Geranoididae

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Geranoididae
Temporal range: Eocene Eocene
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Infraclass: Palaeognathae
Family: †Geranoididae
Wetmore, 1933
Genera

Geranoididae is a clade of extinct birds from the early to late

flightless birds.[1][2][3][4][5] Recent research shows that these birds may actually be palaeognaths related to ostriches.[6]

Classification

It is rather unambiguous that geranoidids are either part of or stem representatives of

eogruiids. The most recent consensus appears to be that geranoidids are outside of Gruoidea, with eogruiids being more closely related to modern cranes.[4] However, Mayr (2019) argued that close affinities between Geranoididae and the palaeognathous family Palaeotididae are at least as well supported as the classification of geranoidids into the Gruiformes.[6]

Taxonomy

The exact number of genera and species are also somewhat controversial. For instance, a recent study recovers Geranoides as possibly synonymous with Palaeophasianus and Eogeranoides as possibly synonymous with Paragrus.[4]

Paleobiology

Most geranoidids appear to have been flightless, with long legs and short wings, and presumably with herbivorous habits, giving them a profile and lifestyle similar to that of modern

ratites. Most if not all of them were forest dwellers, a lifestyle also present in contemporaneous ratites such as Palaeotis and Remiornis.[7] While competition and lack thereof between ratites and eogruiids has been examined extensively,[8][9][10] niche partitioning between geranoidids and ratites has currently not, in spite of factors like geranoidids being most common in North America, where there are no ratites, or the fact that some European ratites were carnivorous.[5][11]

Paleoecology and distribution

Geranoidids are most common in Eocene fossil sites in North America, particularly in the Willwood Formation were up to six species are known. Galligeranoides occurs in the Eocene of France in association with another flightless bird, Gastornis, potentially indicating that geranoidids took advantage of land bridges to arrive to Europe.[3] However, Mayr (2019) considered Galligeranoides to be a member of Palaeognathae closely related to Palaeotis, and formally transferred Galligeranoides from the family Geranoididae to the family Palaeotididae. This transfer restricts the fossil record of the family Geranoididae to North America.[6]

References

  1. hdl:2246/2598
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  2. hdl:2246/597
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  3. ^
    doi:10.4202/app.00083.2014
    .
  4. ^
    S2CID 87692869
    .
  5. ^ a b Gerald Mayr (2009). Paleogene Fossil Birds
  6. ^
    doi:10.4202/app.00650.2019
    .
  7. doi:10.1016/j.earscirev.2014.07.001
    .
  8. ^ Kurochkin, E.N. 1976. A survey of the Paleogene birds of Asia. Smithsonian Contributions to Paleobiology 27:75-86.
  9. ^ Kurochkin, E.N. 1981. New representatives and evolution of two archaic gruiform families in Eurasia. Transactions of the Soviet-Mongolian Paleontologial Expedition 15:59-85.
  10. S2CID 131264199
    .
  11. ^ Houde, Peter; Haubold, Hartmut (June 1987). "Palaeotis weigelti restudied: a small middle Eocene Ostrich (Aves: Struthioniformes)". Palaeovertebrata. 17 (2): 27–42.
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