Elephant birds are extinct flightless birds belonging to the order Aepyornithiformes that were native to the island of Madagascar. They are thought to have gone extinct around 1000 AD, likely as a result of human activity. There are three currently recognised species, one in the genus Mullerornis, and two in Aepyornis. Aepyornis maximus is possibly the largest bird to have ever lived, with their eggs being the largest known for any amniote. Elephant birds were herbivores and major components of Madagascar's pre-human ecosystems. Elephant birds are palaeognaths (whose flightless representatives are often known as ratites), and their closest living relatives are kiwi (found only in New Zealand), suggesting that ratites did not diversify by vicariance during the breakup of Gondwana but instead convergently evolved flightlessness from ancestors that dispersed more recently by flying.
Discovery Elephant birds have been extinct since at least the 17th century. Étienne de Flacourt, a French governor of Madagascar during the 1640s and 1650s, mentioned the Vouron patra, an ostrich-like bird. This has generally been taken as a reference to elephant birds, although it has been argued that he may have been repeating folk tales from generations earlier.Buffetaut, E. Elephant Birds Under the Sun King? Etienne de Flacourt and the Vouron patra. Bol. Do Cent. Port. De Geo-História E Pré-História 2018, 1, 1. In his 1658 work, Histoire de la grande isle Madagascar, Flacourt wrote of the bird (in translation):
There has been speculation, especially popular in the latter half of the 19th century, that the legendary roc from the accounts of Marco Polo was ultimately based on elephant birds, but this is disputed.
Between 1830 and 1840, European travelers in Madagascar saw giant eggs and eggshells. British observers were more willing to believe the accounts of giant birds and eggs because they knew of the moa in New Zealand. In 1851 the genus Aepyornis and species A. maximus were scientifically described in a paper presented to the Paris Academy of Sciences by Isidore Geoffroy Saint-Hilaire, based on bones and eggs recently obtained from the island,Geoffroy Saint-Hilaire I. 1851. Note sur des ossements à Madagascar; dans des alluvions moderns; et provenant d'un Oiseau gigantesque. [Note on bones in Madagascar; in modern alluvial deposits; and originating from a gigantic bird] C. R. Hebd. Séanc. Acad. Sci. Paris 32, 101–107. which resulted in wide coverage in the popular presses of the time, particularly due to their very large eggs. The name "elephant bird" was in use in English to refer to Aepyornis by 1890. The genus Mullerornis was described in 1894 by Alphonse Milne-Edwards & Alfred Grandidier.Milne-Edwards A, Grandidier A. 1894 Observations sur les Aepyornis de Madagascar. C. R. Hebd. Séanc. Acad. Sci. Paris 13, 122–127.
Two whole eggs have been found in dune deposits in southern Western Australia, one in the 1930s (the Scott River egg) and one in 1992 (the Cervantes egg); both have been identified as Aepyornis maximus rather than Genyornis newtoni, an extinct giant bird known from the Pleistocene of Australia. It is hypothesized that the eggs floated from Madagascar to Australia on the Antarctic Circumpolar Current. Evidence supporting this is the finding of two fresh penguin eggs that washed ashore on Western Australia but may have originated in the Kerguelen Islands, and an ostrich egg found floating in the Timor Sea in the early 1990s.
Taxonomy and evolution Like the ostrich, rhea, cassowary, emu, kiwi and extinct moa, elephant birds are ratites and members of infraclass Palaeognathae; they could not fly, and their breast bones had no keel.
Sequencing of ancient DNA obtained from elephant bird remains including eggs, as well as genetic sequencing of other palaeognaths indicate that New Zealand kiwis are their closest known relatives, though the split between the two groups is deep, with kiwis and elephant birds being estimated to have diverged from each other around 54 million years ago, during the early Eocene epoch.
Placement of elephant birds within Palaeognathae, after Takezaki et al. 2023 and Kück and Suh 2026.Historically, it was thought that the ancestor of ratites had been flightless and lived on Gondwana prior to its breakup, and that the various ratite lineages had diverged as a result of vicariance as Gondwana broke up during the Cretaceous. It is now thought, based on genetic evidence, such as the flighted tinamou being nested within the ratites, that ratites, including elephant birds, convergently evolved flightlessness many times considerably after Gondwana broke apart. Madagascar has a notoriously poor Cenozoic terrestrial fossil record, with essentially no fossils from the end of the Cretaceous around 66 million years ago until around 80,000 years ago, during the early Late Pleistocene, leaving the time of arrival and evolution of elephant birds on Madagascar almost entirely unknown. Complete mitochondrial genomes obtained from elephant birds eggshells suggest that Aepyornis and Mullerornis are significantly genetically divergent from each other, with molecular clock analyses estimating the split between the ancestors of Aepyornis and Mullerornis around 27-30 million years ago, during the Oligocene epoch.
Historically, some other extinct birds were included in Aepyornithiformes, such as the emu-sized presumably flightless bird Eremopezus and its synonym Stromeria from the Eocene of Egypt, but they are now considered unrelated. Eggshell fragments found on Lanzarote in the Canary Islands, dating to the early Pliocene, around 4 million years ago, have been suggested by some authors to represent those of close relatives of elephant birds based on their pore morphology, though it is now argued that they likely represent those of ostriches.
Systematic taxonomy and species All elephant birds are usually placed in the single family Aepyornithidae Bonaparte, 1853,Bonaparte CL. 1853. Classification ornithologique par series. [Ornithological classification by series] Ann. Sci. Nat. 1, 139. but some authors suggest Aepyornis and Mullerornis should be placed in separate families within the Aepyornithiformes, with the latter placed into Mullerornithidae Lamberton, 1934.Lamberton C. Ratites subfossiles de Madagascar. Les Mullerornithidae. m.ém. Acad.émie Malgache. 1934;17:125–168. The authority of the order Aepyornithiformes is generally given as Newton 1884, after Alfred Newton's usage of Aepyornithes (originally spelled Æpyornithes) in the "Ornithology" article in the 9th edition of the Encyclopædia Britannica. However, Newton had already used Aepyornithes in an 1877 article in The Annals and Magazine of Natural History.Newton, Alfred: "The nomenclature of the groups of Ratitae". The Annals and Magazine of Natural History 4 (20), 1877, pp. 499–500 The first use of Aepyornithiformes was by Max Fürbringer in 1888.Fürbringer, M. (1888), Untersuchungen zur Morphologie und Systematik der Vögel [Studies on the morphology and systematics of birds] Amsterdam: van Halkema p. XLVIII
At least 11 species in the genus Aepyornis have been named, but the validity of many have been disputed, with numerous authors treating them all in just one species, A. maximus. Up to three species have been described in Mullerornis. A major systematic review by Hansford and Turvey (2018) based on morphological analysis recognised only four valid elephant bird species, Aepyornis maximus, Aepyornis hildebrandti, Mullerornis modestus, and the new species and genus Vorombe titan to accommodate the largest elephant bird remains. However, the validity of Vorombe titan was later questioned by genetic sequencing data, which did not find evidence for a third genus of elephant bird in sampled eggshell DNA sequences, and skeletal remains assigned to Vorombe were found within the genetic group containing Aepyornis maximus skeletal remains and eggshells (including those of the largest elephant bird eggs), and it has thus been proposed that specimens assigned to Vorombe actually represent large specimens of A. maximus, perhaps sexually dimorphic larger females, as is observed in the giant moa genus Dinornis. Eggshells that have had their DNA sequenced from the far north of Madagascar may represent a third species of Aepyornis, due to their genetic distinctiveness from the other two species, but the lack of skeletal remains from this region renders this currently inconclusive, and may instead represent a genetically distinctive subpopulation of A. hildebrandti. Order Aepyornithiformes authority traditionally given as (Newton 1884)Newton, A. 1884. Ornithology. Encyclopædia Britannica 9th ed. 18: p. 44 Genus Aepyornis Geoffroy Saint-Hilaire 1850 (Synonym: Vorombe Hansford & Turvey 2018) Aepyornis hildebrandti Burckhardt, 1893 Aepyornis maximus Hilaire, 1851 Genus Mullerornis Milne-Edwards & Grandidier 1894 Mullerornis modestus (Milne-Edwards & Grandidier 1869) Hansford & Turvey 2018
Description
Elephant birds were large birds, the largest reaching tall in upright standing posture. Like most other ratites, they had long legs and elongate necks, with small heads relative to body size. Their skulls bore straight, thick conical beaks that were not hooked. The skulls of elephant bird species differ little from each other except in size, though the front part of the skull in Mulleronis is less robustly built than in Aepyornis. The tops of elephant bird skulls display punctuated marks, which may have been attachment sites for fleshy structures or head feathers. The wings were vestigial. The spinal column is suggested to have been made up of 24 free unfused vertebrae, 16-17 cervical vertebrae in the neck, and 6-7 thoracic vertebrae. The pelvis of Aepyornis is robust and all its constituent elements (pubis, ilium and vertebrae) heavily fused to each other. The pelvis of Mulleronis is generally three times wider than long. The hindlimb bones, especially the femur and tibiotarsus, are very robust (proportionally stocky/thick) in Aepyornis, with the femur of Aepyornis being distinctly short and wide. The hindlimb bones were somewhat more gracile in Mullerornis. The terminal claw-bearing phalanges in the feet are uncurved and relatively broad, though somewhat more elongate and sharper in shape in Mullerornis.Mullerornis is the smallest of the elephant birds, with a body mass of around , with its skeleton much less robustly built than Aepyornis. A. hildebrandti is thought to have had a body mass of around . Estimates of the body mass of Aepyornis maximus span from around to making it one of the largest birds ever, alongside Dromornis stirtoni and Pachystruthio dmanisensis. Females of A. maximus are suggested to have been larger than the males, as is observed in other ratites.
Biology
Examination of brain endocasts has shown that both A. maximus and A. hildebrandti had greatly reduced optic lobes (a part of the brain that processes visual information), compared to most other ratites, similar to those of their closest living relatives, the kiwis, and consistent with a similar nocturnal lifestyle. The optic lobes of Mullerornis were also reduced, but to a lesser degree, suggestive of a nocturnal or crepuscular lifestyle. A. maximus had relatively larger olfactory bulbs than A. hildebrandti, suggesting that the former occupied forested habitats where the sense of smell is more useful while the latter occupied open habitats. Elephant birds probably heavily relied on their sense of smell. Morphological analysis of their ears suggests that they had relatively poor hearing. Based on the proportions of their leg bones, unlike most living ratites such as ostriches, emus and rheas, but similar to moas, elephant birds are thought to have walked with a relatively slow graviportal locomotion, though the smaller Mullerornis may have been capable of somewhat more agile locomotion than the larger Aepyornis species.
Diet