A team of scientists has discovered what they say is the first evidence in the world – dating back 47 million years – of a snake giving birth to its young.
Most reptiles are oviparous, which means that they are hatched from fertilised eggs.
But other reptiles are viviparous, which means their young gestate inside them, just like other animals including humans.
And now a team of Argentine and German scientists has “discovered the world’s first fossil evidence of live birth in snakes”.
This is according to a statement from the Senckenberg Society for Nature Research obtained by Newsflash on 14th November saying that the “researchers describe bones of snake embryos discovered in the mother’s body.
“The finding shows that viviparous snakes already existed at least 47 million years ago.”
The study, published in the academic journal The Science of Nature on 5th November under the title ‘Live birth in a 47-million-year-old snake’, focuses on a fossil from the Messel Pit, which is a disused quarry near the village of Messel about 35 kilometres (21.7 miles) southeast of Frankfurt am Main, Germany. It is part of the Hessian UNESCO World Heritage Sites.
The Senckenberg Society explained: “Most reptiles alive today lay eggs; this so-called oviparity is their most common mode of reproduction. But there are exceptions: numerous species of lizards and snakes are known to deviate from the norm and give birth to their offspring alive – viviparously.”
And Krister Smith of the Senckenberg Research Institute and Natural History Museum Frankfurt said: “Fossil preservation of reproductive events is generally very rare. In total, only two fossil records of viviparous land reptiles have been discovered to date. We have now succeeded in describing the world’s first fossil evidence of a viviparous snake!”
The statement said: “The fossil Messelophis variatus, from a family of boa-like snakes, is about 50 centimetres long, dates from the Eocene, and is related to modern-day dwarf boas from Central America.”
And Mariana Chuliver, the study’s lead author from the Fundacion de Historia Natural in Buenos Aires, Argentina, said: “The species is among the most common snakes known from Messel. Nevertheless, this specimen, which is about 47 million years old, surprised us: it is a pregnant female with at least two embryos found in the posterior third of her trunk area.”
Her colleague and co-author Agustin Scanferla added: “When examining the fossil, we realized that some of the skull bones present came from small boas no more than 20 centimetres in length.
“These bones were located quite a distance behind the stomach – if they were part of the snake’s prey, they would have already been digested this far back in the intestine and would no longer be recognizable. Thus, they must represent the boa’s embryos.
“The fact that the bones are from very young snakes, yet already further developed than in an unlaid egg, supports the assumption that we are dealing with a pregnant, viviparous female here.”
The statement also said: “In live births, the young remain in the female’s body until they are viable – eliminating the need for a protective eggshell.
“This is considered an advantageous evolutionary strategy for reptiles in cold climates, as the temperature inside the female’s body is more stable and thus safer for their offspring. Therefore, many of today’s viviparous lizards and snakes have evolved in rather cooler climates.”
Smith said: “During the Eocene, however, the Earth was dominated by a persistent greenhouse climate with warm temperatures, a high carbon dioxide content in the atmosphere, and ice-free poles. Around the Messel Lake, average temperatures at that time were about 20 degrees Celsius, and winter temperatures did not fall below freezing.
“Why the boas gave birth to live offspring 47 million years ago in spite of this fact is still unknown. Perhaps additional fossils from this unique site will help us solve this mystery!”
