New data on the ankylosaurian dinosaur from the Late Cretaceous of the Antarctic Peninsula

12 Pages·1996·3.9 MB·

by  Zulma Gasparini

NEW DATAON THEANKYLOSAURIANDINOSAURFROM THELATE
CRETACEOUS OFTHEANTARCTICPENINSULA
ZULMAGASPARINI,XABIERPEREDA-SUBERBIOLA&RALPHE. MOLNAR
Gasparini,Z,Pereda-Suberbiola,X.&Molnar,R.E. 1996 1220:Newdataontheankylosaurian
dinosaurfrom theLateCretaceousoftheAntarctic Peninsula. Memoirsofthe Queensland
Museum39(3)583-594. Brisbane. ISSN0079-8835.
AnkylosaurianremainshavebeenfoundintheLateCretaceous(Campanian)oftheAntarctic
Peninsula (James Ross Island). The material includes a lowerjaw, teeth, cervical, dorsal,
sacral? and caudal vertebrae, ribs, parts of the scapula and ilium, autopodial bones, and
armourfroma single small individual.TheAntarcticankylosaurisprobably anodosaurid,
basedon thetoothform.Thefragmentarymaterial doesn'tpermitaccurateidentificationat
the genericorspecific levels, sothespecimens arereferred toNodosauridaeindet. Current
dataonankylosauriandistributionsupportsthehypothesisofalatedispersalofnodosaurids
from the northern hemisphere to the Antarctic Peninsula via South America, although an
early migration during Late Jurassic or Early Cretaceous time is possible. The Antarctic
ankylosaur was small and lived in a high-latitude, although rather mild climate.
Dinosauria, Ankylosauria, Late Cretaceous, Antarctic Peninsula, Gondwana,
palaeobiogeography.
Z. Gasparini, MuseodeLa Plata, Departamentode Paleontologia de Vertebrados, Paseo
del Bosque, 1900 La Plata, Argentina; X. Pereda-Suberbiola, Universidad del Pais
Vasco/EuskalHerrikoUnibertsitatea,FacultaddeCiencias,DepartamentodeEstratigrafia
VPaleontologia,Aparto644,48040Bilbao,Spain;R.E.Molnar, QueenslandMuseum,P.O.
Box3300, SouthBrisbane, Queensland4101,Australia; 16June 1996.
In January 1986, ankylosaurian remains were includes parts ofthe scapulaand ilium, vertebral
recovered during fieldwork by the Instituto pieces, metapodials andphalanges. In this paper,
Antartico Argentino in Late Cretaceous (Cam- we discuss the affinities of the Antarctic
panian) sediments of James Ross Island, north- ankylosaur in the light of the known material.
east ofthe Antarctic Peninsula (Gasparini et al., New palaeobiogeographical data allow us to
1987). This was the first dinosaur to be dis- comment further on ankylosaurian distribution
coveredontheAntarcticcontinent(Oliveroetal., during the Late Cretaceous.
1991). Subsequently, other dinosaur remains
GEOGRAPHICALANDGEOLOGICAL
have been collected from the Late Cretaceous of
FRAMEWORK
the Antarctic Peninsula, including a hyp-
silophodont ornithopod from the Campanian or
The ankylosaurian material wasdiscoveredby
Maastrichtian of Seymour Island (Hooker et al., the Argentinian geologists E. Olivero and R.
1991;Milneretal., 1992)andatheropodfromthe Scassoabout2kminsideSantaMartaCove,inthe
Coniacian or Santonian of James Ross Island
north ofJames RossIsland(Oliveroetal., 1991).
(Molnaretal.,thisvolume).Otheroccurrencesof The remains come from the Gamma Member of
dinosaurs in Antarctica include a large crested the Santa MartaFormation, inthelowermostpart
theropod, Cryolophosaurus ellioti, and a ofthe Marambio Group (Gasparini etal., 1987).
Plateosaurus-Yike prosauropod from the Lower They were recovered from locality D6-1, about
Jurassic of Mount Kirkpatrick, nearer the South 90m above the base ofthe GammaMember. The
Pole (Hammer & Hickerson, 1994). lithology consists of massive green silty
A
preliminary description ofthe ankylosaurian sandstones with abundant trace fossils. The
material and a discussion of its palaeo- ankylosaurian bones were associated with fish
biogeographical implications were given by vertebrae and marine invertebrates, including
Gasparini et al. (1987) and Oliveroet al. (1991). bivalves, gastropods and nautiloid cephalopods
As a result of the preparation of the matrix in (e.g., Cymatoceras). The unusual association of
which the fossils were imbedded, two additional nautiloid phragmocones with the vertebrate
teeth were found. A latex cast was made from a bones could be explained as the resultofstrand-
mould of three articulated cervical vertebrae. ing of shells along a beach (Woodburne &
Other material not described in the first account Zinsmeister, 1984). The ammonite assemblages
584 MEMOIRS OFTHEQUEENSLANDMUSEUM
foundaboveandbelowthedinosaurbedssuggest includingthesides and uppermargin,butlacking
a probably Late Campanian age (Olivero et al., the ventral margin (Gasparini et al., 1987). Nine
1991; Olivero, 1992). alveoli arevisible, includingtheforaminafortooth
The ankylosaurian remains could belong to a emplacement on the lingual side. Theanterior and
singlespecimen,aspreviouslyreported,although posteriorparts ofthe tooth row are missing. The
size differences between the bones suggest the specimen is about 15mm thick and about 60mm
possibilityoftwodistinct individuals.Thefossils long,aspreserved.Inocclusalview,thetoothrow
were recoveredfroma small areaabout6 meters isslightlycurved.Onereplacementtoothremains
square (Olivero et al., 1991). Most bones are inplaceinthefifthpreservedalveolus.Thecrown
fragmentary and have been much shattered by is broken but it looks like those of two isolated
frost action. Preparation ofthe remains was car- teeth described below. The dentary is a thick
riedoutinthelaboratoryoftheMuseodeLaPlata bone, as usual in ankylosaurs (Galton, 1983). It
using mechanical techniques. bearsnoarmour.Fourforaminaarepresentonthe
Collection designations. MLP, Museo de La labial side of the dentary. Medially, the splenial
Plata, La Plata; QM, Queensland Museum, Bris- is missing and so the Meckelian canal is open.
bane; ROM, Royal Ontario Museum, Toronto. Thelackoffusionofthesplenialsuggeststhatthe
lower jaw does not belong to a fully grown
SYSTEMATIC PALAEONTOLOGY
ankylosaur.
Subclass DINOSAURIAOwen, 1842 Teeth (Fig. 1A-H). In addition to the tooth
OrderORNITHISCHIASeeley, 1888 preserved in situ in the lowerjaw, there are two
SuborderANKYLOSAUR1AOsborn, 1923 isolated teeth. Both teeth retain the crown and
Family NODOSAURIDAEMarsh, 1890 part of the root. The maximum crown width is
Genus and species indet. about 7mm and the crown height about 7.5mm.
MtoAotThEiRnIsiAtuL,tEwXoAiMsoIlaNtEedDt.eeAth,paarctiearlvilcoawlevrejratewbrwaitahnda hAisghp.reTsheervteede,ththaeremtoyrpeiccalolmyplaenktyeltoosoatuhriiasn2,0wimtmh
a latex cast prepared from a natural mould of three a leaf-shaped, laterally compressed crown
articulated cervical vertebrae, two dorsal centra from (Coombs, 1990). They bear seven or eight den-
thepresacral rod, partsofthe?sacrum,threefragmen- ticles on the anterior margin and five on the
tary caudal vertebrae, rib fragments, a fragmentary posterior, each row of denticles separated from
scapula,afragmentofilium,fourmetapodialsandtwo the otherby a small apical cusp. The teeth areof
phalanges, andacollection ofdermalelements,repre- about the same size as those of Minmi (QM
senting fivedifferentkindsofarmour.All theremains F18101), but in Minmi the crowns are relatively
tareebrkaedpots,atMtuhseeDoepdaerLtaamPelanttaowdiethPathleeornetgoisltorgaftaiodnenVuemr-- higher (7.5 X6mm rather than 7.5 X7mm) and
berMLP86-X-28-1. only have five or six anteriorand three posterior
denticles. A prominent, rugose basal cingulumis
PROVENANCEANDAGE.SantaMartaCove,north- visible on each side ofthe crown. The cingulum
ePrenninJsaumlea;slRocoaslsityIDsl6a-n1d,,lnoowretrhesaescttioonfotfhetheAnGtaarmcmtiac itshebeltatbeiraldesivdeelotpheadn aonndtmheoroethebra.saMlolryepolvaecre,dtohne
Member, Santa Marta Formation, Marambio Group;
Late Cretaceous, Upper Campanian (Gasparini et al., lingual cingulum is arched apically and thicker
1987;Oliveroetal., 1991;Olivero, 1992). posteriorly. The presence of a two-faced asym-
metrical cingulum is a common feature among
DESCRIPTION nodosaurids,e.g.,Sauropelta(Ostrom, 1970)and
Edmontonia (Carpenter, 1990). The cingula are
Apreliminarydescriptionofthespecimenswas morenearlysymmetricalinMinmi,withoneonly
givenbyGasparini etal. (1987)and Oliveroetal. slightly morebasalthantheother, andthelingual
(1991). Here we describe for the first time addi- cingulum lacks the archseen here.Onthelingual
tional bones, including teeth, vertebrae, parts of side ofthe crown there are a set ofsmall ridges
the pectoral and pelvic girdles, and autopodial (or sulci) that do not correspond with the den-
elements.Becausetheonlyotherreasonably well ticles, but extend from the bases ofthe denticles
known ankylosaurfromthe southern hemisphere tothecingulum, and may becontinuous withthe
isthespecimenofMinmidescribedinthisvolume vertical wrinkles ofthecingulum. There seem to
(QMF18101), detailedcomparison will bemade be slight ridges on the labial side as well that are
where possible with that specimen. continuous with the denticles, but these extend
Lowerjaw(Fig. 11-J).Theonlypreservedportion only a short distance below them, and do not
of the lowerjaw is a section of the left dentary, extend across the entire crown. The pattern of
ANKYLOSAURIANDINOSAURFROMTHEANTARCTICPENINSULA 585
x^i
D
i *!' i 'I
B
H
FIAGn.ta1r.cMtiLcPPe8n6i-nXs-u2l8a-.]A,,aCn,kytlwoosatueertchriannilaalbiraelmvaiienws;farnodmBt,heD,LaltiengCuraeltvaiceewo;ussc(aClaem=pa5nmiman()4ox)f.JEa,mteosoRthosinslIisnlgaunadl,
view;F,distal;G,labial;andH,mesialviews; scale=5mm.I,Leftdentarywithatoothinsituinmedialview;
scale 10mm; andJ, in occlusal view.
586 MEMOIRS OFTHEQUEENSLAND MUSEUM
H
FIG. 2. MLP 86-X-28-1, ankylosaur vertebrae from the Late Cretaceous (Campanian) ofJames Ross Island,
AntarcticPeninsula.A,D, anteriorcervical vertebrainanteriorview; andB,E,leftlateralview.C,Latexcast
fromamouldofthreearticulatedvertebraeinrightlateralview(0.67x). F,twofuseddorsalvertebraefrom
the ?presacralrodindorsal view; G,ventral; andI,J, anteriorviews. H, Caudalvertebrain anteriorview.
Scale = 20mm.
verticalridgeson thecrown isdifferentfromthat (Coombs, 1990; Coombs & Maryanska, 1990).
of Edmontonia. In the latter, the ridges are con- Therootisslightlyincurvedandlinguallyconvex
tinuous with the denticles, i.e., at the margin of in anterior and posterior views. It is separated
the crown the ridges terminate in denticles from the crown by a slight constriction. If the
ANKYLOSAURIAN DINOSAURFROMTHEANTARCTIC PENINSULA 587
FIG. 3. MLP 86-X-28-1, ankylosaur limb girdle remains from the Late Cretaceous (Campanian) ofthe James
RossIsland,AntarcticPeninsula.A,Scapulainarticular(ventral)view.Theinsetindicatesthehumeral(g)and
coracoid(c) articularsurfaces. Medial istothetop. B, Iliuminlateral view. Scale=20mm.
teethbelongtothelowerjaw,theycomefrom the differin detail. The pedicles ofthe neural arches
left dentary (it is likely that they belong to the seemanteroposteriorly thinnerin A/mm/, andthe
same individual). centra are basically amphiplatyan with only
Vertebraeandribs(Fig.2).Abouttwelvemoreor slightly concave (or convex) central articular
lessfragmentaryvertebraehavebeenrecognised. faces.
Most are quite damaged and shattered. A latex Two co-ossified centra (Fig. 2F-G) which
cast was made from a mould ofthree articulated preservepartsoftheneuralarcheswereoriginally
cervical vertebrae (Fig. 2C). These vertebrae are described as sacral vertebrae (Gasparini et al.,
small, with a total length of the series of about 1987: pi. 2, fig. 3). However, the neural canal of
123mm. The fusion of the neural archs to the the vertebrae, as exposed dorsally, seems to be
centra suggests that they do not belong to a verynarrowforthe sacral region. In addition,the
juvenile individual. The best preserved vertebra centraareonlyslightlycompresseddorsoventral-
consists of part of the centrum, neural arch ly and there is no fusion ofthe diapophyses and
pedicles, transverse processes, prezygapophyses parapophyses lateroventrally, as occurs in the
and the base of the neural spine. The centra are sacrals. Accordingly, these vertebrae probably
slightly amphicoelous, widerthan long, and high come from the presacral rod, not the sacrum.
as is common in ankylosaurs (Coombs & They are tentatively regarded as the first and
Maryanska, 1990). The parapophyses are placed second vertebrae from the rod because the ar-
near the anterior border, at mid-height of the ticularface ofthe best preserved centrum shows
centrum in the first preserved vertebra and be- no trace of fusion with another vertebra. Ver-
come moderately higher in those further back. tebraefromthefrontofthepresacralrodofMinmi
The neural canal is circular to slightly oval, and paravertebra (QM F10329) differ in having a
its diameter reaches a third of the width of the neural canal that is less laterally compressed, but
centrum. The transverse processes are short and centrathat more compressed.
oriented almost horizontally. The prezygapo- On the otherhand, the otherfragmentary fused
physes are well-developed and form an angle elements may belong to the sacral region. The
witheachotherofabout60°.Onthebasisofthese more complete specimen preserves parts oftwo
characters, the vertebrae are interpreted as com- possible co-ossified vertebrae, with broken
ing from the middle of the cervical series (see lateral and dorsal attachments. The ventral sur-
Eaton, 1960). face is flat and narrower in the articular region
In addition, an isolated cervical vertebra is between the elements. The specimen is too frag-
known (Fig. 2F-G, I-J).Thisvertebraisaboutthe mentary foraccurateidentification, but it maybe
same size or slightly smallerthan the articulated part ofthe sacral neural arches.
cervicals. The centrum is also amphicoelous and Abouteightfragmentsofdorsalribsareknown.
widerthan long. The neural canal isbroaderthan TheribsareT-shapedtoL-shapedincrosssection
highanteriorly, buthigherthanbroadposteriorly. proximally, a common morphology among
The parapophyses appearto be on the lowerhalf ankylosaurs (Coombs, 1978), although found in
ofthe lateral side. This suggeststhatthe vertebra some otherdinosaurs as well.
comes from the anterior halfofthe neck and was Atleastthreefragmentary caudal vertebraeare
possiblysituated anteriortothearticulatedseries. present. One of them contains a centrum with a
The cervicals are similar to those ofMinmi, but fragmentary transverse process projecting
588 MEMOIRS OFTHEQUEENSLAND MUSEUM
ventrolaterally (Fig. 2H), in anterior view this
caudalsuperficiallyresemblesthatofamosasaur.
Howeveritisamphicoelous,notprocoelous.Two
other caudals retain only the lower face of the
centrum. Ashallow, median grooveandarticular
surfaces for chevrons are visible ventrally. The
centraare veryshortandprobablycomefrom the
anteriorpart ofthe tail. The caudal vertebrae are
all similar in size and could belong to the same
individual.
A
Scapula (Fig. 3A). fragmentary left scapula is
the only recognisable part ofthe pectoral girdle.
It includes the glenoid region but the scapular FIG. 4. MLP 86-X-28-1, ankylosaur manual or pedal
spine is notpreserved. The scapula and coracoid remainsfromtheLateCretaceous(Campanian)ofthe
were not co-ossified. This, together with small James Ross Island, Antarctic Peninsula. A, B, two
size ofthe scapula, suggests that it could belong metapodials; and C, D, two phalanges in anterior
to an immature individual. view. Scale=20mm.
Ilium (Fig. 3B). The pelvic girdle is represented
by a fragment of ilium. The specimen shows a 1987): a)keeled,hollow-basedscutes;b)massive
slightlysigmoidlateralborder.Thedorsalsurface bulgingplates;c)co-ossifiedflatscutes,overlap-
isconvexbuttheventral surfaceisflat.Thepiece ping each other; d) oval, low-keeled scutes; and
probably comes from the central portion of the e) tiny button-like ossicles.
preacetabular—process of a right ilium which—in Several fragmentary plates ofthe first type (a)
ankylosaurs differently to other dinosaurs are known. These are massive, with an irregular
isunusuallytwistedlaterallytolieinahorizontal dorsal surface and prominentkeel Ventrally, the
plane (Coombs, 1978; Coombs & Maryanska, surface is deeply hollowed in the largest
1990). preserved specimen (Oliveroetal. 1991, fig. 2c).
Metapodials andphalanges (Fig. 4). Four frag- These plates were originally regarded as cranial
mentary metapodials and two phalanges are ossifications and so tentatively referred to the
known. The metapodials are broken and lack Ankylosauridae (Gasparini et al., 1987). The
proximal articular regions. They are relatively specimens are too fragmentary to confirm this.
broadandbearmassivedistalarticulations,which Theoccurrence ofprominentlateralhomyplates
oarfethaeppshraofxti(mFaitge.l4yA-pBer)p.eTndhiecumloadrertaotteherolbounsgtnaexsiss oannkytlheossakuurlildsroo(fMairsyaancsoknas,pic1u9o7u7s; cChoaroamcbtesr o&f
of the metapodials suggests that they could Maryanska, 1990) butsimilarstructurescouldbe
belong to the pes rather than to the manus; al- sporadically present in nodosaurids (Kirkland,
though in fact, ankylosaurian metatarsals are pers. comm., 1995).
more slender than metacarpals (Coombs & Thesecondtype(b)ofarmourconsistsoflarge,
Maryanska, 1990). Three of the metapodials rough-surfaced plates (Gasparini et al., 1987, pi.
seemroughly similar in shapebutcomparatively I, fig. 6; Olivero et al., 1991, fig. 2d). Thedorsal
smaller than metatarsals n, in and IV of the surface is sculptured with numerous small pits
nodosaurid Sauropelta (see Ostrom, 1970: pi. and rugosities. The ventral face is irregular and
26). The phalanges are very different in form. hollowed. These plates were originally inter-
One is cube-shaped, slightly asymmetrical in pretedasapossible tail-clubbutthereisnodirect
ventral view, and longer than wide (Fig. 4C). It evidence (i.e. fusion to distal caudal vertebrae)
probably comes from digitI. The other is a very confirming this.
short, disc-like bone (Fig. 4D). It is tentatively The third kind (c) ofarmour consists ofco-os-
identifiedas the second phalanxofdigitIIorin. sified flat scutes overlapping each other and
The disc-like phalanx is about 1.5 times as wide enclosedbysmallpolygonalossicles(Fig. 5C-D:
as the other. This difference in size can be inter- Gasparinietal., 1987,pi. II,fig.4).Thescutesare
preted in two ways: eitherone phalanx was from subcircular to oval in form, irregular in outline
the manus andthe otherfromthe pes, or they are anddevoid ofa dorsal keel. Thispattern resembles
from two different individuals. that of the sacral armour of Polacanthus-ftke
Armour (Fig. 5). Dermal elements are repre- nodosaurids, which are characterised by the
sented by five different types (Gasparini et al., fusion of a mosaic of plates into a rigid shield
ANKYLOSAURIANDINOSAURFROMTHEANTARCTICPENINSULA 589
(Gasparinietal., 1987,pi.II,fig.
6). These ossicles probably
floated in the skin and formed
acontinuouspavementbetween
the large dermal elements per-
mitting supple movements of
the body (Carpenter, 1984). A
histological study of these os-
sicles is currently in progress
(de Ricqles and collaborators,
in preparation).
The new specimen ofMinmi
(QM F18101) also shows five
typesofdermalarmor,butonly
two of them (types d and e
given here)clearlymatchthose
of the James Ross Island
ankylosaur. These kinds seem
to be found in many
ankylosaurian taxa. Minmi
clearly lacked Polacanthus-
like sacral armor, and had
larger(5-6mmdiameter)dermal
ossicles.
DISCUSSION
The general morphology of
the lowerjaw, teeth, vertebrae,
ilium and armour allow confi-
dentattributionofthedinosaur
FIG. 5.MLP86-X-28-1,ankylosaurdermalplatesfromtheLateCretaceous from James Ross Island to the
(Campanian) ofJames Ross Island, Antarctic Peninsula. Osteoderms, in- Ankylosauria. At least three
cludingA-D, overlappedflatplates; andE, F, anoval low-keeled scute in derived characters of
dorsalview. G, skullroofossification?Scale=20mm (0.5x). ankylosaurs (Sereno 1986;
& Coombs & Maryanska 1990)
(Hulke, 1888;Kirkland Carpenter, 1994;Pereda-
are present: posterior dorsal vertebrae fused to
Suberbiola, 1994). As far as known, a synsacral
form a presacral rod, ilium rotated into the
shield could be present in the Antarctic ankylo-
saur but further material is need to confirm it. horizontal plane, and body covered by a mosaic
ofarmourplates ofseveral shapes.
The small to medium-sized scutes (d) are oval
In a preliminary account, Gasparini et al.
in shape and bear a low dorsal keel (Fig. 5E-F:
(1987) tentatively assigned the material to the
Gasparini et al,, 1987, pi. II, fig. 5). They were
family Ankylosauridae on the following charac-
probably situated in longitudinal rows on the
body, as diagnostic for thyreophorans (Sereno, ters: skull co-ossifications with lateral projec-
1986). The ventral surfaces of the scutes are tions, teeth with cingula, andtail-club. However,
generally flat as in nodosaurids (Coombs, 1978). our redescription ofthe material advises caution
Together with small ossicles, one ofthese scutes in regardtothese features. In fact, on thebasisof
has been preserved associated with a dorsal rib tooth form the ankylosaurian remains from the
andossifiedtendons (Gasparinietal., 1987, pi. I, Antarctic Peninsula look more likely to be
figs 3,4). Thissuggests thatthesmallscutes were nodosaurid than ankylosaurid. Coombs &
arranged in an intercostal position along the Maryanska (1990) pointed out that the two
trunk, as in Minmi and generally among families can usually be distinguished on dental
ankylosaurs. features. These authors cited several characters
Finally, there are numerous polygonal ossicles that are useful in this regard, e.g., conspicuous
4mm
(e) ofvery small size, less than in diameter basal cingulum,cingulumtypicallyhigheronthe
590 MEMOIRS OFTHEQUEENSLANDMUSEUM
TABLE L Gondwananankylosaurs.
TAXON AGE PROVENANCE
Nodosauridae indet. (Coria, 1994) Campanian-Maastrichtian Patagonia,Argentina
Nodosauridaeindet.(Molnar&Wiffen, 1994) Campanian-Maastrichtian NorthIsland,NewZealand
NOloidvoesraouertiadl.a,ei1n9d9e1t).(thispaper;Gasparinietal., 1987; Campanian JPeanmienssuRloassI., Antarctic
Mviolnummiep:arMaovlenratreb&raFrMeoyl,na19r8,71)980(Molnar, 1980, 1991,this Aptian-Albian Queensland,Australia
Ankylosauriaindet.(Rich&Rich, 1989) Aptian-Albian Victoria,Australia
Ankylosauria(Chatterjee&Rudra.thisvolume) Maastricht!an Gujarat,India
lingual face, and grooves on crown generally Suberbiola, 1993) nor Edmontonia (Carpenter,
better developed (Coombs & Maryanska, 1990). 1990).Sotheabsenceoffusionofthesplenialand
Allofthese featuresare presentin the teethfrom dentaryisperhapsmoreconvincing.Fusionofthe
James Ross Island and this suggests that they neural arches to the centra indicates that the
belong to a nodosaurid ankylosaur. The differen- animalwasnotveryyoung. Somostoftheskeletal
ces in tooth form and the absence of a sacral remains from James Ross Island are tentatively
'buckler' in Minmi are the clearest distinctions regarded as those of an immature, small in-
betweentheAntarcticbeastandM—inmi.Thusthey dividual. The estimated body length of the An-
seem not to be closely related insofar as we tarctic ankylosauris 3 or4m.
can tell when many corresponding elements are
eithermissing (in theAntarctic specimen) ornot PALAEOBIOGEOGRAPHICAL
yet exposed (in Minmi). The currently-known SIGNIFICANCE
material from James Ross Island is too fragmen-
tary for generic or specific identification and is Ankylosaurs were quadrupedal, armoured
here provisionally referred to Nodosauridae dinosaurs that lived from the Middle Jurassic to
indet. Further material is needed to accurately the Late Cretaceous (Coombs & Maryanska,
define the affinities ofthe Antarctic ankylosaur. 1990). The distribution of the two families is
The geologists who discovered the material probably vicariant. The more conservative
thought it derived from a single partial skeleton Nodosauridaeare known inEuropefromtheCal-
ofsmall size (Olivero, pers. comm.). Only some lovian to the Maastrichtian (Galton, 1983;
ofthebonefragmentswererecoveredbecausethe Pereda-Suberbiola, 1992), and in North America
ice was very thick around the fossils and the from the Tithonian to the Maastrichtian (Car-
bones were broken by frost action. However, penter & Breithaupt, 1986; Kirkland & Car-
revision of the material at La Plata raised the penter, 1994).Theclub-tailedAnkylosauridaeare
possibilitythattwo individualswererepresented. present in Asia from the Bathonian-Callovian to
Thussizedifferencesbetweensomeofthebones, the Maastrichtian (Maryanska, 1977; Dong,
e.g.,phalanges, wouldbeaccountedfor. Also, on 1993), and in North America during Campanian-
the one hand the neural arches are fused to the Maastrichtian times (Coombs, 1986).
centra, which supports the ideathatthe vertebrae Unquestionable ankylosaurs from Gondwana-
donotbelong toajuvenile. But, on theother, the land include discoveries from the Lower
scapula and coracoid (notfound) were notfused, Cretaceous of Australia and from the Late
in contrast to the usual condition of adult Cretaceous ofNew Zealand, South America and
ankylosaurs (Coombs & Maryanska, 1990). Antarctica (Table 1). Chatterjee & Rudra (this
Nonethelesstheseconditions arebothseen in the volume) alsoreport an ankylosaurfrom India. In
skeleton of Minmi (QM F18101) which clearly Australia, there are fiveAptian-Albianoccurren-
derivesfromasingle(articulated)individual.The ces in Queensland, including the holotype of
differences in sizebetween the phalangesmaybe Minmi paravertebra (Molnar, 1980; Molnar &
due to one being manual and the other pedal. So Frey 1987) and a nearly complete, articulated
there is no strong evidence that two individuals skeleton referable to Minmi (Molnar, 1991, this
are represented. volume), and two occurrences in Victoria (Rich
The absence of fusion of the scapula to the & Rich, 1989). Ankylosaurs are also present in
coracoid suggests immaturity, although fusion the Campanian-Maastrichtian of North Island,
does not take place in Hylaeosaurus (Pereda- New Zealand (Molnar & Wiffen, 1994) and that
ANKYLOSAURIANDINOSAURFROMTHEANTARCTICPENINSULA 591
TABLE2. Specimens fromGondwanalandincorrectlyreferredtotheAnkylosauria.
TAXON AGE PROVENANCE STATUS
LoricosaurusscutatusHuene 1929 Titanosaurid sauropod(Powell, 1980;
(Huene, 1929) Maastricht!an Argentina Bonaparte&Powell, 1980)
L(Maamtelteays,au19r2u3s;iHnudiecnuesM&atMlaetlye1y,9213933) Maastricht)an India C(Cohmapkorsaviairttei,th1e9r3o5p;odW,alskaeurr,op19o6d4a,nMdoclrnoacrod&ilan
Frey, 1987)
BrachypodosaurusgravisChakravarti
1934(Chakravrati, 1934) Maastrichtian India Stegosaur?(Galton, 1981)
StegosaurusmadagascariensisPiveteau
1923(Piveteau, 1923;Russelletal., Campanian Madagascar unknown
1976)
Acanthopholidaeindet(Lapparent, Stegosaur?(Molnar&Frey, 1980;X.Pereda-S.,
Albian Niger
1960) pers.obs.)
of Rio Negro Province, Patagonia, Argentina of Gondwana (Bonaparte 1986). According to
(Coria, 1994; Salgado& Coria, inpress). Thelist Molnar(1980, 1991,this volume), themixtureof
is completed with these remains from the Cam- primitive and specialised characters in Minmi
panian of the Antarctic Peninsula (Gasparini et couldbetheresultofendemicevolution (because
al., 1987; Oliveroetal., 1991). of geographical isolation) of this lineage of
Ankylosaurs have also previously been ankylosaurs in Australia during the Early
reported from the Early Cretaceous of North Cretaceous. There is no evidence of Jurassic
Africa(Lapparent, 1960)andtheLateCretaceous ankylosaurs in Gondwanaland and there seems
of India (Matley, 1923; Huene & Matley, 1933; no close affinity between the Antarctic
Chakravarti, 1934;Coombs, 1978)andMadagas- ankylosaur and Minmi. On the other hand, the
car(Piveteau, 1923; Russell etal., 1976). Never- Late Cretaceous polardinosaurfauna from New
theless, these remains are probably not Zealand, that includes an ankylosaur, has been
ankylosaurian and can be assigned to other interpreted as probably representative of the
groups of dinosaurs or archosaurs (Table 2; see terrestrial assemblages that &inhabited Late
Molnar&Frey, 1987, foradiscussion). As faras Cretaceous Antarctica (Molnar Wiffen, 1994).
known, no conclusive evidence confirms the oc- Unfortunately, a comparison between the
currence of ankylosaurs in Africa (Molnar & Antarctic ankylosaurandthatfrom NewZealand
Frey, 1987; X. P.-S., pers. obs.), India (Chak- is not possible with the available material.
ravarti, 1935; Walker, 1964; Galton, 1981; Second, a late dispersal, during the Late
&
Molnar Frey, 1987) otherthanthatreportedby Cretaceous, via South America. The vertebrate
&
Chatterjee Rudra, nor Madagascar (Sues, interchange between North America and South
1980). Dermal scutes from Argentina America in the Campanian is well documented
(Loricosaurus scutatus Huene, 1929) have been (Bonaparte, 1986; Gayet et al., 1992).
removedfromtheankylosaurstothetitanosaurid AnkylosaurscouldhavetraversedSouthAmerica
&
sauropods (Powell, 1980; Bonaparte Powell, and reach Antarctica. This hypothesis is supported
1980). by the presence of a nodosaurid in Patagonia at
&
The presence of ankylosaurs in Antarctica this time (Coria, 1994; Salgado Coria, in
during the Late Cretaceous can be explained as press). Acontinuous or intermittantlandconnec-
the result of dispersal from the northern con- tion between Antarctica and South America is
tinents to southern Gondwana (see discussion in likelyforsomeperiodduringtheLateCretaceous
Gtaismpeaorifntihiestpala.s,s1a9g8e7;isOnloitvewreolletkanL,ow1n99b1u).t Tthweo ((OWloiovedrbouemteal&., Z1i9n9s1m)eiasntedr,th1e9E8a4r;lyGasPpaalreiongieneet
hypotheses may be considered: al.,1986; Marenssi etal., 1994).
First, an early migration during the LateJuras- The occurrence ofan armoureddinosaurin the
sic via Africa or South America. At this time, Antarctic Peninsula is also interesting because it
nodosaurids were present in Europe and North is one of the rare occurrences of ankylosaurs in
America and palaeobiogeographical evidence high latitudes. During the Late Cretaceous, the
shows that passage to Gondwanaland was pos- Antarctic Peninsula was situated nearits present
sible (Galton, 1977). If so, ankylosaurs were position, at about 64°S (Zinsmeister, 1987).
presentin southerncontinentsbeforethe breakup Other reports of ankylosaurs in high palaeo-
1 :
592 MEMOIRS OFTHEQUEENSLANDMUSEUM
—
latitudes are ofthe nodosaurid Edmontonia from phibious featuresintheirmorphology butper-
the Late Cretaceous ofAlaska (Gangloff, 1995) haps had a broader tolerance of habitats than
at about 70°N, Minmi from the uppermost Early ankylosaurids. To sum up, the Antarctic
CretaceousofAustralia(Molnar, 1980, 1991,this ankylosaur remains were found in shallow
volume) between 70° and 80°S (Veevers et al., marine sediments and in high palaeolatitudes, a
1991), andan indeterminateankylosaurfromthe typical condition among nodosaurids but un-
LateCretaceousofNewZealand(Molnar&Wif- known in ankylosaurids.This indirectly supports
fen, 1994) at least 66°S (see Barron, 1986 and the nodosaurid affinities of the Antarctic
Veevers et al., 1991, for palaeogeographical dinosaur.
maps). In addition to the ocurrence of the An-
ACKNOWLEDGEMENTS
tarctic ankylosaurin highlatitudes, there isinde-
pendentevidenceofadiversifiedflorasuggesting
a rather mild climate and a relatively high We thank J. Moly and O. Molfna for the
humidity, at least in the area where the dinosaur preparation ofthe material (Museo de La Plata),
remains were found (Baldoni, 1992). F. Castets (Museo de La Plata) and C. Abrial
AsnotedbyMolnar&Wiffen(1994),although (CNRS, Paris) for the photographs, M. Lezcano
largeankylosaurs(upto9m)areknownfromboth for the drawings and K. Carpenter and W.P.
AsiaandNorthAmerica,thereisnoindicationof Coombs, Jr, for their helpful comments. The
4anmylforngo,mitnhceluGdoinngdwAuasntaranlicao,nNtienwentZseamloanrde,tAhna-n sMeinlinoreraut(hBorMNapHpr,eciLaotnesdothne)asasnisdtaMnc.e oNforAe.lCl.
(AMNH, New York) during the study of collec-
tarctica, and South America. With the exception
tions in theircare.
ofthelatterfind, alltheothersprobablyrepresent
components ofinsular, near-polar faunas.
LITERATURECITED
Finally, the ankylosaur remains from James
RossIsland were recoveredfrom shallow marine BALDONI,A. 1992.PalinologfadelaFormationSanta
deposits associated with marine invertebrates Marta, Cretacico superiorde la Isla James Ross,
(Olivero et al., 1991). It should be noted that Antartida. Pp. 359-374. In Rinaldi, C. (ed.)
among ankylosaurs, ankylosaurid specimens are 'Geologfa de la Isla James Ross*. (Instituto
knownonlyfromcontinentaldeposits(Table22. AntarticoArgentino, BuenosAires).
ofCoombs &Maryanska, 1990) althougharticu- BARRON, E.J. 1986. Global Cretaceous Paleogeog-
raphy - International Geologic Correlation Pro-
lated nodosaurid bones have (occasionally) been gram Project 191. Palaeogeography,
reported from marine formations (Horner, 1979; Palaeoclimatology, Palaeoecology 59: 207-214.
Carpenteretal., 1995;Coombs&Demere, 1996). BONAPARTE, J.F. 1986. History of the terrestrial
In addition there have been several recent dis- Cretaceous vertebrates of Gondwana. Actas IV
coveries of disarticulated nodosaurid specimens Congreso Argentino de Paleontologia y
in marine formations as well (Coombs, 1995; Bioestratigrafia,Mendoza2: 63-95.
Gangloff, 1995; Holden, 1996; Lee, 1996). This BONAPARTE,J.F.&POWELL,J.E. 1980.Acontinen-
taphonomic difference suggests that by the Late tal assemblage of tetrapods from the Upper
Cretaceous nodosaurids preferred nearshore en- CretaceousbedsofEl Brete,northwesternArgen-
vironments, whereas ankylosaurids probably tina (Sauropoda-Coelurosauria-Carnosauria-
livedinmoreinlandhabitats.Asimilarecological Aves). Memoires de la Society geologique de
segregation has been suggested among CARPFErNanTcEeR1,39K:.1199-8248..Skeletalreconstructionandlife
hadrosaurid dinosaurs (Horner, 1979; Carpenter restoration of Sauropelta (Ankylosauria:
etal., 1995).WalterCoombs(pers.comm, 1996) Nodosauridae) from the Cretaceous of North
pointed out that recent discoveries of specimens America. CanadianJournalofEarth Sciences21
from southern Califoria (Coombs & Demere\ 1491-1498.
1996), Alaska (Gangloff, 1995) and, reportedly, 1990. Ankylosaurs systematics: example using
Hokkaido (Holden, 1996) suggest a circum- Panoplosaurus and Edmontonia (Ankylosauria:
&
Pacific distribution of nodosaurids, reminiscent Nodosauridae). Pp. 281-298. In Carpenter, K.
of that of desmostylians. He also noted that the Currie, P.J. (eds) 'Dinosaur Systematics:
Perspectives and Approaches*. (Cambridge
Alaskanspecimen(referredRtOoEMdmontoniasp.)is University Press: Cambridge).
a skull very like that of 1215 from the CARPENTER, K. & BREITHAUPT, B. 1986. Latest
continental Campanian ofAlberta. This suggests Cretaceous occurrences of nodosaurid
that nodosaurids—were not restricted to marginal ankylosaurs(Dinosauria:Ornithischia)inwestern
marinehabitats and nodosaurids showno am- North America and the gradual extinction ofthe