GIUSEPPI PUORTO / INSTITUTO BUTANTANThe false coral snake Anilius scytale, from the Amazon: a distant relative of the snake fossilGIUSEPPI PUORTO / INSTITUTO BUTANTAN
In mid-July 2003, Brazilian Max Cardoso Langer and Frenchman Emmanuel Fara, both of them paleontologists, went on a journey in search of fossils through the region in the state of Minas Gerais called the Minas Triangle and the northwest of the state of São Paulo. After covering a few localities in Minas Gerais, where they did not find much of interest, they tried their luck in a little town in São Paulo called General Salgado, which has 11,000 inhabitants and is 545 kilometers from the municipality of São Paulo. The choice was not a random one. A Brazilian colleague, Reinaldo Bertini, from São Paulo State University (Unesp), had described in a scientific article a crocodile fossil found in the region. Heartened by this discovery, Langer and Fara – respectively, researchers from the University of São Paulo (USP) in Ribeirão Preto and from the University of Poitiers, in France, – decided to bet on the new and practically unknown paleontological site that seemed to exist in the region. They went to a farm, where they found out where this site was. They spent a whole day searching, searching, and searching – and not a fossil in sight. They must have been in the wrong place.
Disappointed and intrigued, they reread the article by Bertini, which they carried in their luggage, and they realized that a local teacher, José Tadeu Arruda, had assisted his colleague from Unesp in the fieldwork in the region. On the following day, they set out asking for Arruda the teacher, and soon they found him. With the new member of the team, the researchers got into a pick-up truck and followed the coordinates of the man who lived in General Salgado. “As soon as we got out of the car and looked at the ground, we saw a series of small vertebrae in the outcrop”, Langer recalls. They were the remains of the oldest snake found to date in Brazil: a snake of subterranean habits of some 60 centimeters in length, which probably used to live in burrows and must have lived between 70 and 85 million years ago, at the end of the Cretaceous period (and of the Mesozoic era), a little before the mass extinction of the dinosaurs. Until then, the oldest fossil snakes found on Brazilian soil were, at the most, 65 million years old, going back to the Paleocene period, now at the beginning of the Cenozoic era.
Vertebras and ribs
Actually, the importance of the finding was only determined a little later on. As no one who took part directly in locating the fossil was a specialist in ophidians, and the original suspicion was that this was a question of petrified remains of a scaly reptile (snakes, lizards, and amphisbaenia), the researchers decided to hand over the material to paleontologist Hussam El Dine Zaher, from USP’s Zoology Museum. A scholar of the origin and evolution of the this animal group, Zaher pored over the fragile set of fossil fragments recovered from the northwest of São Paulo, basically a dozen fully preserved vertebras and bits of a few ribs and other vertebras. The largest and most significant of these pieces would fit in the palm of your hand: a series of seven complete vertebras connected to portions of a few ribs. As they had been found close to each other and showed common anatomic characteristics, all the fragments appeared to have belonged to a single animal. To be sure, a snake, Zaher concluded.
A series of peculiarities of the fossilized little bones – morphological traits like the shape of the front edge of the neural arch (the upper part of the vertebra that holds the dorsal column of spinal cord of every vertebrate) and the small size of the neural spine (a pointed structure that is on the top of the neural arch and, for the purposes of comparison, is similar to a tiny shark fin) – led Zaher to suggest that the snake from General Salgado must have belonged to an extinct and unknown genus from the super-family of the Aniliidae . Their vertebras are different from those found in the five known (extinct) fossil genera of Aniliidae”, Zaher explains. In Brazil, there is a record of only two of these fossil genera, the Hoffstetterella and the Coniophis, both made up of a single species, Hoffstetterella brasiliensis and Coniophis precedens, discovered in São José do Itaboraí, in Rio de Janeiro, roughly 65 million years old. The other genera are found only in North America, Africa, and Europe. If it is proved that it is a new species not yet described in the specialized literature, the snake rescued from the São Paulo hinterland will be baptized with a scientific name.
From the material collected in the field, it is difficult to tell what the oldest snake in Brazil will look like. One way of imagining how its looks is to glimpse at the only live species of Aniliidae present in the whole American continent, the Anilius scytale, which may be a distant relative of the snake from General Salgado. Typical of the Amazon basin, where it can be found in holes in the middle of the forest, even in urban areas, the A. scytale is a false coral snake, with black and orange stripes and eyes of small dimensions. In spite of being similar to the real coral snakes, which are poisonous, it is completely inoffensive. It has night habits, eats small animals (snakes and lizards), and can reach 1.10 meters in length, almost twice the estimated size of the fossil snake.
So, based on this analogy, can one conclude that the fossil snake was a smaller version of the false coral, present today in the center and the north of the country? Well, not exactly. “Any inference as to the coloring of the fossil is highly speculative and is without any theoretical or empirical grounding”, Zaher ponders. “As to the feeding habits, we will only be able to say something more precise when we find the fossilized skull, or at least the bones that carry its teeth.” A major part of the most modern analyses of evolutionary biology and comparative anatomy of snakes depends on studying their cranium. Apparently, the snake from General Salgado showed a good part of the characteristics of the A. scytale. It must not have been venomous, and lived in a habitat that evoked the present-day Pantanal ( wetlands in the state of Mato Grosso) than actually the Amazon. “The geological analyses show that some 70 million years ago the northwest of São Paulo was a fluvial plain, a low region to which the flows of water coming from Minas Gerais were directed”, Langer explains. Accordingly, the new snake fossil was terrestrial, but lived close to water.
Even though they are very interesting, the tiny vertebras and ribs of the oldest Brazilian snake should be of little use for studying one of the hottest issues amongst herpetologists (specialists in reptiles): what is, after all, the origin of the snakes? Do they derive from lizards that, over 140 million years ago, inhabited the seas or dry land? For being a specimen that is much developed on the evolutionary scale, the snake from General Salgado should not add much to this scientific debate. Zaher and several researchers from abroad have already studied the remains of more ancient and more primitive snakes, like the Haasiophis terrasanctus, a snake with paws, with an approximate age of 95 million years, which was discovered in Israel. Be that as it may, the finds in the northeast of São Paulo enrich the collection of ophidian fossils in Brazil. “Here, it is very difficult to find snake bones preserved in sedimentary rocks”, the researcher from the Zoology Museum ponders. “This fossil may help us to understand what the geographical distribution of snakes was like in the past on the American continent.”
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