Page 78 - The Transitional Form Dilemma

THE TRANSITIONAL-FORM DILEMMA

differences between mammals and reptiles. Reptiles are cold-blooded,
reproduce by laying leathery-shelled eggs, and their bodies are covered
in scales. All reptiles have seven bones in their lower jaws, but only one
bone in their ears.
Mammals, on the other hand, are warm-blooded, give birth to
their young, and have milk glands and fur. They have a single lower
jawbone and three bones in their ears, known to anatomists as the ham-
mer, anvil and stirrup. If mammals, with their exceedingly complex
and interconnected systems and structures, really did evolve from rep-
tiles as the result of mutations, then in the fossil record there should be
a large number of species reflecting that transition. We would expect to
find remains of creatures possessing semi-developed milk glands, with

scales mutating into fur, some legs further extended and others still

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