof track preservation- laterally in the cliffs near Whitby and is seen to die out both distribution oî velebrate tuacesis difficult both to quan- the eastwardsand westwards.At its westernedge it is markedly despite the large databasethat has tify and to summarize dinoturbated. \rylereas at its eastern extremity, on the eastem beenaccumulated. already side of Rail Hole Bight, it is oYerlaPpedby a slightly higher Establishingîhe distributíonoI the various track morpho- sandstore unit containing sauropod Prints (morphotypes Ai types (Fig. 20) \rithin the Ravenscar Group is almost entirely and Aii, Fig. 20) (Romano et ul. 1999).Similar lithologiesto 'swimming dependenton the detailed sedimentologicallogging of suc- the bed' reappearin the vicinity of Saltwick Bay cessionsand oî theiî ìn siîu tracks. In favourablesituations, and mayhave been the sourcebed for someof the looseblocks tmckson looseblocks may be tracedback to sourcebeds, thus noted by Brodrick (1907)in his tust recordsof dinosaurfoot- exterding the data set. The processis illustrated by three pdnts. Kendal (1908)and Kendal & Wroot (1924),however, 'DeltapodLts - 'Un examples(Fig. 23) taken from the lower part of the Saltwick related them to the svndstone' io bed'leYel pa Formation. Sedi- (Fig.23, A), in which they had recognízedprints. As noted by Forrnation and from two s of the Scalby 'Unio mentologicalinterpretation of the logs and deterrninationof Hemingway (1974), the bed' caî be lraced up to 4 km the faciesand habitat u,ill be addressedin a latet publication- SE of Wlritby and it is intcresting to note that Deltapodus has been recordedin loose blocks ftom low in the Saltwick For- The lower part of the SaltwickFormation at Whitby shows mation at Ravgnscar.A varied assemblageof úacks has also dinosaurtracks occurring in three contasting sandstoneunits beenrecorded fiom the lolvestpa of the SaltlvickFormation (Fig. 23, A). Onty the lowest of thesebeds is relatively easily at Port Mulgrave (Fig. 2), 12 km NW of \ryhitby, but the sand- accessiblein the cliff and in all three units, prints ate most stonedominated succession is diJficultto relateitr detail to the obvious in fallen or slumped blocks. The lowest bed, for Whitby section. 'heterolithic conveniencerefered to informally as the bed' long beenknown to occuron the base (Fig. 23, A), is a laminatedunìt of finely interbeddedsand- Dinosaurtracks have 'Burnistonfootpdnt bed' (Fig. 23, B), in the I-ong Nab stone,siltstone and mudstoncpenetuated by vertical rootlet of the Formation (Hargreaves1913; Black el structures. This unit has indeteminate sauropod prints Member of the Scatby 1994).In the past,fallen blocksftom (Group A morphotypes)at its base (Romano er al 1999). dt 1934;Ivens & Watson on the shorebut haYenow Theseare cuEently the oldest,stratigaphically well-located, this bed were relatively common 'heterolithic by collectors.These prints, which pdnts in the RavenscarGroup. Within the bed' been destroyedor removed of tridactyl prints (e.g. Fig. 20. Bix, Bv), and particulady towards its top there are disturbed layers includeseveral types frorn different levels within the which, when seenin plan view, reveal the presenceof both appear to be underprinting a comploxinternal structurewith dpPle Deltapodru(Fig.20, Ay) and tridactyl hansmittedand under- basalbed, which has p nts occur in at least prints (Figs23,24). cross-laminatedunits. Above this bed, two other levelsÌvithin this sandstone(Fig. 23, B). The lower 'heterolithic Above the bed', the secondunit is a cross- of theseis a thin dinoturbatedlayer with underpdnted digits beddedmedium-grained sandstone (Whyte & Romano 1993, îrom ildeterminate clawed tridactyl prints. The upper level 7994) with Deltapodrir, irideterminate tridactyl and svtimming also hastridactyl prints (type BLl, Fig. 20) preservedwithir a prints only on its base (Frgs 23, U\ The unit is informally sideritizedsandstone and thus showingboth underpdrt and referred to as the'Deltapodus sandstone'(Fig. 23, A). The hansmittedfeatures in a relatiyely uncompactedstate. prints of this unit include the type material of Dehapodrts At the steps(Crook Ness),ín the middle of Bumiston Bay, brodrícki (Whyte & Romano 1993, 1994,2001) and are the 'Burniston footprint bed' is soparatedftom underlying impressedinto silty mudstonescontaining the fresh-water curent-beddod sandstonesby 6 m of mudstones and silt- bivalveUnio, which is reputedto bo the earliestoccurrence of stones, ìyithin which trlo thin datk carbonaceous beds form unionaceansin Europe (Kendall & Wroot 1924).Sidedtized usefulmarker beds.Defrnite tacks haYenot been detectedifi mud clastsin the baseof the sandstoneshow that someerosive thesemudrocks though some large disturbancesmight be due modif,cation of the pdnt-bearing surface may have taken to dinoturbation,About 40 m north of the stePsa lenticular place. sandstoneappears c. 1 m beloìYthe'Burniston footPdnt bed'. 's\ryimming The third sandstoneunit, the bed' (Fig. 23, A), This sandstone,which is affected by shrinlage qacks, contains is a composíteunit composedof a number of ripple cross- indeterminatetddactyl prints that underprint to its base.The 'Burniston bedded,fine-gained sandstonelayen with dinotubated inter- footprint bed' can be taced both norÈhwardsand faces and a few thin mudstone partings. The basal sand layer southwards in Bumiston Bay. However, detailed logging has infilled a sauropodtackway (morphotypeAiv, Fig. 20; showsthat to the southitpinches out and is replacedatslightly Romanoer al 1999)and abovethis there are intemal surfaces different levels by other similar sandstoneswhich also contaio with a complex of surface, transmitted and underprinted tridactyt prints.Work is still going on to relate track-beadng tracks (Whyte & Romano 2002). This ichnoassemblageof surfaceswithin thesebads. Farther south, bctween Cromer swimmingand tridactyl morphotypesreveals a more complex Point [030928] and ScalbyNess [037911], the successionhas environmental history for the unit than can be deduced frorn been cut by a number of channels(Black et aL 7934;Naní &

Fig.23. (opposite) Stratigraphical logs of three selectedseqùences within the RavenscarGroup of the Clevelald Basin, sho{ing print morPhoÎypes and horizons. A - basal part of the Saltwick Formation (composite section); Rail Hole Bight, 700 ú east of Whitby Pier. B - middle Part of Iong Nab Member (basal 'l,evel Bedded Series'), Scalby Formation; BumistoD Bay, immediately north of Crook Ness. C - uppermost , panofLong Nab Member, ScalbyFomation;Gristhorpe Bay ruRASSIC DINOSAUR TRACKSAND TRACI(WAYs OF THE CI.EVEI.AND BASIN, YORKSHIRE

-.\

Ò

- MofphotypeA - sauropod

- Morphob,peA - DeLapodus Ò - MorphotypeB

- MorphoBp€C m6 M, ROMANO & M. A. W}TYTE

QUADRUPEDS TRIDACTYLBIPEDS SWIMMING e B c g È g Jlilii I'iiliv lv j| | | |fiIivIv Ivrlurlu'rltr|r IdlriilFilnvlBlnilw' | | n lÍ llv lv lvl lùi s ÈlÒlololol0Èl"odúlúl0lúlúlúl Vlúlolúl rblolslslol sMlùl$lnddtilù v x f - z -:J ;ilÌ- 2 LONG NAB MEMBER == I k ^i5 d| 4ó MOORGBI-T 4 MEMBER EJ

SCARBOqOUGH FORMAIION o + (,tr z GRISIHORPE 6 MEMAEB o IE 'E ? 4z :: t) z t= fr MEMBEFI \€ :

ELIIR z 3 SALTWICK z -<,f

:.2

Fig. 24. Radge chart showitrgîhe distribution of vertebrate tracks (Groups A, B and C) from the Middle JurassicRaveriscat Group of the Cleveland Basin. Vertical bars to the right of the log indicate where lhe tracks have been found m Jit or traced to thet odgfual stratigaphical level (shof ba$), ot found loose and have not been accurately placed within the sequence(loúg baÌs). Also shown are occuFeD@sof crocodilian walking tracks, switrlming traces of fish (Urditfind) and dhosaurian bone.

Leeder 1978)and the sequenceson either sideof the channel- ornithopod (reasu Weishampelef a, 1990). We have recently fitl depositsare difficult to relate to eachother. Both tridactyl discovered a 13 m trackway (Fig. 26), now rather degaded, 'Jackson and Group A morphotype prints (Fig. 20) have been located occurring approximatcly 530m SSE of the Bay' wiîhin the channel deposits and on their upper surfaces. At hackway. Although the tracks in this latter úackway are pre- Cromer Point a within-channeltuackway oÎ Group A (sauro- servedas tuansmittedfeatures, with indistinct margins,their pod) prints is alignedorthogonally to the channelaxis. Else- large size (up to 1m long) and generally rounded outline where within this channel,dinosaws have moved on sloping suggeststhey Ìveremade by a sauropod. sediment surfacesand caused downward displacementof sand, and one of the post-channelfill units has been com- In contrast the ùppermost parts of the l-ong Nab Member pletely dinoturbated. at Gristhorpe are largelymudrocks and siltstonesbut inclùde a number of thin (1-2 m thick) sandstonebeds, which have The upper parts of the current-beddedsandstones (Fig. 23, been so highly dinotubated that primary sedimentarystruc- B) are in placesdisturbed and in Bumiston Bay thesecan be tures have been almost completelyobliterated (Fig. 23, C). seento be due to large transmittedt dactyl prints (possibly The basesof thesebeds have commonly been loadedinto the related to moryhott?e Bi, Fig.20). Large siderite nodules underlying finer sediments.Recognizable prints in these beds within thesesandstones contain indeterminate Íidactyl pints are all Group .4.prints (Fig. 20) though it is possible that here, (also recorded by Ivens & Watson 1994).Smaller tddactyl as elsewhere,large bipedal dirosaurs were also involved.The p nts have been detected in cross-beddedunits slightly highest of these sandstones,a sand-dominatedheterolithic farther north and in places p nts show evidence of having unit, is lessmarkedly dinotubated and is the sourceof some been made on sloping surfaceswith downward displacement impressivedeep sauropodpdnts, Immediately above this, ofsediment.Farther to the south,between Bumiston Bay and smallindeterminate tridactyl pdnts are presentin a thin, thinly Scalby Ness, these units contain not only a range of tridactyl bedded sandstoneand are the highestshatigaphically well- prints but also a number of prominent tackways. The well- locatedprints in the coastalexposures ofthe RavenscarGroup 'Jackson known 11 m long Scalby Bay or Bay' track$,ay (Fig. (Fig.23, c). 25; morphotype Bi, Fig. 20) consistsof 9 tracks (track number 4 is missing)of a northwardmoving bipedaldirosaur (Delait The above threc case studies iìlustate graphically the sort & Sarjeant1985, fig. 3; Ivens& Watson1994, p. 13;Rawson & of information ftom which the distribution chart (Fig. 24) has Wright 2000, fig. 26). This trackmaker may have been an been constructed. In this. the different sandstonesat the base JURASSICDINOSAUR TRACI(S AND TRACKWAYSOF THE CLE\€LAND BASI\ YORKSHIRE 20'1

of the Saltwick Formation at Whitby (Fig. 23, A) have been plotted separatety to reflect the type of data that may be deriyed from individual horizons. Elsewhere in the chart (Fig. 24), however, entries have been pooled to provide data for parts of the succession.Th€ volume of data at different leYels is uneven and the diverseichnoassemblages in the Saltwick in the mid-Scalby Formation are a coDse- N Formation and quence of the gteater areas of exposure of these units and a% perhaps also of our having given more time to their study. Despite this possiblebias in the data, some interestingcon- clusionscan be drawnabout the distdbutionofthe major mor- photype goupirgs within the RaYenscarGroup. Though seldomwell enoughpreserved and displayedto be assigned to one of the four televant Group A morphotypes a0, (Fig. 20, morphotypes Ai-Aiv), sauopod pdnts are wide- spread thoughout the RavenscarGroup. As noted above they occur in severalbeds within the lower part of the SaltlYick Formation and have also been recolded from beds,some of which are extensivelydinoturbated, in the upper part of the Sa.lt\À,ickFormation at Hayburn Wyke. Within the Cloughton '.r0o Formation they have been recorded by us from both the Sycarham and Gdsthorpe members including, from the latter member, the very striking pes and manus prints in a highly carbonaceous mudrock or irnpure mal, which have been infilled by a white sandstone.Saffopod pdnts havealso been 'marine' recorded Ìyithin the Helwelh Beck Member of the ScarboroughFormation. However, they are perhaps most charact€risticof, and abùndantin, the Long Nab Member of the Scalby Formatior (Figs 7, 16). They occur within and particularly on the upper surface of the'CùIrent Bedded 'I-evel Sandstones'and also within the BeddedSeries'. In the latter they are presentboth Ìvithin lenticular channel sand- stones and also in sheet sandstones,which are commonly o0o completelydirioturbated. In conhast, tlte othet quadrupedal track maker' which formed the prints assigled to Deltapodus brod cki (Whyfe &' Romano 1993, 1994) and which was most probably a stegosauriandinosaur (rÙhyte and Romano 2001)' is most characteristicand widcspreadwithin the SaltwickFormation' É. However, the ichnogenusis not restrictedto this formation ÈE# (Fig. 24) and has been found in both of the non-marine members of the Cloughton Formation and in the Scalby For- ma|lon (Ftgs6,27,22). Iodeed the smallestDeltaPodus pliît, which hasso far been documented,comes ftom the Long Nab Member of the ScalbyFormatior (section5). ,,,00 Tridactyl pdnts are widely dispersed throughout the ,equ"n"" but, b"""use ofthe problemsofpreservation, the full disiribution of the various morphoBpes is particularly dimcult to establish.Recotds, such as those for the SaltwickFormation (Fig 24), show as a whole or for Pafs of the Scalby Formation a wide range of morphotyPes.Some common morphotypes (suchas Bix; Figs11, 20) appearto havea long statigraphical cu, ìange and sugÈest that there has been broad constancy of

(JUO

movemellt is towards the north' 204 M, ROMANO & M, A. WITYTE

to be definitelyrecorded from this formation.Interestingly, no ate tridactyl prints from the Cleveland Basin which are as large a5 tha the megalosauridprints recorded ftom the Bathonian of fro Odordshire (Day 20O2)have been recorded yet. Rarer, ù et al. the but distinctive, morphotlpes such as the bird-like morphotype (10 (Fig. 20, Bxv) or the 'chubby'p nt, morphot)?e (Bxvi), d.ri. inevitablyhave more sporadicand restrictedoccurences (Fig. figl 24). th€ tra Swimming prints occur throughout the Ravenscar Group ml: but are most characteristicof and most diverse in the pel (Fig. coveredwith the Saltwick Formation 24). Surfaces dis- der a tinctive parallelraking marks of swimmingdinoturbation are Lo also apparentlyrestricted to this uoit. Not alt of the swim- tef the Saltwick Formatioo ming traces recorded from are mÉ in particuìar, morphotypes necessarilydinosaurian and, Civ hir 'D) to Cvii (Fig. 20) were probably made by crocodilians or che- Mi lonians (see section5). The distinctive swimming type Civ, with its hooked digit imprints, has a-[sobeen recordedfrom the Yons Nab Beds at Cloughton Wyke wiîh associatedtri- ifit dactyl dinosaur prints (type B indet.), though these might have underp nted from a different surfacelevel. Swimming Pr traces, recently recorded frorn the Long Nab Member at st) Bumiston, may alsohave been madeby a crocodilian,and we EX have recordedwalking pdnts of a qocodilian from the Long p€ Nab Member (Fig. 24). A trackway of moryhotlpe Cvii îÌom tri UD the SaltwickFormation of Port Mulgave providesone of the IO few instancesof a body or tail drag-mark, though not of ln dinosaurian origin. The scarcity of swimming taces other fri than in the Saltwick Formation is, however, striking and (1 suggeststhat there was a distinct envfuonmentaldifference tn between the Saltwick Forrnation and other pa s of the ot RavenscarGroup. Perhapsthere were more ìyater bodiesin (1 O\'/ z: trampled the Saltwick environment or flooding events were more persistent.This might also be consistentwith the upward Li trend for increasedaridity recognizedby Morgans(1999) and tri Morgans et al (1999).Curiously, traces that can confidently ls be linked to the activity of flsh are almost entirely absent AT 6-F ftom the Ravenscar Group and the only possible example of B the sinuous trace Undichno Ìvas noticed in a mudrock ftom IE thc Gristhorpe Member (Fig. 24). Pt AI ? It has become customary to refer to 'large' (I-ockley & 'megatracksites' Gillette 1989,p.5) or (Lockley & Hunt 1995, îa p. xiv) when referring to areas where large lumbers of P( tracks/track\yayshave been reliably documented. Such a tracksite has arbitrarily been defined as one in rÀ/hichat least D 1000 tracks or about 100 trackways are present (Lockley & ol Gillette 1989).Although these sites are invariably laterally ju extensiye,the pdnts may be confinedto thin 'tlack rich zones' o or occurthrough a 'significantlythicker' sequence(Lockley & Hutt 1995,p.297). Fig.2ó. Sauropod trackv/ay exposed near high water mark, Scalby c( Bay [03169152],c.530m SSE of the hackway shoqú in Does the Middle Juassic of the ClevelandBasin qualify fr Figure 25. The trackway is presewed on a sand bar within for such a title? ln terms of numbers of tracks there is no a\ chaflnel sandstonesof the Long Nab Member (Scalby doubt that the c 200m thick non-marinesequence (Rawson ÍI Fomation), and consists of al least 12 aliFed transmitted & Wright 2000), extending for approximately 10,000kmz pr prints with the direction of movement towards the southeast. (Bradshawel al 1992,p. 117),contains well in excessof 1000 al The distance apart of the prints dedotes a'wide-gauge' tracks. This number has probably aìready been exceeded nl (Fa trackway ow 1992). from observationsmade by the authors over the past ten s( years. As a crude esîimateas to the number of tracks and N bipedal dinosaur populations throughout the Ravenscar trackways that are present within the 57 m thick Saltwick 0 Group. However, though some large indeterminate tridactyl Formation, p nt data ftom the'Deltapodrri sandstone'dis- ù prints have been recorded ftom the Saltwick Formation, it is cussedpreviously has been used. All trackswere recordedon p noticeable that the two largest tridactyl morphotypes have yet fallen blocks. The bed (0.85 m thick), in which these ichnites d ruRASSIC DINOSAUR TRACKS AND TRACKWAYSOF THE CLEVELAND BASI\ YORKSHIRE zo9

aIe preserved, extends for 100 m along the cliff. Assurning 7. DINOSAUR DTVERSITY AS thzt the n recorded tracks ol D. brodricki were recoveted DEDUCED FROMTHE TRACKS from a 2 m wide band that had fallen from the cliff and that populationsthat were the unit has a lateral extension of approximately 10,000m2 The divenity of the dinosaur Presentin (100 x 100m), then approximately 1350 tracks oÎ D. bro' the Yorkshfue area dudng the Middle Jurassic,and which gave in the rocks of drícki occnr in 1.5% of the Saltwick Formation. If these dse to the range of tÉck morphotypesfound it is figureshave any meaning,then cleatly the Middle Jurassicof the Cleveland Basin, remaitrs to be addressed.Althoùgh 'mega- the Cleveland Basin would qualify for such a title as a not intended here to discussthe likely maker of each mor- the facksite'. If other beds had been chosen,such as the'swim- photype,sone generalcomments are requùed to indicate ming bed' (Whyte & Romaro 2002),where up to 20 tracks possible range of dinosaur R?es and communities that inlab- per r* are not uncommon (and cornrnonly a far gleater ited this Middle Jurassiccoastal plain and fluvial complex. density), then estimateswould have been ordels greater. Despite the obviousathactions and desirabilityof assigoinga Lockley & Hunt (1995,p. 154-5) arguedthat megatracksites maker to eachtype of tack, the autho$ concul with others tend to be associatedlyith the boundaries between fol- (Farlow & Chapman1997, p. 538) that only rarely will this particùlar 'sometype of unconformityor prove possible.Indeed Allen (1997,p. 51'4)concluded that mationsand in v/ith 'unchallengeable hiatus'. The authors have noticed no such associationin the only a yery small petcentageof pdnts yield Middle Jurassicsequence of Yorkshire. taxonomic inJormation'about theh make6 However, even though the assignation of track morphotypes to makers at Whether the Middle Jùrassicof the ClevelandBasin qual- specificor genericlevel will generallyremain an unobtainable 'megatacksite' ifies as a with respect to numbers of track- goal, the authors belieYe that recognition of the maker ways is less certain. Undoubtedly extensive hackways ale occasionallymay be achievedat leastto family level. present in the Yorkshire Middle Jurassicsequence but the style and extent of exposuresmakes it very unlikely that Three major groups of pdnts have been recognized (Fig. examplesof herding (Lockley & Hunt 1995,fig. 5.20),stam- 20), based on a cornbination of morPhological features of the pedes (Thulborn & Wade 1979) or even very tong single prints and inferred behaviour of the maker (section 5). trackways(Santos €l a/. 1994)will ever be recordedftom the Implicit in this classificationis the acceptancethat morpho- rocks of the ClevelandBasin. The ftequency of tlack layen types ftom t\ryodifferent $oups (Group C and A or B) may in a sequencemay also be used to gauge the numbers of well have beenmade by the same(or sametype of) animal. trackspresent. Lockley (19914,figs 8.3, 8.5), Lockley & Hunt The morphotypeswithin Group A (Fig.20, Ai-iv) are those (1995,flgs 5.18,5.47) and Lockley & Meyer (2000,fig. 7.13) made by habitual quadrùpeds.They indicatethat at leasttwo indicated frequency of print layers at Yarioussites through- different typesof sauropodwere probablypresent at this time out the world, using logs on a vadety of scales,and Ensom (Romano ef al. 1999). Îhe BrontopodLls-type (Fig. 20, Ai) (1982,p.I47;1995, p. 80) recognizedftom ten Print laye6 in wide-gaugetrackways have been regardedby Farlow er al 25 m, to four (?five) print layers in 0.332m in the Purbeck (1989), Farlow (1992) ard Moratalla eî ol. (1994) as having Limestone Group of southem England. The frequency of beenmade by brachiosaurs(a camarasaur).wllile the narrow- track layersin the non-marineunits of the RavenscarGroup gauge trackways aÎ Brcviparcpus-type(Fig 20, Aii, Aiii) is at times directly comparableto that recorded by Ensom, indicate a different sauropod group with limbs that were and in the Long Nab Membet at the northern end of angledinwards (Farlow 1992).There is even the slight possi- Burniston Bay, at least nine pdnt horizons have been bility that a third sauropodtype may have been presentand recordedin a heterolithic sequencejust over one metre thick' that it is representedby the morPhotypesho\ryn here as Type Prints tend to be much more abundantin heterolithic facies Aiv (Fig.20, and flg. 3D in Romanoel4l 1999).The localized and along junctions between contrastinglithotypes (Fig. 23, abundancesof sauropod prints may indicate gregarious A-C), althoughtheir apParentabsence or ra ty in homolithic behaviour. The smallestsauropod footprints recorded are facies may simply reflect the reduction in preservational about 0.5m in Ìyidth, i.e. aPproximatelyhalf the size of the potential. largest saùropod prints and the lack of smaller pdnts is We concludeftom the aboYediscussion, that the assignation puzzlingespecially as p nts of other smallerbipedal dinosaurs of the title 'megatracksite' to the Yorkshire sequenceis are abundant.This may indicatethatjuvenile sauropodslived justified and that the area qualifiesas a site of global import- apaÍ from the adults and outside the depositional basin (Fig. ance. (section5). The final p nt type of this group 20, A'v)' assigned to the ichnotaxon Deltapodus brcdrír:ki ('Nhyfe &. Du ng the couÉe of these studiesthe authors haYe dis- Romano 1995),aPpea$ atplesent tobe endemicto the CleYe- covereda few piecesof bone (Fig. 24) that range from small Iand Basin and is suggestedto be a record of a Jurassic fragments to a nearly comPletg sauropod vertebra. The stegosau an dinosau (Whyte & Romano 2001). The authors, Ìvith Dr Phil Manning, are presently d€scribing this panorama(Fig. 27),therefole, includestwo sauropodspecies material. In yiew of the abundanceand divelsity of dinosaur and a stesosaurian. prints, it is perhapssurprising that dinosaurskeletal elem€nts are so rare in the Ravenscar Group. An important factor in the non-preservation of bofle may have been the acidity of the soils and groundwate$. Interestingly,the global record of Middle Jurassic dinosaur bone is also extremely sparse (Romer 1966;Weishampel et aL 1990;Benton 1993)and this underlines the intematioral importance of the Yorkshfue possibly Bw (Fig' prints in helping to determine the nature of contemporary morphotypes Biii, Bvi, Bix, Brii, BÉv and dinosaurcommunities. 20) all 210 M. ROMANO& M. A. WHYTE

print preservation(see sectioq imprints and so may be distinguished (on a morphologicaV sedimentand a shallowlevel Íe (Fig. n)' a minimum of four taxonomicbasis) ftom thoseprints with rounded digit ends' 4). Thus, in this panorama cI( provisionally recognized as The former are consideredto have been made by thelopod bipedal dinosaurs have been two theropodsand two dinosauN, whereas the latter ale proYisionally attributed to iDhabitantsof the ClevelandBasin; 'theropod by large and srnau ornithopods. ìWithin the morphotypes', it is possible ornithopods, each t)?e being represented 'gracile' M to furthèr distinguish more slirùy built forms (such as forms. 'robust' 'Omitho- re Bú, Bix, Bxiy, Bxv) îrom more forns (Biii) p2 C (Fig.20) are pod morphotlpes' have been recognized on the basisof broad The morphotypesinclùded Ì,ithin Group 1 tacks resulting essentially from a swimming behavioural al6t i-ptints, at a tne absenceof claw marks; morphotypes Bi I b( pattern. As such they are all characterized by possessing and Bitinustrate this type. Another feature that may be used U that do not yield much useful to separatesubgroups .r'ithin Groùp B is the presence of for- parallel digit scratch malks pl Some were probably made by admals wardly and evenly tapering digit imprints. In particular, mor- taxonomic information. pr in groups A or B. For example,morpho- photypes BÍ, Biii, Bv and Bxvi show this particularly well. The alreadyrecognized F interpreted as having been made by a divarification of the digit imprints is another possibly usetul type Ci has been ti dinosaur whose more normal walking tridactyl hack has charactedstic that may ultimately prove useful to diagnose IT (Whyte & Romano 2002) and may be morphotlpes. The extremes of total divergence of the outer already been described la large,straight to curveddigit hacesof Cii digiti are represented by morphotypes Bxii (subparallel) ard assignedto Bri. The tÌ in size with those of Av and could possibly Bxv (broadlysplayed). The latter are amongthe most distirc- and Ciii compare l! traces of a Jurassic stegosaurian tive tridactyl prints from the ClevelandBasin and compale represent the swimmirig e The four other morphotypesin this group (Fig. 20, with the birdlike track of Lockley & Hunt (1995,fig. 4.338)' dinosaur- sl having curved digit imprirt ter- Rare specimens erhibiting well-marked metatarsal imp nts Civ-Cvii) are characterizedby tÌvo or four digits. These are con- are represented by morphotlpe Bviii. Although distinctive, rninations and/or imprints of to be examplesof non-dinosaurianprints and could this morphotype may be either a plantigrade behavioural sidered tl crocodilian (Civ-Cvi) and chelonian (Cvii) variant or, more likely, the result of deep penetration in the reDresentboth h

; r I I I I I

ry;-FWr

Middle JÙrassic.Representatives of Îhe Fig. 27. panorama showing possible dinosaur coúmùnity that inhabited the Cleveland Basin during the (tù,o tpes; D, E), orniîhopods (two followirg goups oI ditrosaurs are included: saùópods (two tlpes; A, B), stegosaùid (c), thercpods ' qles; f,-Ó. ei.o hcluded are examples of a crocodiliatr (H) and a cheloniar (I)' ruRASSIC DINOSAUR TRACKS AND TRACK'WAYSOF THE CI.EVELAND BASIN, YORKSHIRE 271

tracks (Fig. 27). The authors have specimens of undoubted Where morphotypes are sufficiently Ìvell-known and with crocodilian walking tracks and these, together with the adeqùatematerial, they arc assignedto a namedichlotaxon; examples in Group C, will be described at a later date. unce ainty is indicated by inverted commas. The morpho- types have been provisioqally divided into three main groups present position We afe not at in a to discuss Yorkshùe (A, B, C) for descriptive purposes only and are not intended way. To Middle Jurassic dinosaur communities in a meaningful to be indicative of an ichnological classification.We fully need to be a certainty that recognize a cornmunity, it Ìvould appreciate that morphotypes from two different groups may all rnore or less contempo- particular ichnoassemblages were well havebeen made by the sameanimal. All oudines (Fig. 20) pictue, it would be desirabla to taneous, and to complete the are taken ùom actual prints recorded in the field by the palaeoenvifonments. be able to reconstfuct thg associated autho6. Morphotogical variation (such as divergence of digit recognized and denned, it is Until such ichnofacies can be imprints, size o{ print), geographical location, stratigaphical present pictùre that illusúates a preferential to a combined level and specimennumber ate given for each p nt lvhen generalized habitat. provisional range of dinosaur types in a known. Note that the scale on Figure 20 is different for Group presents rather conserya- Figure 27 the authors' latest, albeit A prints than thosefor Groups B and C. tive impression of the likely dinosaur types that at one time inhabited the coastal plain and fluyial complex of the Cleve- land Basin. This work has gone a long way towards improving Group A poorly kno\yn global record of tha kDowledge of a hitherto Prints included in this group were all made by habitual progress ìtrill undoubt- Middle Jurassic dinosaurs and work in quadrupeds.In a numberofcases (Aiii, AY) prints of both pes picture from edly refine this picture; a that has ernerged solely and manusare known. studies of dinosaur tÉcks and trackìvays. Ai Very large (up to 1 m) sub-oval print Ìdth up to five digit Acknowledgements- Dudtrg où work on the Yotkshire coastovel imprints, commonly backwardlycurved and reducing in size the past 15 years,numerous people, too rnanyto mention by name, from front to back. ('Brontopodus', Romano et al. 1999, fi.g, have contnbuted to extending our database by recording and report- 3A). Jump Down Bight, Whitby; SaltwickFormation. collected. To these ing speciheds they have observed in the field or Aii Very large (up to 0.8m) bell-shapedpes print \ryithup to for îhei! willingness to helP and we would like to express our thanks 6ye digit imprints,commonly curved, along the straight a[te- their finds. However, we wish to acknowledge in particùlar the share rior margin. ('Brevîparopus', Romano et al. 1999, fig.38)- Ensom, our more regular help from Richard Myerscough, Mt Paul JumpDown Bight, Whitby; SaltwickFormation. past and present researchstudenrs (Dr Phil Manning, Damy Etvidge, SimonJacksotr,Steve Hohoyd, Dr Mike Strook,Dl Matthew Porter), Aiii Very large (up to 0.6 m) bell-shaped pes print with up to Byron Blessed,Mr PeterRobinson, M( Nigel Whittington,Dr Robin five curveddigit impressionsalong the ftont margin and down Scott.Stewart Marsdell^ volunteers of EarthwatchInteEational and the outer lateralmargin. Manus print broadly semi-circularin those keen and dedicatedpeople who, on Dumelousgeological field outline, with one or two indentationson antedor margin and 'approximate' parties (Yorkshire Geological Society, British Association for the up to tìvo on postedormargin. Manus placed in Advancement of Scietrce,Geologists' Association, Leeds Geological position; actual relatíonshipnot known. (Possiblepreserva- Associatiotr, Leicester Geological Society, Dinosaur Society, tional variant of Aii. Romano et 41 1999,fig. 3Ci, iv). NW of ShemeldUúive$ity GeologicalSociety), havelettno stoaeuntumed Maw Wyke, Hawsker Bottoms; Saltwick Formation. to ìrncover just otre more specimen. Thatrks are also 'U-shaped' in an attempt Aiv Large (up to 0.5 m) print, with up to five fiIst laboratory extended to Ms Ruth Hughes for conducting oul curved digit impressionsalong the front margin and down the potential. Technical helP er(penmetrts and for showing us their outer lateral margio. (Possible preservational vadant of Aii, AshuNt and BaÍy received from Paul Coles, Mike Cooper, Rob Romano e/ al. 1999, fr9. 3D). Rail Hole Bight, Whitby; wish to acknowledge Pigotî is gratefully acknowledged. Ftually, we Saltu,ick Formation. the genelous support fiom the Numeld Foundation and EarthwaÎch Intemational. Av Large (up to 0.5 m) pes print, generally triangular in oudine;mesaxonic with three shoÍ digit imprints.Some have corcaye inner margin to pdnt and small digit impression on outer lateral margin. Manùs print entaxonic, irregular but broadly crescenticin outline, occasionalinwardly directed APPENDD( ?pollex impression. (Deltnpodus brodricki'Nhyte & Romano, 1995).Hototype figuredF00768; see Whyte & Romano (1995, Given below are brief descriptions of 29 morphot)?es of figs5, 8A). Rail Hole Bight, Whitby; SaltwickFormation. dinosaùrand other vertebratetracks cuÍently recognizedby the authorsfrom the Middle Jurassicof the ClevelandBasin Group B (Fig. 20). Unlessotherwise stated, all the typesrepresent pes made hacks. Alt prints includedher€ are matkedly tridactyl and were by habitual bipads.It is assumedproYisionally that all of the We haye resisted referring to thesedescriptions as diagnoses prints are thosemade by the pes.HoweYer, it is possiblethat since, for the tridactyl tracks in particulal, these studies have some (such as Bxvii) may turn out to be that of a manus. not yet clearly distinguishedin all casesbetween true mor- photypesthat medt ichnospecificstatus ('[ack-specif,c' and Bi Large (up to 45 cm) mesaxonicprint, consisting of separate of a heel behavioural types) and presewational variants. Hence the and radiating oval digit impressions.No indication Scalby For- desc ptions incorporate size terms that ultimately may not mark. Middle of Scalby Bay; Long Nab Member, prove to be important taxonomiccriteria. mation. 212 M. ROMANO& M. A. WHYTE

(?clawed).Distal part of outer digit with Bii Large (up to 35 cm) mesaxonic print, with tapering digit strongly tapered curvature.'No clear heel imprint' Port Mulgrave; imprints and clawlike terminations. I-ateral digits of more or lateral lesi eoual divereence(40"). Nonh end of ScalbyBay; Long Saltu,ick Formation. Uni- 'birdlike' Nab Member, Scalby Formation. (Specimen F00793' Bxv Small (tessthan 10 crn) mesaxonic print' with Yersityof Sheifleld). stongly divergent(c 145")outer digit imprints Digit imprints g"n"*ily sl"t d". and with phalangealpads No clear.heel i'mprint. Scalby Bay; Long NÀb Member' Scalby Formation' Bxvi Small (less than 10 cn) mesaxonic pdnt, with broad and rapidly narrowing digit imprints Rounded heel imprint' Ha1lsker;Saltwick Formation Bxvii Small(less than 10 cm) barelymesaxonicpdnt, with slim digit inprinis only a little diYergent.Possible rounded heel imprint. Port MulgaYe; Saltwick Formation'

Group C prints included here show between 2 and 4 pes digit mahon. All imprìnts that are essentiallyparallel. They are interPretedas Bv Medium (up to 30cm) mesaxonicprint, \Yith narrowing resulting from a swimming behaviour. middle digit irnpressionshowing constuictions (pads)' Ilteral (up to 25 cm) print, consistingof three elongate digitsdiv;gentand apparentlywith roundedteminations (cf' Ci Medium (hypìchnial) dgeswhich may be shaight, gently curYedor ' Eub rontes'\, Port Mulgave; Saltwick Formation' iinuous.The termiqationofthe ridgesmay be sharpor sharply relatively Bvi Medium (up to 20 cm) mesaxonicprint, \Yith teflexed. (Characíchnost dactyllrs Whyte & Romano, 2002)' with slender digit imprints. Outer digits slightly divergent, Part oî holotype úack'ray; see also associatedspecimen in Úacks with ohalaneeJ padi and terminal claws. Some sarnetrackway in Ronano & Whyte (1996,fig' 2c)' Rail Hole Member' iound.O pad-tite heel print. YonsNab; Gristhorpe Bight, Whitby; SaltwickFormation. CloughtonFormation (Fig. 12). Cii Medium to large (up to 35 cm long) pint, consistingol two relatively Bvii Medium (up to 20 cm) mesaxonic print, with (or more) straight, sub-parallel,parallel-sided digit imprints print Digit long central cligit irnprint c.'15o/ool totLal length which aréjoined transverselyat one end.Long Bight, Whitby; evenly terminations evenly lounded. Posterior margin SaltwickFormation. rounded.Whitby; Salt\YickFormation. Ciii Medium (up to 30 cm long) print, consisting of three pdnt with short Bviii Medium (less than 20 cm) mesaxonic curved, sub-parallel,generally parallel-sideddigit imprints Mulgrave; digit imp nts and long metatarsalimpdnt Port which arejoined transvenelyat one end' Long Bight, Whitby; Saltlvick Formation. SaltwickFormation. Civ Small to medium (10-20 crn) print consisting of three short,broad and tapering,para et digit imprints with hooked onds:more or lessstlaight posteriol margin CloughtonWyke; CloughtonFormation. Crocodilian pnnt. Cv Small (less than 10 cm) pdnt, consistingof up to four, closelyspaced (hypichnial) ridges, narrowing laterally and dis- Port Mul$aYe; SattwickFormation Crocodilian mation (Fig. 11). talty iurved. pdnt. Bx Medium (up to 15 cm) rnesaxonicprint, with fairly short and broad digit impressions.Distal part of digit II impritrt out- Ìvardly curved. Pofi MulgaYe; Saltwick Formation' Bxi Smatl (c 10 cm) mesaxonic print, Yrith tapering digit impdnts, divergent outer digits (85-100') and pronounced between triingular-shapedheeÌ pdnt. Middle digit impdnt dilian pdnt. 50-6ó% of toiat print length. Port Mulgrave; Saltwick For- (less than 10 cm) prints, consisting of two short, mahon. Cvii Small taperingdig]t imprints.Other erd swollenand may be joined Small (c. 10 cm) mesaxonic print, with subparallel digit whitby; Saltwick Formation' Bxii 'Grallator')' to aalaceniriOgè. Long Bight, phalangealpads (cÎ Port imprints. Well-marked ChelonianPrint. Mulgave; Saltwick Formation. mesaxonicprint, v/ith Bxiii Small (less than 10 cm) anchor-like REFERENCES taperingdigit imprints and widelydivergent (c 85") outer digit Scalby Bay; Long Nab imprints. Rounded heel mark. ALEXANDER,J. 1986. Idealised flow modelsto predict alluvial sand- Member,Scalby Formation. sionebody distribution in the MiddleJuassic Yorkshire Basin' Maine and PeúoteumGeologf, 3,298 305 Bxiv Small (less than 10 cm) mesaxonic print, with slim and ALEXANDER,J. 1987- S)"ú-sedimeotary and burial relateddeformation wióely rliveìgent (105') outer digit imprirts' Middle digit JURASSICDINOSAUR TRACKSAND TR.A,CKWAYSOF THE CLE\'EI-AND BASIN, YORKSHIRE 273

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