More than 50 million years ago, the Earth was a hotter place than it is today and horses the size of pet cats roamed the forests of North America, US scientists said on Thursday.
These earliest known horses, known as Sifrhippus, actually grew smaller over tens of thousands of years to adapt to the higher temperatures of a period when methane emissions spiked, possibly due to major volcanic eruptions.
The research could have implications for how the planet’s modern animals might adapt to a warming planet because of climate change and higher carbon emissions, scientists said.
Researchers made the discovery after analyzing horse tooth fossils uncovered in the western US state of Wyoming that showed the older ones were larger, and that the species had shrunk over time.
Many animals became extinct during this 175,000-year period, known as the Paleocene-Eocene Thermal Maximum, about 56 million years ago.
Others got smaller in order to survive with limited resources.
“Because it’s over a long enough time, you can argue very strongly that what you’re looking at is natural selection and evolution — that it’s actually corresponding to the shift in temperature and driving the evolution of these horses,” co-author Jonathan Bloch of the Florida Museum of Natural History said.
Average global temperatures rose by about 12oC during that span owing to a massive increase in carbon that was unleashed into the air and oceans.
Surface sea temperature in the Arctic was about 23oC, much like the temperatures of contemporary subtropical waters today.
The research showed that Sifrhippus shrank by almost one-third, reaching the size of a small house cat (about 4kg) in the first 130,000 years of the period.
Then, the horses grew larger again, to about 7kg in the final 45,000 years of the period.
About a third of known mammals also minimized themselves during this time, some by as much as one-half.
“This has implications, potentially, for what we might expect to see over the next century or two, at least with some of the climate models that are predicting that we will see warming of as much as 4oC over the next 100 years,” co-author Ross Secord of the University of Nebraska-Lincoln said.
Some birds have already been observed to have become smaller in size than in cooler times in the past, he said.
However, the forecast changes are expected to happen over the next century or two owing to a boost in carbon emissions dating back to the start of the Industrial Revolution.
Millions of years ago, the climate change happened much more slowly, taking between 10,000 and 20,000 years to get 10oC hotter, he added.
“So there’s a big difference in scale and one of the questions is: ‘Are we going to see the same kind of response?’ Are animals going to be able to keep up and readjust their body sizes over the next couple of centuries?” he said.
The findings were published in the journal Science.
CONFRONTATION: The water cannon attack was the second this month on the Philippine supply boat ‘Unaizah May 4,’ after an incident on March 5 The China Coast Guard yesterday morning blocked a Philippine supply vessel and damaged it with water cannons near a reef off the Southeast Asian country, the Philippines said. The Philippine military released video of what it said was a nearly hour-long attack off the Second Thomas Shoal (Renai Shoal, 仁愛暗沙) in the contested South China Sea, where Chinese ships have unleashed water cannons and collided with Philippine vessels in similar standoffs in the past few months. The China Coast Guard and other vessels “once again harassed, blocked, deployed water cannons, and executed dangerous maneuvers” against a routine rotation and resupply mission to
GLOBAL COMBAT AIR PROGRAM: The potential purchasers would be limited to the 15 nations with which Tokyo has signed defense partnership and equipment transfer deals Japan’s Cabinet yesterday approved a plan to sell future next-generation fighter jets that it is developing with the UK and Italy to other nations, in the latest move away from the country’s post-World War II pacifist principles. The contentious decision to allow international arms sales is expected to help secure Japan’s role in the joint fighter jet project, and is part of a move to build up the Japanese arms industry and bolster its role in global security. The Cabinet also endorsed a revision to Japan’s arms equipment and technology transfer guidelines to allow coproduced lethal weapons to be sold to nations
Thousands of devotees, some in a state of trance, gathered at a Buddhist temple on the outskirts of Bangkok renowned for sacred tattoos known as Sak Yant, paying their respects to a revered monk who mastered the practice and seeking purification. The gathering at Wat Bang Phra Buddhist temple is part of a Thai Wai Khru ritual in which devotees pay homage to Luang Phor Pern, the temple’s formal abbot, who died in 2002. He had a reputation for refining and popularizing the temple’s Sak Yant tattoo style. The idea that tattoos confer magical powers has existed in many parts of Asia
ON ALERT: A Russian cruise missile crossed into Polish airspace for about 40 seconds, the Polish military said, adding that it is constantly monitoring the war to protect its airspace Ukraine’s capital, Kyiv, and the western region of Lviv early yesterday came under a “massive” Russian air attack, officials said, while a Russian cruise missile breached Polish airspace, the Polish military said. Russia and Ukraine have been engaged in a series of deadly aerial attacks, with yesterday’s strikes coming a day after the Russian military said it had seized the Ukrainian village of Ivanivske, west of Bakhmut. A militant attack on a Moscow concert hall on Friday that killed at least 133 people also became a new flash point between the two archrivals. “Explosions in the capital. Air defense is working. Do not