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Mammal-Like Reptiles

As previously stated, a succession of transitional fossils exists that link reptiles (Class Reptilia) and mammals (Class Mammalia). These particular reptiles are classifie as Subclass Synapsida. Presently, this is the best example of th e transformation of one major higher taxon into another. The morphologic changes that took place are well documented by fossils, beginning with animals essentially 100% reptilian and resulting in animals essentially 100% mammalian. Therefore, I have chosen this as the example to summarize in more detail (Table 1, Fig. 1).

M. Eyes = ?

Nose = ?

Teeth incisors = ?

K. Eyes = ?

Nose = pointy

Teeth incisors = small

J. Eyes = Medium

Nose = stubby

Teeth incisors = BIG

I. Eyes = Medium

Nose = less stubby

Teeth incisors = big

H. Eyes = smaller

Nose = more blunt

Teeth incisors = smaller

G. Eyes = SMALL

Nose = Pointer

Teeth incisors = Skinny

F. Eyes = BIG

Nose = Blunt

Teeth incisors = Thin

E. Eyes = HUGE!

Nose = pointy, again

Teeth incisors = Bigger

D. Eyes = Smaller

Nose = Getting wider

Teeth incisors = Bigger: two!

C. Eyes = Huge, again!

Nose = broader

Teeth incisors = very small

B. Eyes = less huge

Nose = less broad

Teeth incisors = ??

A. Eyes = bigger again

Nose = rounded

Teeth incisors = small

Skulls and jaws of synapsid reptiles and mammals; left column side view of skull; center column top view of skull; right column side view of lower jaw. Hylonomus modified from Carroll (1964, Figs. 2,6; 1968, Figs. 10-2, 10-5; note that Hylonomus is a protorothyrod, not a synapsid). Archaeothyris modified from Reisz (1972, Fig. 2). Haptodus modified from Currie (1977, Figs, 1a, 1b; 1979, Figs. 5a, 5b). Sphenacodo n modified from Romer & Price (1940, Fig. 4f), Allin (1975, p. 3, Fig. 16);note: Dimetrodon substituted for top view; modified from Romer & Price, 1940, pl. 10. Biarmosuchus modified from Ivakhnenko et al. (1997, pl. 65, Figs. 1a, 1B, 2); Alin & Hopson (1992; Fig. 28.4c); Sigogneau & Tchudinov (1972, Figs. 1, 15). Eoarctops modified from Broom (1932, Fig. 35a); Boonstra (1969, Fig. 18). Pristerognathus modified from Broom (1932, Figs 17a, b,c); Boonstra (1963, Fig. 5d). Procynosuchus modified from Allin & Hopson (1992, Fig. 28.4e); Hopson (1987, Fig. 5c); Brink (1963, Fig. 10a); Kemp (1979, Fig. 1); Allin (1975, p. 3, Fig. 14). Thrinaxodon modified from Allin & Hopson (1992, Fig. 28.4f);Parrington (1946, Fig. 1); Allin (1975, p. 3, Fig. 13). Probainognathus modified from Allin & Hopson (1992, Fig. 28.4g); Romer (1970, Fig. 1); Allin (1975, p. 3, Fig. 12). Morga nucodon modified from Kermack, Mussett, & Rigney (1981, Figs. 95, 99a; 1973, Fig. 7a); Allin (1975, p. 3, Fig. 11). Asioryctes modified from Carroll (1988, Fig. 20-3b). Abbreviations: ag = angular; ar = articular; cp = coronoid process; d = dentary; f = lateral temporal fenestra; j = jugal; mm = attachment site for mammalian jaw muscles; o = eye socket; po = post orbital; q = quadrate; rl = reflected lamina; sq = squamosal; ty = tympanic. .

Are you convinced yet?

Oscillating eye sizes,

head shapes that shift back and forth,

teeth that are large, then small, then large again.

Yeah; I believe this stuff!

(The chart is from The Fossil Record: Evolution or "Scientific Creation" by Clifford A. Cuffey. It is on part 5 of a multipart article. The beginning of the article is here. )

There are some Evo's who think... "It effectively demolishes the entire creationist argument. Excellent reading!"

After seeing these pix; do you?

Nothing wrong with big teeth/little teeth once you understand that it's the DNA making the difference, and it has "on" and "off" switches.

I think you have a better argument focusing on those "on" and "off" switches. There has to have been some high order data processing going on to come up with that one.

Those aren't pics - they're drawings.