Your six friends are now exploring Ellsmere Island in Canada. On this Island, in 2005, scientists discovered the fossil of Tiktaalik roseae, a famous “transition fossil” between swimming fish and four legged vertebrates (the tetrapods). Your friends begin to discuss Tiktaalik’s (pronounced tik-TAA-lik) origin. This is what they said: Courtney: “Obviously, there was not enough food in the sea, so a mutation occurred and that caused Tiktaalik to be able to go on the land.”

Jose: “Courtney, I agree with you. Tiktaalik must have needed to develop fins that were capable of supporting movement on land.”

Raquan: “You two might be onto something. Clearly, Tiktaalik encountered a changing environment and it adapted to it.”

Mike: “Yeah, Raquan, once it acquired the trait of fins capable of supporting movement on land, as Jose suggested, it passed them onto its offspring.”

Keisha: “Alright, so then do we think this is an example of evolution? If so, then this form must have evolved into the tetrapods we see today over a very long time.”

Alex: “Keisha, I agree with you that this process of change took a long time, but I’m not so sure if Tiktaalik evolved into the tetrapods we see today. If Tiktaalik is a fossil, it should be extinct.”

Directions: Based on each person’s statement, identify if you agree or disagree by placing an Agree or Disagree next to the name and then explain your reasoning.

Courtney
Jose
Raquan
Mike
Keisha
Alex