The ancestors of modern-day fish were vertebrate chordates. Vertebrate chordates are believed to have evolved from invertebrate chordates, which were similar to modern-day tunicates.

What change must have occurred during the evolution from invertebrate chordates to vertebrate chordates?

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.

d we did this already

characteristics of hydrocarbons