January 28, 2015
What has been puzzling Paleontologists for years concerning the dinosaur-ending Baptistina asteroid which gouged out the “Chicxulub” crater in the Yucatan peninsula 65 million years ago, there should be large "killing fields" of dinosaurs when the asteriod struck the Earth. So far no "killing fields" have been found. The thinking is that the dinosaurs were extinct before the Baptistina asteroid hit the Earth.
The evolutionary transfer of the production site of ascorbic acid from the kidneys to the liver was a monumental step. It has been established that during the Permian period known as “The Age of Amphibians” the site of ascorbic acid synthesis was in the kidneys. During the Permian period earth contained an exceedingly high level of environmental oxygen at 30% to 35%. The environmental oxygen during the Quaternary period “The Age of Man” is about 21%. The end of the Permian period closes with the largest mass extinction ever. Dr. Chatterjee’s research indicates that this massive die off was caused by global hyperoxia (an abnormally increased supply or concentration of oxygen) that was spread over millions of years. When the amphibians made a concerted effort to colonize the land it has been conjectured that the amphibians could not increase their ascorbic acid production to combat oxygen toxicity. The reason being, the amphibian’s ability to exploit both aquatic and terrestrial habitats did not consistently expose them to the evolutionary pressures which are necessary to facilitate the transfer of the manufacturing site of ascorbic acid from the kidneys to the liver.
For a long time it was believed that the dinosaurs were cold blooded. During the 1960’s paleontologist Robert Bakker and Dr. John H. Ostrom proposed the notion that dinosaurs could have been warm-blooded. Since then researchers have analyzed the growth lines on dinosaur bones and have concluded that dinosaurs had a high metabolic rate and a high growth rate which meant they were warm-blooded. The high rate in bone growth suggests a dramatic increase in collagen synthesis which is dependent on an increase in the production of ascorbic acid. If the dinosaurs were cold-blooded their dominance on the earth would have been considerably shorter because the warm blooded mammals (even though they were much smaller than the dinosaurs) would have eventually out-competed them. For example the small but warm blooded mammals would have wreaked havoc with the egg laying cold-blooded reptiles. If a significant number of the reptilian eggs were destroyed this in turn would have a negative impact on the mating habits and genetic diversity of the reptiles. As the reptilian eggs were being destroyed this would create a small gene pool from which to breed, otherwise there would be a greater chance for inbreeding. In order for the reptiles to have been the dominant species on the earth for approximately 183 million years and to co-exist with the small warm-blooded mammals they had to be warm-blooded. This allowed the female reptiles to nurture their young for longer periods of time than if they were cold-blooded. The high percentage of environmental oxygen which occurred during the Permian period was a major factor in ending the dominance of the amphibians on earth. Chatterjee further speculates that very high concentrations of environmental oxygen during the Carboniferous-Permian period (30%-35%) may have been the catalyst for the accelerated diversification and mass extinction of the tetrapods. Dr. Chatterjee continues to hypothesize that there may never have been a mass extinction but an extinction that was spread out over millions of years caused by global hyperoxia.
It has been speculated that the high percentage of environmental O2 continued through the Triassic, Jurassic and Cretaceous periods. The high O2 was a major evolutionary force which facilitated the change of ascorbic acid synthesis from the kidneys to the liver. It is quite ironic that a high level of environmental oxygen would eventually be detrimental to the dominance of the amphibians; on the other hand it became an evolutionary benefit to the reptiles and mammals. An increase in ascorbic acid synthesis was necessary to counter the effects of planetary hyperoxia because ascorbic acid along with being an anti-oxidant is an excellent free radical scavenger of reactive oxygen species (ROS). ROS experimentally has been responsible for causing oxidative damage in vivo (within a living organism; example animal testing). Another evolutionary factor which contributed to the transferring of the synthesis of ascorbic acid from the kidneys to the liver was proposed by the late Irwin Stone PhD. Stone proposed that the evolutionary change from the kidneys to the liver took place at a time when temperature regulatory mechanisms were evolving and warm-blooded (Homeothermic) animals were developing from the previous cold-blooded (Poikilothermic) vertebrates.
Research conducted by Dr. Indu B. Chatterjee has demonstrated that during the Mesozoic Era the reptilian exposure to very high levels of oxygen in the environment (30%-35%), required the reptiles to synthesize optimal amounts of ascorbic acid for protection against oxygen toxicity. The large size of the liver had the capacity to synthesize optimal amounts of ascorbic acid to satisfy the high metabolic rate of being warm blooded and also to combat the effects of oxygen toxicity. It is quite ironic that being hyperascorbemic has been implicated in the accelerated diversification of the tetrapod’s during the Carboniferous-Permian period because of the protection it provided against oxygen toxicity. This protection also ensured respiratory adaptation and survival on land. Being hypoascorbemic has been implicated in the mass extinctions of the late Permian period because of the inability to afford amphibians the needed protection against oxygen toxicity. In summary global hyperoxia which is the main cause of oxygen toxicity may have been a major factor during the late Permian period for the extinction of most of the early amphibians and reptiles.
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