Recently discovered fossil evidence casts doubt on the evolutionary theory that dinosaurs are more closely related to...

Mehran February 22, 2014

So let's break down this argument. Recently discovered fossil evidence is casting doubt on the evolutionary theory that dinosaurs are more closely related to reptiles than to other classes of animals. The fossils show that "some dinosaurs had hollow bones - a feature found today only in warm blooded creatures." We know that dinosaurs have a well developed sense of sight and hearing, a characteristic not true of present day cold blooded creatures like reptiles. Also, the highly arched mouth roof of some dinosaurs would have permitted them to breathe while eating, as fast breathing animals need to do. We are told that today, all fast breathing animals are warm-blooded. Lastly, the fossils revealed that many dinosaurs had a pattern of growth "typical of warm blooded animals."

Now let's look at answer choice (D): "assuming that if all members of a category have a certain property then all things with that property belong to the category." So (D) is essentially stating: if all members of A have property B, then all things with property B are members of A. The argument does not use this method. (D) is describing the flaw of "Don't Just Reverse," i.e. assuming the existence of the necessary condition guarantees the existence of the sufficient condition.

Now let's take a look at answer choice (E): "presenting evidence that a past phenomenon is more similar to one rather than the other of two present day phenomenon." This is exactly what the argument is doing; a past phenomenon (i.e. dinosaurs) is more similar to one (i.e. warm blooded creatures) than the other (i.e. reptiles) of two present day phenomena. The fossil evidence clearly shows how dinosaurs are more similar to warm blooded creatures than to reptiles.

Hope this helps! Please let us know if you have any other questions.

AdamH November 3, 2018

Thanks for the explanation Mehran. I picked D as well cause I had a hard time considering a warm blooded creature/reptile as a phenomenon. But totally understand now.

saskipper February 26, 2020

^Agreed. Would never use the word "phenomenon" to describe a bird...

Shirnel June 1, 2020

When I read this argument, although I got the right answer, I didn't realize that the stimulus was differing between reptiles and warm blooded animals. I thought all the evidence of warm blooded animals supported the first sentence. How could I have better made/understood the difference.

jcefalu88@gmail.com July 22, 2020

Phenomenon just = a thing, not necessarily something extraordinary. Made me second guess for a moment too.