Provide definitions or explanations for the following: $1$. Recapitulation theory (Biogenetic law) and $2$. Palaeontology.

(N/A) $1$. Recapitulation theory (Biogenetic law): This theory states that "Ontogeny recapitulates phylogeny," meaning an individual organism repeats its evolutionary history during its embryonic development.
$2$. Palaeontology: This is the study of past life based on fossil records. It provides the most direct and reliable evidence for the process of evolution.