Anatomical Similarities and Evolutionary Relationships Practice Test

Four anatomical models show skulls in the same side-view orientation with a 1 cm scale bar.

• Skull 1 and Skull 2 both show a similar pattern: a single lower jaw bone, a similar position of the eye socket, and a similar arrangement of teeth types (front cutting teeth followed by flatter back teeth).
• Skull 3 shows many small jaw bones and teeth that are mostly the same shape.
• Skull 4 shows a beak with no teeth.

Anatomical similarities can suggest relationships.

Which inference about relationships is supported by the skull evidence?

Four anatomical models show front limbs in the same orientation with a 4 cm scale bar. The student is told: anatomical similarities can suggest relationships.

• Organism Q: one upper bone, two lower bones, wrist bones, five digits.
• Organism R: one upper bone, two lower bones, wrist bones, five digits.
• Organism S: one upper bone, two lower bones, wrist bones, two digits.
• Organism T: many small bones with no clear one-upper/two-lower arrangement.

Which of the following is the best supported relationship inference based on the structural patterns?