There are gaps between fish-amphibian (Talk.Origins)
- There are no transitional fossils between fish and tetrapods.
- Morris, Henry M., 1974. Scientific Creationism, Green Forest, AR: Master Books, pp. 82-83.
- Watchtower Bible and Tract Society, 1985. Life—How Did It Get Here? Brooklyn, NY, p. 72.
First of all, note that both of the cited sources predate all of Talk Origins' references, so at worst they are out of date.
Furthermore, the Watchtower Bible and Tract Society is not a good source of creation literature. At best, its authors show signs of poor scholarship.
(Talk.Origins quotes in blue)
1. There are several good transitional fossils:
Evolutionists see every animal and person as a transitional form, and they tend to interpret the fossil evidence from this standpoint. They often use remains that are so fragmented as to allow plenty of room for evolutionary assumptions. They sometimes ignore their own dating methods, placing "older" fossils after "younger" fossils to make the order agree with the theory. They may also ignore bigger differences that eliminate any possible trend.
- Reference: Transitional forms
a. Most fish have anterior and posterior external nostrils. In tetrapods, the posterior nostril is replaced by the choana, an internal nostril opening into the roof of the mouth. Kenichthys, a 395-million-year-old fossil from China, is exactly intermediate between the two, having nostrils at the margin of the upper jaw. [Zhu and Ahlberg 2004]
First of all, Kenichthys is based on one incomplete skull with no articulated bones, making it impossible to assemble an entire skull. The so-called internal nostril is what seems to be a notch between the premaxillary and maxillary. This notch could result from missing bone.
The lack of pictures or even illustrations of this incomplete skull makes an independent analysis impossible. Most articles on this fossil are so filled with evolutionary interpretations that they have no independently useful data. Also, the fossil is from China, where there is known to be a large fake fossil industry, and there is no indication that the authors personally found the fossil in the ground. If they bought it from a dealer, it could be a result of this fake fossil industry.
Even if they are right about the notch being an internal nostril, it is dated as 25-30 million years too old to be transitional between fish and amphibians. There are several types of lobe-finned fish that are considered ancestors to amphibians that are dated younger than Kenichthys but show no evidence of this internal nostril. This fact alone eliminates Kenichthys from being a transitional fossil between fish and amphibians.
- Reference:Article 15 — Nostrils
b. A fossil shows eight bony fingers in the front fin of a lobed fish, showing that fingers developed before land-going tetrapods [Daeschler and Shubin 1998].
It is known as Sauripterus. Its fins have eight finger-like digits, the same as the number on the feet of some amphibians. Sauripterus could not walk—the bones were too thin—and it is not even considered an ancestor to amphibians. So it is just a kind of fish with an unusual fin.
- Reference: Fins and Fingers in One Fishy Fossil
c. A Devonian humerus has features showing it belonged to an aquatic tetrapod which could push itself up with its forelimbs but could not move it limbs back and forth to walk [Shubin et al. 2004].
So both reptiles and mammals have totally aquatic kinds—so what? Maybe this is a totally aquatic kind of amphibian. It's hard to tell from just a vague reference to a humerus.
d. Acanthostega, a Devonian fossil, about 60 cm long, which probably lived in rivers [Coates 1996]. It had polydactyl limbs with no wrists or ankles [Coates and Clack 1990]. It was predominantly if not exclusively aquatic: it had fishlike internal gills [Coates and Clack 1991], and its limbs and spine could not support much weight. It also had a stapes and a lateral sensory system like fish.
Acanthostega seems to have been an almost totally aquatic amphibian. Both reptiles and mammals have totally aquatic kinds, so totally aquatic amphibians are possible as well. Furthermore, there is no evidence of a connection to fish; the fossil evidence is too fragmented. Also it is dated as contemporary with Ichthyostega, so there is no clear indication of what Acanthostega would be transitional from and to.
- Reference: Transitional forms
e. Ichthyostega, a probably amphibious tetrapod from Devonian streams, about 1.5 m long. It had seven digits on its rear legs (its hands are unknown). Its limbs and spine were more robust than those of Acanthostega, and its rib cage was massive. It had fish-like spines on its tail, but fewer and smaller than Acanthostega's. Its skull had several primitive fish-like features, but it probably did not have internal gills. [Murphy 2002]
- Ichthyostega was a largely aquatic amphibian that was capable of walking on land. This is known to occur in mammals such as seals. There are too many differences with Acanthostega to support evolution, in the absence of intermediate forms.
- Reference: Ichthyostega stensioei
- Reference: Ichthyostega: fossils
- Reference: Transitional forms
f. Tulerpeton, from estuarine deposits roughly the same age as Acanthostega and Ichthyostega, had 6 digits on its front limbs and seven on its rear limbs. Its shoulders were more robust than Acanthostega, suggesting it was somewhat less aquatic, and its skull appears to be closer to later Carboniferous amphibians than to Acanthostega or Ichthyostega.
Tulerpeton is based on fragmented fossil remains. The pectoral girdle is nearly complete, as are one fore and hind limb. The skull and pelvis are fragmented. The fossil also included some small belly scutes. It is claimed that Tulerpeton was less aquatic and that its skull is more like Carboniferous amphibians than those of Acanthostega and Ichthyostega. However, they are dated as roughly contemporary with Acanthostega and Ichthyostega, thus eliminating Tulerpeton as transitional between Acanthostega and Ichthyostega, and Carboniferous amphibians.
- Reference: Tulerpeton curtum
So of these "good transitional fossils," one is dated as tens of millions of years too old; one is not considered ancestral to amphibians; one is known only from a humerus; three are dated as contemporary with each other with no transitions indicated between them or fish. So the claim stands, there are no transitional fossils between fish and tetrapods.
However, since evolutionists do claim these fossils are transitional, based on their presupposition of evolution, it should be updated to read "There are no real transitional fossils between fish and tetrapods."