rain can be a friend or enemy for paleontologists. It can wash away the floor or erode rocks and possibly reveal exciting fossils or already make exposed, delicate specimens crumbling.

This is currently particularly true for the south of Brazil. In May, devastating floods in the state of Rio Grande do Sul frank pieces of at least 35 primeval animals, including a 233 million year old skeleton, which is one of the oldest dinosaur fossils in the world. But the rain showers and moist conditions have caused the researchers to hurry to recover other smaller, more susceptible specimens that are also valuable.

The urgency is reinforced by the unprecedented nature of the floods. Between April 27 and May 27, the capital of the state, Porto Alegre, recorded about 66 centimeters of rain - almost half of what it normally receives in one year. Many other cities in the state were also flooded. Some paleontological sites are still under water.

"If paleontologists are not there to collect material when it becomes visible, we risk that part of it is lost forever," says Leonardo Kerber, coordinator of the Paleontological Research Center Quarta Colônia (Cappa) at the Federal University of Santa Maria in São João Do Polêsine.

exceed expectations

Since the rains in May, paleontologist Rodrigo Temp Müller and his colleagues at the Cappa have intensified their surveillance of the excavation sites near São João do Polêsine, about 280 kilometers west of Porto Alegre.

A close -up of a dinosaur fossil

On May 15, about two weeks after the heavy rains, which led to the banks of the river system of Rio Grande Do Sul, Müller and the team discovered a 2.5 meter long fossil of a carnivorous, two -legged dinosaurs from the Herrerasauridae family. "We were sure that we would find something after the heavy rains," says Müller, but the copy still exceeded expectations.

Herrerasauriden appeared in the Triassic age (about 250 to 200 million years ago) and disappeared and were the "first top predators appearing among the dinosaurs," says Aline Ghilardi, palaeontologist at the Federal University of Rio Grande do Natal, Brazil. During the Jura age (200 to 145 million years ago) they were replaced by larger dinosaurs, the Theropoden, to which two-legged carnivores like Tyrannosaurus Rex belong.

Some researchers argue that the Herrerasaurids were the first Theropodes, but this classification is still controversial. "That is why the discoveries of the Cappa are so important - you can help us to clarify open questions like this," says Ghilardi.

work against the weather

But it was difficult to celebrate the discovery, says Müller. The floods affected almost 2.4 million people in Rio Grande Do Sul, including 183 people who died and 27 who are still missing, according to local authorities. "The people near the excavation site lost their houses," he adds.

Since their fossil find, Müller and his colleagues have taken rock and earth layers back to their laboratory with the Herrerasauridae specimen to carefully extract the bones. So far you have removed enough material to be carefully excited: You think it could be the most second fossil of its kind that has ever been found.

An aerial frame of flooded roads in Porto Alegre

But the team cannot relax yet. Since it continues to rain intermittently, the researchers still hurry to save fossils from many small animals - animals that normally do not make headlines but are still important. "Everyone likes great dinosaurs," says Kerber. But "the greatest biodiversity is always with the smaller animals". Such fossils help to reconstruct paleontologists how types are evolved and to uncover details about the environments in which they lived.

Even the tiniest bones of animals, whether large or small, are a concern. They are the first to disappear when rain hits an excavation site, says Juan Cisneros, paleontologist at the Federal University of Piauí in Teresina, Brazil. "They are rare and difficult to find." Ohrbones of small reptiles, for example, can only be millimeters long, but they give a lot about the brain of an animal and its possible intelligence.

treasury

About a week ago, the researchers of the Cappa discovered the skull of a baby rhynchosaur-a parrot-borne, herbivorous reptile, which could be about 1 meter long and dominated the earth in the middle to late triads (247 to 200 million years before today). Although these rhynchosaur fossils are numerous, says Müller, "they are important because they are numerous". In particular, they play a stratigraphic role in research because they mark triad sites, he adds. "Where there is a rhynchosaur, a gentleman is probably."

The fossil-rich area in which the paleontologists work, houses 29 excavation sites, of which the Cappa team has had access to 21 since the floods, according to Müller and Kerber. Four are still practically completely under water.

An advantage is that Cappa is so close. "We don't have to plan long trips, but can work in the field every week," says Müller. The next challenge that the researchers have to face is the question of what they do with all the fossils they mount - the center has no museum. "It would be important to have one, not just to store the fossils that we find," says Kerber, "but also to educate the local population about how rich their region is."