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paleontology

Wings from the past

Fossils of a mini-condor and a giant bird reconstitute the prehistory of winged beings in Brazil

MIGUEL BOYAYANFossils of the extinct bird Wingegyps cartellei: a miniature version of the present-day California condor MIGUEL BOYAYAN

The neighbors no longer wonder about the deliveries made at the house of Herculano Alvarenga, in Taubaté, a city some 120 kilometers from São Paulo’s capital city. In July, a truck pulled up at number 99, Colômbia Street, with hundreds of kilos of fossils discovered in the Northeast, where this 56-year-old physician had undertaken an exploratory mission in March. On another occasion, an international remittance of 62 kilos came, sent by a friend from the National Museum of Natural History, in Washington, the American Storrs Olson, one of the most renowned contemporary ornithologists. Inside it, of course, more petrified bones of animals from millions of years ago. The major part of the material unloaded there adds weight to the collection of fossils belonging to this citizen of São Paulo that tots up to roughly 2,000 skeletons – replicas and originals, entire or incomplete – of prehistoric animals.

Besides enriching Alvarenga’s collection, which next year should be permanently on display to the public at large with the inauguration of the Taubaté Natural History Museum, a fraction of these fossils, the skeletons of winged beings, is also the object of a series of scientific researches. This is because Alvarenga is doubly impassioned by bones. In his practice as an orthopedist, he looks after the joints of the living. At home, he concerns himself with the dead: he carries out his parallel activity as a paleontologist specialized in bird fossils, and studies skulls, humeri (the main bone on the wings) and the femurs of animals that lived on Earth thousands or millions of years ago. “I always found it easy to analyze bones, and I liked zoology”, says the physician, who concluded his doctorate in this discipline at the University of São Paulo (USP) in the 1990’s. Although he is no longer formally connected with any university, Alvarenga has now discovered and described 15 new species of bird fossils, themajority of them found at sites in the Taubaté basin. These finds have made him well known among the academics. “Much important material could have been lost, were it not for Alvarenga’s work”, explains Castor Cartelle, a paleontologist from the Federal University of Minas Gerais (UFMG).

In the last few months, in collaborations with colleagues who occupy seats at research institutions, Alvarenga published three articles reporting his finds. With Edson Guilherme, from the Paleontology Laboratory of the Federal University of Acre (Ufac), he chalked up an article in the September issue of the Journal of Vertebrate Paleontology, in which he describes two new species of darters that lived about 5 million years ago, the Macranhinga ranzii and the Anhinga minuta. It was a discovery full of superlatives. “These species represent, respectively, the biggest and the smallest known darters”, comments Alvarenga, who analyzed bone fragments from these animals that were discovered by scientists from Ufac at two points of the banks of the Acre river.

This kind of bird, of which only two live species are left in the world, is reminiscent of the pelican and lives on the banks of rivers and lakes, where it feeds on fish. The Macranhinga ranzii ought to weigh from 8 to 10 kilos and be 1.5 meters in height, with a 20% advantage over the stature of the equally extinct Macranhinga paranensis, which was found in Argentina and regarded, up until now, as the largest darter. The body mass of A. minuta was probably no more than 600 grams, and its height would border 50 centimeters. For the purposes of comparison, the only living species of darter on the American continent, including Brazil, the Anhinga anhinga, weighs 1.5 kilos and reaches 90 centimeters in height.

Perhaps one of the most interesting prehistoric birds described by the paleontologist-orthopedist is the mini-condor Wingegyps cartellei, which probably cruised the skies of Bahia and Minas Gerais 12,200 years back. Forming a pair with Storrs Olson, from the National Museum of Natural History, of the United States, Alvarenga presented the ancient bird in the most recent issue of the Proceedings of the Biological Society of Washington magazine. The fossils of the specimens of this winged being, which are limited to a skull and two humeri, rescued, respectively, from caves in Bahia and Minas Gerais, may be important for a better understanding of the emergence of the Vulturidae family.

Condors and vultures are the two groups that form this family. As nowadays condors are big and vultures relatively small (compared with the former), many ornithologists think that this difference in size has always existed. Hence, according to this line of thought, the smaller birds of the Vulturidae family always ought to have been classified as vultures, while the bigger ones would automatically be denominated as condors. The W. cartellei shows that things were not quite like that. “In the past, there was a greater diversity of condors, with large species and small species”, explains Alvarenga. “We can state today that what distinguishes a condor from a vulture are peculiarities in their skeletons, above all in the skull, and not their size.”

Approximately half a meter in length (the distance between the tip of the beak and the end of the tail) and a wingspan of some 130 centimeters, the mini-condor W. cartellei had more modest dimensions than those shown today by the smallest living representative of Vulturidae family, the lesser yellow headed vulture (Cathartes burrovianus). This present-day bird, whose natural habitat extends from Mexico to Argentina (with, in Brazil, a more common presence in Amazonia), measures about 60 centimeters in length and its wings, when open, extend for a little over 1.5 meter. To get an idea of how the tiny specimen of the Vulturidae family, whose vestiges were found in Minas and in Bahia used to be, you just have to look at the California condor (Gymnogyps californianus), a species under threat of extinction typical of the southeast of the United States. A bird like this, of which there are only 200 specimens, can reach up to 1.4 meters in length, and its wingspan comes to 3 meters. “The W. cartellei is a miniature of the California condor, and its closest known relative”, Alvarenga compares.

It is not only small and medium sized birds, like darters and the mini-condor, that have been recently described by Alvarenga. In another work with Olson, published in 2002 in the Proceedings of the Biological Society of Washington, the paleontologist-orthopedist, who dedicates himself to his fossils in his in moments of spare time from his medical practice, identifies a new genus and species of a giant bird, the Taubatornis campbelli, which inhabited the Taubaté basin (hence the scientific name of the genus) some 23 million years ago. Belonging to the extinct Terathornithidae family, made up of some imposing winged beings that must have been predators of other animals or simply eaters of carcasses and garbage, the T. campbelli is the oldest and the smallest of the giant birds found by man. “It is four times older than the Argentavis magnificens, which lived roughly 6 million years ago”, says Alvarenga, who found an incomplete specimen of the animal in the Tremembé formation, inside the Taubaté basin.

A colossus of the skies from the central and northern zones of Argentina, the A. magnificens is the largest flying bird that ever winged through the airs of this world. Its length is believed to have exceeded 3 meters and – here is the most impressive detail – its wings, when open, extended for 8 meters, enough, for example, to cover two economy cars in a row. With its modest size for a member of the Terathornithidae family, the T. campbelli had a wingspan four times smaller, of roughly 1.9 meters. Even so, as can be seen. It was an imposing animal. So much so that it joined the family of giant birds. “The fossil lends even more strength to the theory that this family originated in South America”, explains Olson, who has now been a guest three times at Alvarenga’s house, so as to study his Brazilian collaborator’s material. The oldest vestiges of giant birds found in North America are from the end of the Tertiary period (around 5 million years ago).

The São Paulo orthopedist started to become a specialist in prehistoric birds – and a collector of bones of other kinds of animal from the past – almost 30 years ago. In a stroke of luck, during an excursion through the Taubaté basin, known for being rich in animal fossils, he came across his first find: an almost complete skeleton of an animal that he would later baptized with the scientific name of Paraphysornis brasiliensis. It was precisely the kind of bird that had fascinated him since childhood: a carnivorous 2-meter tall superchick, weighing some 180 kilos, which was incapable of flying, and must have perambulated over the region 23 million years ago. After analyzing the skeleton at home for some time, the orthopedist thought of handing it over to a professional paleontologist, Diógenes de Almeida Campos, from the National Mineral Production Department (DNPM), of Rio de Janeiro. “But he told me that it would take a long time to study the bones in details, like I had done”, Alvarenga says. “And he encouraged me to carry on with the studies and to publish a scientific article about the bird.”

Thus began the career of bird fossil hunter. Since then, the orthopedist has been attending paleontology congresses, he occasionally gives lessons in universities, and he writes scientific articles. To increase his collection of bones, he usually makes replicas of his findings, to swap them for copies of skeletons of animals that are not yet part of his collection, with scientists and institutions from here and from abroad. For this reason, those who visit the Taubaté Natural History Museum in the middle of next year, the time scheduled for its inauguration, will see a lot more than fossils of birds. There will be a bit of everything in the enterprise, which enjoys the support of the local city hall: replicas of mammals, fish, reptiles and dinosaurs, like the famous Tyrannosaurus rex.

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