Cold blooded creatures maintain a constant blood temperature, by hiding in the shade when they get too hot, or basking in the Sun when they become too cool. This method of sunning and cooling keeps their blood at an even and steady temperature for the creature to survive.
Warm blooded creatures or mammals differ, in that they use some form of gland, similar to the human thyroid gland, situated near their throat. This gland keeps a constant check on the air temperature breathed in, and compares it directly with the temperature of the blood being pumped from the heart to the brain. It then releases a thyroxin (a hormone), into the body which affects the rate at which cell oxidation occurs, and through perspiration or raised energy levels, a constant and steady metabolism and blood temperature is achieved.
Whether a creature is cold blooded or warm blooded, the blood flowing to the creatures brain needs to remain a steady 100 degrees Fahrenheit. A drop in temperature by just a few degrees will induce coma, shortly followed by death.
This is precisely why mammals, such as polar bears, can survive in extreme climates, whilst reptiles are forced to inhabit areas of the planet that maintain a constant high temperature all year round.
Whilst a climatic change from a meteor explosion would certainly lower the temperature enough to kill off reptiles, it doesn’t explain why smaller reptiles survived, or why these same reptilian giants were able to survive globally around the world, before the meteor hit, in areas that exhibited extreme seasonal changes today.
Surely if these gigantic creatures were so affected by cold weather, they would not be able to survive a harsh winter either.
As well as this distinct and sudden change from cold blooded to warm blooded creatures, there was an equally dramatic change to the planets flora.
Before the KT event, the primary form of plant life and vegetation on Earth was gymnosperms such as ferns, pine trees, and other non flowering plant life. The term ‘evergreen’, derives from the apparent lack of change these plants or trees have all year round. Though they do not flower, these plants do produce spores or seeds. In fact the term ‘gymnosperm’ means ‘naked seed’, and as such they have no protective coating, and fail to thrive in harsh environments with dramatic seasonal change.
After the KT event, the change shifted dramatically to ‘angiosperms’, meaning ‘covered seed’. These forms of vegetation flower each year, then die, and grow anew from their protected seeds the following season. Similarly trees of this type will blossom, grow new leaves, which in turn die during winter, and completely re-grow the following year.
Angiosperms are a very good example of plant life that thrive in environments which exhibits seasonal change, and in fact rely on these seasons to prompt their life cycle. The hardened coverings of the seeds they produce enable them to withstand these climatic changes that occur all year round.
With this in mind, the conclusion from the KT event, should not therefore be the change from one species to another, but rather a global environmental change, from a temperate non-seasonal tropical climate, to one that cycles through spring, summer, autumn, and winter. The environment, atmosphere, and ecology of planet Earth changed from a steady unchanging climate, to one with diverse seasonal changes.
So how could this possibly be? Why was it that before the KT event we had no distinct seasons, the climate remained the same all rear round, and after the event we shifted through hot and cold periods throughout the year.
To answer this question, we first need to look at how the seasons work in the first place.
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