The
near passerineNear passerine or higher land-bird assemblage are terms often given to arboreal birds or those most often believed to be related to the true passerines due to ecological similarities; the group corresponds to some extent with the Anomalogonatae of Garrod . All near passerines are land birds...
birdBirds are winged, bipedal, endothermic , vertebrate animals that lay eggs. There are around 10,000 living species, making them the most numerous tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the Bee Hummingbird to the ...
order
Cuculiformes traditionally included three families as below:
- Musophagidae - turacos and allies
- Cuculidae - cuckoos, coucals and anis
- Opisthocomidae - Hoatzin
However, the taxonomy of this group is now controversial. The
Sibley-Ahlquist taxonomyThe Sibley-Ahlquist taxonomy is a radical bird taxonomy proposed by Charles Sibley and Jon Edward Ahlquist. It is based on DNA-DNA hybridization studies conducted in the late 1970s and throughout the 1980s....
raises the Musophagidae to an order Musophagiformes which may or may not be warranted.
The
near passerineNear passerine or higher land-bird assemblage are terms often given to arboreal birds or those most often believed to be related to the true passerines due to ecological similarities; the group corresponds to some extent with the Anomalogonatae of Garrod . All near passerines are land birds...
birdBirds are winged, bipedal, endothermic , vertebrate animals that lay eggs. There are around 10,000 living species, making them the most numerous tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the Bee Hummingbird to the ...
order
Cuculiformes traditionally included three families as below:
- Musophagidae - turacos and allies
- Cuculidae - cuckoos, coucals and anis
- Opisthocomidae - Hoatzin
However, the taxonomy of this group is now controversial. The
Sibley-Ahlquist taxonomyThe Sibley-Ahlquist taxonomy is a radical bird taxonomy proposed by Charles Sibley and Jon Edward Ahlquist. It is based on DNA-DNA hybridization studies conducted in the late 1970s and throughout the 1980s....
raises the Musophagidae to an order Musophagiformes which may or may not be warranted. The
HoatzinThe Hoatzin , also known as the Hoactzin, Stinkbird, or Canje "Pheasant", is an unusual species of tropical bird found in swamps, riverine forest and mangrove of the Amazon and the Orinoco delta in South America...
continues to be enigmatic; it is probably best regarded as a distinct,
monotypicIn biology, a monotypic taxon is a taxonomic group with only one type. The usage differs slightly between botany and zoology:In botany, a monotypic taxon is a taxon that has only one species: Ginkgo is a monotypic genus, while Ginkgoaceae is a monotypic family...
order, especially if the turacos are also considered one. The coucals and anis are sometimes considered subfamilies of the Cuculidae, or otherwise assigned to families of their own, the Centropodidae and
CrotophagidaeThe anis are a small family of gregarious birds occurring in the Americas. They are part of the cuckoo order Cuculiformes and sometimes placed as a subfamily Crotophaginae within the cuckoo family Cuculidae....
respectively.
Evolution
The fossil record of this group is much debated. The unique
anatomyAnatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy and plant anatomy...
of Cuculidae (in the old sense) often allows for the easy identification even of isolated bones. Cuckoos of prehistoric
generaGenera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
are known since the Late
EoceneThe Eocene epoch, lasting from 55.8 ± 0.2 to 33.9 ± 0.1 Ma , is a major division of the geologic timescale and the second epoch of the Palaeogene period in the Cenozoic era. The Eocene spans the time from the end of the Paleocene epoch to the beginning of the Oligocene epoch. The start of the...
, some 40-35 million years ago. Turaco fossils are known from much later only.
A number of other
PaleogeneThe Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic era...
fossils have at times been assigned to the Cuculiformes, but they are not usually included here anymore in more recent treatments: The Late Paleocene to mid-Eocene Gracilitarsidae were at first believed to be cuculiforms but this is not generally accepted today. They remain mysterious though, due to their apomorphic anatomy, and might be close to the equally enigmatic Sylphornithidae known from the mid-Eocene to the Early Oligocene. From the Early Eocene,
Parvicuculus and
Procuculus might be
CypselomorphaeCypselomorphae is a clade of birds. It includes the living families and orders Caprimulgidae , Nyctibiidae , Apodiformes , as well as the Aegotheliformes whose distinctness was only recently realized...
of a hitherto unrecognized lineage.
ForoForo is a mysterious genus of bird that lived during the early to mid-Eocene around the Ypresian-Lutetian boundary, some 48 million years ago. It is known from fossils found in the Green River Formation of Wyoming. Only a single species, Foro panarium, is known.Its relationships are unknown. It is...
might be allied with the Hoatzin; it had been touted as a "
missing linkThe term Missing link may refer to:* Any transitional fossil, especially one connected with human evolution.**for specific "missing link" fossils, see List of transitional fossils...
" between this bird and the Cuculiformes proper but as noted above, it is just impossible to closely ally the Hoatzin with
any extant birds.