It has scales, fins, a flat head with eyes on top, huge interlocking ribs that suggest it had lungs, hip bones, and a neck. 15.
Describe the transition between fish and tetrapods. Was it abrupt or gradual? The transition was gradual and other specimens were more fish-like than the Tiktaalik and others that were more tetrapod-like than the Tiktaalik. This transition happened over about 15 million years. After viewing the film, there is a follow-up exercise to do. Go to the Great Transitions Interactive exercise at: https://www.biointeractive.org/classroom-resources/exploring-
transitional-fossils Fill in the following chart with the information from the interactive: Name of animal Scales/gills Lungs/humerus wrist, pelvis, ribcage, neck number of digits flat head? Eusthenopteron yes yes no 0 no Panderichthys yes yes no 0 yes Tiktaalik yes yes yes 0 yes Acanthostega yes yes yes 8 yes Ichthyostega yes yes yes 7 yes Tulerpeton no yes yes 6 yes Pederpes no yes yes 6/5 no Coelacanth yes yes no 0 no 1.
At which point (name the animal) do the animals develop tetrapod features (wrist, pelvis, etc)? They started to develop fish and tetrapod features at Eusthenopteron, but the first solely tetrapod feature was a flathead with Panderichthys.
2.
At which point do they lose fishlike features of scales and gills? They lose them at Tulerpeton but gain them back at Coelacanth. 3.
How many of them share the features of both fish and tetrapods? Name them, these are the transition fossils. All of them share lungs and a humerus, which are both fish and tetrapod features. 4.
Can you tell at which point a fish becomes a tetrapod? Why or why not? Yes, the Tulerpeton becomes a tetrapod because it lost its features that make it part fish. 5.
Explain how transition fossils support the theory of evolution. Transition fossils give physical evidence of evolutionary change by preserving intermediate forms between ancestral and descendant species, demonstrating the steady transition of organisms over time and confirming the hypothesis of natural selection.