While this process of dwarfism among mammals has previously been linked to the largest of the heating events, this research work found out that this evolutionary process can take place in smaller such events as well.
These findings could help us in shaping a comprehension of underlying effects of the current climate change caused by humans.
"We know that during the largest of these hyperthermals, known as the Paleocene-Eocene Thermal Maximum, or PETM, temperatures rose an estimated 9 to 14 degrees Fahrenheit and some mammals shrank by 30 per cent over time, so we wanted to see if this pattern repeated during other warming events, the hope is that it would help us learn more about the possible effects of today's global warming," said the lead author of the study Abigail D'Ambrosia, a PhD student at New Hampshire University.
In this study, which was published in the journal Science Advances, the researchers collected jaw and teeth pieces in the Bighorn Basin region of Wyoming in the US, which is very rich in its fossil presence. Their main focus was on the various early mammals which include Arenahippus, an early horse which was of the size of a small dog, and Diacodexis, a predecessor to hoofed mammals which was as small as a rabbit.
Using the size of the molar teeth as a proxy for body size, these researchers ended up finding a significant change (decrease) in the body size of these mammals during a 2nd, smaller, hyperthermal, called the ETM2.
Arenahippus was found to be decreased by about 14 per cent in size, and the Diacodexis was found to be decreased by about 15 per cent.
"We found evidence of mammalian dwarfism during this second hyperthermal. However, it was less extreme than during the PETM," D'Ambrosia said.
A smaller size of the body would allow the animals to cool down faster. The availability of nutrients and the quality in plants may also have played a role in decreasing the body heat.
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