It’s not hypothetical, it’s confirmed by paleontologist. See #352.
Incompleteness is not the word paleontologist use. The correct description of the fossil record is “no support for gradual change”.
Stephen Jay Gould said “The fossil record with its abrupt transitions
OFFERS NO SUPPORT FOR GRADUAL CHANGE.
All paleontologists know that the fossil record contains precious little in the way of intermediate forms; transitions between major groups are characteristically abrupt." (Natural History, pp. 22, 24.)
The 375 mya Tiktaalik cannot be the missing transitional form between fish and the first four-legged creature because the 395 mya footprints of four-legged creatures found in poland (18 million years older than Tiktaalik) disproves Tiktaalik as the transitional link.
2010, Nature wrote “Some prints, showing individual digits, were found in limestone slabs unearthed in a quarry near Zachełmie, Poland, dated to about 395 million years ago — more than 18 million years before tetrapods were thought to have evolved.”
Discovery pushes back date of first four-legged animal - Nature
2010, NewSientist.
Oldest footprints of a four-legged vertebrate discovered | New Scientist
What is Tiktaalik?
Tiktaalik is a fossil of an animal with features like fish and four-legged vertebrates. It has crocodile-like flathead with a neck that allows the head to move independently from the body, scales on its back like a fish, ribcage that suggest lungs, some sort of fins which believed to provide some support to the body on land. But as stated in an article by the gardian “The scientists have yet to find a Tiktaalik hind fin bone”.
Tiktaalik fossils reveal how fish evolved into four-legged land animals | Fossils | The Guardian
So what is the big deal about Tiktaalik?
Tiktaalik has a mix of characteristics that appears to give it the ability of alternating between aquatic and terrestrial habitats and was considered as the missing link between fish and tetrapods.
Amphibians/semiaquatic animals (such as newts and Axolotl) are present species with a mix of characteristics between fish and tetrapods. They can breathe with both gills and lungs and alternate between aquatic and terrestrial habitats. They are no missing link.
When most amphibians are young, they live in water, and they use gills to breathe in the water. When they become adults, they go through a process called metamorphosis, in which it experiences a number of physiological changes that help the species adapt to life on land. They lose their gills, their lungs gets developed, muscle tone in limbs gets increased, eyelids developed, the skin's permeability to water gets reduced, etc. all of that happen during the transition to adulthood not gradually through random mutations and natural selection in millions of years. No speciation, No transitional forms. No missing links. The offspring of an amphibian just continue to repeat the same life cycle. The mix of characteristics of the 375 mya Tiktaalik simply suggest an extinct amphibian.
Mixed characteristics of an amphibian specially if it dies at a specific age can be interpreted as a transitional form between fish and tetrapods but it’s simply nothing but an amphibian in a certain stage of its live.
The mix of characteristics of the 375 mya Tiktaalik as an aquatic animal with lungs, independently moving head and potentially four limbs, suggest an extinct amphibian similar to the present example of Axolotl (amphibian), which breathes with gills (external) and also has functional lungs. See Axolotl in the link below.
Tiktaalik flathead with eyes on top could be an extinct bottom-dwelling species similar to the Crocodilefish and it also bears a strong resemblance to the Gar fish (Alligator Gar) that also exist today. But if Tiktaalik did have lungs and possibly some sort of four limbs, with the ability to live both on land and under water then it’s as close as it can be to some present amphibians such as the South China giant salamander which is just an amphibian, not a missing link.
Giant Chinese Salamander can reach 1.8 meters and weigh around 64 kilos and is an endemic species of the streams of the forested and mountainous areas of eastern China. : NatureIs****ingLit (reddit.com)
Many explanations are possible but regardless; evidence has already proven that four-legged creatures existed 18 MILLION years before Tiktaalik. Tiktaalik is not the transitional form between fish and the four-legged creature, Tiktaalik is an extinct amphibian/semiaquatic animal. It’s an example of how a false prior leads to a false interpretation of observations.
The theory entails the existence enormous number of transitional fossils, if hardly any is found and with major problems, it discredits the theory.
It didn’t other than inaccurate interpretations of few questionable fossils in light of a one unfalsifiable hypothesis. The fact is organisms do appear fully formed (without intermediates) in the fossil record.
Stephen J. Gould said “Sudden appearance. In any local area, a species
DOES NOT ARISE GRADUALLY BY THE STEADY TRANSFORMATION of its ancestors; it
APPEARS ALL AT ONCE AND 'FULLY FORMED.'"
See#352
Darwin himself acknowledges the lack of intermediates as the most obvious and serious objection to his hypothesis of gradual transformation. Paleontologists confirmed that the fossil record doesn’t support “gradual steady transformation”.
Darwin stated in his book the Origin of Species “But just in proportion as this process of extermination has acted on an enormous scale,
SO MUST THE NUMBER OF INTERMEDIATE VARIETIES, WHICH HAVE FORMERLY EXISTED, BE TRULY ENORMOUS. Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is
THE MOST OBVIOUS AND SERIOUS OBJECTION WHICH CAN BE URGED AGAINST THE THEORY.”