Final answer:
Molecular data utilizing mitochondrial DNA, nuclear DNA, rRNA, and proteins have significantly refined the phylogenetic trees, thereby elucidating the relationships between most animal phyla and transforming our understanding of animal evolution.
Step-by-step explanation:
Molecular data have played a crucial role in resolving the relationships between most animal phyla. Through genetic analysis such as mitochondrial DNA, nuclear DNA, rRNA, proteins, and extensive molecular analysis, our understanding of these complex relationships has drastically improved. Phylogenetic trees, which are continually updated with new findings, now more accurately reflect evolutionary relationships.
Historically, classification relied heavily on visible characteristics, leading to some inaccurately represented relationships, like the evolutionary closeness of hippos and whales versus hippos and pigs. However, as molecular research has advanced, significant corrections have been made to these classifications. For example, lophophorates, previously believed to be primitive deuterostomes, have been reclassified as protostomes. This led to the distinction of the protostome clade Lophotrochozoa.
The use of molecular data has introduced clarity in taxonomy, transforming and refining our understanding of the evolutionary history of animal phyla and prompting revisions to older, morphologically-based phylogenetic trees. Advancements in molecular biology have enabled these more accurate representations of phylogenetic relationships, emphasizing the importance of genetics in the study of evolution.