Archaeopteryx part 2

Let's say we decide that the bone structure of the

Archaeopteryx is definitely reptilian, from which line of reptiles

is it related? Surely, there would be traces of one or the other.

Martin, Stewart, and Whetstone, "The Auk" (Ornithological Journal)

January 1980 page 86 "The Origin of Birds: Structure of the Tarsus

and Teeth"

"...virtually every major group of reptiles has been

purported to be closely related, if not ancestral to birds."

In the report they briefly mention two hypotheses concerning

Archaeopteryx and proceed to push their own- crocodile ancestry

based on teeth. The hypotheses are:

1) A theory of their ancestry from Triassic pseudosuchian

archosaurs.

2) A theory of direct derivation of birds from theropod

dinosaurs.

3) A close relationship between birds and crocodilians.

It should be noted that in their report that altho' they

concentrated on the Archaeopteryx, the authors clearly related the

teeth of this bird to the teeth of later Mesozoic birds and spoke

of them as one in the same. They were mainly dealing with the

origin of teeth in all teeth-bearing birds.

In another report that I mentioned a while back in "Nature"

Sept 8 1983 pp99-100 entitled "No consensus on Archaeopteryx" The

author Dr. Michael Benton (not to be confused with Dr. Michael

Denton) concerning the different theories:

" The relationships of Archaeopteryx and the origin of the

birds are controversial. In a recent review, Thulborn and Hamley

identified seven hypothses concerning the affinities of

Archaeopteryx, three of which appear to have supporters at

present."

Just prior to this, Dr. Benton discusses the results of

Archaeopteryx cranial studies:

"In the new work that has been done on the braincase of

Archaeopteryx by Whetstone, the cranium of the 'London'

specimen has been removed from its limestone slab and painstakingly

prepared by mechanical means.

This has shown that the skull is much broader

and more bird-like than had been thought. Details of

the braincase and associated bones at the back of the skull seem

to suggest that Archaeopteryx is not the ancestral bird, but an

off-shoot from the early avian stem." He goes on for the rest of

the paragraph discussing very briefly how it is primitive in some

respects and advanced in others. But basically the Archaeopteryx

has been, according to him, relagated from the lofty position of

being the transition between reptile and modern bird to that of

just another "side branch" of evolution.

So you see, the reptilian features of the Archaeopteryx are

so obscure and ambiguous that trying to pin down its ancestral

relationship is just about impossible. Forcing the Archaeopteryx

into the role of transition has proved to be nothing but a

fruitless exercise.

But let's say for the sake of arguement that the

Archaeopteryx's bony structure can be related to reptiles as well

as birds. Does this still necessarily force us to conclude that

it is transitional?

"Evolution: Nature and Scripture in Conflict?" by Dr. P.T.

Archaeopteryx has been cited frequently as the transitional

type between reptiles and birds. It has a birdlike skull and wings

with feathers. The reptile features are presented by clawlike

appendages, the possession of teeth, and the long vertebral column

that extends to the tail. The flying power of this organism was

presumably slight, for the wingspread is much less than that of

the poor flyers among modern birds.

Since most skeletal features of birds can be matched by some

archosaurian reptiles, feathers have been considered the only

distinctive feature of birds. Feathers are essential to birds for

insulation against loss of body heat, and this contrasts greatly

with reptiles since they are cold-blooded. Therefore,

Archaeopteryx was definitely bird.

However the presumed small sternum, the

primitive reptilian structure of wing bones, and

especially the long tail set Archaeopteryx apart from most modern

birds, requiring a separate subclass to represent it. However,

some reptilian structures of this fossil are shared by some

modern-day birds. For example, the juvenile stages of

Opisthocomus hoatzin of South America and Touraco cory thaix of

Africa possess claws, and both are flyers...

...More specifically, L. de Nouy, an evolutionist, commenting

on the status of Archaeopteryx has made a very succinct statement

concerning the establishment of "true links" between major groups.

While recognizing the morphological similarities of Archaeopteryx

to reptiles and birds, he nevertheless concluded:

"By link, we mean a necessary stage of transition

between classes such as Reptiles and Birds, or between

smaller groups. An animal displaying characters belonging to

two different groups can not be treated as a true link as

long as the intermediary stages have not been found, and as

long as the mechanism of transition remains unknown."