Geodesy

Rainforest

Ecology

Biology

Predation

Tropical climate

Amazon rainforest

Fauna

Plateau (mathematics)

Latitude

Paleontology

Climate change

Mathematics

Geography

Bergmann's rule

Insectivore

Mathematical analysis

Charadriiformes

Tropics

Nature

The discovery of the world's largest known snake — living around 60 million years ago in tropical South America — has important implications for our understanding of the evolution of global climate. The fossil, found in northeastern Columbia — is of a relative of the boa constrictor; it was 13 metres long (compared to about 10 metres for the longest live snakes reported) and would have weighed more than a tonne. A snake this size would have required mean annual temperatures between 30 and 34 ° C, higher than the tropics today. This calls into question the idea that the climate system has a 'thermostat' that regulates tropical temperatures. The discovery of the world's largest snake has important implications for our understanding of the evolution of global climate. The snake, a relative of the boa constrictor, was 13 metres long and would have weighed more than a tonne. It lived in tropical South America around 60 million years ago. A snake this size would have required mean annual temperatures between 30–34 °C, higher than the tropics today. The largest extant snakes live in the tropics of South America and southeast Asia1,2,3 where high temperatures facilitate the evolution of large body sizes among air-breathing animals whose body temperatures are dependant on ambient environmental temperatures (poikilothermy)4,5. Very little is known about ancient tropical terrestrial ecosystems, limiting our understanding of the evolution of giant snakes and their relationship to climate in the past. Here we describe a boid snake from the oldest known neotropical rainforest fauna from the Cerrejón Formation (58–60 Myr ago) in northeastern Colombia. We estimate a body length of 13 m and a mass of 1,135 kg, making it the largest known snake6,7,8,9. The maximum size of poikilothermic animals at a given temperature is limited by metabolic rate4, and a snake of this size would require a minimum mean annual temperature of 30–34 °C to survive. This estimate is consistent with hypotheses of hot Palaeocene neotropics with high concentrations of atmospheric CO2 based on climate models10. Comparison of palaeotemperature estimates from the equator to those from South American mid-latitudes indicates a relatively steep temperature gradient during the early Palaeogene greenhouse, similar to that of today. Depositional environments and faunal composition of the Cerrejón Formation indicate an anaconda-like ecology for the giant snake, and an earliest Cenozoic origin of neotropical vertebrate faunas.

Giant boid snake from the Palaeocene neotropics reveals hotter past equatorial temperatures