© Royal Australasian Ornithologists Union 2001 10.1071/MU00052 0158-4197/01/040317
Emu, 2001, 101, 317–321
A new emu (Dromaiinae) from the Late Oligocene Etadunna Formation
Walter E. Boles
Division of Vertebrate Zoology, Australian Museum, 6 College Street, Sydney, NSW 2000;
and School of Biological Sciences, University of New South Wales, NSW 2052, Australia.
Abstract. A new emu (Emuarius guljaruba, sp. nov.) is described from the Late Oligocene Etadunna Formation
(Ngama Local Fauna), based on a complete tarsometatarsus. While exhibiting evidence of cursorial abilities
advanced over those of cassowaries (Casuarius), this taxon was not as cursorially adapted as the living Emu
(Dromaius novaehollandiae). This taxon is provisionally referred to the genus Emuarius, although a deﬁnite generic
assignment cannot be made.
Emus (Dromaius) are one of the most characteristic elements
of the modern Australian avifauna. There is only a single
living species, D. novaehollandiae, although the Tasmanian
population (possibly speciﬁcally distinct) and two dwarf
species, D. baudinianus (Kangaroo Island) and D. ater (King
Island), have gone extinct within the past 200 years. There
have been several nominal fossil species erected, primarily
by C. W. De Vis towards the end of the 19th century (De Vis
1888, 1892). The fossil record of emus was reviewed by
Patterson and Rich (1987), who reduced D. patricius De Vis,
1888, D. gracilipes De Vis, 1892 and the putative kiwi
Metapteryx bifrons De Vis, 1892 to the synonymy of the
living D. novaehollandiae. The only previously described
palaeospecies they accepted was D. ocypus, described by
Miller (1963) from a tarsometatarsus from the Pliocene-aged
Mampuwordu Sands at Lake Palankarinna, South Australia
(Palankarinna Local Fauna).
In addition, Patterson and Rich (1987) described a new
species, D. gidju, from the Lake Ngapakaldi Leaf Locality,
South Australia (Wipajiri Formation; Kutjamarpu Local
Fauna), considered to be early Miocene. This was based on
an associated distal tibiotarsus, proximal tarsometatarsus
and shaft, and complete pes. Boles (1992) reported a femur
from the type locality of D. gidju. He considered that this
belonged to the same species, but noted that, while the lower
limb was very emu-like, the femur retained characteristics of
the cassowaries (Casuarius). The dichotomy between the
Casuariinae and Dromaiinae represents the acquisition in the
latter of a more cursorially modiﬁed lower hindlimb (tibio-
tarsus and tarsometatarsus), as evidenced by the relative
elongation of both bones and other associated characters.
Within the Dromaiinae, Boles (1992) recognised a second
dichotomy between taxa that had acquired modiﬁcations of
the upper hindlimb (femur) and those that had not, repre-
sented by the genera Dromaius and Emuarius, respectively.
Emuarius has the advanced lower limb but retained the prim-
itive character states of the upper limb; that is, it is a combi-
nation of the cassowary-like femur and the derived emu-like
tibiotarsus and tarsometatarsus.
Specimens referred to Emuarius gidju have subsequently
been found in the Late Oligocene–early Late Miocene of
Riversleigh, Queensland (Boles 1992, 1997). Two specimens
from the Late Miocene deposits at Alcoota, Northern
Territory, were ﬁrst mentioned by Patterson and Rich (1987)
as Dromaius indeterminate, and cannot be distinguished
from Emuarius from other sites; they are now considered to
belong to E. gidju (Vickers-Rich and Rich 1993; personal
observation). This gives a known temporal range for this
species of Late Oligocene to Late Miocene.
Described herein is a new emu based on a complete tarso-
metatarsus, mentioned initially (‘an emu leg bone’) by
Pledge (1984) among taxa comprising the Ngama Local
Fauna recovered from Mammalon Hill.
Geology and Geography
Mammalon Hill is located near the north end of the western side of
Lake Palankarinna, South Australia (28°41′S, 138°24′E). Fossils at this
site have been recovered from the Etadunna Formation. On the basis of
the mammalian component of the fauna, ﬁve faunal divisions of this
Formation can be recognised (A–E, from the bottom to the top, respec-
tively). Faunal Zone D, from which the emu fossil was recovered, crops
out at Mammalon Hill. It lies between Zones C and E, with a range of
marsupials intermediate in their state of evolution between those in
these zones. Pledge (1984) recognised the Ngama Local Fauna for the
fossils from Zone D, as typiﬁed at Mammalon Hill. On the basis of
ektopodontid and pseudocherid possums (Marsupialia), the age of this
site is considered to be between the Etadunna Formation Faunal Zones
A–C and the Kutjamarpu Local Fauna (Rich et al. 1991). A depauperate
pollen ﬂora immediately below the site was interpreted as mid-Miocene
(Truswell and Harris 1982); subsequently, magnetostratigraphic data
placed the age of the Etadunna Formation at 24–26 million years ago
(Woodburne et al. 1993). Avian families represented in the Ngama
Local Fauna include Anatidae, Accipitridae, Rallidae, Burhinidae,
Palaelodidae, Phoenicopteridae and Columbidae; most have yet to be
studied, but are consistent with the depositional environment being
318 W. E. Boles
primarily lacustrine, with limited ﬂuviatile situations. For further infor-
mation on the geology, age and vertebrate taxa recovered from the
Ngama Local Fauna, see Stirton et al. (1961), Pledge (1984), Rich et al.
(1991), Woodburne et al. (1993) and references therein.
Measurements were made with digital calipers and rounded to the
nearest 0.1 mm. Osteological nomenclature follows Baumel and
Witmer (1993), including the use of ‘dorsal’ and ‘plantar’ to designate
the ‘front’ and ‘back’ of the tarsometatarsus, respectively.
The Mammalon Hill specimen (P23977) is held in the
palaeontological collection of the South Australian Museum
(SAM), as are the holotypes of E. gidju and D. ocypus. The
specimen described here consists of a left tarsometatarsus,
nearly complete other than minor loss of material somewhat
distal to the midpoint where the reconstructed proximal and
distal portions connect and on the plantar side of the cotyla
medialis. There is slight abrasion to the dorsal surfaces of tro-
chleae metatarsi II and III, and trochlea metatarsi II has been
reconstructed; otherwise there is little crushing or distortion.
The tarsometatarsus is known for all species of Dromaius
and for Emuarius gidju, thus permitting direct comparisons
with this specimen. Examination of the Mammalon Hill Emu
shows that it warrants recognition as a new species. Because
Emuarius and Dromaius are separated by character states of
the femur, in the absence of this element it is not possible to
deﬁnitively refer the new specimen to either genus. Rather
than make the assumption that the Mammalon Hill Emu pos-
sessed a derived femoral morphology, this taxon is provi-
sionally allocated to Emuarius, although in the following
discussion, comparisons are made with species of both
genera. (Although D. ocypus is, like E. guljaruba, known
only from the tarsometatarsus, its possession of an advanced
stage of reduction of trochlea metatarsi II allows it to be
placed in Dromaius.)
Emuarius guljaruba, sp. nov.
SAM P23977, a complete left tarsometatarsus with minor
damage (Fig. 1).
Mammalon Hill, the north end of the west side of Lake
Palankarinna, South Australia (28°41′S, 138°24′E).
Formation, age and fauna
Etadunna Formation (Late Oligocene); Ngama Local Fauna
(= Etadunna Formation Faunal Zone D).
This species is separated from Dromaius and Emuarius gidju
by the following suite of characters: the distal end is propor-
Fig. 1. Tarsometatarsi of fossil and Recent dromaiines, dorsal view. (A) Emuarius gidju
(proximal end, holotype: SAM P26779, Leaf Locality, Kutjamarpu Local Fauna; distal end,
AM F78587, Gag Site, Riversleigh); (B) Emuarius guljaruba (holotype: SAM P23977,
Mammalon Hill, Ngama Local Fauna); (C) Dromaius ocypus (holotype: SAM P13444,
Lawson Quarry, Palankarinna Local Fauna); (D) Dromaius novaehollandiae (Recent). Bar
equals 50 mm. Distal tarsometatarsus in (A) added to photograph digitally.
A new emu from the late Oligocene 319
tionally narrow relative to the proximal end, the shaft is
slightly compressed anteroposteriorly but markedly com-
pressed mediolaterally on its distal half, and the trochlea
metatarsi II is not reduced relative to the other trochleae.
The reconstructed length of the tarsometatarsus is about
equal to that of the holotype of Dromaius ocypus and
approaches the predicted length for Emuarius gidju (Boles
1997) (Table 1). Morphologically, the proximal end is similar
to that of both Emuarius and other species of Dromaius, but
in size it is considerably larger than E. gidju, approaching
D. ocypus. The eminentia intercotylaris is low and broad.
The sulcus extensorius is moderately deep and rather broad,
although it is not as deep distally as in D. ocypus. While the
shaft does not have the pronounced degree of anteroposterior
compression that characterises E. gidju, it is somewhat more
compressed than in D. novaehollandiae, particularly on the
distal half of the medial side, where it is more rounded on the
plantar surface, rather than as a raised, ﬂattened platform as
in D. novaehollandiae. Otherwise, E. guljaruba resembles
D. ocypus and D. novaehollandiae in the structure of its
plantar surface. The distal end of the shaft is mediolaterally
compressed, particularly relative to the proximal end. The
lateral borders of the shaft converge to about the midpoint,
then are roughly parallel distally, until the divergence of the
distal end. In contrast to the proximal end, the distal end is
much smaller than in either D. ocypus or D. novaehollandiae,
but is similar to that of E. gidju. This specimen, although
about the same length as the holotype of D. ocypus (SAM
P13444), has a relatively and absolutely much smaller troch-
lea metatarsi III, particularly in width, a shorter trochlea met-
atarsi IV, a longer trochlea metatarsi II and a less splayed
distal end (trochleae metatarsi II and IV are less divergent).
The sides of trochlea metatarsi III, as preserved, are roughly
parallel, not diverging distally as in the other species of Dro-
maius, although this may be inﬂuenced by wear. The incisu-
rae intertrochlearis are narrow.
‘guljaruba’; Bagandji language, lower Darling region of
New South Wales, meaning ‘emu’ (Hercus 1982), consid-
ered a noun in apposition.
The absence of a femur of guljaruba means that it is not pos-
sible to allocate this taxon to either Emuarius or Dromaius
with certainty, which admits two possible interpretations.
The ﬁrst is that two species of Emuarius were contempora-
neous in the Late Oligocene (Fig. 2). Although not yet known
from the same deposits as Emuarius gidju, the Ngama Local
Fauna, of which guljaruba is part, overlaps in time with
several of the Riversleigh local faunas in which gidju occurs.
The other possibility is that guljaruba represents the oldest
known species of Dromaius, extending the fossil record of
this genus to the Late Oligocene. In neither case is it obvious
what ancestor–descendent relationships, if any, existed
between guljaruba and any species of the Dromaiinae.
Fossils considered to be emus by Patterson and Rich (1987)
are known from much of the intervening period between gul-
jaruba and D. ocypus, but much of this material was consid-
ered by these authors to be indeterminate below generic
level. As that study was conducted before the recognition of
Emuarius, the indeterminate femoral specimens merit
Because Emuarius gidju had acquired the derived
morphology of the lower hindlimb, Boles (1992) considered
that it post-dated the cladistic event between emus and
Table 1. Tarsometatarsal measurements for Emuarius guljaruba compared with those of Emuarius gidju and species of Dromaius
All measurements are in millimetres. The estimated length for E. gidju is taken from Boles (1997), based on the holotype (SAM P26779) for the
roximal end and AM F78587 (Riversleigh: Gag Site: Dwornamor Local Fauna) for the distal end. Other measurements for E. gidju are summarised
from Boles (1992, 1997, and unpublished data). Measurements for D. novaehollandiae are summarised from Patterson and Rich (1987)
Emuarius gidju Emuarius guljaruba Dromaius ocypus Dromaius novaehollandiae
Length est. 340 c. 335 362 322–422
Proximal width 36.8–37.9 44.3 48.1 47.2–54.0
Depth, cotyla medialis 19.1–22.9 26.6 >25.3 25.4–27.6
Depth, cotyla lateralis >16.8–18.5 – c. 26.3 19.9–23.7
Depth, dorsal side of area
intercotylaris across hypotarsus
27.2–c. 29.5 37.9 >35.6 36.0–41.3
Minimum shaft width – 19.8 – 11.6–17.3
Distal width 44.1–c. 47.4 c. 46.9 53.3 47.4–54.6
Width, trochlea metatarsi II >9.5–10.5 12.6 11.8 9.0–11.1
Depth, trochlea metatarsi II >10.5–15.5 >15.1 18.1 13.0–17.6
Width, trochlea metatarsi III 17.6–21.7 20.6 27.8 21.9–28.9
Depth, trochlea metatarsi III 19.3–21.7 20.6 26.1 19.0–24.3
Width, trochlea metatarsi IV >12.2–14.5 >15.4 15.0 12.2–14.9
Depth, trochlea metatarsi IV 13.4–c. 15.5 >>13.4 18.0 14.3–17.2
320 W. E. Boles
cassowaries, and, although probably close to the mutual
ancestor of these groups, could not itself have been that
ancestor. The Late Oligocene occurrence of E. guljaruba
adds support to this conclusion. Boles (1992) noted that the
conclusion of Sibley and Ahlquist (1990), based DNA–DNA
hybridisation data, of a cassowary–emu division at 20–25
million years ago, was too recent to account for Emuarius.
The recently proposed divergence date of 35–38 million
years ago by Cooper et al. (2001) is more reasonable.
Boles (1992, 1997) remarked upon the proportions of the
hindlimb elements of Emuarius gidju relative to those of the
more primitive cassowaries and their implications about this
bird’s mode of locomotion. Some characters of the hindlimb
of E. gidju are more similar to either Casuarius or Dromaius,
while others are intermediate in structure between living
members of these genera. Notably, E. gidju exhibited three
morphological correlates with advanced cursoriality relative
to the condition in Casuarius: overall lengthening of the
lower hindlimb elements, lengthening of the tarsometatarsus
relative to the tibiotarsus, and a reduction in the relative size
of digit II. For these reasons, Boles (1992, 1997) considered
that this taxon appeared to mark in the Casuariidae a stage in
the transition from a generalised cursor to more specialised
cursorial locomotion. From this, he suggested that the
increased cursoriality may have been related to the occur-
rence of more open habitat in addition to the rainforest
usually considered to have been present.
Emuarius guljaruba has the same modiﬁcations of the tar-
sometatarsus that led Boles (1992, 1997) to infer developing
cursoriality in Emuarius relative to Casuarius. In comparison
to D. ocypus and D. novaehollandiae, the trochlea metatarsi II
of E. guljaruba does not exhibit marked reduction (similar to
E. gidju, but more so than in Casuarius), indicating that spe-
cialisation for open-country locomotion was still at a much
lower stage of development. Nonetheless, the longer, more
slender tarsometatarsus of E. guljaruba compared with Cas-
uarius is suggestive of an animal capable of more rapid loco-
motion, and thus the presence of more open habitat, although
this is not the only explanation for the lengthened lower limb
element (see Boles 1997). Obviously there is still much to be
learnt about the early stages of emu evolution.
I particularly thank Mr N. Pledge, Curator of Fossils, South
Australian Museum, for allowing me to work on this
specimen and for discussion and information on the age and
geology of the Mammalon Hill locality, Mr T. Peters, South
Australian Museum, for taking the photograph, and
Mr J. Peters, Birds Australia, for information on the
Aboriginal name. Ms S. Cowan prepared the specimen. This
paper has beneﬁted considerably from comments by an
anonymous referee, which assisted in the clariﬁcation and
reﬁnement of the ideas presented here.
Boles, W. E. (1992). Revision of Dromaius gidju Patterson and Rich,
1987, with a reassessment of its generic position. In ‘Papers in Avian
Paleontology Honoring Pierce Brodkorb’. (Ed. K. E. Campbell Jr.)
Natural History Museum of Los Angeles County, Science Series 36,
Boles, W. E. (1997). Hindlimb propor tions and locomotion of
Emuarius gidju (Patterson & Rich, 1987) (Aves: Casuariidae).
Memoirs of the Queensland Museum 41, 235–240.
De Vis, C. W. (1888). A glimpse of the post Tertiary avifauna of
Queensland. Proceedings of the Linnean Society of New South
Wales 3, 1277–1292.
De Vis, C. W. (1892). Residue of the extinct birds of Queensland as yet
detected. Proceedings of the Linnean Society of New South Wales 6,
Hercus, L. A. (1982). ‘The Bagandji Language.’ (Australian National
Miller, A. (1963). Fossil ratite birds of the late Tertiary of South
Australia. Records of the South Australian Museum 14, 413-420.
Patterson, C., and Rich, P. V. (1987). The fossil history of the emus,
Dromaius (Aves: Dromaiinae). Records of the South Australian
Museum 21, 85-117.
Fig. 2. Chronological occurrence of Dromaius and Emuarius, based
on Miller (1963), Patterson and Rich (1967), Boles (1992, 1997) and
this work. The Recent dwarf species D. ater and D. baudinianus have
A new emu from the late Oligocene 321
Pledge, N. S. (1984). A new Miocene vertebrate faunal assemblage
from the Lake Eyre Basin: a preliminary report. Australian
Zoologist 21, 345–355.
Rich, T. H., Archer, M., Hand, S. J., Godthelp, H., Muirhead, J.,
Pledge, N. S., Flannery, T. F., Woodburne, M. O., Case, J. A.,
Tedford, R. H., Turnbull, W. D., Lundelius, E. L. Jr, Rich, L. S. V.,
Whitelaw, M. J., Kemp, A., and Rich, P. V. (1991). Appendix I.
Australian Mesozoic and Tertiary terrestrial mammal localities. In
‘Vertebrate Palaeontology of Australasia’. (Eds P. Vickers-Rich,
J. M. Monaghan, R. F. Baird and T. H. Rich.) pp. 1005–1058.
(Pioneer Design Studio Pty Ltd: Melbourne.)
Sibley, C. G., and Ahlquist, J. E. (1990). ‘Phylogeny and Classiﬁcation
of Birds: A Study in Molecular Evolution.’ (Yale University Press:
Stirton, R. A., Tedford, R. H., and Miller, A. H. (1961). Cenozoic
stratigraphy and vertebrate paleontology of the Tirari Desert, South
Australia. Records of the South Australian Museum 14, 19–61.
Truswell, E. M., and Harris, W. K. (1982). The Cainozoic
palaeobotanical record in arid Australia: fossil evidence for the
origin of an arid-adapted ﬂora. In ‘Evolution of the Flora and Fauna
of Arid Australia’. (Eds W. R. Barker and P. J. M. Greenslade.)
pp. 67–76. (Peacock Publications: Frewville, SA.)
Vickers-Rich, P., and Rich, T. H. (1993). ‘Wildlife of Gondwana.’
Woodburne, M. O., Macfadden, B. J., Case, J. A., Springer, M. S.,
Pledge, N. S., Power, J. D. Woodburne, J. M., and Springer, K. M.
(1993). Land mammal biostratigraphy and magnetostratigraphy of
the Etadunna Formation (Late Oligocene) of South Australia.
Journal of Vertebrate Zoology 13, 483–515.
Manuscript received 23 October 2000; accepted 2 March 2001