Pelecaniformes is an order of medium-sized and large waterbirds
found worldwide. As traditionally—but erroneously—defined, they
encompass all birds that have feet with all four toes webbed. Hence,
they were formerly also known by such names as totipalmates or
steganopodes. Most have a bare throat patch (gular patch), and the
nostrils have evolved into dysfunctional slits, forcing them to
breathe through their mouths. They feed on fish, squid or similar
marine life. Nesting is colonial, but individual birds are monogamous.
The young are altricial, hatching from the egg helpless and naked in
most. They lack a brood patch.
Sulidae (gannets and boobies),
Phalacrocoracidae (cormorants and shags),
Anhingidae (darters) and 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
Phaethontiformes and Suliformes, respectively.
1 Systematics and evolution
4 External links
Systematics and evolution
Classically, bird relationships were based solely on morphological
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
Sibley and Ahlquist's landmark
DNA-DNA hybridisation studies (see
Sibley-Ahlquist taxonomy) led to them placing the families
traditionally contained within the
Pelecaniformes together with the
grebes, cormorants, ibises and spoonbills, New World vultures, storks,
penguins, albatrosses, petrels, and loons together as a sub-group
within a greatly expanded order 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. Mounting evidence pointed to the shoebill as a close
relative of pelicans. 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.
Reviewing genetic evidence to date, Cracraft and colleagues surmised
that pelicans were sister to the shoebill with the hamerkop as the
next earlier offshoot. 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. 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 this heron and ibis group a
sister to the pelican/shoebill/hamerkop clade.
International Ornithological Committee classification has
pelicans grouped with the shoebill (Balaenicipitidae), hamerkop
(Scopidae), ibises and spoonbills (Threskiornithidae) and herons,
egrets and bitterns (Ardeidae).
Recent research strongly suggests that the similarities between the
Pelecaniformes as traditionally defined are the result of convergent
evolution rather than common descent, and that the group is
paraphyletic. 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
The Pelecaniform lineages appear to have originated around the end of
Monophyletic or not, they appear to belong to a
close-knit group of "higher waterbirds" which also includes groups
such as penguins and Procellariiformes. It is interesting to note that
there are quite a lot of fossil bones from around the
Paleogene boundary which cannot be firmly placed with any
of these orders and rather combine traits of several of them. This is
of course only to be expected, if the theory that most if not all of
these "higher waterbird" lineages originated around that time is
correct. Of those apparently basal taxa, the following show some
similarities to the traditional Pelecaniformes:
Lonchodytes (Lance Creek
Late Cretaceous of Wyoming, US)
Torotix (Late Cretaceous)
Tytthostonyx (Late Cretaceous/Early Palaeocene)
Cladornis (Deseado Early
Oligocene of Patagonia, Argentina)
"Liptornis"—a nomen dubium
The proposed Elopterygidae—supposedly a family of Cretaceous
Pelecaniformes—are neither monophyletic nor does Elopteryx appear to
be a modern bird.
^ Jarvis, E.D. et al. (2014) Whole-genome analyses resolve early
branches in the tree of life of modern birds. Science,
346(6215):1320-1331. DOI: 10.1126/science.1253451
^ a b Hedges, S.Blair; Sibley, Charles G (1994). "Molecules vs.
morphology in avian evolution: the case of the "pelecaniform" birds".
PNAS. 91 (21): 9861–65. doi:10.1073/pnas.91.21.9861.
^ Mayr, G. (2007). "Avian higher-level phylogeny: Well-supported
clades and what we can learn from a phylogenetic analysis of 2954
morphological characters". Journal of Zoological Systematics and
Evolutionary Research. 46: 63–72.
^ Mikhailov, Konstantin E. (1995). "Eggshell structure in the shoebill
and pelecaniform birds: comparison with hamerkop, herons, ibises and
storks". Canadian Journal of Zoology. 73 (9): 1754–70.
^ Cracraft, Joel; Barker, F. Keith; Braun, Michael J.; Harshman, John;
Dyke, Gareth J.; Feinstein, Julie; Stanley, Scott; Cibois, Alice;
Schikler, Peter; Beresford, Pamela; García-Moreno, Jaime; Sorenson,
Michael D.; Yuri, Tamaki & Mindell, David P. (2004): Phylogenetic
Relationships Among Modern Birds (Neornithes): Toward an Avian Tree of
Life. In: Cracraft, J. & Donoghue, M.J. (eds.): Assembling the
Tree of Life: 468-489. Oxford University Press, New York.
ISBN 0-19-517234-5 PDF fulltext
^ Ericson, P. G. P.; Anderson, C. L.; Britton, T.; Elzanowski, A.;
Johansson, U. S.; Källersjö, M.; Ohlson, J. I.; Parsons, T. J.;
Zuccon, D.; Mayr, G. (2006). "Diversification of Neoaves: integration
of molecular sequence data and fossils". Biology Letters. 2 (4):
543–547. doi:10.1098/rsbl.2006.0523. PMC 1834003 .
^ Hackett, Shannon J.; Kimball, Rebecca T.; Reddy, Sushma; Bowie,
Rauri C. K.; Braun, Edward L.; Braun, Michael J.; Chojnowski, Jena L.;
Cox, W. Andrew; et al. (2008). "A Phylogenomic Study of Birds Reveals
Their Evolutionary History". Science. 320 (5884): 1763–68.
doi:10.1126/science.1157704. PMID 18583609.
International Ornithological Committee (2 January 2012). "Ibises to
Pelicans & Cormorants". IOC World
Bird Names: Version 2.11.
WorldBirdNames.org. Retrieved 30 April 2012.
^ Mayr (2003)
^ Mortimer (2004)
Bourdon, Estelle; Bouya, Baâdi & Iarochene, Mohamed (2005):
Earliest African neornithine bird: A new species of Prophaethontidae
(Aves) from the Paleocene of Morocco. J. Vertebr. Paleontol. 25(1):
157–170. DOI: 10.1671/0272-4634(2005)025[0157:EANBAN]2.0.CO;2 HTML
Mayr, Gerald (2003): The phylogenetic affinities of the Shoebill
Balaeniceps rex). Journal für Ornithologie 144(2): 157–175.
[English with German abstract] HTML abstract
Mortimer, Michael (2004): The Theropod Database: Phylogeny of taxa.
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