Dromornithidae
Encyclopedia
Dromornithidae — the dromornithids — were a family of large, flightless Australian bird
s of the Oligocene
through Pleistocene
epochs. All are now extinct
. They were long classified in the order Struthioniformes, but are now usually classified as a family of Anseriformes
1. Their closest living relatives are waterfowl
such as duck
s and geese
.
Dromornithids were part of the Australian megafauna
; one species — Dromornis stirtoni — was 3 metres tall and may have been the largest bird that ever lived. The collective term "Australian megafauna" is used to describe a number of comparatively large species of animal
s that lived in Australia until 50,000 to 20,000 years ago. The causes for the disappearance of these animals are under dispute (see "Extinction" below).
It is also not clear to what degree dromornithids were carnivore
s. The massive, crushing beak
s of some species suggest that at least some members of the family were a combination of carnivorous
predators and scavenger
s (much like today's hyena
s) or omnivore
s. Other features, such as the "hoof-like" feet, stomach structure, and eye structure that resulted in a wide field of vision but likely also created a centre blind spot of about forty degrees (which would hinder hunting significantly) suggest a more herbivorous
, migratory lifestyle.
dromaios ("swift-running") and ornis ("bird"). Additionally, the family has been called Thunder birds, giant emus, giant runners, demon ducks and Mihirungs. The latter word is derived from Djab Wurrung
mihirung paringmal for a "giant emu
". The name used in this article, dromornithids, is derived from the family name.
s or moa
s. Most were heavy-bodied, with powerfully developed legs and greatly reduced wings. The last bones of the toes resembled small hooves, rather than claws as in most birds. Like emus and other flightless birds, dromornithids lost the keel on the breastbone (or sternum
), that serves as the attachment for the large flight muscles in most bird skeletons. Their skull also was quite different from that of emus. These birds ranged from about the size of a modern cassowary
(1.5 to 1.8 metres) up to 3 metres in the case of Dromornis stirtoni, possibly the largest bird that ever lived.
As of 2005, 5 genera
and 7 species have been described, and at least one new genus is currently under study. The smallest species was Barawertornis tedfordi
, a bird about the size of a modern cassowary
, weighing 80–95 kg. The two species of Ilbandornis (Ilbandornis lawsoni and Ilbandornis woodburnei) were larger birds, but had more slender legs than the other dromornithids and were similar to ostrich
es in their build and size. Bullockornis planei (the Demon Duck of Doom) and Genyornis newtoni (the mihirung) were more heavily built, stood about 2-2.5m tall and probably reached weights of 220 to 240 kg. The largest dromornithids were Dromornis australis and the massive Dromornis stirtoni (Stirton's Thunderbird). Genyornis
is the best known genus.
and Western Australia
. At some Northern Territory
sites they are very common, sometimes comprising 60-70% of the fossil material. A fragment of a dromornithid-sized foot bone has been found in Antarctica, but whether it represents these birds is uncertain.
deposits at Riversleigh
, northwest Queensland
. There are foot impressions from the Early Eocene
in southeast Queensland that may be referable to dromornithids. The most recent evidence, of Genyornis newtoni, has been found at Cuddie Springs
, north central New South Wales
and dated at 31,000 years old.
.
The first Europeans to encounter the bones of dromornithids may have been Thomas Mitchell and his team. While exploring the Wellington Caves
, one of his men tied his rope to a projecting object which broke when he tried to descend the rope. After the man had climbed back up, it was found that the projecting object was the fossilised long bone of a large bird. The first species to be described was Dromornis australis. The specimen was found in a 55 metre deep well at Peak Downs
, Queensland, and subsequently described by Richard Owen
in 1872.
Extensive collections of any dromornithid fossils were first made at Lake Callabonna
, South Australia
.
In 1892, E.C. Stirling and A.H. Zietz of the South Australian Museum received reports of large bones in a dry lake bed in the northwest of the state. Over the next years, they made several trips to the site, collecting nearly complete skeletons of several individuals. They named the newfound species Genyornis newtoni in 1896. Additional remains of Genyornis have been found in other parts of South Australia and in New South Wales and Victoria.
Other sites of importance were Bullock Creek
and Alcoota
, both in the Northern Territory. The specimen recovered there remained unstudied and unnamed until 1979, when Patricia Rich described five new species and four new genera. As of 2005, another new genus and species is under study at the Australian Museum.
and Dirk Megirian, of the Northern Territory Museum in Australia, recovered enough skull material of Bullockornis to give a good idea of what that bird's head looked like. It is now known that Bullockornis' skull was very large, with the enormous bill making up about two-thirds of it. The bill was deep, but rather narrow. The jaws had cutting edges at the front as well as crushing surfaces at the back. There were attachments for large muscles, indicating that Bullockornis had a powerful bite. More fragmentary remains of the skull of Dromornis suggest that it, too, had an oversized skull.
Bones are not the only remains of dromornithids that have been found:
The very large skull and deep bill of Bullockornis, however, are very unlike those found in large herbivorous birds such as moas. If this dromornithid ate plants, it was equipped to process very robust material that has thus far not been identified. Growing and maintaining such a large head would be detrimental and probably not occur unless it provided a substantial benefit of some sort, although it may have just been a social signal - this, however, would require a highly developed or complex social structure to evolve.
It has been suggested that, despite the indications of herbivory in some dromornithids, Bullockornis may have been a carnivore or possibly a scavenger. The jaws could easily cut meat and their robust structure could have resisted damage if it bit into bones. The bird could easily have fed on the carcasses of large animals.
It is, of course, not necessary that all dromornithids had the same diet. There is good evidence that Genyornis, at least, was a plant eater. Amino acid
analysis of eggshells indicates that this species was herbivorous. Bullockornis and Dromornis, with larger heads, may have had different diets.
of South America.
.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s of the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
through Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
epochs. All are now extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
. They were long classified in the order Struthioniformes, but are now usually classified as a family of Anseriformes
Anseriformes
The order Anseriformes contains about 150 living species of birds in three extant families: the Anhimidae , Anseranatidae , and the Anatidae, which includes over 140 species of waterfowl, among them the ducks, geese, and swans.All species in the order are highly adapted for an aquatic existence at...
1. Their closest living relatives are waterfowl
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
such as duck
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
s and geese
Goose
The word goose is the English name for a group of waterfowl, belonging to the family Anatidae. This family also includes swans, most of which are larger than true geese, and ducks, which are smaller....
.
Dromornithids were part of the Australian megafauna
Australian megafauna
Australian megafauna are a number of large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives...
; one species — Dromornis stirtoni — was 3 metres tall and may have been the largest bird that ever lived. The collective term "Australian megafauna" is used to describe a number of comparatively large species of animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s that lived in Australia until 50,000 to 20,000 years ago. The causes for the disappearance of these animals are under dispute (see "Extinction" below).
It is also not clear to what degree dromornithids were carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
s. The massive, crushing beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
s of some species suggest that at least some members of the family were a combination of carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
predators and scavenger
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
s (much like today's hyena
Hyena
Hyenas or Hyaenas are the animals of the family Hyaenidae of suborder feliforms of the Carnivora. It is the fourth smallest biological family in the Carnivora , and one of the smallest in the mammalia...
s) or omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s. Other features, such as the "hoof-like" feet, stomach structure, and eye structure that resulted in a wide field of vision but likely also created a centre blind spot of about forty degrees (which would hinder hunting significantly) suggest a more herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
, migratory lifestyle.
Names
The scientific name Dromornithidae derives from GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
dromaios ("swift-running") and ornis ("bird"). Additionally, the family has been called Thunder birds, giant emus, giant runners, demon ducks and Mihirungs. The latter word is derived from Djab Wurrung
Djab Wurrung
The Djab wurrung people are Indigenous Australians who occupy the volcanic plains of central Victoria from the Mount William Range of Gariwerd in the west to the Pyrenees range in the east encompassing the Wimmera River flowing north and the headwaters of the Hopkins River flowing south. The towns...
mihirung paringmal for a "giant emu
Emu
The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia...
". The name used in this article, dromornithids, is derived from the family name.
Appearance
Dromornithids looked superficially like very large emuEmu
The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia...
s or moa
Moa
The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ....
s. Most were heavy-bodied, with powerfully developed legs and greatly reduced wings. The last bones of the toes resembled small hooves, rather than claws as in most birds. Like emus and other flightless birds, dromornithids lost the keel on the breastbone (or sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
), that serves as the attachment for the large flight muscles in most bird skeletons. Their skull also was quite different from that of emus. These birds ranged from about the size of a modern cassowary
Cassowary
The cassowaries are ratites, very large flightless birds in the genus Casuarius native to the tropical forests of New Guinea, nearby islands and northeastern Australia. There are three extant species recognized today...
(1.5 to 1.8 metres) up to 3 metres in the case of Dromornis stirtoni, possibly the largest bird that ever lived.
Species
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
and 7 species have been described, and at least one new genus is currently under study. The smallest species was Barawertornis tedfordi
Barawertornis
Barawertornis tedfordi was a dromornithid , a huge flightless anseriform bird hailing from Late Oligocene to Early Miocene. The only species in the genus Barawertornis, its fossil remains are found in strata of the Riversleigh deposits located at two sites in Northwestern Queensland, Australia...
, a bird about the size of a modern cassowary
Cassowary
The cassowaries are ratites, very large flightless birds in the genus Casuarius native to the tropical forests of New Guinea, nearby islands and northeastern Australia. There are three extant species recognized today...
, weighing 80–95 kg. The two species of Ilbandornis (Ilbandornis lawsoni and Ilbandornis woodburnei) were larger birds, but had more slender legs than the other dromornithids and were similar to ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
es in their build and size. Bullockornis planei (the Demon Duck of Doom) and Genyornis newtoni (the mihirung) were more heavily built, stood about 2-2.5m tall and probably reached weights of 220 to 240 kg. The largest dromornithids were Dromornis australis and the massive Dromornis stirtoni (Stirton's Thunderbird). Genyornis
Genyornis
Genyornis was a monotypic genus of large, flightless bird that lived in Australia until 50±5 thousand years ago. Many species became extinct in Australia around that time, coinciding with the arrival of humans....
is the best known genus.
Distribution
Records of these birds are known only from Australia. Most of the records of dromornithids come from the eastern half of the continent, although fossil evidence of has also been discovered in TasmaniaTasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
and Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. At some Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
sites they are very common, sometimes comprising 60-70% of the fossil material. A fragment of a dromornithid-sized foot bone has been found in Antarctica, but whether it represents these birds is uncertain.
Age
The earliest bones identified were found in Late OligoceneOligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
deposits at Riversleigh
Riversleigh
Riversleigh, in North West Queensland, is Australia's most famous fossil site. The 100 km² area has fossil remains of ancient mammals, birds and reptiles of Oligocene and Miocene age...
, northwest Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
. There are foot impressions from the Early Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
in southeast Queensland that may be referable to dromornithids. The most recent evidence, of Genyornis newtoni, has been found at Cuddie Springs
Cuddie Springs
Cuddie Springs is a notable archaeological and paleontological site in the semi-arid zone of central northern New South Wales, Australia . Cuddie Springs is an open site, with the fossil deposits preserved in a claypan on the floor of an ancient ephemeral lake...
, north central New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
and dated at 31,000 years old.
Discovery
The most recent species, Genyornis newtoni, was certainly known to Aborigines during the Late Pleistocene. Cave paintings thought to depict this bird are known, as are carved footprints larger than those considered to represent emus. At Cuddie Springs, Genyornis bones have been excavated in association with human artifacts. The issue of how much of an impact humans had on dromornithids and other large animals of the time is unresolved and much debated. Many scientists believe that human settlement and hunting were largely responsible for the extinction of many species of the Australian megafaunaAustralian megafauna
Australian megafauna are a number of large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives...
.
The first Europeans to encounter the bones of dromornithids may have been Thomas Mitchell and his team. While exploring the Wellington Caves
Wellington Caves
The Wellington Caves are a group of limestone caves located 8 kilometres south of Wellington, New South Wales, Australia.- History :The Wellington region was long inhabited by the 'Binjang mob' of the Wiradjuri people. While there is no direct evidence that they entered any of the caves at...
, one of his men tied his rope to a projecting object which broke when he tried to descend the rope. After the man had climbed back up, it was found that the projecting object was the fossilised long bone of a large bird. The first species to be described was Dromornis australis. The specimen was found in a 55 metre deep well at Peak Downs
Peak Downs
Peak Downs may refer to:* Shire of Peak Downs, a Local Government Area of Queensland, Australia* Peak Downs Mine, a mine in Queensland, Australia...
, Queensland, and subsequently described by Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
in 1872.
Extensive collections of any dromornithid fossils were first made at Lake Callabonna
Lake Callabonna
Lake Callabonna is a dry salt lake with little to no vegetation in northeastern South Australia, approximately southwest of the junction of South Australia, Queensland and New South Wales at Cameron Corner. It is an important site for late Pleistocene fossils...
, South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
.
In 1892, E.C. Stirling and A.H. Zietz of the South Australian Museum received reports of large bones in a dry lake bed in the northwest of the state. Over the next years, they made several trips to the site, collecting nearly complete skeletons of several individuals. They named the newfound species Genyornis newtoni in 1896. Additional remains of Genyornis have been found in other parts of South Australia and in New South Wales and Victoria.
Other sites of importance were Bullock Creek
Bullock Creek
The Bullock Creek Fossil site is one of three known vertebrate fossil sites in the Australia's Northern Territory, along with the Alcoota Fossil Beds on Alcoota Station and the Kangaroo Well site on Deep Well Station. It is located about 550km south-southeast of Darwin, on Camfield Station...
and Alcoota
Alcoota
The Alcoota Fossil Beds are an important paleontological site located on Alcoota Station in Central Australia, 200km north-east of Alice Springs. It is notable for the occurrence of well-preserved, rare, Tertiary vertebrate fossils, which provide evidence of the evolution of the Northern...
, both in the Northern Territory. The specimen recovered there remained unstudied and unnamed until 1979, when Patricia Rich described five new species and four new genera. As of 2005, another new genus and species is under study at the Australian Museum.
Fossils
The best represented bones of dromornithids are vertebrae, long bones of the hindlimb and toe bones. Ribs and wing bones are uncommonly preserved. The rarest part of the skeleton is the skull. For many years, the only skull known was a damaged specimen of Genyornis. Early reconstructions of dromornithids made them appear like oversized emus. Peter MurrayPeter Murray
Peter Murray may refer to:*Peter Murray , prominent British architectural journalist*Peter Murray , lecturer at Harvard Law School*Pete Murray, Australian singer-songwriter*Pete Murray...
and Dirk Megirian, of the Northern Territory Museum in Australia, recovered enough skull material of Bullockornis to give a good idea of what that bird's head looked like. It is now known that Bullockornis' skull was very large, with the enormous bill making up about two-thirds of it. The bill was deep, but rather narrow. The jaws had cutting edges at the front as well as crushing surfaces at the back. There were attachments for large muscles, indicating that Bullockornis had a powerful bite. More fragmentary remains of the skull of Dromornis suggest that it, too, had an oversized skull.
Bones are not the only remains of dromornithids that have been found:
- The polished stones that the birds kept in their gizzardGizzardThe gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including birds, reptiles, earthworms and some fish. This specialized stomach constructed of thick, muscular walls is used for grinding up food; often rocks are...
s (muscular stomachs) occur at a number of sites. These stones, called gastrolithGastrolithA gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith's...
s, played an important role in their digestion by breaking up coarse food or matter that was swallowed in large chunks. - Series of footprints, called trackwayFossil trackwayA fossil trackway is a type of trace fossil, a trackway made by an organism. Many fossil trackways were made by dinosaurs, early tetrapods, and other quadrupeds and bipeds on land...
s, have been found at several sites. - Impressions of the inside of the skull cavity (endocranial casts or endocasts) have been found. Endocasts are formed when sediments fill the empty skull, after which the skull is destroyed. These fossils give a fairly accurate picture of dromornithid brains.
- Almost complete eggs have been found on occasion and eggshell fragments are common in some areas of sand dunes.
Diet
It has been generally thought that the dromornithids were plant eaters. This belief is based on:- the lack of a hook at the end of the bill
- the lack of talons on the toes
- the association of gizzard stones (caveatCaveatCaveat , the third-person singular present subjunctive of the Latin cavere, means "warning" ; it can be shorthand for Latin phrases such as:...
: gastroliths are also found the stomachs of some carnivores, such as modern crocodileCrocodileA crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s) - the large number of individuals occurring together, suggesting flocking behaviour.
The very large skull and deep bill of Bullockornis, however, are very unlike those found in large herbivorous birds such as moas. If this dromornithid ate plants, it was equipped to process very robust material that has thus far not been identified. Growing and maintaining such a large head would be detrimental and probably not occur unless it provided a substantial benefit of some sort, although it may have just been a social signal - this, however, would require a highly developed or complex social structure to evolve.
It has been suggested that, despite the indications of herbivory in some dromornithids, Bullockornis may have been a carnivore or possibly a scavenger. The jaws could easily cut meat and their robust structure could have resisted damage if it bit into bones. The bird could easily have fed on the carcasses of large animals.
It is, of course, not necessary that all dromornithids had the same diet. There is good evidence that Genyornis, at least, was a plant eater. Amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
analysis of eggshells indicates that this species was herbivorous. Bullockornis and Dromornis, with larger heads, may have had different diets.
Locomotion
Because of their enormous size, dromornithids have been considered to have been slow lumbering creatures. Their legs are not long and slender like those of emus or ostriches, which are specialised for running. However, biomechanical analysis of the attachments and presumed sizes of the muscles suggest that dromornithids might have been able to run much faster than originally thought, making up for their less than ideal form with brute strength. This would make them less likely candidates for a herbivorous diet, much like the similar yet more predatory terror birdsPhorusrhacidae
Phorusrhacids , colloquially known as "terror birds" as the larger species were apex predators during the Miocene, were a clade of large carnivorous flightless birds that were the dominant predators in South America during the Cenozoic, 62–2 million years ago. They were roughly 1–3 meters tall...
of South America.
Phylogeny
What the nearest relatives of this group are is a controversial issue. For many years it was thought that dromornithids were related to ratites, such as emus, cassowaries and ostriches. It is now believed that the similarities between these groups are the result of similar responses to the loss of flight. The latest idea on dromornithid relationships, based on details of the skull, is that they evolved early in the lineage that includes waterfowlWaterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
.