''Hoazinoides'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s from the Middle Miocene (

Laventan The Laventan ( es, Laventense) age is a period of geologic time (13.8 to 11.8 Ma) within the Middle Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Colloncuran and precedes th ...

) from the "Monkey Beds" of the

Villavieja Formation The Honda Group ( es, Grupo Honda, Tsh, Ngh) is a geological group of the Upper and Middle Magdalena Basins and the adjacent Central and Eastern Ranges of the Colombian Andes. The group, in older literature also defined as formation, is in its ...

of the Honda Group at the Konzentrat-Lagerstätte of

La Venta La Venta is a pre-Columbian archaeological site of the Olmec civilization located in the present-day Mexican state of Tabasco. Some of the artifacts have been moved to the museum "Parque - Museo de La Venta", which is in nearby Villahermosa, t ...

, Colombia.

Description

It is a member of the family Opisthocomidae, which also includes the

hoatzin The hoatzin ( ) or hoactzin ( ), (''Opisthocomus hoazin''), is the only species in the order Opisthocomiformes. It is a species of tropical bird found in swamps, riparian forests, and mangroves of the Amazon and the Orinoco basins in South Ameri ...

and several other extinct genera. The only known species is ''Hoazinoides magdalenae''. Its

generic epithet Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

refers to its refers to its resemblance to modern hoatzin, and its specific name refers to its discovery near the

Magdalena River The Magdalena River ( es, Río Magdalena, ; less commonly ) is the main river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much of ...

basin. Like many other fossil birds, it is known from fragmentary remains, including the back portion of the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

, the specimen

UCMP The University of California Museum of Paleontology (UCMP) is a paleontology museum located on the campus of the University of California, Berkeley. The museum is within the Valley Life Sciences Building (VLSB), designed by George W. Kelham and ...

42823 and other bones of the extremities. From these remains it appears that this bird was similar to that of hoatzin, although smaller, and distinguished from it in the parietal wall of the skull is concave and the

coracoid A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...

and

sternum The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sha ...

were not fused. This is why Tab Rasmussen (1997) erected a new family, Hoazinoididae, for it.Rasmussen, Tab, (1997). "Birds". In: R.F. Kay; R.H. Madden; R.L. Cifelli & J.J. Flynn (eds.) ''Vertebrate paleontology in the neotropics – the Miocene fauna of La Venta, Colombia''. Smithsonian Institution Press, . Its feet were like those of modern

owl Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...

s, in which the fourth toe can rotate backwards. Additionally, the remains of its distal

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

and carpal-

metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...

suggest that its arms were similar to those of hoatzins.

References

External links

Paleobiology Database: Hoazinoides
Prehistoric bird genera Miocene birds of South America Laventan Neogene Colombia Fossils of Colombia Honda Group, Colombia Fossil taxa described in 1953 {{paleo-bird-stub