Jakarta, domclub Indonesia
—
Anaconda
, an endemic giant snake that lives in tropical rivers
South America
, apparently has a stable size or has not changed for more than 12 million years.Listen to the facts.
A recent study in the Journal of Vertebrate Paleontology reveals that giant anacondas have been able to maintain their ancient size since the Miocene period, even when many other giant animals became extinct due to climate change and habitat loss.
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Warm temperatures, extensive marshes, and abundant food during the Middle and Upper Miocene periods (12.4 million to 5.3 million years ago) allowed many animal species to grow much larger than their modern relatives.However, few of these giant animals survive today.
Andrés Alfonso-Rojas, study author and vertebrate paleontologist from the University of Cambridge, in his latest study explains that giant anacondas are able to survive despite decreasing temperatures and shrinking habitat.Meanwhile, this condition actually causes many other animal species to decrease in size or become extinct.
“Other species such as giant crocodiles and giant tortoises have become extinct since the Miocene period, possibly due to falling global temperatures and shrinking habitat,” said Alfonso.
“However, the giant anaconda snakes survived, they are very tough,” he continued.
Anacondas are a group of predatory snakes that include some of the heaviest species in the world today.Modern anacondas generally have a length of 4 to 5 meters, but the largest size can reach up to 7 meters.
Scientists are unsure whether anacondas were ever larger during the Miocene period, or whether they were always this size.
To estimate the size of ancient anacondas, Alfonso and his colleagues measured 183 fossilized anaconda vertebrae from at least 32 individual snakes collected in Venezuela.
They also used a technique called ancestral state reconstruction, to predict the body length of ancient anacondas based on the characteristics of related species.
Based on these calculations, the team found that anacondas had an average length of about 5.2 meters (17 feet) when they first appeared in the Miocene epoch 12 million years ago, a similar length to modern anacondas.
“This was a surprising result because we expected to find an ancient anaconda snake measuring seven or eight meters (23 to 26 feet),” Alfonso said.
“However, we have no evidence of larger snakes from the Miocene period when global temperatures were warmer,” he said.
To date, it is still unclear why anacondas do not get smaller over time.
Although warm weather and abundant wetlands may have allowed anacondas to reach giant sizes early in their evolutionary history, cooler temperatures and shrinking habitats have not forced these snakes to decrease in size as a form of adaptation.
This suggests that these factors were not the main reason why these snakes remained large over the following thousands of years, as the researchers wrote in the study.
The researchers also said that predator-prey interactions likely do not play a major role in maintaining the snakes’ body size.
The lack of competition for food may have allowed the snakes to grow to their current size.However, they did not get smaller when other predators entered South America.
During the Pliocene (5.3-2.6 million years ago) and Pleistocene (2.6 million-11,700 years ago) periods, which suggests that food availability was not a major factor in the anaconda’s giant size.
(wpj/dmi)
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