THE APPENDICULAR SKELElDN OF LIOLAEMUS OCCIPITALIS

Rev. Brasil. Biol. 46(4)727-740
Novembro, 1986 - Rio de Janeiro,
RJ
THE APPENDICULAR SKELElDN OF LIOLAEMUS
OCCIPITALIS BOULENGER, 1885 (SAURIA, IGUANIDAE)*
CLAUDIA KELLER** LÍGIA KRAUSE***
Universidade Federal do Rio Grande do Sul (lnst. de Biociências - Depto. de Zoologia)
(With 14 figures)
RESUMO
Esqueleto apendicular de Liolaemus occipitalis Boulenger, 1885
(Sauria, Iguanidae)
A osteologia apendicular do iguanídeo Liolaemus occipitalis é descrita e analisada,
comparando-se suas características com os dados para sáurios em geral e algumas informações específicas para a família e o gênero. As principais particularidades estão relacionadas
com a cintura escapular (ausência de fenestra escapular e processo pró-escapular, característicos em iguanídeos); esterno (ausência de fontanela esternal, característica para o gênero);
ausência de sesamóides sobre as epífises dos ossos longos; úmero, que discorda em alguns aspectos do modelo iguanídeo; ausência de epi-ísquio; e tíbia, que apresenta uma pronunciada
crista laminar ao longo de metade da diáfise e para a qual não se encontrou citação na literatura. Vários dos aspectos da morfologia do esqueleto apendicular provavelmente estão relacionados com adaptações ao ambiente em que este animal vive - áreas arenosas, principalmente nas costas do Rio Grande do Sul e Uruguai.
Palavras-chave:
Reptilia, Iguanidae, Liolaemus occipitalis, osteologia, esqueleto apendicular.
ABSTRACT
The appendicular skeleton of the iguanid Liolaemus occiptalis is described and analysed
in terms of general saurian features and compared with some specific data for the family and
the genus. Main differences and particularities were found to be related to the pectoral
girdle, sternum, humerus and tibia, and a number of them probably represent adaptations to
the singular habitat of the species, which lives on sand dunes, where vegetation is low and
sparsely distributed.
Key-words: Reptilia, Iguanidae, Liolaemus occipitalis, osteology, appendicular skeleton.
Received August 2, 1985
AcceptedJuly
3,1986
Distributed November 30, 1986
* Dissertation of the first author to obtain bachelor
degree in Biological Sciences - Zoology, at the Federal
University of Rio Grande do Sul, under tutorship of the second author.
**. Fellowship holder of the National Research
Council (CNPq)
** * Research fellow of the National Research Council
(CNPq)
KELLER
728
and KRAUSE
INTRODUCTION
The genus Liolaemus is composed, according
to Donoso-Barros (1966), of approximately 80
species, being probably a polimorphic genus, of
great ecological versatility and wide geographical
range, encompassing the whole southern half of
South America, between parallels 25 and 55".
Liolaemus occipitalis is a small and agile
animal, with a uniform pale beige coloring, which
lives in coastal environments of Rio Grande do Sul
(Brazil) and Uruguay. It was first cited and described
by Boulenger (1885), having Rio Grande (RS) as
typelocality. Vanzolini and Ab'Saber (1968) restrict
its habitat to the sand dunes and sandy areas next to
the sea, but since then it has also been reported in
areas further inland in Rio Grande do Sul by Lema
(1980).
Despite the great number and high
diversification of species, this genus has rarely been
studied from the osteological point of view. The
only papers known to us dealing with this matter are
those of Fabian-Beurmann and Vieira (1980) and
Simões-Lopes (1984), both concerning cranial
osteolgy. Much more nurnerous are studies
concentrating
on
taxonomy
and
external
morphology of Liolaemus, e.g. Cei (1971, 1973,
1980), Cei and Scollaro (1981), Donoso-Barros
(1961, 1966, 1971), GalIardo(1966), Laurent (1982),
Peters and Donoso-Barros (1970) and Petrere
(1979). Also numerous are the papers concerning
ecology and biogeography of Liolaemus, e.g. Fuentes
(1977), Fuentes and Cancino (1979), Fuentes and
Ipinza (1979), Fuentes and Jaksié (1979, 1980),
Hellmich (1952), Jaksié et al. (1980), Jaksié and
Nufiez (1970), Nufiez and Yánez (1984) and
vanzolini and Ab'Saber (1968). Works on osteology
are more frequet for other iguanid groups, such as
those of Avery and Tanner (1964), Brinkman (1980,
(1981), Cox and Tannet(l977), Etheridge(1960, 1962,
1965), Jenkins and Tanner (1968) an Presch (1969),
arnong others (referring only to the publications
which include appendicular osteology).
This paper is concerned with the complete
description and analysis of the appendicular skeleton
of Liolaemus occipitalis, airning to provide basic
information for further evolutionary and adaptation
analysis. In the absence of any more specific studies
about Liolaemus, we had to use data referring to
Iguanidae as a whole and, occasionally, to the genus
Liolaemus, mentioned in papers of a wider scope, in
particular those of Camp (1923), Donoso-Barros
(1966), Etheridge (1960) and Lécuru (1968a, 1968b,
1969).
MATERIAL AND METHODS
Five specimens of Liolaemus occipitalis from
the herpetological collection of the Department of
Zoology (IB-UFRGS) were analysed. Collection
numbers are: DZRS 0018, 0024, 0025, 0166 and
0178, ali collected in Rio Grande do Sul. Main
external dimensions and sex are expressed on
table I.
Manual dissection was done under a Zeiss
stereornicroscope (10 x 1,6), except with specimen
0178, which was diafanized according to Taylors
technique (1967). DZRS 0166, being the largest
specimen, was chosen as main material for
description and drawings. Measurements indicated in
the text belong to this individual. The hight of the
pectoral girdle refers to the distance from the dorsal
border of the suprascapula to the ventral border of
the epicoracoid; and of the pelvic girdle to the
distance between the dorsal extremity of the ilium
and the ventral plane of the girdle.
Drawings were made with a Wild M-3
stereomicroscope (10 x 6,4 and 10 x 16), equipped
with a camera lucida (final drawings with nankin).
The foot is represented in ventral view for better
visualization of the tarsal elements. The sutures
between scapula and coracoid and between the
components of the pelvic girdle are indicated by a
traced line, since they are only present in juvenile
individuals.
Osteological nomenclature follows Lécuru
(1968a) for the pectoral girdle, Lécuru (1969) for
the distal extremity of the humerus and Etheridge
(1960) for the sternum. Otherwise the nomenclature
of Romer (1956) was used (including names of
muscles occasionally cited and orientation of the
epipodial elements) and sometimes indicated in
parentheses afther the terms of other authors.
DESCRIPTION AND ANAL YSIS
Pectoral Girdle (Figs. 1 and 2, Diagram 1)
The . pectoral girdle is composed of 8
endocondral elements (suprascapulas), scapulas,
coracoids) and 3 dermal element (clavicles and
interclavicle). Suprascapulas and epicoracoids
remain cartilaginous. The suture between scapula
and coracoid is present in juveniles but disappears in
adults, according to the normal condition in iguanids
(Lécuru, 1968a). Each blade of the girdle is 11,3 mm
high.
SUPRASCAPULA - The suprascapula (fig.
1) is the most dorsal element of each pectoral blade,
APPDENDICULAR
SKELETON
TABLE
Main external
Nr.
DZRSOOl8
DZRS0024
DZRS0025
DZRSOl66
dimension
sex
c3
<7
J
c3
of the analysed
OF LlOlAEMUS
I
specimens
L
SV
120,1
107,4
59,0
131,9
59,3
54,0
49,0
69,3
62,3
54,1
10,0
56,4
84,0
37,0
47,0
DZRSOl78
729
OCC/PTALlS
of Liolaemus occipitalis (in mm)
T
+ 5,5
+ 3,8
OBS.
tail fractured
tail bifurcated
L - total length; SV - snout to vent lenght; T - taillength;
.J - juvenile (reproductive organs not yet differenciated)
5 mm
:;
j/
Diagram I - Proportional,
positional and articular relationships of the components of the appendicular skeleton of
Liolaemus occipitaüs. A. - left arch of the pectoral girdle (lateral view) and left forelimb (dorsal view). B - Pelvic girdle (ventral view) and left hind limb (ventral view).
extending from the dorsal borde r of the scapula,
with the same width as the latter for its first half and
then expanding anteroposteriorly, reminding the
form of a trapezium. In dorsal view the two
suprascapular cartilages are separeted by the fifth,
sixth and seventh cervical vertebrae. Right over its
anteroventral angle the suprascapula forms an
incipient acromial process, to which the clavicle
attaches.
SCAPULOCORACOID - The scapulocoracoid
(fig. 1) has a subtriangular form (dorsal apex and
medioventral base), with dorso ventral orientation in
sequence to the suprascapula. Its posterior portion is
KI,LLU<
730
ano KRAUSI:
SSC
sc.c.t,
c.for.
/- ..•. ..:.~.
,
--L.._COr
Figs. 1 e 2 - Pectoral girdle of Liolaemus occipitalis: Fig. 1 - left arch in lateral view and Fig. 2 - ventral view and its
relation to the sternurn. a.c.f. - anterior coracoid fenestra; a.p. - acromial process, c. for. - supracoracoid
foramen; cI cIavicule; I - intercIavicule; msc - rnesocoracoid; mtc - rnetacoracoid; pc - procoracoid; p.c.f. - posterior coracoid fenestra; s
- sternurn; sc - scapula, ssc - suprascapula; sc.c.f. - scapulocoracoid fenestra.
thick, particularly where it forms the glenoid fossa.
At its anterior border it becomes thinner, forming 3
deep emarginations, namely the scapulocoracoid,
anterior coracoid and posterior coracoid fenestrae.
The presence of only 3 fenestrae is in disagreement
with the almost universal occurrence of 4 fenestrae
in Iguanidae, stated by various authors (Camp, 1923;
Etheridge, 1960; Lécuru, 1868a). The fourth
fenestra, when present, is related to the scapula. Ali
fenestrations are covered by a very thin membrane.
In juveniles there is a marked suture between
scapula and coracoid, running from the middle of the
glenoid fossa to the posteroventral border of the
scapulocoracoid fenestra (indicated in figo1).
The scapula is the dorsal elements, having the
form of a triangle with dorsal base and apex at the
glenoid fossa. Above the scapulocoracoid fenestra
the scapular blade becomes very thin, possibly
indicating the tendency for the formation of the
scapular fenestra. The coracoid is the ventral
element,
being
thinner
and
expanding
anteroposteriorly from the suture line. The processes
that separate the fenestrae are, respectively, the
procoracoid (between scapulocoracoid and anterior
coracoid f.), mesocoracoid (between anterior and
posterior coracoid f.) and metacoracoid (the region
situated ventral and posteriorly to the posterior
coracoid f.). The glenoid fossa is formed by the
joining of the posteroventral and posterodorsal
angles, respectively, of scapula and coracoid. At
approximately half distance between the posterior
border of the anterior coracoid fenestra and the
coracoid half of the glenoid fossa there is the
supracoracoid foramen.
The scapulocoracoid and the anterior coracoid
fenestrae are well developed, while the posterior
coracoid fenestra is much smaller. Camp (1923)
states that the distribution and heigh frequency of
scapulocoracoid and anterior coracoid fenestrations
in Sauria indicates their paleotelic condition, while
the irregular occurrence and, frequently, incipient
formation of the distal fenestrae indicate that they
represent
more
recent
specializations. Ali
fenestrations are related to area increasing for
muscular insertions.
Lécuru (1968a) mentions 3 types of
scapúlocoracoids for Iguanidae:
1 - heigh, narrow and massive, in arboricole forms
with compressed body form;
2 - wide, with two fenestrae, in forms with depressed body;
3 - medium, with intermediary width and well fenestrated, in iguanids lacking higher specialization.
L. occipitalis seems to be situated in between
categories 2 and 3 (wide scapulocoracoid, no fourth
fenestra. but the two main ones are well developed).
This is corroborated by the external form of the
animal, which has a depressed body, but not to the
point of, for exarnple, Phrynosoma.
APPENDICULAR
SKELETON
L. occipitalis is similar to L. nitidus (analysed
by Lécuru,1968a)in what concerns the absence of the
fourth fenestra and scapulocoracoid suture.
Nevertheless, the latter species presents also the
posterior coracoid fenestra only indicated by a
tltinning of the bone.
EPICORACOID - The epicoracoid (fig. 1) is
a cartilaginous extension of the ventral and anterior
borders of the coracoid. It reaches its maxirnum
extension at its anteroventral angle. From that point
it extends anterodorsaIly along the ventral border of
the coracoid, undergoing progressive narrowing. In
the anteromedial regions there is no overlapping
neither contact of the two epicoracoids (fig. 2), in
contrast to what happens in several other saurians
(Costelli and Hecht, 1971; Krause, 1983). There is
even a gap between the epicoracoids, equivalent to
the width of the interclavicle, but without any
contact with the latter. The ventral and
posteroventral borders of the epicoracoid fit into a
slit or grove along the anterior margin of the
sternum, along which they run forward or
backward, according to the position of the forelimb.
Anteriorly it forms the anterior border of the
scapulocoracoid and anterior coracoid fenestrae and,
ventraIly, the ventral border of the posterior
coracoid fenestra.
OF UOlAEMUS
OCClPrrALIS
731
STERNUM (Fig. 2 and Diagram 2)
The sternum is related either to the axial or to
the appendicular skeleton according to one or other
description of different authors. Romer and Parsons
(1977) state that the sternum, though related to the
axial skeleton, is actually an appendix of the
appendicular skeleton, being analysed hereby for its
close relation with the pectoral girdle, offering areas
of attachement and completing the pectoral arch
ventraIly.
The sternum consists of a medioventral sheet
of calcified cartilage of sub-pentagonal form, with a
smaIl posterior border opposing to the anterior
vertex. The pentagonal form is common in Iguanidae
CLA VICLES - The clavicles (figs. 1 and 2)
are long, slender bones (4,1 mm long), which run
along the anterior border of the pectoral girdle,
articulating dorsaIly with the acromial process, and
medioventraIly on the ventral anterior extremity of
the interclavicle (fig. 2). The ventral (proxirnal)
extremity of the clavicle has the form of a
non-perforated, rounded bar, which is the normal
condition for Iguanidae (Camp, 1923). From its
medial end the clavicle extends mediaIly and then
lateraIly, until it reaches the acromial process, thus
being sigmoid shaped. According to Etheridge
(1960) the median portion of the clavicle in
Iguanidae is frequently expanded as a thin, flat
proscapular processoAs there is no such well defined
element in the examined material we prefer to
consider it absent in L. occipialis.
INTERCLA VICLE - The interclavicle (fig.
2) (5,0 mm on its longitudinal axe) is arrow-shaped,
with its lateral processes directed posterolateraIly,
representing the normal condition in Iguanidae,
along with the T-shaped interclavicle, from which
the former originated (Cope, 1892; Camp, 1923;
Lécuru, 1968a). The interclavicle fixes ventraIly on
the anterior third of the sternum through the
posterior half of its longitudinal axe. The anterior
half projects anteriorly. Its width is uniform, not
tapering posteriorly.
Diagram 2 - Stemum, xiphistemum and parastemum
of Liolaemus occipitalis in relation toits vertebral colurnn and
dorsal ribs. Scheme model following Etheridge (1960). ps parastemum; s - sternum; xi - xiphistemum. Vertebrae: c cervical; pt - post-thoracix; t - thoracic; s - sacral. Parts of
ribs in black = cartilage; in white = bone.
KELLER and KRAUSE
732
d
(Lécuru, 1968b). There is no stemal fontanelle,
although there is a circular, less calcified area on the
midline of the stemum of the diafanized juvenile.
The absence of a fontanelle is in disagreement with
the státement of Etheridge (1960), which indicates a
~reat fontanelle for the genus Liolaemus. Along the
anterolateral borders of the sternum there are the
already mentioned grooves into which the
epicoracoids fit. Each posterolateral border presents
slight
cmarginations
and
projections.
These
Fig.4a
latter
form attachement points for 3 cartilaginous stemal
ribs, which join their bony dorsal counterparts,
originated from the vertebral column, and for a
xiphistemal rod, which runs posteriorly until it
bifurcates, giving origin to 2 cartilaginous
xiphistemal ribs (diagram 2). The latter elements run
lateraIly until they also meet their dorsal
counterparts.
A . series of cartilaginous elements - the
parastemal ribs
occur posteriorly to the
xiphistemal ribs. They are fixed to the distal
extremities of dorsal ribs, while their ventral
extremities are free (diagram 2). This kind of
parasternum occurs normally in Liolaemus, as well
as in the majority of South American iguanids
(Etheridge, 1960, 1965). Lécuru (1968b) indicates 6
pairs of fixed ribs for Iguanidae, where the possible
combinations of stemal + xiphisternal pairs are
6+0, 4+2 or 3+3. Nevertheless, L.occipitalis has
only 5 pairs (3 sternal and 2 xíphísternal),
Lécuru (1968b) estab!ishes, in Iguanidae, a
relationship between a broad stemum and a short
interclavicle, with great lateral processes. Etheridge
(1960) relates a broad sternurn, with two well
separeted and divergent xiphisternal rods, with
terrestrial habits and tendency to depressed body
formo Both characteristics are applyable to
L.occipitalis.
h.c,
h.c.
PO
AN
E
E
lD
ect
~~tJJ
a
ect
ent
ent
Fig.3
ul.c.
b
d
Fig.4b
FORELIMB (Figs. 3-7 and Diagram 1)
The forelimb is 27 mm long and is composed
of 3 long bones - humerus (propodium), radius and
ulna (epipodium) -, 9 carpal ossicles (mesopodium)
and manus, with 5 digits, composed of metacarpals
(metapodium) and phalanges. There are no
sesamoids on the articular surfaces of the long
bones.
HUMERUS - The humerus (fig. 3) is circular
at the middle of the shaft, but expands broadly in
direction of the epiphysis. The bone is 8,1 mm long
and its proximal extremity is broader than the distal
(2,7 and 2,4 mm across the respective heads). The
humeral torsion angle is of 41°. Along the shaft,
more on the dorsal than on the ventral half, run
several more or less pronounced longitudinal !ines,
related to muscle origins and insertions.The proximal
Figs. 3 and 4 - Left humerus of Liolaemus occipitalis:
Fig. 3a - dorsaI view, Fig. 3b - ventral view, Fig. 4a proximal terminal view, Fig. 4b - distal terminal view. am.t.
- anteromedial tuberosity; dp.cr. - deltopectoral crest; ectectepicondyle; ent - entepicondyle; h.c. - humeral condyle;
po.t. - posterior tuberosity; rd.c. - radial condyle; sc.fs. supracondylar fossa; sup.p. - supinatory process; ul.c. ulnar condyle. AN - anterior; PO - posterior; d - dorsal; vventral.
expansion forms a ventraIly concave and dorsaIly
convex arch, which articulates into the glenoid fossa.
The central and most developed element of this arch
is the humeral condyle (fig. 4a), expanded
transversaIly and with its posterior border curved
over the dorsal surface, aIlowing a more significant
elevation of the dista! extrernity (Krause, 1978).
lB'L IOTEC'
do
PA
APPENDICULAR
SKELETON
OF UOLAEMUS
733
OCC/prrAUS
Ventrally on the proximal head, in anterior and
lower position to the humeral condyle, is the
anteromedial
tuberosity,
which extends distally
along the anterior margin of the humerus, forming
the deltopectoral crest, well observed in ventral view
(fig. 3b). The crest gets less pronounced as it reaches
the rnidpoint of the shaft. Both tuberosity and crest
provide insertion areas for the pectoral rnusculature.
Posteriorly, right under the humeral condyle, there is
the
posterior
tuberosity
to
which
the
"subcoracoscapularis"
muscle fixes (Lécuru, 1969).
Because of the dorsal displacement of the humeral
condyle,
a ventral, sub- triangular
concavity
is
formed between the anteromedial
and posterior
extrernities, with its vertex directed to the rnidpoint
of the shaft,
On the distal extrernity of the humerus there
are 2 condyles, both dislocated to the ventral surface
of the epiphysis and separated by a well marked
groove (figs. 3b, 4b). The largest one, oval and
anteriorly
situated,
is the radial condyle (or
capitelum), while the other, smaller, rounded and
posteriorly
situated,
is the ulnar condyle (or
trochlea).
Both condyles articulate with radius and
ulna, respectively. Anterior to the radial condyle is
the ectepicondylar expansion. Posterior to the ulnar
condyle is the much larger entepicondyle. Above the
ectepicondyle,
on the anterior
margin of the
humerus, is the well developed ectepicondylar crest
(or supinatory
process),
for insertion
of the
supinator rnuscle. Above the radial condyle there is
an oval, excavated
region,
representing
the
supracondylar fossa, only seen in ventral view (fig.
3b), and without any evidence of the epicondylar
foramen, common in other saurian forrns.
The humerus of L. occipitalis fits into the
characteristics of the iguanid humerus, presented by
Lécuru (1969), in the following aspects:
stoutness
rate ("rapport
de robustesse)
length/rnaxirnum
medium diameter
= 12,13,
indicating a long, slender bone, with small
diameter (the rate varies from 10 to 17);
- circular shaft;
proximal extremity broader than the distal;
well developed deltopectoral crest;
ventral excavation of the proximal extremity
forms an acute angle;
radial condyle with the form of a serni-disk;
- humeral torsion angle between 23 and 610 (410
corresponds to a mean value);
entepicondyle
developed
and
ectepicondyle
reduced.
ln the following aspects there has been no
RADlUS - The radius (fig. 5), medial or
preaxial element of the epipodium, is thinner and
shorter (6,8 mm long) than the hurnerus. The shaft is
round and the extrernitiesare slightly expanded. The
surface of the shaft is smooth, except for a slightly
marked dorsal crest near the distal extrernity (fig.
5a). The proximal extremity forms on oval concavity
(fig. 6a) for articulation with the radial condyle of
the humerus and is n dose contact with the ulna on
its posterior margin. The articular surface of the
distal extrernity is even and oblique in relation to the
longitudinal axe of the shaft, being visible only in
dorsal view (figs. 5a, 6b). It articulates with the
radial carpal.
agreement:
Figs. 5
occipitalis: Fig.
view, Fig. 6a
terminal view.
fossa; U - ulna.
ventral.
-
deltopectoral crest forms an acute angle with the
proximal extremity;
unlar condyle larger than the radial;
ectepicondylar foramen present.
v
Fig.6a
PO
AN
PO
R
U
E
E
io
T'
//~:r
,
\.1'
a
b
Fig.5
v
~I
""">'"
v, ... \.::;':~'",:,:"
Ô
",
:::-....:.:.
'. ~
.
d
,~-
.
,
Fig.6b
and 6 - Left radius and ulna of Liolaemus
5a - dorsal view, Fig. 5b - ventral view,
- proximal terminal view, Fig. 6b - distaJ
01 - olecranon; R - radius; sig.fs. - sigmoid
AN - anterior; PO - posterior; d - dorsal, v-
734
KELLER and KRAUSE
ULNA - The ulna (fig. 5), lateral or postaxial
element of the epipodium, is somewhat longer than
the radius (7,3 mm long). The shaft is also circular,
but the proximal expansion is more acentuated,
presenting a marked projection on its posterodorsal
border, known as the olecranon (figs. 5b, 6a). The
anterior or medial terminal concavity so formed is
called the sigmoid fossa, which articulates with the
ulnar condyle of the humerus, and is in contact with
the proximal extremity of the radius through its
anterior border (fig. 6a). Actually the two bones
form a functionally continuous biconcave proximal
articular surface, adjusting to the morphology of the
two distal humeral condyles. On the posterior
surface of the olecranon, at the lirnit between ulna
and humerus, occurs a little, round uInar patella
(diagram 1). The dista! extremity of the ulna is
rounded (fig. 6b), articulating with the ulnar carpal
and, posterolaterally, with the pisiform. Along the
shaft of the ulna there are several prominences for
muscle attachement. Radius and ulna are in close
contact proximally, but quite separated distally.
111
CARPUS - The carpus (fig. 7) is formed by 9
well ossified elements, disposed in 3 series: proximal,
with 3, central, with 1, and distal, with 5 ossicles.
The proximal elements are the radial, ulnar and
pisiform. The radial is flattened proximodistally,
with even surfaces, while the ulnar, lateral in
position, is concave proximally, in order to receive
the rounded extremity of the ulna. The rounded
pisiform is lateral and posterior to the ulnar. The
intermedium carpal was not identified here, and
seems to be fused with the ulnar, according to the
position of various authors. There are 5 distal
carpals, the fourth being larger than the others.
Distally they articulate with the respective
metacarpals. Between the dista! and proximal carpals
is a single central carpal, which articulates with all
the others, except distal 5 and the pisiform, which,
owing to their lateral position, articulte only with the
ulnar (fig. 7). Proximal contacts are made by radial
with radius and ulnar and pisiform with ulna. Upon
the ventral face of the carpus there is a large and
thin sesamoid. This element is quite frequent in
Sauria, being localized upon the area of junction of
the flexor tendons of the digits (Cope, 1892).
MANUS - The manus of L.occipitalis (fig. 7)
has 5 digits, 111and IV being the longest and equal
in length to one another, followed, in decreasing
order, by digits lI, V and I. Themanus, including the
carpus, is 11 mm longoMetacarpals 11,lU and IV are
considerably longer than the phalanges, 111being the
longest, followed by IV and 11in decreasing order.
The metacarpals, as well as the phalanges, have
slightly expanded extremities, the proximal being
concave and the dista! convexo The phalangeal
formula is 2+3+4+5+3,
corresponding to the
normal condition in Sauria (Cope, 1892). The claws
are well developed and longer than the terminal
phalanges.
AN
PELVIC GIRDLE (Figs. 8, 9 and Diagram I)
E
E
ln
Fig.7
Fig. 7 - Left carpus and manus of Liolaemus
occipitalis (dorsaI view). c - central carpal; me - metacarpals;
pis - pisiform; r - radial carpal; R - radius; U - ulna; u + iulnar + intermedium carpals; 1 to 5 - distal carpals; I to V digits. AN - anterior; PO - posterior.
The pelvic girdle is composed of 3 bony,
endocondral, paired elements (ilium, ischium and
pubis) and 2 cartilaginous, unpaired elements
(epipubis and hypoischium). It forms 2 symetric
tri-radiate halves, which unite ventrally upon the
midline of the body. The sutures between the
endocondral elements are only visible in juveniles,
disappearing in the adults. The cartilaginous
elements, in medioventral positivon, make the
already mentioned contact between the 2 halves of
the girdle. Height = 7mm.
ILlUM - The ilium (fig. 8) is an elongated
bone, dorsal to the acetabulum, of which it forms the
posterodorsal third. It extends posterodorsally,
forming a 33° angle with the frontal plane of the
body, being broad at its base an than tapering. The
APPENDICULAR
SKELETON
OF L/OLAEMUS
OCCIPffALIS
735
epu
ac
E
E
in
115
epu
h is
Fig.9
Fig.8
Figs. 8 and 9 - Pelvic girdle of Lio/aemus occipitalis: Fig. 8 - left arch in lateral view, Fig. 9 - ventral view, acacetabulum; epu - epipubis; his - hypoischium; il - ilium; is - ischium; mis.p - metaischial process; ob.fo. - obturator
foramen; obt.f. - obturator fenestra; pac.p. - preacetabular process; ppu.p. - prepubic process; pu - pubis.
anterior border is continuous with that of the pubis,
and the posterior border with that of the ischium.
Along its dorsal third the ilium undergoes a slight
torsion (the anterior border in lateral direction and
the posterior border in medial direction) for the
articulation with the 2 sacral vertebrae, through its
medial face. There are no scars or other marks in the
suture zone. The anterodorsal border of the
acetabular
cavity
is
thicker,
forming
a
supra-acetabular arch, which develops as a form of
resistance against the friction of the femur toward
this region during dislocation (Krause, 1978).
PUBIS - The pubis (figs. 8 and 9) is the
anteroventral and thinnest element of the pelvic
girdle,
flatenned
dorsoventrally.
Near
the
acetabulum it thickens, forming the anterior third of
the acetabular cavity. Its dorsal surface is convex,
while the ventral is concave, the posterior border
forming the anterior limit of the obturator fenestra.
The two pubis extend ventrally, meeting each other
on the midline of the body, at an angle of 116°, and
being intercalated by a small, cartilaginous, calcified,
round epipubis. On the anterior border of the pubis
occurs a prepubic process (or pectineal process),
projected posteroventrally and connected with the
anteroventral pubic extremity through a very thin
bony sheet. Between the prepubic process and the
acetabulum there is the obturator foramen, observed
in ventral view (fig. 9).
ISCHIUM - The ischium (figs. 8 and 9) is the
posteroventral-element of the pelvic girdle. Near the
acetabulum (of which it forms the posteroventral
third) it is approximately as broad and thick as the
pubis,
becoming
broader
and
flatter
anteroposteriorly, as it extends ventrally. Its anterior
border is concave, forming the posterior margin of
the obturator fenestra. Right under the acetabulum
the posterior border constricts slightly an then
expands posteriorly, forming the metaischial process
(lslam, 1956) or tuber ischii (Cope, 1892), which
receives ligaments and insertions of the caudal
musculature (fig. 8). The process is connected to the
ventral extremity of the posterior border of the
ischiurn through a thin bony sheet, which is also
cited by Islam (1956) for Uromastix hardwickii.
Both ischii unite ventrally through a
symphysis. Between them is a long, narrow,
cartilaginous hypoischium, which extends anterior
and posteriorly from the borders of the ischii. The
posterior extension is quite longer than the anterior.
The latter projects approximately until the half of
the obtura tor fenestra, and, in case it is limited by
suture with the hypoischium or separated from the
latter by juxtaposition of the ischii, it is called
epischium (EI Toubi, 1949; Islam, 1956; George,
1956; Krause, 1978, 1983). George (1956)
establishes no delimitation between epi and
hypoischium, as happens in L.occipitalis, the
nomencIature, in this case, having only topographic
connotation. Therefore we consider here only the
presence of a hypoischium, which is connected to
the epipubis by a thin, cartilaginous ligament, and
separating the obturator
fenestra
in two
cartilaginous ligament, and separating the obturator
halves in ventral view (fig. 9). Camp (1923)
considers the hypoischium as being orginated by
736
KELLER and KRAUSE
condrification
or
even
calcification
of
the
"ligamenturn
hypoischium",
which represents
the
medium ending of lhe great transverse
perineal
muscles, responsible for lhe constriction of the base
of the tail.
~l
prox,
art.
int.
Ir.
int.tr.
inl.fs.
·1
i
AN
,
I
PO
E
E
io
PO
I
I
AN
!
!
ant.e.
pos!.
c.
ico.fs ,
b
Fig.10
d
Fig.11b
Figs. 10 and 11 - Left femur of Liolaemus occipialis:
Fig. lOa - dorsaI view, Fig. lOb - ventral view, Fig. IIaproximal terminal view, Fig. llb - distal terminal view.
ant.e. - anterior eondyle; ieo.fs. - intereondylar fossa; int.fs.
- intertrochanterie
fossa; mt. tr. - internal troehanter;
pop.dep. - popliteal depression; post.e. - posterior eondyle;
prox.art. - proximal artieulation. AN - anterior; PO posterior; d - dorsaI; v - ventral.
HIND LIMB (Figs, lO-14 and Diagram
1)
The hind limb of L.occipitalis is quite long in
relation to the forelimb (approximately 40 mm long).
It is composed of femur (propodiun), tibia and fibula
(epipodium),
3 well
ossified
tarsal
eIements
(mesopodium)
and pes with 5 digits, composed of
metatarsals
(metapodium)
and
phalanges.
No
sesamoids have been observed.
FEMUR - The femur (figs. lO and 11) is the
longest bone of the skeleton (11,2 mm long). The
shaft is nearly circular, expanding slightly toward
the extremities. The most prominent element of the
proximal extremity is the articular head, compressed
laterally, so to appear oval in terminal view (fig. l Ia)
and which is going to articulate with the acetabulum.
The head projects dorsally, so that its terminal
surface
is slightly
oblique in relation to the
longitudinal axe of the shaft. The same happens with
the distal extremity, except that, in a compensatory
movernent, ir projects ventrally, 50 that the articular
surfaces
become
ventroterminal.
According
to
Romer (1956) this movement enables the lizards to
assume their typical resting position,
with the
epipodium
projected
backwards
and the foot
extending laterally.
Lateral and anterior to the articular head there
is a second,
smaller projection
- the internal
trochanter.
On the ventral surface, between the
articular
head and the internal trochanter,
is a
shallow intertrochanteric
fossa (fig. IOb), which
forms, together with the trochanter,
the insertion
area for the "puboischiofemoralis
externus" muscle,
A poorly pronunced crest along the external border
of the internal trochanter
gives insertion to the
adductor muscle. There is no evidence of an adductor
ridge. The little projection that appears right under
the articular head in ventral view might be the
fourth trochanter (fig. lOb), although Romer (1956)
mentions its absence in Lepidosauria. ln dorsal view
(fig. lOa) there is a small tuberosity on the proximal
posterior surface, probably related to the insertion
of the "iliofernoralis" muscle (Romer, 1956).
The dista! expansion of the femur forms 2
condyles - the anterior
and the slightly larger
posterior condyle - for articulation
with tibia and
fibula. Both are rounded,
the anterior
being
elongated
anteroposteriorly
and
the posterior
transversally (fig. lOb). They are more prominent in
ventral view, forming between them the popliteal
depression
or cavity.
ln dorsal
view is the
intercondylar
fossa, into which the tendon of the
"quadriceps
fernori"
muscle
inserts. The distal
terminal
surface
(fig. l1b) is relatively
even,
presenting only a shallow concavity separating the
two condylar surfaces. The whole terminal area and
the ventrally dislocated condyles articulate with the
APPENDICULAR
SKELETON
OF UOLAEMUS
737
OCCIPfFAL/S
proximal head of the tibia. Only a small portion of of Islam (1956) for Uromastix hardwickii. In anterior
the posterior face of the posterior condyle : positíon (dorsal view), right under the proximal
extremity, is a conspicuous cnemial crest, which
articulates with the fibula.
acts as insertíon point for the tendon of the main
extensor muscle of the propodium (Romer, 1956).
also on the anterior margin, approximately from the
midpoint of the sha:ft, extends a crest or blade for 4
mm in distal directíon, its maximum height being
almost equal to the mean diameter of the shaft, No
such structure was mentíoned in the consulted
bibliography. The distal terminal surface of the tíbia
(fig. 13b) is smooth and approximately retangular,
articulating with the astragalus. Both extremitíes of
the tíbia are curved posteriorly, so that the bone is
slightly concave along the posterior border and
convex anteriorly.
IV,'
.·<4~/
::'\,
-,.'
E
E
11
a
b
Fig.12
d
Fig.13b
Figs. 12 and I3 - Left tibia and fibula of Liolaemus
occipitalis; Fig. Ia - dorsal view; Fig. I2b - ventral view;
Fig. I3a - proximal terminal view; Fig. I3b - distal terminal
view. cn.c. - cnemial crest; F - fibula; T - tíbia. AN anterior, PO - posterior, d - dorsal, v - ventral.
TIBIA - The tíbia (figs. 12 and 13) is medial
or preaxial, being the stoutest of the epipodial
elements (10 mm long). The shaft is circular at its
midpoint, but thenexpands in directíon of the
extremities. In terminal view (fig. 13a) the proximal
extremity forms an approxirnately triangular
surface, boarder on its poterior half, which
articulates with the distal extrernity of the femur. An
elevatíon along the longest axe of the tíbial head
suits in a slight terminal concavity between the two
femural condyles, in similar way to the description
Fig, 14 - left tarsus and pes of Liolaemus occipitaüs
(ventral view). as - astragalus; cal - calcaneum; mt metatarals; 3 and 4 - distal tarsals; I to V - digits. AN anterior; PO - posterior.
7.1 x
KELLER
and KRAUSE
FIBULA - The fibula (figs. 12 and 13), lateral
or postaxial bone of the epipodium, is slender and a
little longer than the tibia (10,8 mm long). The
proximal extremity is curved in preaxial and the
distal in postaxial direction, so that the bone looks
like an "S" in dorsal view. The shaft is compressed
anteroposteriorly and has no circular transverse
section. The proximal extremity is strongly
acuminate (fig. 13a), the apex being tilted toward the
tibia and articulating with the posterior lateral face
of the posterior femoral condyle. The distal
extremity is elongated anteroposteriorly (fig. 13b)
and its terminal surface forms a median keel, which
articulates on the calcaneum and against the lateral
border of the astragalus. Proximally tibia and fibula
are close together, for articulation with the femur,
while distally they articulate separately with the
astragalus-calcaneum (diagram 1).
and V distally and with the astragalus-calcaneum
proximally.
PES - The foot (including the tarsus) is 20 mm
longo There are 5 well developed digits, that get
longer from I to IV, being 11,lU and IV considerably
longer than their subsequent phalanges. Costelli and
Hecht (1971) mention the possible fusion of
metatarsals I and 11 of Shinisaurus
with their
respective tarsals. The same does Mahendra (1950)
for the metatarsal V of Hemidactylus jlaviviridis.
This might be true for metatarsals I and U of
Lioccipitalis,
as indicates their greater proximal
extension.
The metatarsal V is much shorter and stouter,
having a complex form that reminds a hook (in
ventral view). It articulates with metatarsal IV
through a medial facet and with the calcaneum
through its proximal lateral surface. According to
Robinson (1975) the development of a hooked fifth
metatarsal is owed to the fusion of the tarsal
elements, diminishing intratarsal flexibility. The
hooked form enables the fifth digit to oppose the
otthers, giving more stability to the plantar positíon
and increasing the efficiency of the musculature of
the foot and epipodium.
The phalanges diminish slightly in length in
distal direction. The claws are well developed, being
larger than the terminal phalanx. The phalangeal
formula is 2+3+4+5+4.
The proximal extremity
of each phalanx is concave, while the distal is convex
(as well as the metatarsals). The terminal phalanges
bear conical projections for insertion of the claws
(the same happening in the forelimb).
TARSUS - The tarsus (fig. 14) is composed
of one proximal (astragalus-calcaneum) and 2 distal
elements. The fusion of astragalus and calcaneum is
a common feature of the Sauria. The suture between
them is visible on1y in juveniles. It is abone of
complex topography, presenting several articular
faces. It is elongated mediolaterally, more expanded
on its medial half (corresponding to the astragalus).
The proximal surface presents 2 local constrictions a slight one and a more accentuated lateral one -,
which receive, respectively, the distal articular areas
of tibia and fibula, On its distal surface the
astragalus-calcaneum articulates, in mediolateral
direction, with metatarsals I and V, and distal tarsals
3 and 4.
The lateral, not expanded portion corresponds
FINAL CONSIDERATIONS
to the calcaneum, homologous to the fibular
proximal tarsal, On what concerns the homology of - Liolaemus occipitalis has no scapular fenestra, as
the astragalus, there are great divergences arnong
well as Linitidus, cited by Lécuru (1968a). The
thé authors that discuss its origin and composition
presence of this fenestra is characteristic for
along the saurian evolution. Different combinatio~s
Iguanidae.
of tibial, intermedium, central and fibular are
AIso according with Linitidus, the adults of
presented,always with the presence of at least two
L.occipitalis present no scapulocaracoid suture.
of them. The fusion of the original elements is - On what concerns fenestration development,
L.occipitalis fits in between categories 2 and 3 of
sustained by the identification of 3 ossification
centers in young fossiles of Captorhinus (Peabody,
Lécuru (1968a) (see description of the
1951). The fusion of the proximal tarsals occurs to
scapulocoracoid), indicating that this species is·
parcially adapted for the habits of iguanids with
give better support to the tibia when the hind limb is
in the twisted position (Romer and Parsons, 1977).
typical depressed body formo In fact, it is an
essentially terrestrial animal, having the habit of
According to Donoso-Barros (1966) the astragalus
of Liolaemus results from the fusion of tibial +
burrowing itself in the sand.
intermdium + central; which is certainly suggested - Clavicles and interclavicle correspond to the
by its great size and contact area within the tarsus.
normal iguanid condition.
On1y distal tarsals 3 and 4 are present in - The proscapular process of the cJavicJe, cited by
Etheridge (1960) as common in iguanids, is
Lioccipitalis,
as in most saurians, although
Donoso-Barros (1966) indicates the presence of
absent in L.occipitalis.
distal 5 for Liolaemus. The third is quite smaller and
L. occipitalis
presents no sternal fontanelle,
articulates on1y with metatarsal 111 and the
although Etheridge (1960) states the presence of
astragalus. the fourth articulates with metatarsals IV
a large one for the genus.
APPENDIClIl.,\i{
SI-:LU,TON 01' LlOLAEMUS
- L.occipitalis presents the normal parasternum of
the genus, also normal condition of most South
American iguanids (Etheridge, 1960, 1965).
- L.occipitalis has only 5 pairs of sternal (3) and
xiphisternal (2) ribs, while, Lécuru (I 968b)
mentions 6 pairs for the genus.
- L. occipitalis has a broad, pentagonal sternum,
with two separated and divergent xiphisternal
rods, condition linked by Etheridge (1960) with
terrestrial habit and tendency to depessed body
form, exactly as happens in this case.
There are no sesamoids on the epiphysis of the
long bones.
The humeral morphology of L.occipitalis agrees
with most aspects of the iguanid humerus of
Lécuru (1969), but disagrees with some of them
(see description of the humerus).
The hypoischium is long and projects anteriorly
from the ischiatic symphysis, being connected to
the epipubis by a thin cartilaginous ligament.
There is no epischium.
Long hind limb, stout epipodium and expanded
astragalum-calcaneum probably are adaptations
for a more efficient locomotion on the sand,
which does not offer much resistance to
dislocation.
- In the same way, the well developed laminar crest
on the anterior margin of the shaft of the tibia
may represent a resistance surface for the tibial
musculature, increasing the efficiency of muscle
contraction when the foot works against the
sand.
- The long and strong claws on fore and hind limbs
probably are adaptations for the burrowing
habits.
Tarsal V, which appears in the scheme of
Donoso-Barros (1966) for Liolaemus, is not
present in L.occipitalis.
To establish the relative importance of these
features in the systematics and phylogenetic
relationships of the genus Liolaemus a number of
interspecific comparative studies has to be carried
out.
OCClPITALlS
Iguanidae) and other lizards. Can J L""I. 58 (~):
277-89
BRINKMAN, 1981, The hind limb step cycle of Iguana and
primitive reptiles. J Zool, 181: 91-103.
CAMP, C.L. 1923 Classification
Nat Hist, 48 (11): 289-481.
of lizards. Bull Amer Mus
CEI, J.M., 1971, Herpetologia patagonica.
grupo magellanicus.
Caractertsticas
genéticas.Phvsis, 30(81): 417-24.
L Liolaemus del
taxonámicas
y
CEI, J.M., 1973, Comentários se i! una nova especie argentina de saurio: Liolaemus emmae Donoso-Barros
(1970). Boi Soe Biol Coneepeion, 46: 223-5.
CEI, J.M., 1980, On the : .nspecificity ofthe iguanid lizards
Liolaemus chacoensis and Liolaemus emmae . Copeia,
1980 (4): 936-7.
CEI, J.M. and J.A. SCOLLARO,
1981, A new northern
subspecies of Liolaemus kingi in Argentina. J Herp. 15
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COPE, E.D., 1892, The osteology of Lacertilia. Proe Amer
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COSTELLI, J. and M.K. HECHT, 1971, The post-cranial
osteology of the'
ard Shinisaurus: the appendicular
skeleton. Herpetoi. "a, 27 (I): 87-98.
COX, o.c. and W.W. 'L lNER, 1977, Osteology and
myology of Calisaurus, Cophosaurus, Holbrokia and
Uma (Reptilia: Iguanidae). Great Basin Nat, 37 (I):
35-56.
DONOSO-BARROS,
R., 1971, A new Liolaemus from Neuquen (Argentina). Herpetologica, 2 (1). 49-51.
DONOSO- BARROS, 1961, Three new lizards of the genus
Liolaemus from the highest Andes of Chile and Argentina. Copeia, 1961 (4): 387-91.
DONOSO-BARROS,
1966, Reptiles de Chile. Santiago, Ediciones Univ. Chile.
EL- TOUBI, M.R., 1949, The post-cranial osteology of the
Iizard Uromastix aegyptia (Forskal). J. Morph, 84:
281-92.
ETHERIDGE,
R., 1960, The relationships of the Anoles
(Reptilia, Sauria, Iguanidae): an interpretation based
on skeletal morphology. University of Michigan Thesis,
ETHERIDGE,
R., 1962, Skeleta1 variation in the iguanid
lizard Sator grandaevus. Copeia, 1962 (3): 613-9.
ETHERIDGE, R., 1965, The abdominal skeleton of lizards
in the farnily Iguanidae. Herpetologica, 21: 161-8.
FÁBIAN-BEURMANN,
M.E. and M. IBARRA VIEIRA
1980, Sobre a osteologia craniana de Liolaemus
occipitalis Boulenger (1885), Liolaemus lutzei Mertens
(1938) e Liolaemus multiformis simonssi Boulenger
(1902), (Lacertilia, Iguanidae). lheringia Ser Zool,
(56): 95-102.
FUENTES,
E.R.,
1977, Autoecología
de Liolaemus
nigromaclatus
(Lacertilia, Iguanidae). An Mus Hist
Nat Valparaiso, 10: 169-77.
FUENTES,
E.R. and J. CANCINO, 1979, Rock-ground
patchiness in a simple Liolaemus lizard community
(Reptilia, Lacertilia,
Iguanidae). J Herp, 13 (3):
343-50.
FUENTES, E.R. and J. IPINZA, 1979, A note on the dietof
Liolaemus monticola (Reptilia, Lacertilia, Iguanidae).
J. Herp, 13 (4): 123-4.
FUENTES,
E.R. and F.M. JAKSIé,
1979, Activity
temperatures of eight Liolaemus (Iguanidae) species in
central Chile. Copeia, 1979 (3): 546-8.
o
Aeknowledgements
- We wish to thank Dr. Aldo M. de
Araújo and Dr. Carlos O. Diefenbach for the revision of the
english translation. This study was supported by grants from
the National Research Council (CNPq) Proc. n2 120551-82
(1.C.) for the first author.
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