In 2010, scientists excavated a skull fossil that provides evidence of a newly discovered species of big cat. based on the evidence, scientists hypothesize that big cats branched off from smaller wild cats about 6 million years ago. which of these resources did the scientists most likely rely on to form their hypothesis?

This question is incomplete. The complete question is listed below.

In 2010, scientists excavated a skull fossil that provides evidence of a newly discovered species of big cat. Based on the evidence, scientists hypothesize that big cats branched off from smaller wild cats about 6 million years ago. Which of these resources did scientists most likely rely on to form their hypothesis? 

A a food web showing feeding relationships of organisms where the fossil skull was found. 
B. Population and migration data for small wild cats living in the ecosystem where the skull was found 
C fossil record and DNA comparisons 
D. The historical record of interactions between different species of big cats

The answer to this question is C: fossil record and DNA comparisons. DNA sequencing and the similarity in DNA between different species can assist in determining their taxonomy and evolutionary distance between species. The fossil record can also assist in identifying the relationships between species, particularly in respect to their common ancestor, which may be extinct. The study of the fossil record can identify when mutations in a common ancestor first appeared, leading to a taxonomic divergence.