Honey, I Shrunk the Horse 
by Sid Perkins
When the earliest horses appeared about 56 million years ago,  they were about the size of a miniature schnauzer. Then, over the next  130,000 years,         these “protohorses” became even smaller, shrinking to the size  of a house cat (artist’s reconstruction of Sifrhippus sandrae,  right,         compared with a modern-day Morgan horse, which weighs a  half-ton).
The shrinkage, researchers have found, is due exclusively to  warmer temperatures. In         their analysis, the scientists estimated the body size of each  protohorse by measuring its fossilized teeth, and they used the ratios  of oxygen         isotopes in the teeth of aquatic mammals that lived alongside  the protohorses—a reliable paleothermometer—to estimate average annual  temperature         in the region.          As global temperatures rose between 5° and 10°C during that period, the protohorses lost about 30% of their body mass, the team reports online today in Science.
Other data, including analyses of the sediments surrounding the  fossils,         reveal that the climate got wetter—and the ecosystem was  presumably more productive—as average temperatures climbed, nixing the  notion that these         animals shrank because of a reduced food supply. After the peak  of the ancient warm spell, the creatures evolved back to a larger size  as climate         cooled, setting them on the evolutionary road that produced the  saddle-worthy horses we know and love today.
(via: Science NOW)    
(image: Danielle Byerley/Florida Mus. of Natural History )

Honey, I Shrunk the Horse

by Sid Perkins

When the earliest horses appeared about 56 million years ago, they were about the size of a miniature schnauzer. Then, over the next 130,000 years, these “protohorses” became even smaller, shrinking to the size of a house cat (artist’s reconstruction of Sifrhippus sandrae, right, compared with a modern-day Morgan horse, which weighs a half-ton).

The shrinkage, researchers have found, is due exclusively to warmer temperatures. In their analysis, the scientists estimated the body size of each protohorse by measuring its fossilized teeth, and they used the ratios of oxygen isotopes in the teeth of aquatic mammals that lived alongside the protohorses—a reliable paleothermometer—to estimate average annual temperature in the region. As global temperatures rose between 5° and 10°C during that period, the protohorses lost about 30% of their body mass, the team reports online today in Science.

Other data, including analyses of the sediments surrounding the fossils, reveal that the climate got wetter—and the ecosystem was presumably more productive—as average temperatures climbed, nixing the notion that these animals shrank because of a reduced food supply. After the peak of the ancient warm spell, the creatures evolved back to a larger size as climate cooled, setting them on the evolutionary road that produced the saddle-worthy horses we know and love today.

(via: Science NOW)    

(image: Danielle Byerley/Florida Mus. of Natural History )

  1. sweetpeacelove reblogged this from rhamphotheca
  2. theclassicals reblogged this from rhamphotheca
  3. yesysabella reblogged this from rhamphotheca
  4. amerains reblogged this from rhamphotheca
  5. sanitychallenged reblogged this from crownedrose
  6. carriemp reblogged this from rhamphotheca
  7. einsteinandvangogh reblogged this from rhamphotheca
  8. mangabottle reblogged this from rhamphotheca
  9. incogpollywog reblogged this from rhamphotheca
  10. bcrowsnest reblogged this from rhamphotheca
  11. spiletta42 reblogged this from rhamphotheca
  12. knsculpt reblogged this from rhamphotheca