Walter and Luis Alvarez hypothesized that an asteroid impact caused the formation of a 66-million-year-old
layer of clay containing high levels of iridium. How did
geologists test this hypothesis? What evidence did they
look for?

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation

the alkaline earth metals (beryllium (be), magnesium (mg), calcium (ca), strontium (sr), barium (ba), and radium (ra)) are a group of chemical elements in the s-block of the periodic table with very similar properties: shiny. silvery-white. hopefully this ? i didn't fully understand the question