{"id":5159,"date":"2011-11-30T19:27:19","date_gmt":"2011-11-30T21:27:19","guid":{"rendered":"http:\/\/revistapesquisa.fapesp.br\/2011\/11\/30\/a-longa-viagem-da-cigana-2\/"},"modified":"2017-02-23T16:03:17","modified_gmt":"2017-02-23T19:03:17","slug":"a-longa-viagem-da-cigana","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/a-longa-viagem-da-cigana\/","title":{"rendered":"The hoatzin\u2019s long journey"},"content":{"rendered":"
\"\"

Geoff Gallice \/ Wikicommons <\/span>Opisthocomus hoazin<\/em>, the hoatzin: its ancestors must have migrated from Africa to South America on board small rafts made of plants that crossed the Atlantic at the mercy of the winds and sea currentsGeoff Gallice \/ Wikicommons <\/span><\/p><\/div>\n

It flies awkwardly in the midst of vegetation along the river in the Amazon Forest, its only contemporary habitat. There it eats leaves and nothing else. It has a large beak and its digestive system is reminiscent of that of a ruminating mammal. Its feces smell of cow-dung. Taxonomists have not yet been able to reach an agreement as to how to classify it. For some of them, it\u2019s a distant relative of the chicken, although its appearance and size somewhat remind one of the cuckoo, to which, according to other taxonomists, it is related. There are also those who place it beside the touraco, an African bird.\u00a0For more than 230 years since its discovery, the hoatzin (Opisthocomus hoazin<\/em>), which is typical of the Amazon and Orinoco river basins, has intrigued researchers, who nowadays tend to regard it as the only living member of an order of birds that is separate from the rest, the Opisthocomiformes<\/em>. However, the discovery in Brazil of the oldest extinct species of birds related to the hoatzin \u2014 a fossil more than 20 million years old named Hoazinavis lacustris <\/em>\u2014 and the confirmation, which there was at some point in Africa\u2019s distant past, at least one life form similar to the current Amazonian bird, provided important clues regarding the likely origins of this mysterious animal. Up to this point there had not been any record of birds belonging to this order outside of South America.<\/p>\n

The two finds were disclosed in a study published this month in the German scientific journal Naturwissenschaften <\/em>by paleontologists and ornithologists from Brazil, Germany and France. According to the researchers, analysis of all the material suggests that the origins of the South-American bird lie in Africa, the oldest species related to the hoatzin had been found in the State of S\u00e3o Paulo.\u00a0\u201cDespite being more recent, the African fossils exhibit more primate anatomical characteristics than those present in our material,\u201d explains the paleontologist Herculano Alvarenga, founder and director of the Natural History Museum of the city of Taubat\u00e9, in inner-state S\u00e3o Paulo and one of the authors of the study. If this line of reasoning is correct, it is reasonable to assume that there must be fossils that are older than those of H. lacust<\/em>ris somewhere on the continent. The problem is that they have not yet been found and there is no guarantee that they ever will be.<\/p>\n

More surprising than the possible African roots of the Amazonian hoatzin is how this bird\u2019s ancestors must have made the long migration from Africa to South America, dozens of millions of years ago. At that time there was no longer any land connection between the two continents. Africa and South America had separated much earlier and the Atlantic Ocean, although not as wide as it is today, was an obstacle to be overcome in a transcontinental crossing.\u00a0Flapping its wings during a journey of thousands of kilometers and crossing the ocean by air was an impossible task for the ancestors of this South American bird, whose flying capabilities were as limited as those of the hoatzin. By exclusion, the only way they could have come was by sea. \u201cThese ancient birds must have crossed the Atlantic Ocean on raft-like remains of plants, which functioned as tiny floating islands connecting the two continents,\u201d states Alvarenga, a specialist in bird fossils.<\/p>\n

At the mercy of the winds and the currents<\/strong>
\nThis assumption may seem fanciful to a layman, but there is scientific evidence to support it. \u201cAll reconstitutions of how the winds and the sea currents were at that time favor the displacement of species from Africa to South America, rather than the other way around,\u201d declares the ornithologist Gerald Mayr, from the Senckenberg Museum, in the city of Frankfurt, one of the other authors of the article. There has never been a documented case of birds with limited flying capacity making this kind of intercontinental crossing, on board some kind of raft composed of plants that must have crossed the Atlantic at the mercy of the winds and the currents.\u00a0However, it is possible that other animals came here in this way. \u201cThis is the most widely accepted idea as to how caviomorph rodents and platyrrhini primates got from Africa to South America,\u201d comments the paleontologist C\u00e9cile Mourer-Chauvir\u00e9, from the University Claude Bernard – Lyon 1, another one of the authors of this scientific paper. Caviomorph rodents include animals that are typical of South America, such as the capybara and the paca, and the platyrrhini primates include the so-called New World monkeys, found only in the Americas.<\/p>\n

\"Hoatzin

Lu\u00eds F\u00e1bio Silveira<\/span>Hoatzin chick: the bird flies awkwardly and has a \u201cruminant\u2019s\u201d beakLu\u00eds F\u00e1bio Silveira<\/span><\/p><\/div>\n

The formulation of this new theory that tries to explain the origins of the South American bird was only possible thanks to the discovery on Brazilian soil of the new extinct species and to the work of reviewing the little fossil material related to the Opisthocomiformes<\/em> that can be found in the international museums. This double pronged approach enabled the researchers to do something that had not been possible up until now: to outline a scenario of evolutionary relationships between ancient birds and the only living member of this order of birds, the hoatzin.<\/p>\n

The oldest of the extinct species of the Opisthocomiformes<\/em>, the H. lacustris<\/em> inhabited the Trememb\u00e9 Formation, in the Taubat\u00e9 region, which is rich in animal fossils, between 22 and 24 million years ago. Three parts of the skeleton of a single example of this bird \u2014 a complete humerus (the main wing bone), a piece of the scapula and another of the coracoid (waist bone) \u2014 were found by Alvarenga in the sediment of an ancient lake (which is where the name lacustris<\/em> comes from) in 2008.\u00a0\u201cThe morphology of these three associated bones leaves no doubt that this bird was related to the hoatzin,\u201d explains the paleontologist from the State of S\u00e3o Paulo. The study of these fragments of the skeleton also revealed that the ancient bird must have had a large beak, which may well have contained bacteria that helped break down part of the bird\u2019s diet before the food reached its stomach. All of that was very similar to the current hoatzin. The description of the fossil was made by the Brazilian and his European colleagues in a paper published in the journal Naturwissenschaften<\/em>.<\/p>\n

Wishbone<\/strong>
\nBefore H. lacustris<\/em>, the remains of a single example of another species of extinct bird that was apparently related to the hoatzin had been found in the late 1990s in South America. In this case it was a fragment of a skull from a Hoazinoides magdalenae<\/em>, an animal that lived in the Villavieja Formation to the west of the Andes, in what is now Colombia, between 11.8 and 13.5 million years ago. Although there is little bone material to make any detailed comparison, the H. magdalenae<\/em> appears to have been very similar to the current hoatzin. It was just slightly larger than its modern Amazonian relative.\u00a0It is interesting to note that the two extinct species of Opisthocomiformes<\/em> found in South America occupied parts of the continent outside the Amazon region, which is the hoatzin\u2019s current home \u2014 an indication that the older forms of this bird may have been distributed over a much larger geographical area.<\/p>\n

\"048-051_Ave<\/a>The reclassification of an extinct species of African bird, the Namibiavis senutae<\/em>, within the hoatzin\u2019s phylogenetic order expanded the ancient domains of this group of winged creatures, with a large beak and a vegetarian diet, even further. First described at the start of the first decade of the new millennium, the fossils of the species were found in Namibia and were originally classified as members of an extinct group of birds from that continent, the Idiornithidae<\/em>.\u00a0However, the analysis undertaken by Alvarenga and his European colleagues changed this classification, placing the N. senutae<\/em>, which lived about 17 million years ago, with the genus Opisthocomiformes<\/em>. \u201cThe fossils found in Africa are more different from the modern hoatzin than the H. lacustris<\/em> found in Brazil,\u201d states Mayr. \u201cBut they are still very like the current bird.\u201d Among the more primitive anatomical differences that can be observed in the extinct African species, the French scientist C\u00e9cile highlights the fact that the coracoid and furcula bones \u2014 the latter consisting of the two clavicle bones connected to the sternum, a part of the structure of birds commonly known as the \u201cwishbone\u201d \u2014 had not yet fused, as if they were a single structure. In adult examples of the modern hoatzin the fusion of these and other bones is already complete.\u00a0It was precisely these more ancestral traits of the bones of the N. senutae<\/em> that supported the formulation of the hypothesis of the African origins of the genus Opisthocomiformes<\/em>.<\/p>\n

For the biologist Lu\u00eds F\u00e1bio Silveira, curator of the University of S\u00e3o Paulo (USP) Zoology Museum\u2019s ornithological collections, the new theory that places the birthplace of the hoatzin\u2019s ancestors outside South America should be taken seriously and tested as and when new fossils are discovered. \u201cThe study is very interesting as well as beneficial,\u201d states Silveira, who was not involved in the project.\u00a0\u201cThe hoatzin\u2019s origins and, consequently, its degrees of kinship are among the greatest unsolved problems in the classification of birds. Nobody knows whether this bird is more closely related to chickens, cuckoos or touracos.\u201d This question has not been resolved by the new study. However, if the origin of this order of birds does indeed lie in Africa, then paleontologists and ornithologists may well have to shift their focus to that continent, instead of South America, which is where the hoatzin is now found.<\/p>\n

Scientific article<\/em>
\nMAYR, G. et al.<\/em>\u00a0Out of Africa: Fossils shed light on the origin of the hoatzin, an iconic Neotropic bird<\/a>. Naturwissenschaften<\/strong>. v. 98, n. 11, p. 961-66. nov. 2011<\/p>\n","protected":false},"excerpt":{"rendered":"Origins of the Amazonian bird that \u201cruminates\u201d ","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[159],"tags":[231,255],"coauthors":[101],"class_list":["post-5159","post","type-post","status-publish","format-standard","hentry","category-science","tag-evolution","tag-paleontology"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/5159","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=5159"}],"version-history":[{"count":0,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/5159\/revisions"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=5159"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=5159"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=5159"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=5159"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}