LASIORHINUS LATIFRONS (OWEN, 1845) AND VOMBATUS URSINUS (SHAW, 1800) (MARSUPIALIA : VOMBATIDAE)

byG. G. Scott &K. ^C. Richardson

Summary

Many of the bones from the axial skeleton of the extant hairy-nosed wombat, Lasiorhinus latifrons

(Owen, 1845) and common wombat Vombatus ursinus (Shaw, 1800) are

statistically

significantly different. The gross morpohological features are summarised

to facilitate

rapid specimen

identification

at

the generic

level.

osik()logicaldiffkrkn( ^softheaxialskf;i>:tonbetwi;i:n lasiorhinus lath rons (owkn, 1845) and vombatls lrsfms

(shaw, 1800)

<\1

arscim \ua: vomba tidae)

29

G

^G.

SCOTT &

K. C.

RICHARDSON

SCOTT,

C.x;..

& RICHARDSON,

K.C. I"S7, Ostcoloincal differences o\ the axial skeleton of C&StorhtmiXhtifmis(Owen, IM4.S) ami Vnruhoms nninus (Shaw. IK(HI) (Marsupiulia: Vombatidae).

Kn\

S 4(/-vrAf//.\-22il) 29-39

Many

ot the hones from the axial skeletonoftheextant hairy nosed wmnhidJAisiorhJmis knifrons (Owen, $451 and

common

wombat. \,>inhotu\ mx/ntts (Shaw. 1X00) arc statistically significantly differentThegross morphological features arc summarisedlo facilitate rapidspecimenidentification atthe genericlevel.

\numberofnewlyrecogniseddiagnostic differencesarcrecorded:0)atlas,(a)transverse processes, shortand cylindrical in/, farif'rons.

hm

femjj and flat in \ ur\hw\,(hicranial articularsurface,dorsal border beginsaboverooloftransverse processinL (uitjnms. burbelow inI ,ar\ttms.tc.iintervertebral fonimcu.small

m

/, idtijiinis.but laryein V tusimts,(d)neural arch, tubercle presentattheapexinL.

(oiijh'tis.hutasulcusin \ ursinus.(c)transverse foramen, almost enclosed by bone in\ WS1MULbut open

m

ⁱ faiffti>n,\, (0 lamina, cranial bordertlat in/ , htfijhm, butarched in\. tn\hun:{i]}_{faft, (a)} transverse processes.extend latcrocuudallybeyond caudalsurfaceol vertebral bodyinI ursfnti.\, bin terminate level with, or before. caudal surface ol vertebral body in L hittnms (hi dens, directed crauiodorsally,ape\Iotaabovedorsal surlaccol vertebralbodyinL.lut([n>n>,bul projecls eranially,and apex liesbelow dorsalsurfaceol vertebral body

m

\ unhmy. ^liii)manubriumofsternum,(a)artuulat proccs* torclavicle,corneal in /-. latijnm.s, bul laterally flattened in \ ttr\inn.\; (biclavicular notch, shallow hi t, iittijnws. but deep in V ttrstmiw Significant differences in s»/c were found for touxrs.

lamtnathickness,laminadiameter,dens length:lii)thoracicvenebiue.dorsovcntraldiamelcrofbodyof

allhut the3rd vertebra,cramocaudaldiameterotvertebralbodyof1st.2nd.7ih.^l'lh. ¹0th, IIth, I2ihjih!

I Mb vertebrae: ith) lumbar vcriebrae.

maMmum

transverse process diameter of 1st. 2nd and ird vertebrae- (tv)sacralvertebrae,

maximum

transverseprocessdiamelerof2nd. 3rdand4thvertebrae;and

(\)shalldiameterlor ribs 11.12 and Ih

fi.Ci- .Srotl

A

K,C Richardson. Schoolo\'Veterinary Studies, Murdoch Idiversity.

Murdnck

Western Australiaftt|50, Manuscriptreceived IsJune 10S7.

The common wombat

\ tnahaiits utwinu.s (Shaw,

IK0O)was^firstdiscoveredbyBassonClarkeIslandin

Bass Snailin1797, A^I(houghtheskullaroused consid- erableUtxoiioitiicdiscussion from IK00,itwasonlyin

1K3K Ihul

Owen

first described i(s axial skelelon.

Owen

added lo this description in IK3*), Subsequent

work

on the axial skeleton by Eveiett (1853) and

Home

( 1853) provided no

new

information.

hvcii though (he hairy-nosed

wombat

Lasiorhtnus A;///n>//.v(Owenf 1845)was firstdiscoveredin 1845,it

wasin 1X67thatMuricdescribeditsaxialskeletonand

compared

il wilh I' h/Mhu\. Other workers such as Lydekker (IX°4), Murie (IS92) and

Marlow

t.1965) confitmed, to part,

many

ofMurie's (1867) ^findings, but added hllle loIheexisting information

Todate the descriptionsoftheaxialskeletonoi the

two wombat

genera have lacked adequate detail. In

many

instances, theywetenotaccompanied nyhtgtfttS

ordefinitionst* allow ready specimen identification especially ^ol isolated small bones.

Thispaperpresentsa

number

ot newlyrecognised diagnostic features mid incorporates, where valid, previously described diagnostic features

M,MhKIA1.Sanu

Mi

nioos Specimens

Bones ofIhe axial skelelon ofL. Idtifnvis and 1

ursttms were examined in (he colleclionsof(he Aus-

tralian

Museum.

Sydney;

Museum

ofVictoria,

Mel

bourne; Queensland

Museum,

Bnshane; South Aus-

tralian

Museum.

Adelaide; and Western Australian

Museum.

Penh.Feuthisstudyadditionalspecimensof

I Idfifrtm* were collected ai Blanchetoan, Roonk.i and

Swan

Reach inSouih Australia;andofI. urs'mns overtheGreat Dividing

Range

andadjacent regions.

MciiMitvmvms

Themorphology oftheaxialskeletonboneswasex

amined

and any diagnostic features not previoiisU recorded in the literaturenoted, Both adult and jtivti

nile specimens were examined, bul onJy bones from adultswere

compared

lordiagnosticpurposes Linear measurements were

made

with vernier callipers ^<.,.

adult specimens.

30 G- O.

SCOTT &

K.C.

RICHARDSON

Altai Skeleton

Measurements

1 Atlas

(i) lamina, craniocaudal diameter^at summit;

(ii;

maximum

dorsovcmralheightfrom apexof arch toventral surfaceof body.

2. Axis

ii^>

maximum

dorsovenlralheightfrom apexof spinous processto ventral surface ofbtxly.

(ii) lamina, thicknessat pointof

maximum

constriction dorsal tothecaudal articular surface;

(ui) lamina, craniocaudal diameterut point of

maximum

constriction dorsal lo thecaudal articularsurface:

(iv) dens, length from ventral surface toapex;

(v) dens,

maximum

^{lateral diameter;}

(vi) vertebralbody, dorsoventral diameter^at midline:

(Vii) vertebral body, craruocaudal diameter.

including dens,atmidline;

(viii) spinousprocess, length from apexof vertebral foramento

summit

ofspine.

3. Cervical Vertebrae

(i)

maximum combined

diameter ofthe transverse processes.

4.Thoracic Vertebrae

(i) vertebralbody, dorsoventral diamelcrat midline;

(ii) lamina, craniocaudaldiameteratpoint of

maximum

constriction dorsal tucaudal articularsurface;

(hi) spinousprocess, length from apexof vertebral foramen ^to

summit

ofspine;

(iv)

maximum combined

diameter ofthe transverse processes;

<v)

maximum

dorsoventralheightfrom apexof spinous process loventral surfaceol body;

<vi) vertebral body, craniocaudal diameteraI

midline.

5.

Lumbar

Vertebrae

ft)

maximum combined

diameter ofthe trans- verseprocesses.

6.Sacral Vertebrae

(i)

maximum combined

diameterofthe trans- verseprocesses.

7. CoccygealVertebrae

(i)

maximum combined

diameterofthe transverse processes,

(ii) vertebral body, craniocaudaldiauietet :it

midline.

8. Sternum

(i)

manubrium,

craniocaudallengthatmidline:

(ti)

w.Ribs

(i)

maximum

diameter opposite articular surfaces for 1st ribs.

shall,

maximum

diameter immediately distal totubercle.

Ostcological terminology used ^{is asin the}No/vino AtuitomieoVeterinona ^(Mabelvt ol. 1983).

Analysis

Methodology

includes Student's Mcst. 2-'luiled\

andbivariate analysis(Simpsonel al.1960).^Bivariate regression analysisofspecimensof

known

^sex

^shows

nosignificant sexualdimorphism forany^ofthechar- actersexamined,someasurementsolboth sexeswere combined.

Rest i is

(iettcral

Size range overlapexistsbetween \ .urstnusand

L

lotifrottsformost measurements. However,^V.urstnus

issignificantly largerfor:

1. Axis,(i)lamina. dorsoventral thickness

(P<

0.001 );

(ii) lamina, craniocaudal diameter {P

<

0.001l;(iii>

dens, length t/^J

<

0.001).

2.

Lumbar

vertebrae-

maximum combined

diameterof the transverseprocesses Of^{the 1st,}2ndand 3rdvcrte brae(P

<

0.001).

3. Sacral vertebrae,

maximum combined

diameterof the transverseprocessesofthe2nd. 3rdand4thverte- brae

(P<0O0

¹>

L, latifnms is significantly larger than V. urstnus

lor:

1 Thoracicvertebrae, (i)vertebralbody, dorsoven-

traldiameter.

T2

and 1 I

(P<

0.O01);TI. 4, 6,7 and ¹2 (P

<

0,01); and T5.S, 9, 10 and ¹³ (P

<

0.05): (ii)

Vertebralbody, craniocaudal diameter,

T

I (/^>

<0.00

1):

andT2.7,9,

^{10, II, I2ancl}

I3(f

<0.05).

2.

Lumbal

^vertebrae,

maximum

combincddiamelerof the transverse processes ofthe 1st,2nd and3rd verte- brae

(P<

0.001).

3. Sacral vertebrae,

maximum combined

diameter of thetransverseprocessesol"the2nd, 3rdand4thverte- brae

iP<

^{001 >.}

4. Ribs, shaftdiameter ofthe 12thand ^I3lh(/⁵<O.OOI and l!ih(/ⁱ<0.05>.

Axial skeleton measurements for both taxa are given inTables 2-16.

Specific

I(

-nehml Column

As Owen

(1839),

Wood

^Jones (1923), Lydekkcr

j 1894). Mutie (\H61) and

Marlow

(I9f>5) correctly pointedout.

V

^urstnusandL.latifronspossessdiffer- ent

numbers

of vertebrae in several parts of their vertehral

column

(Table 1 ).

AXIAL SKELETONS OF VOMBATIDAl-

t V'/'V7iy//

Vvrwlmw

Iiieseare rhesmallest vertebrae,excludingthecoc- cygeal vertebrae. Only the atlas ami axis

show

any consistentgross morphologicaldifferences.

Linear measurements

show

no significant differ- ences between thetwo

wombat

genera (Table2.)

Adas

L,lattfums

V

UlMtlUX Transverse ^shortand longand process. cyeluidneal. dorsoventrally

flattened.

Cranial articular beginsnboVc ^begins below

surface. levelof level of

transverse transverse

process. process.

Intervertebral small. large.

foramen

-

Tubercle. present al absenl,a ape*ofneural sulcus.

arch.

Transverse open. almost

foramen. enclosed

1 junina. cranial border

flat.

arched

Ve.ntralarch V-shaped. shallow.

incomplete

A u

^v

L

hitifroris \

', ursinus

Dens. directed directed

craiuodorsally. rostrally.

apex lies above apex liesbelow dorsal surface dorsal surface ofvertebral ofvertebral

body. body

Spinous^process. shortand thick, long and narrow, Transverse terminates level terminates process. wilh,or before, beyondcaudal

caudal surfaceof surface of vertebralbody. vertebral body.

Significant size differences in theaxis were found

for: (i) dorsoventral lamina thickness, iii)eranioeau-

tlal lamina diameter, and (iii)dens length (Table 3).

No

gross morphological or significant size differ- ences were found between the two taxa for the five caudal cervical vertebrae(Table4i.

Thoracic Yeriehrae

Thesearcmorphologicallysimilarinthe

two wom-

bat raxa. L, latifrons is signtfieallv larger than V, ursinusin dorsoventraldiameter ofthe vertcbal body forthefolIowingvcncbrae:T2and11

(P<0.QU1

>;TI,

4,o,7and

12(^-0.01); T5.S.9, I(land

U(/V0.05)

(Table 5), There were

no

significant sizedifferences between (he two

wombats

forcraniocaudal diameter ofthe lamina (Fable o). and ^length ofthe spinous process (Table7).

Maximal combined

diameter of^the transverseprocesses decreasesfrom

T

^I to a

minimum

althe 12th vertebratn V ursinus, butatthe

\MU

in /\

latifrons. There is no significant si/e difference be (weenthemeasurementsappearing inTable X. Maxi-

mum

dorsoventral height o\ the vertebrae also de- creaseseaudallytoa pointof

minimum

si/eatthe13th vertebrain V.ursinus. but I2lhin/-.fafifrons

There

is

no significant si/e difference between the measure- ments in Table y. Contrary to this, craniocaudal diameter of the vertebral body increaseseaudally

m

bothgenera.L.latifnnisissignificantly largerthan\

tuvnns forvertebrae:

T

^I (F<0.0UI¹andT2,_{7, 0. 10,}

1 1. 12, ^{1.1 {[>}< 0.05) (Table ^ICM.

Mammillary

proc- esses usually presentatthe ¹2ththoracic vertebrain\

ursinus, progressively increase in si/e to the second lumbarvertebra, thendecreasein sizetotheendofthe sacrum.In^/., iatijnmsthey weregenerally present al

the 13th thoracic verlebrae then progressively in- creased in size to the founh lumbar vertebra, and decreasedinsi/etothe\ytu\ofthesacrum. Thisisonly ofdiagnosticvalue

when

measurementsfordorsoven-

tral vertebralbodydiameter (Table5)andcraniocau dalvertebralbodydiameter (Table 10) are alsoavail able.

Lumbar

Vertebrae

Thesearemorphologicallysimilar inthe

two wom-

bat tava. However,

V

ursinus possesses four, but L, fat ifrans has ^six lumbal vertebrae (Table ¹I).

Muxi

mum combined

diameter ofthe transverse processes ofthefirstthreevertebraeissignificantlygreaterinV^. ursinus\ there is no si/e overlap between the

iwo

genera.

Saaal

Vertebra*

In defining die

number

of sacral vertebrae in V ursinus,

Owen

(I8b7) said.if

we

regard those venc- braeonlyas sacralwhichjointheossatnnominatathen there are butthree. Ifon theotherhand, anchylosisis

thetest, then the sacral vertebrae

may

vary from 3 to 4-5,in

number

indifferentspecimens'.

On

theanchy- losis criterionnoneofthe \ ursinus specimensthat

we examined

had only threevertebrae,but the major

ily(4b.\%. na 22) possessed four.

On

theotherhand threeout of^fouroftheL, latifmns specimensthat

we examined

had four vertebrae, in addition,IheZ.. lab-

pans

sacrum is rostrally broader bul narrows ntOTC sharplyeaudally i.e.the5thvertebra isapproximately

n

^{(V G,}

^{SCOn &}

^{K. l\}

^RICHARDSON

44%

narrower

dun

the 1st in L. larifroits, but -I'i narrower in V. tosinus. Therearc no gross morpho- logical differences in the individual vertebrae todis- linguish them between ihe

two wombat

tuxa. Lincai measurement*;

show

significant differences for (he rollowingvenebrae:S2.3and4(A^?<0.(K)l)(Table|2).

Cm

^{( v,e/*ty/\trtebt}ae

Therearenoconsistentgrossmorphologicalorsig- nificant sizedifference inthe individualbones todis- tinguish them between ^thetwo

wombat

nixaITables

I3and 14).

Manubrium

of^theSternum

Gross morphologicaldifferencesinthe

manubrium

ol theiwo

wombat

generawereioundinthe following features;

Articular process for the clavicle.

Clavicular notchi

/..latifrans conical.

shallow,

V. Ursinux laterally flattened

deep,

There were no significant size differences lot

meas

urementsappearinginTable15.Other stemebracIrani the

wombats

were similarin form foreachspecies.

Ribs

These are similar in the two

wombat

genera. The cranial ribs are

more

curved than those succeeding them, and

maximum

shaft diameter generally de- creasescaudally throughthe rib scries,

The

^ribshaft diametersforV,ursinusare significantly ^mallei than those for L.

hmfnms

for ribs: II

(P<

6.05l

\1(P<

0.001) and 13(P

<

0.00_)){Tabic 16).

OlSC'.'SSION

Vertebral differences in ihe asial 4.clvion hihtui variationsinburrowing^{behaviourof/_} ftjftjuws wid

V uf\inus. For example,differences in ihe moiphol ogy ofthealia*andak\<Utc reflectedinAngas"11

KM

observation thai \ . ursinusdves noi hold ^its bead as ereelasdocs/,.ItJtifrnns

when

standing.Indeed thisis

suggested by thedorsocranial orientationoftheileus oftheaxisin/., tulipmi*, a* wellashythepresenceop the skull of

a

well developed nuchal crest at the lunetioM Of ^{the parietal} n^i occipital boiWS flW the attachmentot

mm,

re*ffuf<upilts,hicontrast thedens of I fvn/WMisdirectedcramallyand(he parietalbone

i$ flat.

However,

ihe transverseprocessesoftheatlas ol v. urstuusarevery large indeed

when compared

10 those^{in /.} /rtrt/ronO'bisallowsagreater surface areu

f<m

muscle atmchmem.

paniculatly

mm, ohfiumnMip-

ilts and

mm

m{fftnw.svcisunt tfltigHX, and pinimhly

facilitatesagreaterdegreeofheadrotation,aswell as

more

powerful lateral and ^dorsal head

movements

in V. imimis.

As

forthe difference inthe

number

ofthoracic ver- tebrae and thus thoracic ribs,

Owen

(1H3K) believed thai I.urstnus hadIhe greater

number

i.e. 15 pairsol ribs because

The

pressure to which thetrunk ofthe

Wombai

musioccasionallyhesubjected,initssubter- ranean borrowings, is probably the condition of^the developmentoftheadditional pairsofribs'.Unfortu- nately L. hinfrtiths isalso "athorough adeptinthean' ofburrowing (Angas 1861).

The

reason probably lies with t . ursimts being greaterin body size. However, thepoint of

minimum combined

vertebraltransveise process diameter, and

minimum

overall dorsoventral si/e ofdie vertebrae, which together indicate the eeolrc ofgreatest spinal mobility,occursataboutthe

same

point, iheanticlinal vertebra, in the axial skeleton ^ol both genera. This Mipports Slijpcr's 11946)conclusion that the inelina uon _ofthe neural spine does not depend on thecon- structionof the trunkinitsentirety,but insteadmustbe affected only by the

demands

of the muscles and ligamentsattachedtorhem.In othci words,thereason forV

unimt

^{shaving 1}5 pairsofribs,while L.Utfifnms only has 13pairs,is astructural reflectionofthenee*!

to transmit agtcater visceral weight via theribs,and the oblique and transverse abdominal muscles, di rectlyto the body's u\isthan docsL.lufip-orfs.

Slijper (1946) also found thai spinous process length is proportional to the mechanical

demands

^of

thebody. They areonaverage, with iheexceptionof thoracicvertebrae6.7and8,the longestinI fatijr"n.\.

This provides Ihe added mechanical advantage of a longer lever 10

move

the diaphragmatic vertebrae which, togetherwith iwtl fewerribs,

would

undoubt- edlyincrea.setheabilityof£-h,ittp*>n\\obenditsbody

laterally intocurving tunnels

t'nfnriiinnlely no mobility studies of the vvombal vertebfot

column

have yet been undertaken. But the getvruI

gn

iss

morphology

ofthecervical.thoracicand luniks Wricbt&C ^{>t.^esi} a shift iti vcitchial

column

mobility

The

ccTtfitfttti «u$

Wty

^{mobile in both dor-}

Mtveniral and lateral directions, especially in theera nialpartof(he

column

inboth genera, becauseolthe

'free' and 'uncnihiaetng"natureol theunionbetween the prc-and

posuygapophyses

of successive cervical vertebrae.ThoracicvcrtehraI mobility ^is parrieulailv g^at in bothgenera.

However,the I4l|iand I5lhthoracicvenehraeinI

KfMfunate decidedly lumbar-like in appeal onee. but

|mv..m;sslibs' Indeed lumbarvertebraenumbers 3-6

m

L Idjifrum are

more

comparable

m

^{si/c to l-J in *}

ursirny 'Tabic I 1 1. In horhgenera, Inmborvertebrae Of(bepostdiupOuiematic regionofthe spine are

much

less mobile in (he dorsal direction and almost absolutely immobile in the ventral direction Lai eraI

mobility ^ls negligible, the vertebrae being 'locked'