The postcranial morphology of Meiolania platyceps and a review of of the Meiolaniidae

172 Pages·1996·43.8 MB·English

by  Gaffney, Eugene S

THE POSTCRANIAL MORPHOLOGY
OF MEIOLANIA PLATYCEPS
AND A REVIEW OF THE
MEIOLANIIDAE
EUGENE S. GAFFNEY
BULLETIN
OF THE
AMERICAN MUSEUM OF NATURAL HISTORY
NUMBER 229 NEW YORK: 1996
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THE POSTCRANIAL MORPHOLOGY
OF MEIOLANIA PLA TYCEPS
AND A REVIEW OF THE
MEIOLANIIDAE
EUGENE S. GAFFNEY
Curator, Department ofVertebrate Paleontology
American Museum ofNaturalHistory
BULLETIN OFTHE AMERICAN MUSEUM OFNATURALHISTORY
Number 229, 165 pages, 113 figures, 20 tables
Issued September 25, 1996
Price: $15.00 a copy
Copyright © AmericanMuseumofNaturalHistory 1996 ISSN0003-0090
CONTENTS
Abstract ................................. 3
Introduction ................................. 4
Acknowledgments ................................. 4
Institutional Abbreviations ........ 5
.........................
Shell Morphology ................................. 5
Carapace 5
........................................
Plastron ................................. 33
Limb Morphology ................................. 39
Shoulder Girdle ................................. 39
Pelvis ................................. 39
Humerus ................................. 42
Ulna ................................. 44
Radius 46
........................................
Carpus and Manus ................................. 47
Femur ................................. 51
Tibia ................................. 54
Fibula ................................. 56
Tarsus and Pes ................................. 56
Skull Morphology ................................. 62
Review ofthe Family Meiolaniidae ........... 67
......................
Niolamia ................................. 72
Ninjemys ................................. 78
Warkalania ................................. 83
Meiolania 92
........................................
Meiolaniaplatyceps ................................. 93
Meiolania mackayi ................................. 94
Meiolania brevicollis ................................. 97
Meiolania cf. platyceps ................................. 97
Meiolaniidae Indeterminate to Genus ................................. 97
Relationships ofTaxa Within the Meiolaniidae ................................. 112
Biogeography ................................. 123
Relationships ofMeiolaniidae to Other Cryptodires ............................... 125
Basic Taxa ................................. 125
Characters Used in the Analysis ........... 132
......................
References ................................. 162
2
ABSTRACT
Aseriesofpartialshellsanddisarticulatedshell Thelimbs andgirdlesarecompletelyknownin
elements is the basis for a nearly complete resto- Meiolaniaplatyceps and are represented by both
ration ofthe carapace and plastron ofMeiolania articulated and disarticulated specimens. The
platyceps from the Pleistocene ofLord Howe Is- shouldergirdleisastoutelementwithawidescap-
land, New South Wales. The carapace is broadly ular-acromion angle and without a glenoid neck.
domed, with C-shaped bridge peripherals, but is Thecoracoidiswideandflat,flaringmedially.The
not as arched as in living testudinids. A small pelvis has large but widely separated thyroid fe-
cervical scale lies on a protuberant nuchal bone nestrae and a small epipubic process. The ilium
thathastwomidlinearticulationfacetsonitsven- flares slightly dorsally. There are two sacral ribs
tralsurfaceforthe 7thand8thcervicalvertebrae. and, usually, the rib ofthe firstcaudal is fusedto
The bones ofthe shell are usually fused with su- the second sacral.
tures present in a small number ofdisarticulated ThehumerusinMeiolaniaisexpandeddistally
specimens. The shellbonestendto be thin in the and proximally which contrasts to the narrower
central areas withthe peripherals and othermar- condition in nearly all cryptodires, but is similar
ginal areas thicker. The bone surface is coarsely to Proganochelys. The articular and surface mor-
textured with irregular grooves, pits, and foram- phology, however, ismore similartobaenidsand
ina. The scale sulci are usually poorly defined, otherprimitivecryptodires. Theulna, radius, tib-
shallowtroughs. In most specimens the posterior ia, fibula, and femur ofMeiolania are similar to
margin is strongly serrated with no caudal notch. thosebonesinProganochelysandprimitivecryp-
There are 8 costals and 11 peripherals, but the todires,exceptthatinMeiolaniatheyaregenerally
numberofneuralsandthepresenceofapygaland stockierand more robust, with widerends.
suprapygals are unknown. The first thoracic cen- ThecarpusofMeiolaniahassevencarpalbones:
trumfacesdirectlyanteriorlyandthefirstthoracic ulnare, intermedium, medial centrale, and four
rib reaches the axillary buttress on the third pe- distal carpals. The manus formula is 2-2-2-2-2
ripheral. with broad, flat unguals. The tarsus ofMeiolania
In theplastron the epiplastra meet onthe mid- hasanastragalocalcaneum showingno sign ofsu-
line and bear a short median process, apparently tures or fusion. Two distal tarsals are definitely
nothomologoustothatinProganochelysandKay- known,butfourwereprobablypresent. Thepedal
entachelys, thatbifurcatesdorsallyandarticulates formula ofMeiolania is 2-2-2-2-0.
withthescapula.Theepiplastraarerelativelybroad ArevisionofthefamilyMeiolaniidaerecognizes
and bear two pairs ofscales, about equal in size, four genera: Niolamia (Eocene, Argentina), Nin-
withmoderateanteriorprojections.Nootherplas- jemys (Pleistocene, Queensland), Warkalania
tralscalesulciaredeterminable. Theentoplastron (Miocene, Queensland), and Meiolania (Miocene
isalarge,ovoidbonewithalongposteriormedian to Pleistocene, Northern Territory, Queensland,
process that separates the hyoplastra formuch of Lord Howe Island, New Caledonia). A PAUP
theirlengthonthedorsalsurface.Theaxillaryand analysisof22charactersresultsinonecladogram:
inguinalbuttressesdonotextendontothecostals, (Niolamia (Ninjemys (Warkalania, Meiolania))).
andcontactperipherals 3 and8,respectively. The The relationships ofmeiolaniids are analyzed
hyoplastron and hypoplastron send digitate pro- using 17 taxa and 40 characters. Within the eu-
cessestotheperipheralsproducingathin,partially cryptodires the shortest cladogram in a PAUP
ligamentous contact with numerous fontanelles. analysis is as follows: (Plesiochelyidae (Xin-
Mesoplastraareabsent.Alarge,irregular, median jiangchelys (Meiolaniidae (((Sinemys, Dracoche-
fontanelle is present atthejunction ofhyoplastra lys) Ordosemys) (Chelydridae (Chelonioidea
andhypoplastra.Theposteriorplastrallobetapers (Trionychoidea, Testudinoidea))))))). The data
strongly in contrast to the squared offend ofthe matrix consists of 19 cranial characters, 12 ver-
anteriorlobe. Smallarticulationfacetsarepresent tebral characters, and 9 shell characters. The cer-
on the xiphiplastra forthe pubis. vicalvertebraeprovetobeparticularlysignificant
The available shell material ofMeiolania pla- inresolvingtheextincteucryptodires.Inthisanal-
tycepsshowsagreatrangeofvariation.Mostshells ysis thebiconcave caudal, ligamentous bridge at-
have an extensive peripheral overhang but some tachment, andnarrowepiplastraare seento orig-
specimens have almost no overhang. The shell inatewithintheextincteucryptodires. Thefamily
sulciare usuallybroadandindistinctbutin some level name Sinemydidae is expanded to include
specimenstheyarefinelyincisedwithraisededges. Sinemys, Dracochelys, and Ordosemys.
3
4 BULLETIN AMERICAN MUSEUM OFNATURALHISTORY NO. 229
INTRODUCTION
The meiolaniids are a group of extinct, to make their very large and sometimes un-
Southern Hemisphere turtles with a bizarre wieldy collection available to me.
appearance, sporting cranial horns and frills Otherinstitutionsandindividualstowhom
andatail club. Some specieswere very large, I am grateful for access to specimens and
with lengths probably in excess of3 m. The informationare: J. Pickett, MiningandGeo-
relationships of the meiolaniids have been logicalMuseum,Sydney;A.Milner,C.Walk-
controversialsincethedaysofRichardOwen er, S. Chapman, Natural History Museum,
(1881), who first described them as giant London; D. Megirian, Northern Territory
horned lizards. Phylogenetic work on meio- Museum of Arts and Sciences, Darwin; N.
laniidshasbeenhamperedbyincompleteand Pledge, SouthAustralianMuseum, Adelaide;
misinterpretedmaterial.Asanexample,even M. Archer, A. White, University of New
thoughmeiolaniids havebeenknownforover South Wales, Sydney; G. McNamara, James
100 years, this paper provides the first de- Cook University, Townsville; R. Molnar, A.
scription ofa meiolaniid carapace. Bartholomai, Queensland Museum, Bris-
The present paper is the last in a series on bane;T. Rich,NationalMuseumofVictoria,
the morphology ofthe best known meiolan- Melbourne; P. Vickers-Rich, Monash Uni-
iid, Meiolaniaplatyceps. The skull morphol- versity, Melbourne; I. Hutton, J. Dorman,
ogywasdescribedinGaffney(1983), andthe Lord Howe Island.
vertebralmorphologyinGaffney(1985a).The In addition to that provided by the Amer-
presentpapercompletesthe morphologic se- icanMuseumofNaturalHistory, thisproject
ries by describing the shelland limbs. A sys- has received support from NSF grants DEB
tematic review ofall other known meiolan- 8002885 and BSR 8314816.
iids is presented here along with a review of The figures are the workofFrank Ippolito
the family. Lastly, there is a phylogenetic and Ed Heck. Once again, their talent and
analysis ofthe relationships ofthe Meiolan- skill will provide a permanent contribution
iidae to other cryptodires. in the form of high quality figures. Anna
Thispaperhasbeeninpreparationforover Schermerhorn improvedthe manuscriptand
tenyearsandsomeofthetaxonomicsections devoted time to its preparation. Dr. Anne
havealreadyappearedinprint(Gafiney, 1992; BurkeandMs.AmyDavidsonpreparedsome
Gaffney et al., 1992). These sections are re- ofthe specimens.
peatedhere as updated and modified forthis Dr. Richard Tedford, my colleague at the
paper. AMNH and the collector ofcentral Austra-
lian meiolaniids, has often taken the time to
help me in this project with his extensive
knowledge ofAustralian paleontology. Asin
ACKNOWLEDGMENTS
the past, I am verygrateful to my colleagues
Myworkonmeiolaniidsbeganin 1976and Drs.DonBrinkman,HowardHutchison,and
sincethattimeIhavebeendependentonthe Peter Meylan for making freely available to
support and encouragement of many insti- me information on specimens that they are
tutions and individuals. I am particularly currently working on. The cryptodire PAUP
gratefultotheAustralianMuseuminSydney, analysishaditsoriginina 1992meetingwhen
New South Wales, for their support of the Drs. Meylan, Hutchison, Brinkman, and I
project. In 1980 they awarded me a visiting producedadatamatrixandanalysistowhich
curatorshipwhichmadeitpossible formeto allfourofuscontributed. Iamagaingrateful
studytheirmeiolaniidcollection, theworld's tomythreecolleaguesforallowingmetouse
largest, andtomakenewcollections onLord theintellectualfruitsoftheseefforts.Dr.Dirk
Howe Island. Megirianhasprovided mewithcastsandin-
Particularthanksanddeepappreciationgo formation aboutMeiolania brevicollis.
toDr.AlexRitchieandMr. BobJonesofthe Thispaperhasbeensignificantlyimproved
Department ofPalaeontology ofthe Austra- by comments from Drs. Peter Meylan, Dirk
lian Museum. In addition to collecting new Megirian, and Don Brinkman. I appreciate
specimens, they often went to heroic lengths the time they took to read this.
1996 GAFFNEY: POSTCRANIAL MORPHOLOGY OFMEIOLANIA PL,ATYCEPS 5
INSTITUTIONAL ABBREVIATIONS NTM Northern Territory Museum,
Darwin
QM Queensland Museum, Brisbane
AMNH American Museum of Natural SMNS Staatliches Museum fur Natur-
History, New York kunde, Stuttgart
AM Australian Museum, Sydney TMP Royal Tyrrell Museum of Pa-
BMNH Natural History Museum, Lon- laeontology, Drumheller
don UCMP University of California Muse-
MM Mining and Geological Muse- um ofPaleontology, Berkeley
um, Sydney
NMV National Museum of Victoria,
Melbourne
SHELL MORPHOLOGY
SPECIMENS
CARAPACE (figs. 1-26) WITH LARGE PORTIONS OF
CARAPACE PRESERVED
The carapacial outline of Meiolania pla-
tyceps is ovoid, protuberant anteriorly, and AM F:57984 (figs. 12-15).-The restored
lacking a cephalic notch ofthe sort seen in skeleton, figures 1 and2,(alsoGaffney, 1983:
Ordosemys and Macrobaena. The sides are fig. 1; Burke et al., 1983: figs. 1, 2, 4-8, 18)
roughly parallel and the posterior margin is is based primarily onAM F:57984. The car-
serrated. There is no caudal notch. apaceconsistsoftheanteriormarginplusthe
As restored, the carapace is moderately central area ofthe carapace; bridge and pos-
vaultedorarched (figs. 1, 2), more similarto teriormarginsaremissing.Whiletheanterior
thoseoftestudinidslikeGopherusratherthan marginappearstobeundistorted, thecentral
Geochelone. Thedegreeofvaulting,however, areais flattened-unusual forLord Howe Is-
is problematical. The only preserved cara- land preservation. For the restoration, the
pace that is nearly complete, AM F:61110, central carapace area was cast in flexible
isrelativelyflatbuthasbeencrushedtosome rubber and fitted to a pre-determined shell
extent.Photographs(fig. 3)ofacompleteshell, curvature (based on a number ofother spec-
AM F:49141, before collection and conse- imens, butprimarilyonAMF:61402 andon
quentcollapse, also showaflatcarapace, but extrapolations oftheanteriormarginsinAM
thisspecimenclearlycollapsedalongthecos- F:57984 andAM F:49141). The central area
to-peripheral sutures. The preserved periph- consistsoftwolargepiecesfromtherightand
erals show that the carapace was vaulted. left series ofcostals, and these halves have a
Smallersectionsofcarapace,particularlyAM good series ofcontacts via posterior neurals.
F:61402 (figs. 21, 22), thatseemtoretainthe Theanteriormargin,however,doesnothave
original shell curvature, also show a moder- goodcontacts with the central section and it
atedegreeofvaulting. Thebridgeperipherals seemslikelythatthecentralsectionwasplaced
(figs. 10, 31) are C-shaped in cross section too far forward in the restored cast. The po-
rather than V-shaped, also consistent with a sitionofthe firstthoracic ribis clearonboth
vaulted shell. sides andthe head ofthe firstcostal rib (left)
The surfaceofthecarapaceandplastron is ispreservedinthecentralsection.Intheorig-
coarselytexturedwithirregulargrooves, pits, inal restoration, the first costal rib head was
andforamina(figs. 3, 27, 83).Althoughthere placed slightly ahead of, rather than behind,
isnoregularpatterntothistexture,itisnone- thelineofthefirstthoracicrib.Itwasthought
thelessdistinctiveenoughtobedistinguished atthetimethattheseelementscurvedtopro-
from that ofmost other turtles in the Aus- duce this relationship, but this now seems
tralasian fauna. The peripherals tend to be unlikely. The distance between the two car-
thick and the more medial parts ofthe car- apace sections is increased in the new res-
apace are much thinner. toration (figs. 5, 6) so that the first thoracic
6 BULLETIN AMERICAN MUSEUM OFNATURAL HISTORY NO. 229
Fig. 1. Reconstructed skeleton ofMeiolania platyceps, Pleistocene, Lord Howe Island, New South
Wales. About 60% ofthe skeleton consists ofAM F:57984. Upper, anterodorsal oblique view. Lower,
anterolateral view.
andfirstcostalribslineupastheyareinAM though this area is completely unknown in
F:61110 and AM F:61402; that is, at right AM F:57984, based on the new restoration
angles to the midline. ofAM F:611 0, and some disarticulated el-
Therestoredcastprobablyalsoerrsinhav- ements, the posterior rib heads should be
ingtoo much area between the last rib heads closer to the peripherals. The total length of
andtheposteriormarginofthecarapace. Al- thenewrestorationisonlyafewinchesshort-
1996 GAFFNEY: POSTCRANIAL MORPHOLOGY OF MEIOLANIA PLATYCEPS 7
Fig. 2. Reconstructed skeleton ofMeiolaniaplatyceps, Pleistocene, Lord Howe Island, New South
Wales. About 60% ofthe skeleton consists ofAM F:57984. Upper, lateral view. Lower, ventral view,
plastron is AM F:18775.
erthan the old, butthe position ofthe entire ration is not possible. Only the internal sur-
costal/rib head section is moved posteriorly. face is visible, the rest being encased in ma-
AMF:61110(figs. 17-20).-Thisspecimen trix. AM F:61110 is also difficult to restore
hasthemostcompletecarapaceofanyMeio- because itis sodifferent from theotherspec-
lania, but some areas are broken and dis- imens. AM F:611 10 has a very narrow free
placed so that a completely confident resto- edge on the peripherals and the body wall
8 BULLETIN AMERICAN MUSEUM OFNATURALHISTORY NO. 229
|rJ-L¶i~J.i-- &P 4 -
Fig. 3. Meiolaniaplatyceps, AM F:49141, in situ in Ned's Beach Cliff, Lord Howe Island (locality
5 in Gaflhey, 1983). Photo taken between July 20 and 22, 1959, probably by Elizabeth Pope, curator,
Australian Museum. Alongwith the shell were articulated cervicals (described by Gaffney, 1985a) and
limbs (figs. 41-44, 48). Most ofthe carapace and plastron weredestroyed afterthese photographs were
taken. The remaining articulated portions are shown in fig. 10. Upper, left side ofshell in anterolateral
view. Lower, posterolateral viewofleft side ofshell.
margin is very close to the shell margin, in to have produced significant distortion. The
contrast to AM F:57984 and AM F:49141, rightlateral marginofthecarapacelacksnat-
bothofwhichhavearelativelylargefreeedge, ural edges but the left side has some ofthe
or overhang, on the peripherals. bridge present and much ofthe remainder is
The anterior margin on the left side is in anatural moldintherock. Theleftposterior
good condition from the midline to the ax- quadrant is broken free from the rest ofthe
illarybuttress. Thereisacrackonthemidline carapace and displaced anteromedially.
that slightly separates rightandleft halves of Shifting this back and aligning it with the
the anterior margin but this does not seem bridgeandposteriormargin producesagood