Page 130 - The Evolution Impasse 2

128 Origin of Reptiles

aque ous de vel op ment. These eggs land, the am phib i an's egg would
are high ly po rous, they have a trans - have to be come an am ni ot ic one
par ent mem brane and a jel ly-like with in a sin gle gen er a tion. This
con sist en cy. Reptiles, on the oth er could hard ly oc cur through mu ta -
hand, lay their eggs on land, and tion and nat u ral se lec tion, the two
their eggs are ide al ly suit ed to dry sug gest ed mech a nisms of ev o lu tion.
con di tions. The hard shell of the rep - On the oth er hand, the fos sil
tile egg, known as an am ni ot ic egg, record al so re moves the pos si bil i ty
con tains an air sac, and is im per me - of an ev o lu tion a ry or i gin for rep tiles.
a ble to wa ter. The wa ter need ed by In an ar ti cle, "Problems of the Origin
the young is con tained in side the of Reptiles," the well-known ev o lu -
egg un til it hatch es. tion ist pa le on tol o gist Lewis L.
Were am phib i ans to de pos it their Carroll ad mits as much:
eggs on land, they would soon dry Unfortunately, not a sin gle spec i men
out and the em bry os in side would of an ap pro pri ate rep til i an an ces tor is
die. This is a point that the ev o lu tion known pri or to the ap pear ance of true
the o ry, which main tains that rep tiles rep tiles. The ab sence of such an ces tral
grad u al ly evolved from am phib i ans, forms leaves many prob lems of the am -
can not ex plain. To be gin life on dry phib i an-rep til i an tran si tion un ans -
wered. 135
Robert L. Carroll, re gard ed
as an au thor i ty on ver te -
brate pa le on tol o gy,

Seymouria
fos sil