Possible affinities between Varanus giganteus and Megalania prisca

1 Pages·1996·0.26 MB·

by  M S Y Lee

:
232 MEMOIRS OFTHEQUEENSLAND MUSEUM
POSSIBLE AFFINITIES BETWEEN VARANUS ESTES, R., DE QUEIROZ, K. & GAUTHIER, J. 1988.
GIGANTEUSANDMEGALANIAPRISCA,Memoirsofthe Phylogenetic relationships within Squamata. Pp. 119-
Queensland Museum 39(2):232. 1996:- Molnar (1990) 281 In Estes, R. & Pregill, G. K. (eds). 'Phylogenetic
describedtwo frontals, and aparietal, ofagiant Pleistocene relationshipsofthelizardfamilies'.(StanfordUniver-
varanidatKingCreek,eastern DarlingDowns.Thematerial sityPress: Stanford).
wasassignedtoMegalaniaprisca,theonly varanidofcom- MOLNAR, R.E. 1990. New cranial elements of a giant
parable size. This identification is probably correct since varanidfromQueensland. MemoirsoftheQueensland
undoubtedremainsofMegalaniaoccurinthesamedeposits. Museum29:437-444.
Molnar(1990) noted that the frontals and parietal ofthe PIANKA,E.R. 1995. Evolutionofbodysize: varanidlizards
KingCreekvaranidexhibitedmany unusual features, which asamodelsystem. AmericanNaturalist 146: 398-414.
couldnotbefoundinanyvaranidskullsexamined,andwere PREGILL,G.,GAUTHER,J.&GREENE, H.W. 1986.The
thus presumably derived within varanids. Among these fea- evolutionofhelodermatidsquamates,withdescription
turesweretheprominentsagittalcrestalongthemediansuture ofanewtaxonandanoverviewofVaranoidea.Trans-
betweenthefrontals,andtheparalleltransverseridgesextend- actionsoftheSanDiegoSocietyofNaturalHistory21
ing at right angles to this crest. Both these features are also 167-202.
found in Varanusgiganteus(Fig. 1) and are absent in other RIEPPEL,O. 1980.Thephylogenyofanguinomorphlizards.
speciesofVaranus(Molnar, 1990)andinthenearestoutgroup Denkschrifte Schweizerbartsche Naturf. Gesellshaft
taxa, Latuhanotttsand Heloderma(Rieppel, 1980; Pregill et 94: 1-86.
al., 1986; Estes et al., 1988). They are thus derived within M.S.Y. Lee, SchoolofBiologicalSciences, UniversityofSyd-
V«ra/?M^suggestingaffinitiesbetweentheKingCreekvaranid ney,NSW2006,Australia; 10December1995.
andV.giganteus.Molnar(1990)notedthat,intheKingCreek
varanid as in V. giganteus (Fig.l), the sagittal crest and
parallel transverse ridges were confined to the frontals, and
didnotextendontotheparietals.Thisphylogeny isbasedon
veryincompletematerialandonlytwocharacters.
Megalaniaprisca, Varanusgiganteus, V. salvadoriand V.
komodoensisarethe4largestknown varanids(Pianka, 1995).
DespitethelattertwonotbeingAustraliannatives,all4belong
to a discrete radiation of Australian monitors, the 'gouldii
speciesgroup' (Baverstocketal.,1993). If Megalaniaprisca
has affinities with V. giganteus and thus belongs within the
gouldiispeciesgroupMegalaniawillhavetobesynonymised
with Varanus. Relationships within thegouldii species group
arenotyetwellestablished(Baverstocketal. 1993).:thereisa
distinctpossibilitythat,whenrelationshipswithinthisradiation
are resolved, V. giganteus, V. salvadori, V, komodoensis, and
Megalaniapriscawillformaclade.Ifso,thiswouldmeanthat
the four largest varanid species represent a single discrete
radiationofgiantpredatory lizards.
IthanktheAustralianResearchCouncilforfunding,Jenny
ClackandRaySymondsforloanofthefiguredspecimen,and
MalcomRickettsforphotography.
LiteratureCited
BAVERSTOCK, P.R., KING, D., KING, M., BIRRELL,J.
&KRIEG,M. 1993.Theevolutionofthespeciesofthe
Varanidae: Microcomplement fixation analysis of
serum albumins. Australian Journal of Zoology 41:
621-638.
A
B
FIG. I.SkullofVaranusgiganteus(UniversityMuseumofZoology,CambridgeR9586)in(A)dorsal,and(B)rightlaterodorsal
view,showingthesagittalcrestanddermal sculptureonthefrontalsbetweentheorbits. Scalebar=3cm.