The term fish is used for any any swimming vertebrate with fins. it includes a diverse group of animals, divided into four taxonomic classes, agnatha, chondrichthyes, osteichthyes, and placoderma. taxonomists first divided all "fish" into two classes, agnatha and placoderma. the placoderma are considered ancestors of all other fish. what fossil evidence taxonomists separate all "fish" into these two branches for classification?

Jaw or jawless.

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The scientific method is a series of steps followed by scientific investigators to answer specific questions about the natural world. it involves making observations, formulating a hypothesis, and conducting scientific experiments.the steps of the scientific method are •observation-the first step of the scientific method involves making an observation about something that interests you•question-once you've made your observation, you must formulate a question about what you have observed. •hypothesis-once you've made your observation, you must formulate a question about what you have observed. •experiment-once you've developed a hypothesis, you must design and conduct an experiment that will test it.•results-the results are where you report what happened in the experiment. •conclusion-the final step of the scientific method is developing a conclusion.i hope that this you : )