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Share this:. Share on Tumblr. By ascertaining where herbivores were feeding, and how geochemical signatures of prey became locked in carnivore teeth, paleontologists could narrow down the preferred habitats and prey of Miracinonyx.
Furthermore, a poster presented by Natalia Kennedy and coauthors at the SVP meeting outlined a new attempt to compare the spine of the modern cheetah to that of Miracinonyx and other extinct cats to see how skeletal anatomy influenced flexibility and lifestyle. Miracinonyx might have been the reason for the swiftness of pronghorn. False cheetahs and archaic pronghorn overlapped in time, if not habitat, for as much as three million years.
But saying Miracinonyx was certainly a speed demon that gave pronghorn a reason to run is only supported by the barest amount of evidence. The Just-So story of how the pronghorn got its speed has yet to be tested by the evidence which resides in the fossil record. Adams, D. The Cheetah: Native American.
Barnett, R. Evolution of the extinct sabretooths and the American cheetah-like cat. Current Biology. Hodnett, J. Kennedy, N. A geometric and kinematic backbone model of the cheetah, Acinonyx jubatus , and its application to understanding the spinal kinematics of Miracinonyx trumani , in Programs and Abstracts, Journal of Vertebrate Paleontology.
Martin, L. A cheetah-like cat in the North American Pleistocene. Van Valkenburgh, B. Journal of Vertebrate Paleontology. Walker, D. Plains Anthropologist. All rights reserved. References: Adams, D. Yet even those fleet-footed ones of hide, bone, flesh, blood, and guts that appear to be invincible are mortal. One legendary animal that seems ambiguous, hovering as it does in between the real that you can touch and the humanly unattainable, is the pronghorn antelope of the American plains. It has been clocked running at 61 miles per hour—almost twice as fast as a racehorse—and not just in a short sprint.
It can reputedly cover 7 miles in 10 minutes. The Hopi tribe believed the antelope to be a spirit messenger and a powerful medicine.
It is, of course, a mammal, and to the tiniest detail of our anatomy and biochemistry, we are also mammals.
For over at least 4 million years, the pronghorn Antilocapra americana has coexisted with predators on the open plains of North America. It has evolved in a habitat that offers long views in many directions, and it has survived not by hiding from its predators but by outrunning them. In turn, the predators—most likely saber-toothed tigers, wolves, cheetahs, giant short-faced bears, dire wolves, dholes, and hyenas—have had to come close to matching its running performance. Weaknesses were exposed and culled out of the gene pool.
John A. Rate of oxygen uptake sets a limit on the sustained exercise level. The workload can then be increased still further, but only for a very short time—seconds—at the cost of the buildup of lactic acid in the blood. The extra oxygen that must be taken in after the exercise to oxidize the lactic acid produced during the exercise is called the oxygen debt.
The increased speed bought by running for a few seconds beyond the O2 max always costs dearly later. The cost of that speed is worth it only if the chase is reliably short and yields results. In one study by Stan Lindstedt and colleagues, pronghorns were galloped on a treadmill at 10 meters per second wearing polyethylene masks to collect air for measuring aerobic work output.
The incline of the treadmill was then increased to 11 percent, and the antelopes then registered an impressive O2 max of milliliters of oxygen per kilogram of body weight per minute.
Aside from sampling the air from the mask, blood was withdrawn from an artery within three to four minutes of running at O2 max to examine blood gas content and also to check for lactate to verify that the animals were indeed running at their O2 max and not beyond it.
Smaller animals generally have far greater rates of power output per unit of body mass, as the above comparison of a moth, a bird, and a human indicated. But taking the effect of body mass into account, the maximum aerobic capacity of the antelopes was still about three times greater than predicted for their approximately pound body mass. What does the antelope get from its extraordinarily high.
V O2 max? The answer is, the same as human athletes do. A high rate of power output converts to the potential for high sustained running speed. To answer that question, researchers made comparisons with a similar-sized ruminant mammal, the goat.
Goats are neither swift nor long runners. They are instead good climbers, and they evade predators not by outrunning them but by inhabiting inaccessible mountain ledges.
In all structural aspects relating to physiology that were examined and that relate to rate of oxygen use, the antelopes were superior to the goats. Antelopes have more massive windpipes, three times larger lung volumes, greater gas diffusion capacity through lung tissue, an oversized heart, more cardiac output, greater amounts of hemoglobin concentration in the blood, more muscle mass, and greater numbers of mitochondria and hence more oxidative enzymes in their muscles.
They also regulate their muscle temperature 2. There is no magic. There are no tricks. By: Tanner Saul. Copyright Scripps Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
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