Pelecaniformes

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Pelecaniformes
Temporal range: Late
Ma[1]
Possible an early origin based on molecular clock[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Clade: Aequornithes
Order: Pelecaniformes
Sharpe, 1891
Suborder and Families

The Pelecaniformes

altricial, hatching from the egg helpless and naked in most. They lack a brood patch
.

The pelicans, shoebill and hamerkop form a clade within the order, with their next closest relatives being a clade containing the herons, ibises and spoonbills. The

Phaethontidae (tropicbirds) were traditionally placed in the Pelecaniformes, but molecular and morphological studies indicate they are not such close relatives. They have been placed in their own orders, Suliformes and Phaethontiformes, respectively.[3]

Systematics and evolution

Classically, bird relationships were based solely on morphological characteristics. The Pelecaniformes were traditionally, but erroneously, defined as birds that have feet with all four toes webbed (totipalmate), as opposed to all other birds with webbed feet where only three of four were webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes. The group included frigatebirds, gannets, cormorants, anhingas, and tropicbirds.[4]

Ciconiiformes
, a radical move which by now has been all but rejected: their "Ciconiiformes" merely assembled all early advanced land- and seabirds for which their research technique delivered insufficient phylogenetic resolution.

Morphological study has suggested pelicans are sister to a gannet-cormorant clade, yet genetic analysis groups them with the hamerkop and shoebill, though the exact relationship between the three is unclear.[5] Mounting evidence pointed to the shoebill as a close relative of pelicans.[4] This also included microscopic analysis of eggshell structure by Konstantin Mikhailov in 1995, who found that the shells of pelecaniform eggs (including those of the shoebill but not the tropicbirds) were covered in a thick microglobular material.[6] Reviewing genetic evidence to date, Cracraft and colleagues surmised that pelicans were sister to the shoebill with the hamerkop as the next earlier offshoot.[7] Ericson and colleagues sampled five nuclear genes in a 2006 study spanning the breadth of bird lineages, and came up with pelicans, shoebill and hamerkop in a clade.[8] Hackett and colleagues sampled 32 kilobases of nuclear DNA and recovered shoebill and hamerkop as sister taxa, pelicans sister to them, and herons and ibises as sister groups to each other, with the heron and ibis group a sister to the pelican/shoebill/hamerkop clade.[9]

The current

Ardeidae).[10] The phylogenetic relationships between the families is shown in the following cladogram:[11][12]

Pelecaniformes

Threskiornithidae – ibises, spoonbills (36 species)

Ardeidae
– herons, bitterns (72 species)

Balaenicipitidae – shoebill

Scopidae – hamerkop

Pelecanidae – pelicans (8 species)

Recent research strongly suggests that the similarities between the Pelecaniformes as traditionally defined are the result of

polyphyletic.[13] All families in the traditional or revised Pelecaniformes except the Phalacrocoracidae have only a few handfuls of species at most, but many were more numerous in the Early Neogene. Fossil genera and species are discussed in the respective family or genus accounts; one little-known prehistoric Pelecaniforms, however, cannot be classified accurately enough to assign them to a family. This is "Sula" ronzoni from Early Oligocene rocks at Ronzon, France, which was initially believed to be a sea-duck
and possibly is an ancestral Pelecaniform.

The pelecaniform lineages appear to have originated around the end of the

taxa
, the following show some similarities to the traditional Pelecaniformes:

The proposed

monophyletic nor does Elopteryx appear to be a modern bird.[14]

References

  1. ^ Mayr, G. et al. (2018) A fossil heron from the early Oligocene of Belgium - the earliest temporally well-constrained record of the Ardeidae. Ibis, 161(1) DOI:10.1111/ibi.12600
  2. PMID 32781465
    .
  3. PMID 25504713
    .
  4. ^
    PMID 7937906
    .
  5. S2CID 59486699
    .
  6. doi:10.1139/z95-207
    .
  7. ISBN 0-19-517234-5 PDF fulltext Archived 2013-05-14 at the Wayback Machine
  8. PMID 17148284
    .
  9. S2CID 6472805
    .
  10. ^ International Ornithological Committee (2 January 2012). "Ibises to Pelicans & Cormorants". IOC World Bird Names: Version 2.11. WorldBirdNames.org. Archived from the original on 1 March 2012. Retrieved 30 April 2012.
  11. PMID 28369655
    .
  12. PMID 32781465
    .
  13. ^ Mayr (2003)
  14. ^ Mortimer (2004)

Further reading

External links

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Pelecaniformes (category)
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