Mesozoic should be the correct answer.
The answer is the short-term memory. It is the ability to recall and remember the small memories for a short period. According to Atkinson-Shiffrin, it can only last for 15 to 30 seconds. The longer the input of data to the memory the shorter time it stays, this was explained by Peterson and Peterson.
Source: https://www.simplypsychology.org/short-term-memory.html
There are some reasons which could be mentioned:
1)Energy is lost as heat at each feeding level
2)Consumers who feed directly on plants have more energy for themselves than consumers feeding on other consumers. Indeed, energy again is lost in each level.
3)Feeding cattle is not productive, because energy must be transferred from plants to the cattle and then to people.
Answer it would be the bird
