Scientists once believed that tyrannosaurus rex dragged its tail along the ground. today, they know that t. rex did not drag its tail but held it aloft, above the ground. this change in scientific consensus happened because

Because all the scientific discoveries must be supported by various studies in order to regarded as valid.

Explanation:

It is known that scientific discoveries are getting updated and renewed constantly, however, both of these have nothing to do with the believing in one's idea more than another. It is also witnessed that some of the scientists do support the notion that the T-rex dragged its tail. However, now it is known that T-rex did not drag its tail but held its aloft above the ground. This change in scientific consensus by various scientific discoveries, which would have been supported by numerous studies in order to be regarded as valid.

d. the weight of the book