Eogruidae Temporal range:Late Eocene–Early Pliocene PreꞒ Ꞓ O S D C P T J K Pg N
Detailed depiction ofErgilornis in its habitat
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Infraclass:	Palaeognathae
Order:	Struthioniformes
Family:	†Eogruidae Wetmore, 1934
Genera
†Eogrus †Sonogrus †Ergilornithinae †Amphipelargus †Ergilornis †Sinoergilornis †Urmiornis

Eogruidae (also spelledEogruiidae in some publications) is an extinct family of large, flightless birds that inhabited Asia from theEocene toPliocene epochs. Related to modernostriches, it was formerly thought to be related tocranes,limpkins andtrumpeters and that the similarities with ostriches were due to similar speciations tocursoriality, with both groups showing reduced numbers of toes to two in some taxa.^[1][2][3] It has been suggested that competition from true ostriches has caused the extinction of these birds,^[2][3] though this has never been formally tested and several ostrich taxa do occur in the late Cenozoic of Asia^[4] and some species do occur in areas where ostrich fossils have also been found.^[1] It has been suggested that the family isparaphyletic, with Ergilornithidae more closely related to modern ostriches than toEogrus orSonogrus.^[5]

Most eogruids are known from rather sparse remains, mostly the tarso-metatarsals and toes. The former are generally slender with a distinct crest along the lateral side of the plantar surface. The trochlea for the second toe shows a progressive reduction along the various taxa, culminating in its utter absence inAmphipelargus.^[4][3]

Other skeletal remains are rare. Wing elements are known in a few taxa; these are generally highly reduced, suggesting that these birds were flightless. The exception appears to beEogrus itself, which does not show much phalange reduction and hypothetically could still fly,^[4] though the rest of the postcranial skeleton is already specialised for cursoriality.^[2][3]

Eogruids were formerly considered to beGruiformes within thecrane-limpkin-trumpeter line, Gruoidea, the exception being Olson 1985 which declared them to be stem-ostriches.^[4] A study in 2021 based on newly described remains found that eogruids and the relatedErgilornithidae are indeed members of Struthoniformes.^[6]

More derived taxa such asErgilornis andAmphipelargus were sometimes classified as a separate family,Ergilornithidae, but they are now generally accepted to be a subfamily within Eogruidae.^[1] Eogruids are rather similar toGeranoididae, a clade of similar flightless gruiforms fromNorth America andEurope, and both groups have occasionally been classified as sister taxa. Recently geranoidids have been recovered as basal to the rest of Gruoidea, however, while eogruids are sister-taxa to cranes.^[7]

There is some contention in regards to ergilornithine genera, particularlyAmphipelargus andUrmiornis, which have assimilated each other's species from study to study. The most recent consensus is that nearly all Neogene eogruid remains belong toUrmiornis, while a few western Eurasian taxa can be referred to asAmphipelargus.^[1]

• †Eogrus
  • †Eogrus aeola
  • †Eogrus crudus
  • †Eogrus turanicus
• †Sonogrus
  • †Sonogrus gregalis
• †Proergilornis
• †Ergilornithinae
  • †Ergilornis
    • †Ergilornis rapidus
    • †Ergilornis minor (Synonym/s - "Proergilornis")
  • †Amphipelargus
    • †Amphipelargus majori
    • †Amphipelargus cracrafti
    • †An unnamed species possibly within this genus.^[1]
  • †Urmiornis
    • †Urmiornis brodkorbi
    • †Urmiornis dzabghanensis
    • †Urmiornis maraghanus
    • †Urmiornis orientalis
    • †Urmiornis ukrainus

• Ratites
• Prehistoric birds of Asia
• Extinct flightless birds
• Prehistoric bird families

• Articles with short description
• Short description is different from Wikidata
• Articles with 'species' microformats