Q20 - A Revised Dinosaur Phylogeny Overturns Assumptions About Traits

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Mary Anning (1799-1847) developed the concept of prehistoric life, by collecting fossils. Richard Owen (1804- 1892) coined the term dinosaurs, whilst Thomas Huxley (1825-1895) used fossils to show birds (Aves) evolved from, and are, dinosaurs (Dinosauria). Until last year, scientists believed the dinosaur phylogeny was as shown in (1). In 2017, British scientists analysed many more fossils and produced a new tree (2) based on hundreds of characteristics, including those shown. For birds, the characters are representative of ancestral birds.

Figure 1 for Q20: A Revised Dinosaur Phylogeny Overturns Assumptions About Traits

This question mixes multiple-choice/numeric-estimate parts with True/False statements - answer each part using the information and data above.

A. Some sauropods (Sauropoda; the group farthest left in each tree) were feathered.

B. Bird-like hips evolved multiple times (convergence)

C. Exclusive carnivory evolved multiple times.

D. The earliest dinosaurs evolved in the Southern hemisphere.

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Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions