Both the lecturer and the reading passage discuss Lambeosaurus, a dinosaur that had a crest on its head. The lecturer casts doubt on the author's assertion on several plausible reasons why Lambeosaurus possessed an axe shaped crest, by presenting three counter-arguments.
First, the lecturer asserts that the use of Lambeosaurus' crest to attract mate is disputable. He says that most reptiles use behaviour and sound method to attract mates, and not by using its crest. For example, croccodiles communicate with its opposite sex by lifting its hand high above or by making a loud noise. Lambeosaurus would use a similar method to these species. this counters the author's assertion that crests have been used to attract mates.
Second, the lecturer claims that crests, used for combat, is problematic. This is because an analysis of Lambeosaurus' fossil indicates that the crest is placed backwards, and not forwards. If crests were actually used for fighting and defending against other Lambeosaurus, the crest should be forward. Also, the crests are too fragile for combat. This contradicts the author's assertion that crests are used for protection and fighting against others.
Lastly, the lecturer argues that it is highly unlikely that the crest was to supply air when Lambeosaurus are underwater. This is because the size of the crest, compared to its body, is too small for storing enough air for Lambeosaurus to use underwater. Instead, Lambeosaurus would simply take a deep breath to provide air, without the help of its crest. This refutes the author's claim that crest, as a source of air, permitted Lambeosaurus to remain underwater for a long time. |