are sharks more related to amphibians or rodents? I feel as if its rodents because they both give live birth but im not sure cause based on my photogenic tree amphibians are underneath sharks

Sharks are not closely related to either amphibians or rodents. Let me explain how we can determine the evolutionary relationships between organisms.

The study of evolutionary relationships is done through a field called phylogenetics. Scientists use various sources of evidence, such as morphology, genetics, and fossils, to determine how different organisms are related to each other. One commonly used tool is constructing a phylogenetic tree.

Phylogenetic trees show the evolutionary relationships among groups of organisms. They illustrate how species are related through a common ancestry. When constructing a phylogenetic tree, scientists consider several factors, including similarities in physical characteristics, genetic sequences, and reproductive strategies.

If we consider sharks, they belong to the group of fish known as cartilaginous fish or Chondrichthyes, which also includes rays and chimaeras. Amphibians, on the other hand, comprise a diverse group of tetrapods that includes frogs, toads, salamanders, and caecilians. Rodents, such as mice, rats, and squirrels, belong to the mammalian order Rodentia.

While rodents and sharks may both exhibit live birth (viviparity) in some species, this does not indicate a close evolutionary relationship. Viviparity has evolved independently in different groups of animals and is not a reliable trait for determining overall ancestry.

Based on phylogenetic evidence, sharks belong to the lineage of jawed vertebrates, whereas amphibians and rodents are part of the different lineages of tetrapods and mammals, respectively. Therefore, sharks are neither more related to amphibians nor rodents.

To understand the relationships between organisms accurately, it's essential to consult scientific research and rely on accepted phylogenetic frameworks constructed by experts in the field.