The KT boundary marks a mass extinction event. the KT boundary is the time between the Cretaceous and Tertiary periods. An asteroid hit the earth at the end of the Cretaceous and that caused the end of the Cretaceous period. Before the KT boundary, pollen from angiosperms and gymnosperms is high. After the meteor hits the earth, a mass extinction occurs and the amount of pollen from gymnosperms and angiosperms decreases dramatically, while the amount of spores from ferns increases. During the Cretaceous period there were many species of gymnosperms and angiosperms but they disappeared at the KT boundary, when the asteroid hit the earth.
Tibialis anterior.
Explanation:
Tibialis anterior is the muscle of lower limb that originates from the upper two-third of lateral surface of tibia and attaches the heel (calcaneous ) via heel cord and plantar.
When the knee is extended, this muscle results in flexing of the foot .
This injury also functions in keeping the balance of the body when we are standing or even when we are walking.
Involved a dramatic and sudden increase
The hormone calcitonin is controlled by a negative feedback mechanism because it's release leads to the decrease of calcium blood levels.
<h3>What is negative feedback mechanism?</h3>
A negative feedback mechanism is the defined as a type of regulatory mechanism in the body where by the increased output of a system leads to a decrease of another system.
Therefore, the release of the hormone calcitonin (increased level of calcitonin in the blood) will lead to decrease in blood levels of calcium.
Learn more about hormones here:
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