PBDB Taxon

Basic info	Taxonomic history	Classification	Included Taxa
Morphology	Ecology and taphonomy	External Literature Search	Age range and collections

Kustokazanser formosus

Reptilia - Anseriformes

Taxonomy

Cygnavus formosus was named by Kurochkin (1968). Its type specimen is PIN, no. 2432/36, a limb element ( distal fragment of a right tibiotarsus), and it is a 3D body fossil. Its type locality is Kiin Kerish (lower Aksyir svita), which is in an Eocene terrestrial horizon in Kazakhstan.

It was recombined as Kustokazanser formosus by Zelenkov (2024).

Synonymy list

Year	Name and author
1968	Cygnavus formosus Kurochkin p. 95 figs. Fig. 2
1986	Cygnavus formosus Mlíkovsky and Svec p. 262
2024	Kustokazanser formosus Zelenkov p. 11

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
subclass	Eureptilia	()
—	Romeriida
—	Diapsida	()
—	Archosauromorpha	(Huene 1946)
—	Crocopoda

Rank	Name	Author
—	Archosauriformes	Gauthier 1986
—	Eucrocopoda
—	Archosauria	()
informal	Avemetatarsalia
—	Ornithodira
—	Dinosauromorpha
—	Dinosauriformes
—	Dinosauria	()
—	Theropoda	()
—	Neotheropoda
—	Averostra	Paul 2002
—	Tetanurae
—	Coelurosauria	()
—	Maniraptora
—	Paraves
class	Aves
subclass	Neornithes	Gadow 1893
—	Neognathae	(Pycraft 1900)
—	Pangalloanserae	Gauthier and de Queiroz 2001
—	Galloanserae	Sibley and Ahlquist 1990
superorder	Galloanserimorphae
order	Anseriformes	Wagler 1831
genus	Kustokazanser
species	formosus	()

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

†Kustokazanser formosus Kurochkin 1968

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Diagnosis

Reference	Diagnosis
N. Zelenkov 2024	Kustokazanser formosus is distinguished from all anatids in: poorly medially expanding distal extremity (Fig. 4A, m), distal opening of canalis extensorius positioned very close to cranial apex of condylus medialis (Fig. 4A, arrow), and additionally in narrow notch in distal margin of bone, formed by incisura intercondylaris (in cranial view). Kustokazanser differs from A. semipalmata in: shorter and generally much smaller condylus medialis, lack of pronounced concavity in lateral margin of bone just by condylus lateralis (in cranial view), much shorter pons supratendineus, and notably deeper incisura intercondylaris in distal view. Kustokazanser formosus differs from anhimids and presbyornithids by narrow condylus medialis, and from anhimids also by lack of pneumatic foramina and non-thickened medial margin of shaft at the level of pons supratendineus. Differs from Conflicto antarcticus Tambussi, Degrange, De Mendoza, Sferco, and Santillana, 2019 in: cranially less protruding condyles, narrow incisura intercondylaris, and generally medially deflected distal end of tibiotarsus.