Imprimir Republish


Ancient animals of Terra Brasilis

Recently discovered birds, reptiles and mammals widen the diversity of the South American fauna from millions of years ago

From Rio de Janeiro

CIÊNCIA DA TERRA, CIÊNCIA DA VIDA - CAHAPADA DO ARARIPE/FAAPWooden beasts of prey: on this and the following pages are artisan works from the Master Noza Center of Popular Culture in the town of Juazeiro do Norte, Ceara StateCIÊNCIA DA TERRA, CIÊNCIA DA VIDA - CAHAPADA DO ARARIPE/FAAP

It would be difficult for the archive of the Brazilian fauna species from millions or thousands of years ago to be larger than that of the United States. It is not just a case of the consequences of a research budget – in our case twenty-two times lower. The main reason, which might seem a little strange, is another: Brazil does not have deserts, in which the fossils can conserve themselves much more easily than under the forests that cover the most land of our country. Brazilian paleontologists do not have many places in which to dig, although they do not lose the opportunity to put on their field hat and their well worn working clothes and yet again take a chance in some spot along the Bauru Basin or the Araripe Plateau.

The Bauru Basin, a vast section of sedimentary rock that runs through the states of São Paulo, Minas Gerais, Paraná, Goiás and Mato Grosso, houses the remains of animals that lived some 80 million years ago, at the end of the era of the dinosaurs. The problem is that access is not always possible. Regions such as the northwest of the state of São Paulo, proven to be rich in its diversity of species from millions of years ago, can no longer be churned up as they have been taken over for sugarcane plantations. One of the few other alternatives for returning with something valuable in a backpack is the Araripe Plateau, one of the most fertile territories for fish and reptile fossils in the country, which extends through the States of Ceará, Pernambuco and Piaui. In this region 110 million-year old fossils are common to the extent of even inspiring the local artisans, which has resulted in pieces such as those illustrated on these pages.

On the other hand, the Argentinean paleontologists no longer hide their pride in telling that in their country around one thousand species of fossilized vertebrates have been identified, the equivalent of at least four times the Brazilian total. Their delight is due, in part, to the benefits of a dry climate, which has helped to preserve the remains of animals that had previously occupied the current desert of Patagonia. But there is another motive: “Paleontology in Argentina has been a tradition for 150 years”, explains the zoologist Zulma Gasparini, a professor at the University of La Plata who has been working in this area for almost 35 years. “Paleontology began before physics and medicine and for the last 40 years has been considered a profession.”

Even with the above mentioned disadvantages, national paleontology is alive. At the Second Latin-American Congress on Vertebrate Paleontology, held last month in Rio de Janeiro, around 30 new fossil species of South American animals were presented and of those at least half were from Brazil. As yet subject to confirmation by way of the publication of scientific papers in specialized magazines, such discoveries attest to the maturity of the discipline within the country and highlight the importance of Latin America as an irradiation center for new animal species. It can be noted that one of the oldest species of dinosaur, the Staurikosaurus pricei, was found in the State of Rio Grande do Sul, where it had lived some 230 million years ago, evidently without suspecting that from its height of 1.8 meters and modest weight of 30 kilograms, would come some millions of years later huge beasts such as the Tyrannosaurus rex, one of the symbols of paleontology in the northern hemisphere.

On the same Mother Earth
Although unbeatable in popularity, probably because they provoke our atavistic fears of monsters, the dinosaurs did not live alone on ancient Earth. They were, it is true, the largest, most abundant and most successful animals during the major part of the time in which they lived, between 230 million and 65 million years ago. But there were other reptiles, birds and mammals, whose fossils, whenever they come out of the rocks, not only reveal a diversity and geographical distribution beyond imagination, but also provide evidence on the transformations through which the Brazilian landscape has undergone.

On the lands then occupied only by a chopped up vegetation intermingled with small forests, roamed mammals similar to elephants. They were the mastodons, at least three times larger than the tapirs, the largest Brazilian land mammal of today, which is almost two meters in length. Some 50,000 years ago, the mastodons were spread from north to south, but it was not known that they could also have occupied what is now the State of Rondonia, as has been indicated by the discovery of two mastodon craniums that are almost intact. There were also other mammals as large as the mastodons – the Pyrotheria. In the region of the town of Taubaté, lying between the cities of Sao Paulo and Rio de Janeiro, there lived the first Brazilian Pyrotheria, with a trunk longer than that of an elephant, although smaller in size. The animal, unearthed by São Paulo and Rio de Janeiro  researchers is impressive for its manner, size, and for the time in which it lived: around 30 million years ago.

Also, in the small caverns of the State of Rio Grande do Norte a reptile similar to the current broad snouted alligator (caiman latirostris) had lived, in an indication that the climate was very different and probably there had been a lot more water in this region that today is so dry. “There was a mosaic of different vegetation in the current Brazilian semi-desert region”, attests Gisele Lessa, a researcher at the Federal University of Viçosa (UFV), after having studied another group of animals: bats. With immense difficulty, due to the extreme fragility of their bones of 1 or 2 centimeters and teeth of around 1.5 millimeters, the specialists have identified 27 species of bats aged up to 20,000 years old, mainly in the States of Bahia, Minas and Goias.

The most recent was discovered by Patrícia Hadler Rodrigues, a doctorate student from the Federal University of Rio Grande do Sul (UFRGS), on an archeological site in the northeast of Rio Grande do Sul. This is the first example of a bat of around 30 centimeters of wingspan, named Eptesicus fuscus, which today live on a vast territory running from the south of Canada to the Amazon, but which more or less 9,000 years ago also lived in southern lands – and nobody is risking to say why they left. Also in the State of Rio Grande the fossil of a lizard known as tegus or Tupinambis sp., the largest on the continent, has been found for the first time, with a 60 centimeter tail that makes up half of its body size. Some 1.5 million years ago it was at least a palm size larger.

The doubts emerge with the same generosity as the findings. It is still not known for sure how the majority of the groups of animals came about or even how some superimposed themselves upon others, at times very close together. Between 57 million and 38 million years ago, lizards belonging to the current iguanas group occupied on their own two islands Seychelles and Reunion, to the southeast of Africa, whilst another group, the lacertilians,  were exclusive to the near neighboring island of Madagascar. In intercalated times, according to Marc Auge, from the National Natural History Museum of France, these two species disappeared, reappeared, and went back to disappearing – a phenomenon known as competitive substitution that probably must also have occurred on this side of the Atlantic, since South America was linked  to Africa, to Europe and to India around 100 million years ago. They had formed a super continent, known as Gondwanaland.

Competition for sure had always been intense although it is not enough on its own to explain why some species did well and others not so well – or why some only evolved after others had died out. “The mammals remained in the background of the dinosaurs, although the two groups had come about roughly at the same time”, exemplifies Lillian Bergqvist, from the Federal University of Rio de Janeiro (UFRJ), one of the discoverers of the first Brazilian Pyrotheria, along with her student Leonardo Avilla, de Herculano Alvarenga, from the Natural History Museum of Taubate, and Ricardo Mendonça, from the University of São Paulo (USP).

“It was the extinction of the dinosaurs that brought about the pathway for the irradiation of the mammals”, says Lillian. Previously hidden, small and nocturnal, the mammals then left their borrows and took on the light of the day. Little is known about this era, but Marcelo Tejedor, from the Saint John Bosco National University of Patagonia, has presented a molar tooth of a small herbivorous marsupial that must have been the oldest Cenozoic mammal in South America, of around 65 million years old. This is an indication that during this era there had been an intense substitution of animal species.

“South America had its very own fauna, since many fossils from here are not found in the United States or Canada”, says Marcelo Reguero, from the Museum of La Plata, in Argentina. But this luck did not last for long. By the isthmus of Panama, which for the last 2.5 million years has united the two Americas, many species arrived from the north and in numbers probably higher than the species that left from the south. The result: the fight for space and food eliminated the majority of the large South American mammals. One of the groups that did not receive a drop of compassion was the notoungulates, some of them similar to the current hippopotamus, with a short bony raised up nose. They came about some 65 million years ago, but 10,000 years ago there was no sign of the tens of species of ungulates already described. Probably these animals lived part of their time in the water and part on land, just like the hippopotamus, in accordance with studies carried out by Ana Maria Ribeiro, from the Zoo-Botanic Foundation of the city of Porto Alegre.

During the three days of debate carried out at a hotel fronting Copacabana beach, there was no lack of gripping reports of probable new animal species that had lived many millions of years ago, although as yet subject to the traditional scientific confirmation by way of articles to be published in specialist magazines. Alvarenga, from the Natural History Museum of Taubaté, presented what should be the fossils of two or three probable new species of birds, studied in conjunction with William Nava, from the Paleontology Museum in the town of Marilia. Found some two months ago near the town of Presidente Prudente, in the west of the state of Sao Paulo – some smaller than the diameter of a ten-cent coin – they show that these birds of size close to that of a sparrow, had lived between 70 million and 80 million years ago. Before this discovery, the oldest species, also described by Alvarenga, had been around 50 million years old.

These new examples represent the enantiornithes., a sister group to the modern birds. Of these already extinct lineages, which probably had a beak full of teeth, something very strange when compared to a chicken, had only had their feathers registered at the Araripe Plateau. Small enantiornithes such as those from Brazil also lived in China, but in the north of Argentina they were at least three times larger, around the size of a current hawk.

At some moments in time, the succession of scientific reports appeared to be a contest, although somewhat elegant, to see who could exhibit the oldest, most complete or most surprising fossil. Jorge Calvo and Juan Porfiri, from the National University of Conahue, Argentina, announced the discovery of a herbivorous dinosaur of 35 meters in length that had lived between 125 million and 130 million years ago and is perhaps the largest representative of the sauropod family found throughout the world. But one of the highest bids – or rather the oldest – came from Max Langer, a researcher at the University of Sao Paulo (USP) in Ribeirao Preto, with a dinosaur from the ornitholestes group that lived around 230 million years ago. Indeed, it would be one of the most primitive of South America. If confirmed, this would be the thirteenth species of dinosaur found in the country, which is slowly filling up the world archive of currently around one thousand described species. The problem is that whilst the paleontologists take from the rocks what must be the oldest species, it becomes more difficult to differentiate the true dinosaurs from the other reptiles: this new herbivorous dinosaur of 1.5 meters in height, for example, had a beak. Even Langer himself had shown surprise when he was exhibiting the group of bones that he had excavated at Agudo, in the State of Rio Grande do Sul, and in front of an audience of more than 300 people questioned: “What the devil are these?”

The most emotional moments of the congress were exactly those in which ancient ideas fell down, even disorientating the specialists. “We’re at a moment of profound conceptual revision”, comments professor Sergio Azevedo, the director of the National Museum. He attributes the abundance of the findings and the moving forward of the debate to the intensive work of relatively young scientific leaders – aged around forty years – who go out into the field in the hunt for fossils, who defend daring proposals and who are training students, mainly in the States of Rio de Janeiro, Sao Paulo, Minas e Rio Grande do Sul.

For example, to have feathers is no longer the privilege of birds: dinosaurs could also well have had feathers and wings – and could also have flown. During the first day of the congress, Alexander Kellner, a paleontologist from the National Museum of the Federal University of Rio de Janeiro, who has described five of the twelve species of Brazilian dinosaurs, presented two replicas, both produced at the National Museum itself. One of them, made by Maurílio Oliveira, was that of an Archaeopteryx, one of the most primitive birds ever found. Of almost 40 centimeters in length, it is no longer seen as a transition animal between the birds and the dinosaurs. The other replica, exhibited for the first time in Brazil, is a piece of work by Orlando Grillo: the Microraptor gui, a species of dinosaur from China. Of almost 60 centimeters in length, it looks like a bird: it has feathers on its arms and legs, although it would not have flown.

The Microraptor reopens a polemic idea: were the birds really the descendents of the dinosaurs? Terry Jones, from the State University of California, in the United States, does not believe that there can be a direct relationship between the two groups. In his opinion, to have feathers is not necessarily a signal of kinship. “Very, very few dinosaurs if there was even one, had feathers”, he says. “What seems to be feathers in the majority of cases are not feathers, which do not break when fossilized, but form fossilized bacteria.” Alexander Vargas, from the University of Chile, has obtained some evidence to defend the opposite hypothesis: the birds descended specifically, according to him, from carnivorous dinosaurs such as the Tyrannosaurus.

Dealing with a group which had literally slithered around the feet of the dinosaurs, Hussam Zaher, from the Zoology Museum of USP, is perhaps dismantling another idea, one that is a little more subtle: based on the molecular analysis of five genes of current species, the macrostomata snakes, such as the boas, which make up the group that feeds on large sized prey, had not come about only once, but at least twice, throughout the evolution of snakes, having first appeared at least 110 million years ago. “This study draws attention to the fact that molecular data should be interpreted with caution and reinforces the importance of the inclusion of fossils and of morphological data, thus creating a more complete analysis”, he comments. The chaos of the evolutionary history of snakes comes from the basis: as yet it is unknown from which group of lizards they originated. “If we were to find this out, we could solve the essential doubts with respect to the origin of snakes”, Zaher believes.

But there are two problems that get in the road of this search: snakes are very different amongst themselves, without showing transitions, which would very much facilitate this intricate historical reconstruction, and as well, the current species represent only a small sample of the groups that practically came about at the same era as the dinosaurs. Also, it is unknown if they had originated on land, on which Zaher is betting, or in the sea. In this case, they would have evolved from marine lizards, those called mosasaurs, a theory that Michael Caldwell, from the University of Alberta in Canada, intends to prove by searching through the coast of the Adriatic Sea in search of fossils that could prove his idea. Perhaps it would be possible to know within ten years who is working along the right lines in the face of the evidence that each one will have the luck to find.