Question

The first fossil of Archaeopteryx, which lived about 150 million years ago, was found in the Solnhofen Quarry in Germany. Archaeopteryx has an interesting collection of characters that led to the hypothesis that it represented an evolutionary transition between modern-day birds and small bipedal dinosaurs. The fossil reveals the imprint of feathers, which connect Archaeopteryx to birds, although they do not present direct evidence of flight. Unlike birds, however, Archaeopteryx was shown by the fossil record to have had teeth, functional claws on the wings that may have been used for climbing trees or holding prey, and a long, bony tail. Birds have a fused collarbone, which was found in Archaeopteryx as well. However, the structure of the sternum differed between the two. In birds, the sternum is keeled (raised and slightly concave); the keel of the sternum serves as an attachment site for the flight muscles. Archaeopteryx had a flat sternum, similar to that found in reptiles.

If you were constructing a phylogenetic tree for the evolution of birds, which characters found in Archaeopteryx might provide evidence that birds and dinosaurs had a common ancestor?
A. feathers, wings, wishbone
B. teeth, feathers, keeled sternum
C. keeled sternum, claws, long forelimbs
D. teeth, flat sternum, claws

Answer 1

Traits of Archaeopteryx that support the theory of a common ancestor with birds and dinosaurs are feathers, teeth, and wing claws. Its flat sternum also indicates a reptilian link.

Step-by-step explanation:

The characteristics found in Archaeopteryx that might provide evidence that birds and dinosaurs had a common ancestor include its feathers, presence of teeth, and functional claws on its wings. Feathers connect Archaeopteryx to birds, while the presence of teeth and wing claws are traits it shares with non-avian dinosaurs.

Its flat sternum, while not seen in modern birds, is a reptilian characteristic that birds and non-avian dinosaurs share, supporting the theory of a common ancestor. Therefore, the most indicative traits to include on a phylogenetic tree to show the evolutionary relationship between birds and dinosaurs would be answer D: teeth, flat sternum, and claws.