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A new emu (Dromaiinae) from the Late Oligocene Etadunna Formation

December 2001
Emu 101(4):317-321

Authors:

Australian Museum

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.

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.

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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.

Introduction

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.

Methods

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.

Systematic palaeontology

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.

Holotype

SAM P23977, a complete left tarsometatarsus with minor

damage (Fig. 1).

Type locality

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).

Diagnosis

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.

Description

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.

Etymology

‘guljaruba’; Bagandji language, lower Darling region of

New South Wales, meaning ‘emu’ (Hercus 1982), consid-

ered a noun in apposition.

Discussion

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

further examination.

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.

Acknowledgments

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.

References

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,

195–208

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,

437–456.

Hercus, L. A. (1982). ‘The Bagandji Language.’ (Australian National

University: Canberra.)

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.

Emuarius

gidju

Emuarius

guljaruba

Dromaius

ocypus

Dromaius

novaehollandiae

Dromaius

indeterminate

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

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

een omitted.

A new emu from the late Oligocene 321

http://www.publish.csiro.au/journals/emu

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:

New Haven.)

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.’

(Reed: Sydney.)

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

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Jul 2016

Federico Agnolin

Agnolin, F.L., July 2016. Unexpected diversity of ratites (Aves, Palaeognathae) in the early Cenozoic of South America: palaeobiogeographical implications. Alcheringa 41, xxx–xxx. ISSN 0311-5518. Ratitae is represented in South America exclusively by Rheidae. Recently, the oldest purported fossil rheid, Diogenornis fragilis, was attributed by several authors to various other ratite clades. A new revision of museum fossil specimens from Argentina has resulted in the discovery of several ratite specimens that clearly do not belong to Rheidae, but resemble other clades. The newly identified specimens derive from Paleogene and Miocene strata. The great diversity of non-rheid Patagonian ratites ended via extinction of several groups by the late Miocene, probably owing to enhanced aridity that also favoured the dispersal of arid-adapted rheids. The new specimens described here reinforce the hypothesis that the traditional vicariant biogeographical model, which proposes ratite clades originated exclusively before the breakup of the Gondwana supercontinent, is questionable owing to the unexpected diversity of various ratite clades in South America, and also in Europe and Africa. This might indicate that the history of Ratitae was more complex than previously envisioned. Federico L. Agnolin* [[email protected]], Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, Av. Ángel Gallardo, 470 (1405), Buenos Aires, Argentina. *Also affiliated with: Fundación de Historia Natural ‘Félix de Azara’, Departamento de Ciencias Naturales y Antropología, Universidad Maimónides, Hidalgo 775 (C1405BDB) Ciudad Autónoma de Buenos Aires, República Argentina.

Opisthocomiformes (Hoatzins), “Columbaves” (Doves, Cuckoos, Bustards, and Allies), and Strisores (Nightjars, Swifts, Hummingbirds, and Allies)

Chapter

Feb 2022

Gerald Mayr

The affinities of the taxa included in the present chapter have long been—and for most parts still are—difficult to resolve. The Opisthocomiformes (hoatzins) remain a phylogenetic enigma and are recovered in disparate positions in different analyses of molecular data. Several other notoriously difficult-to-place taxa, such as the Columbiformes (doves), Musophagiformes (turacos), Cuculiformes (cuckoos), and Otidiformes (bustards), form a clade in analyses of molecular sequences, for which the name Columbaves was proposed. Opisthocomiformes and the taxa of the Columbaves resulted in close proximity to the Strisores (nightjars, swifts, hummingbirds, and allies) in some molecular analyses. The exact interrelationships between these birds are, however, controversially resolved in different analyses, none of which recovered a clade including all of the above taxa. Whereas the fossil record of the Opisthocomiformes and the taxa of the “Columbaves” is very sparse, the Strisores are abundantly represented in various Paleogene fossil sites in Europe and North America. These fossils not only shed light on the evolutionary history of the higher-level taxa they belong to but also show that various groups of the Strisores with a geographically restricted extant range had a much wider distribution in the past.

Mirandornithes (Grebes and Flamingos), Charadriiformes (Shorebirds and Allies), and Gruiformes (Rails, Cranes, and Allies)

Chapter

Feb 2022

Gerald Mayr

The three clades discussed in the following are obtained in varying positions in current phylogenetic analyses, and their inclusion in the present chapter is not meant to reflect close affinities. It should be mentioned, however, that some analyses supported a sister group relationship between the Mirandornithes and the Charadriiformes, and others recovered a clade including the Charadriiformes and the Gruiformes. Some extinct taxa of the Gruiformes are well represented, but the Mirandornithes and Charadriiformes have a rather scant early Paleogene fossil record even though various Mesozoic and early Paleogene fossils were identified as flamingos or “transitional Charadriiformes” by earlier authors.

Palaeognathous Birds

Chapter

Feb 2022

Gerald Mayr

The Tinamiformes were long considered to be the sister group of the flightless palaeognathous birds, which were classified as “ratites”. However, current molecular analyses congruently supported a clade including the Tinamiformes, Casuariiormes, and Apterygiformes. Accordingly, flightlessness must have evolved independently within several palaeognathous lineages, as has already been assumed by some earlier authors. The distribution of extant palaeognathous birds is mainly restricted to the Southern Hemisphere, but several fossil taxa were reported from the Paleogene of Europe and North America. Most interesting from an evolutionary point of view are various long-legged, crane-like birds from Eurasia and North America, which are likely to be stem group representatives of the Struthioniformes. Rheiformes and Casuariiformes have a Paleogene fossil record in their current ranges, whereas Paleogene fossils of the Tinamiformes, Dinornithiformes, Apterygiformes, and Aepyornithiformes have not yet been found.

Basic Terminology and the Broader Phylogenetic and Geological Framework

Chapter

Feb 2022

Gerald Mayr

Many readers will be acquainted with phylogenetic terminology and avian osteology, and it is beyond the scope of the present work to provide an in-depth overview of these topics, each of which could fill a book on its own. For those less familiar with essential terms and definitions, these are outlined in the present chapter, which also introduces major features of the skull and some of the limb and pectoral girdle bones. Current hypotheses on the interrelationships of extant birds are reviewed, which constitute a phylogenetic framework for the study of fossil taxa. In order to set the following chapters on Paleogene birds into a full context, the Mesozoic fossil record of neornithine birds is furthermore discussed and an overview is given of major Paleogene fossil localities.

Nocturnal giants: evolution of the sensory ecology in elephant birds and other palaeognaths inferred from digital brain reconstructions

Article

Full-text available

Oct 2018

The recently extinct Malagasy elephant birds (Palaeognathae, Aepyornithiformes) included the largest birds that ever lived. Elephant bird neuroanatomy is understudied but can shed light on the lifestyle of these enigmatic birds. Palaeoneurological studies can provide clues to the ecologies and behaviours of extinct birds because avian brain shape is correlated with neurological function. We digitally reconstruct endocasts of two elephant bird species, Aepyornis maximus and A. hildebrandti, and compare them with representatives of all major extant and recently extinct palaeognath lineages. Among palaeognaths, we find large olfactory bulbs in taxa generally occupying forested environments where visual cues used in foraging are likely to be limited. We detected variation in olfactory bulb size among elephant bird species, possibly indicating interspecific variation in habitat. Elephant birds exhibited extremely reduced optic lobes, a condition also observed in the nocturnal kiwi. Kiwi, the sister taxon of elephant birds, have effectively replaced their visual systems with hyperdeveloped olfactory, somatosensory and auditory systems useful for foraging. We interpret these results as evidence for nocturnality among elephant birds. Vision was likely deemphasized in the ancestor of elephant birds and kiwi. These results show a previously unreported trend towards decreased visual capacity apparently exclusive to flightless, nocturnal taxa endemic to predator-depauperate islands.

Vertebrate palaeontology of Australasia

Book

Full-text available

Jan 1991

Patricia Vickers Rich

*Pledge, N.S. (1984) A new Miocene vertebrate faunal assemblage from the Lake Eyre Basin: a preliminary report. The Australian Zoologist 24(4): 345355.

Article

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Jan 1984

Neville Stewart Pledge

Revision of Dromaius gidju Patterson and Rich, 1987 from Riversleigh, northwestern Queensland, Australia, with a reassessment of its generic position

Article

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Jan 1992

Walter E Boles

Dromaius gidju Patterson and Rich 1987, from the Mio cene Kurjamarpu local fauna of central Ausrralia, was described on the basis of associated hindlimb elements. New hindlimb material from the type locality and from Oligocene/Miocene deposits in Riversleigh, northwestern Queensland, are referred ro this taxon. Tibiotarsal and tarsometatarsal remains of D. gidju are more similar ro those of emus than those of cassowaries, whereas the femora are more similar to femora of cassowaries. All hindlimb elements of D. gidju show some affinity ro both cassowaries and emus. The combination of hindlimb characters indicates an earlier stage in the development of increased cursoriality, so [ propose a new genus for this taxon, Emuarius, which is interpreted ro be nearer the mutual ancesror of the emu and cassowary lineages than any other described form.

Hindlimb proportions and locomotion of Emuarius gidju (Patterson & Rich, 1987) (Aves: Casuariidae)

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Full-text available

Jun 1997

Walter E Boles

Using proximal and distal fragments, the length of the tarsometatarsus of Emuarius gidju is estimated and compared to that of other hindlimb elements. From these proportions and other hindlimb morphology, the inferred locomotory mode of E. gidju is compared with Recent casuariids. Emuarius gidju appears to have been more cursorially adapted than Casuarius and dwarf Dromaius, suggesting at least some open habitat in the Riversleigh palaeoenvironment. Using the relationship between weight and least circumference of the femur and tibiotarsus in Recent birds, the weight of E. gidju is suggested to have been 19-21kg.

Land mammal biostratigraphy and magnetostratigraphy of the Etadunna Formation (Late Oligocene) of South Australia

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Full-text available

Jan 1994

Field work recently completed in the Lake Eyre Basin, South Australia, has resulted in the development of a land mammal (marsupial) biostratigraphy of the Etadunna Formation. Whereas traditional interpretations of the age of this sequence suggest it is about 15 m.y. old, new information indicates that the Etadunna likely is 24–26 m.y. old. In either case, it appears possible to document a four-fold fossil mammal zonation of this rock unit at lakes Palankarinna, Kanunka, Pitikanta, and Ngapakaldi, in a composite section of strata that spans at least 30 m. Magnetostratigraphic data for the same succession are generally consistent with the correlation of the Etadunna Formation sites at Lake Palankarinna with of those at lakes Kanunka, Pitikanta, and Ngapakaldi to the north, as based on paleontological information. The magnetic polarity zonation of these Etadunna Formation strata is consistent with a correlation to the world magnetic polarity time scale at about 24–26 m.y. This is the first fine-scale zonation based on fossil land mammals for strata of late Oligocene age in Australia. The combined mammal and magnetic data show promise of developing the Etadunna Formation as a reference standard for land mammal correlations within Australia and the relation of these to land mammal zonations beyond the Australian continent.

Phylogeny and Classification of the Birds: A Study in Molecular Evolution

Book