Cuculiformes
Encyclopedia
The near passerine
Near passerine
Near 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...

 bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

 order Cuculiformes traditionally included three families as below:
  • Musophagidae - turacos and allies
  • Cuculidae - cuckoos, coucals, roadrunners and anis
  • Opisthocomidae
    Opisthocomidae
    Opisthocomidae is a group of birds, the only named family within the order Opisthocomiformes. The only living representative is the Hoatzin Opisthocomus hoazin, which lives in the Amazon and the Orinoco delta in South America. Several fossil species have been identified, including one from Africa....

     - Hoatzin (or Opisthocomiformes)


However, the taxonomy of this group is now controversial. The Sibley-Ahlquist taxonomy
Sibley-Ahlquist taxonomy
The Sibley-Ahlquist taxonomy is a 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 Hoatzin
Hoatzin
The Hoatzin , also known as the Hoactzin, Stinkbird, or Canje Pheasant, is a 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, monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 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 Crotophagidae
Crotophagidae
The anis are a small family of gregarious birds occurring in the Americas. They are part of the cuckoo order Cuculiformes and are sometimes placed as a subfamily Crotophaginae within the cuckoo family Cuculidae....

 respectively.

Evolution

The fossil record of this group is much debated. The unique anatomy
Anatomy
Anatomy 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 genera
Genera
Genera 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 Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene 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 Paleogene
Paleogene
The 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 Cypselomorphae
Cypselomorphae
Cypselomorphae 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. Foro
Foro (bird)
Foro 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 link
Missing Link
Missing link is a nonscientific term for any transitional fossil, especially one connected with human evolution; see Transitional fossil - Missing links and List of transitonal fossils - Human evolution.Missing Link may refer to:...

" between this bird and the Cuculiformes proper but as noted above, it is just impossible to closely ally the Hoatzin with any extant birds.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK