Global warming could lead to snakes as long as BUSES and horses shrinking to the size of CATS, scientists warn



Fossils have revealed the unusual size of creatures 55 million years ago



These included a turtle the size of a SmartCar and horses the size of cats



At this time temperatures rose by about 6 °C over a period of 200,000 years

Scientists claim another warning event could change mammal and reptile size in the future

Imagine a world with giant snakes as long as buses that are so fat that they can only just squeeze through the door.

Turtles the size of SmartCars would hunt crocodiles, while horses as small as cats could be found roaming fields.

This was Earth around 55 million years ago, according to U.S. researchers who have been studying the link between the size of animals, reptiles and a change in climate.

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Titanoboa cerrejonensis measured 48 feet and weighed as much as a car. The monster relative of the boa constrictor lived in northern Colombia 60 million years ago

Now scientists are warning massive reptiles and shrinking mammals could be found on our planet again if global warming takes hold.

Jonathan Bloch, a paleontologist at the Florida Museum of Natural History, last week told a conference in Gainesville that there is a clear link between global warming and unusual animal fossils.

Dr Bloch has been looking at a period known as the Paleocene-Eocene Thermal Maximum which occurred around 55 million years ago.



At this time global temperatures rose by about 6 °C over a period of 200,000 years.

Dr Bloch has seen evidence of these strange creature first hand. Last year he helped discover 60-million-year-old South American giant turtle that lived in what is now Colombia.

The 'coal turtle' had massive, powerful jaws that would have enabled the omnivore to eat anything nearby, such as other smaller turtles or even crocodiles

COULD GLOBAL WARMING LEAD TO 10FT REPTILES?

Fossils of a giant lizard discovered in Burma have led scientists to believe a rise in temperature 40 million years ago caused plant-eating lizards to grow to the size of the 10ft dragons. Scientists previously thought that large meat-eating dragons grew larger than their herbivore cousins because of a lack of predators.

These findings, released by the University of California and University of Nebraska-Lincoln earlier this year, suggest that a warmer climate is needed for large lizards to grow. The lizard king was dubbed Barbaturex morrisoni, which means Bearded Morrison, and was named after The Doors' frontman Jim Morrison. It is thought to have been around six-foot long from nose to tail. Scientists believe it would have weighed about 68lbs and could have resembled the modern-day bearded dragons, but around six times the size.



Temperatures at the time the lizard roamed the earth - thought to be around 40 million years ago - are believed to be significantly hotter than the current climate.

The Carbonemys cofrinii, which means 'coal turtle', was part of a group of turtles known as pelomedusoides.

The specimen's skull measured 24cm, and the shell was 172cm, or about 5 feet 7 inches, long.

In addition to the turtle's huge size, the fossil also shows that this particular turtle had massive, powerful jaws that would have enabled the omnivore to eat anything nearby, such as other smaller turtles or even crocodiles.

The giant version appeared five million years after the dinosaurs vanished, during a period when giant varieties of many different reptiles – including Titanoboa cerrejonensis, the largest snake ever discovered – lived in this part of South America.

Titanoboa was a killer snake that was longer than a bus, as heavy as a small car and which could swallow an animal the size of a cow.

Weighing an impressive 1.25 tons, it slithered around the tropical forests of South America 60million years ago, just five million years after the last dinosaurs were wiped out.

At the time of the discovery Dr Bloch said: 'Truly enormous snakes really spark people's imagination, but reality has exceeded the fantasies of Hollywood.

'The snake that tried to eat Jennifer Lopez in the movie Anaconda was not as big as the one we found.'

Titanoboa would have been bigger than any anaconda that has ever lived, and even bigger that the snake shown in the 1997 film Anaconda

Researchers believe that a combination of changes in the ecosystem, including fewer predators, a larger habitat area, plentiful food supply and climate changes, worked together to allow these giant species to survive.

But at the same time as turtles and snakes where increasing in size, mammals were shrinking.

U.S. researchers presented evidence last week that mammals shrank significantly during at least two ancient global warming events.

University of Michigan palaeontologist Philip Gingerich said that, as well as the Paleocene-Eocene Thermal Maximum, mammalian ‘dwarfing’ also occurred during a separate, smaller global warming event 53 million years ago.

‘The fact that it happened twice significantly increases our confidence that we're seeing cause and effect, that one interesting response to global warming in the past was a substantial decrease in body size in mammalian species,’ said Dr Gingerich, a professor of earth and environmental sciences.

U.S. researchers have found that mammals shrunk significantly during at least two ancient global warming events. This image shows an artist's rendering of the early horse Hyracotherium (right) alongside a modern-day horse

Scientists believe a shrinking body size is a common evolutionary response by mammals to extreme global warming events, known as hyperthermals.

They claim this may be ‘a predictable natural response for some lineages to future global warming.’

The smaller, later warming event analysed in the latest study, known as Eocene Thermal Maximum 2 (ETM2), lasted 80,000 to 100,000 years.

For example, the study revealed that a lineage of early horses the size of a small dog, called Hyracotherium, experienced a body-size decrease of about 19 per cent during ETM2.

The same horse lineage showed a body-size decrease of about 30 per cent during the PETM.

After both events, the animals rebounded to their pre-warming size.

Jawbone fossil of the early horse Hyracotherium, collected in the Bighorn Basin region of Wyoming. Researchers found that Hyracotherium body size decreased 19 per cent during a global warming event about 53 million years ago

‘Interestingly, the extent of mammalian dwarfism may be related to the magnitude of the hyperthermal event,’ said team member Abigail D'Ambrosia of the University of New Hampshire.

The ancient warming events may have been caused by the release of seabed methane clathrates, a kind of methane ice found in ocean sediments, though this topic remains an area of active research, Dr Gingerich said.

The parallels between ancient hyperthermals and modern-day warming make studies of the fossil record particularly valuable, said team member Will Clyde of the University of New Hampshire.