APPENDICULAR SKELETAL DIFFERENCES OF WOMBATS 97

98 G.G.

SCOTT &

K.C

RICHARDSON

B

A

^c

FIGURE

3. Cranial view oftheleft humerus in (A)

L

latifrons and (B) V. ursinus. Where a, teres tuberosity;

b, deltoid tuberosity;c, medial epicondyle;d, lateral epi-

condyloid crest. Scale line is 2 cm.

B

FIGURE

5. Craniomedial viewof the left radius in (A)

V. ursinus and(B)L. latifrons. Where a, neck; b, radial tuberosity;c,arrowed,styloid process. Scalelineis2 cm.

B

FIGURE

4. Lateralviewoftheleft ulnain(A) V. ursinus and (B) L, latifrons.

Where

a, olecranon; h, arrowed, coronoidprocess; c.arrowed,pit For Ihe radial tuberosity;

d, styloid process. Scale line is 2cm.

Humerus

L. latifrons Deltoid acutely angled tuberosity ridge

Teres tuberosity small

Lateral epi- straight caudal shallowly condyloid crest border convex proxi-

mally, concave distallv

V. ursinus shallow angled ridge

elongate

Ulna Anconeal

process

(i) crantoproxi

mal

surface

(ii) viewed

laterally

Coronoid

process Shaft

(i) Depression for radial tuberosity

(ii) Lateral surface

L, latifrons

K

ursinus

ridge large process

cranial surface sickle-shaped parallel to

caudal surface

elongated circular

shallow larger circular pit

Hat proximally, concave

and

concave

distally

,*?,?•?*

^{Proximal view of^ft radial carpal bone in}

(A)

L

latifronsand(B) V.ursinus. Wherea,radialsurface- b. palmar tuberosity; c, medial tubercle. Proximal view ofright ulnar carpal bone in(C)L. latifronsand(D) V

ursinus. Whered, palmartuberosity;_eTulnarsurface.Scale line is 5

mm.

Radius

Neck

L. latifrons V. ursinus shallow con- deeply concave cavity proximal

to radial tuberosity

Shaft

Lateral surface flat

Distalforelimb Radial carpal bone:

deep oblique depression

Palmar

tuberosity

A. latifrons

small

Medial tubercle small

and

tapered

V. ursinus large

massive

and

blunt

Ulnar carpal hone; Third carpal bone:

L. latifrons V. ursinus

L

^{latifrons V. ursinus} Mediodistal large

and

broad

and

Ulnar articular small

and

oval large, concave process pointed squat

facet

and

semi- shallow deep

circular Proximal sulcu3

Accessory car- small pal articular

facet

circular with

pronounced

lateral tubercle

Fourth carpal bone:

L, latifrons

Palmar

artic- small

and

V. ursinus large arid deep

Palmar

facet

elongate for 3rd

and

4th carpal

circular

ular facet for 4th

and

5th metacarpals

shallow

bones

Hamulus narrow

broad at its

Accessory carpal bone: ^base

L. latifrons Ulnar carpal lateral border articular facet short

and

square

V. ursinus lateral border elongate

Body

of ulnar shallow fossa carpal separated

from

hamulus

by-

deep fossa

Medial prox- imal tubercle Shaft

small

pronounced

broad

and

Hat constricted in

middle

B

No

consistent gross morphological differenceswere found forthe first carpalbone,second carpal bone, metacarpals or phalanges.

Pelvis

L. latifrons V. ursinus Iliac crest (i) points points caudally

laterally

and

'sickle-shaped' forms sharp

angle with

body

of ilium pointed

(ii) lateral extremity broad

Iliac fossa present absent

lliopectineal large small

eminence

Ramus

of

same

width as half width of pubic

bone

pubic

bone

bet- pubic

bone

bet

\y

FIGURE

^{7. Proximal view oftheright} accessory carpal bone in (A) L. latifrons and (B) V. ursinus. Where a, proximal face! for the ulnar carpal bone; b, constricted shaft. Medioproximal viewof theright 3rd carpal bone

in (C)Li latifrons and (D) V, ursinus.

Where

c, medial process; d,sulcus;e,articular surfacefor3rd metacarpal.

Proximal view of the right 4th carpal bone in (£) ^A.

latifronsand(F) V.ursinus. Where^f, hamulus;g, articular facet forulnar earpa)bone; h» fossa.Scale lineis4

mm.

ween

the obtur-

ween

the obtur- ator foramina ator foramina Rectus femoris

deep

fossa

on

indistinct

m.

origin

body

of ilium Surface area of approximately Ischiatic table

same

as obtur-

ator

foramen

Ischiatic tuberosity

narrow, approximately 20

mm

wide at point of maxi-

mum

width

much

smaller

well-developed, approximately

40 mm

^wide

too G.G.

SCOTT &

K.C.

RICHARDSON

;•::^::::; '

v.v

o ³

i^% ^*

*

FIGURE

^{8- Ventralview}ofthe pelvisin(A)

L

latifronsantl(B) V.ursinus. Wherea,iliaccrest;b,arrowed,iliopeetineal eminence; c, arrowed, pecten; d, obturator foramen; c, acetabulum; f, ischiatic table; g, ischiatic tuberosity. Scale line is 2 cm.

M

i.

^^hEbmSP

FIGURE

9.Dorsalviewofrightepipubicbonein (A)L.

futifronsand (B) V. ursinus. Where a, articularsurface forpecten ofpubis;b.arrowed, proximaltubercle; c,shaft.

Scale line is 2 cm.

FIGURE

10. Cranial viewofleft femurin(A)/.. latifrons and(B) V. ursinus. Where_a,head; b, greatertrochanter;

c,3rd trochanter;d»lessertrochanter;e, medialcondyle.

Scale line is 2cm.

Epipubic

bone Femur

Articular sur- face for pectin o( pubic

bone

L. latifrons elongate with medial surface

much

broader

V. ursinus

narrow

elongate with parallel sides

Greater trochanter

L. latifrons deeply grooved

V. ursinus indistinct groove than lateral

surface

Lesser trochanter

present

pronounced

Proximal ven- concave Hal

tral surface

Lateral tubercle indistinct

pronounced

Third trochanter

pronounced

present

B

—

a

FIGURE

^II.Lateral view ofleft tibia in (A) /.. lutifrons and(B) t ur&inus. Wherea,arrowed,medialintercondylar eminence: b. arrowed, articular surface For fibula. Scale line is 2 cm.

Tibia

Medial inter-

eondylar

L'lJlillCllCC

/.,

Uuifmns same

size as lateral

Lateral condyle

(i) lateral almost flat

surface

(ii) articular circulai surface for

lateral condyle of femur

V. ursinus latgei Ihaii lateral

angled elongate

Fihuta Malleolus (plantar view)

/.. lutifrons

K

^ursttms

rounded, square medial surfaces

Distal hindlitnh

Tarsal

bone morphology

variedconsiderably within each genus.

No

diagnostic differences were found between the two

wombat

genera for the tibiolarsal, fibulartarsal, centraltarsal bones, or for 1st, 2nd, 3rd

and

4th tarsal bones.

No

morphologicaldiffer- ences were observed for the metatarsals

and

phalanges.

Distt SSION

This Study found that a

number

ofthe

morphea

logical features claimed by

Murie

(1867) as being diagnostieally significant forseparating the fore-limb

boneso(L.

Uuifmns

from those of \. ursinub are not reliable. For instance Murie's claim ihai a

marked

differenceexists between the proportion of lengthtobreadth ofthescapulaoftheiwo

wombat

taxa

(56%

in L. lutifrons

and

72'Vo in V. ursinus) was found to bemarginal.

Other

differences such as scapula shape

and

curvature of the scapular

spine,as well asthe varialions indepthof(hesulcus forthebicipital lendonasdescribed by

Murie

(1867) werefound to be inconsistent

and

of

no

diagnostic- value.

Likewise

Murie

(1X67)claimed that the anterior border of the ilium points

downwards

in I.

lutifrons, but outwards in

K

^ursinus,

and

that the femoral shaftbreadth isgreatest in

L

lutifrons.

He

also reported thai the fibula length

was

equal in

both

wombat

genera,

and

that the fibula shaft Wfifl

straighler inL. tatifrons.

None

o\ these findings art supported in this study.

The

current study tabulates a

number

ofdiag- nostic morphological differences allowing

many

individual

wombat

bones of^the appendicularskele- tonto be identified to generic level. In addition to this it was noted that thescapula of ^I' ursinus bears a larger surface area for the insertion of

M,

trapezius

and M.

deltoidius than does the scapula of L, tatifrons. However, the

L

^{laiifrons scapula}

possesses a larger

and more

developed surface loi

(he insertion of

M. rhomboideus and M,

serratus ventralis.

The

significance Of this difference in muscle insertion sites is reflected not only in differences in the overall structural mechanics of the thoraciclimb

of

the two

wombat

taxa, but also

in differences in their burrowing

and locomotor

behaviour.

For example,

R

^ursinus

^more

^readily

accommo-

dates the actionsofthe trapezius muscleto elevate

and

protract thelimb

and

the dcltoideus muscleto flex the shoulderjoint as well as tolift thehumerus,

By

contrast L. lutifrons is

more

adapted to

accom- modate

the action of

rhomboideus

muscle

which

elevates

and

retracts the limb

and

shoulder,

The

ventral serrate muscle supports the trunk,

and

carries the trunk forward or backward. These features are probably linked to L. tatifrons being a plains dweller

which

digs burrows into a flat,

usuallylimestone-underlaid, topography; while

K

ursinus is an inhabitant of the

mountainous

eucalyptus forests,

and commonly

resorts todigging

its burrows into

decomposed

granite.

The

bones oftheforearm inbothgenera are well adapted for pronation

and

supination, both impor- tant prerequisites for their burrowing. Il *9 also evident, that except for relative size, the general overall morphological structure

oT

the forelimb skeleton in the

wombat

is guile similar tothoseof the

kangaroo and

the koala.

Ultimately, differences in forelimb osteology of L. tatifrons

and

I ursinus can he explained by reference to differences in their

myology and

structural mechanics.

Sonntag

(1923),

and more

recently Hildebrand(1974) have set the lead in this respect. However, Sonntag only lookedat the

myo-

logy of V. ursinus* while Hildebrand only consid- ered thestructural mechanics

of

the forelimb of

L

laiifrons. In both cases their

work was

generalised

102 GJG.

SCOTT & KjC RICHARDSON

and

did not attempt to explain the functional

anatomy

of the

two wombat

genera.

Of

all the hindlimb bones studied, the pelvis

shows more

pertinent morphological differences between the

two

extant

wombat

species, However, relating these differences to the functional

anatomy

ofthe pelvis,

and

the hindlimb in general, awaits comprehensive information

on

themusculatureof thehindlimb ^inthetwo

wombat

species.

No

detailed

work

has been

done on wombat

hindlimb myology.

Waterhouse

(1846), Macalister (1850),

Sonntag

(1923),

and Elftman

(1929) provided only general information

on wombat

^(V. ursinus) musculature.

Their studies described the origins

and

insertions of a small

number

of muscle groups, but lacked detail, definitions

and

^{figures. In}

most

instances they areof^littlevalue for interpreting the functional musculoskeletal

anatomy

ofthe pelvicregionofthe two

wombats.

Although

this paper has

compared

the ost- eological differencesofthehindlimb of

L

latifrons

and K

ursinus, the interpretation of these differ- ences in terms of their respective functional ana-

tomy

awaitsadetailed investigationofthe

myology

of the pelvic limb,

ACKNOWl.fcUC.Mb.NTS

We

would like to lhank

Dr

C.P. Groves, Australian National University; DrT. Flannery, Australian Museum, Dr

D

^Horton, Instituteof AboriginalStudies;JoanDixon, National

Museum

ofVictoria; DrR. Molnar, Queensland Museum; DrC. Kemper, South Australian

Museum,

for making material available to us; and Dr D. Kitchener, WesternAustralian

Museum

forthespecimens usedinthe photographs. DrsC.P. Groves and D. Horton both gave valuable advice and support over the duration of the project.

We

wishtothank

Mr

G.Griffiths forphotography and

Ms

D.Passmoreforsocarefullytypingthepaperand

earlier drafts,Theprojectwasprimarilysupportedbyan Australian National Universitv Research Grant,

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TWO NEW LARVAL MITES (ACARINA: ERYTHRAEIDAE)