You sound like a rational honest person. I appreciate that.
'Stephen Jay Gould is best known for the theory of punctuated equilibrium which proposes that evolution of species is not a slow, gradual process of change, but in fact consists of long periods of stability broken by shorter periods of rapid change.'
Source:
Stephen Jay Gould - Biography, Facts and Pictures
If you look at the unbolded part of the quote you provided, "
transitions between major groups are characteristically abrupt" you can see Gould's acknowledgement that transitions exist.
'Eldredge and Gould proposed that the degree of gradualism commonly attributed to
Charles Darwin[7] is virtually nonexistent in the fossil record, and that stasis dominates the history of most
fossil species.'
Source:
Punctuated equilibrium - Wikipedia.
In other words presumably Darwin was wrong about evolution being a steady gradual process, instead the process of change is relatively rapid in relatively short periods followed by longer periods of no or little change. But it is still evolution, and since Darwin is not some sort of infallible Prophet, disproving the minor details of his ideas does not disprove evolution in it's entirety, it simply means that our ideas about how evolution occurs had to be modified.
As a Paleontologist, Stephen Jay Gould knew beyond any doubt the fact that “a species does not arise gradually by the steady transformation of its ancestors; it appears all at once and 'fully formed” but as an evolutionist, he held the (false) prior that there is only one single unfalsifiable hypothesis on the table (gradual evolutionary transition). That is why he used the word transition to describe the observed abrupt characteristics in major groups because of that prior. Regardless, he knew that real world observations contradict that hypothesis, that’s why he dismissed the hypothesis of “slow and steady transformation” and proposed, “punctuated equilibrium”.
The problem is that “slow and steady transformation” is a fundamental principal of the ToE, that’s why critics referred to his theory of punctuated equilibrium as "evolution by jerks" and his supporters responded by referring to phyletic gradualism as “evolution by creeps”. There was never an agreement and after Gould’s passing, "slow and steady gradual transformation" returned to be the ruling dogma. Richard Dawkins didn’t agree with punctuated equilibrium and described it as a theory that was oversold by some journalists. See # 160
Regardless of real world observation in the fossil record that clearly disproves “slow and steady” but the ToE was back to square one after Gould’s passing. Gould summed it up when he honestly said, “The extreme rarity of transitional forms in the fossil record
persists as the trade secret of paleontology. The evolutionary trees that adorn our textbooks have data only at the tips and nodes of their branches; the rest is inference, however reasonable,
not the evidence of fossils.”
We discussed the same in earlier posts. Please see #145.
If those footprints are of the first four legged creature (your nature article notes that, "The find is not supported by fossil bones at the site, and palaeontologists familiar with the discovery say they have reservations about the tracks, because they may have been made by some natural process")
NewSientist wrote, ”Evidence that four-legged vertebrates walked on Earth some 10 million years earlier than previously believed could force a radical rethink of where they evolved, as well as when.”
“Our discovery suggests that the current scientific consensus is mistaken not only about when the first tetrapods evolved, but also about where they evolved,” says Grzegorz Niedźwiedzki
then no one (that I know of) is saying that Tiktaalik was a transtion between fish and the first four legged creature mentioned in your nature article.
Professor Neil Shubin found Tiktaalik fossil in 2004 and consider it as the very first fish ventured out onto land or first vertebrates animal on land.The discovery was published in the April 6, 2006, issue of Nature.
Nature wrote, “Here we report the discovery of a well-preserved species of fossil sarcopterygian fish from the Late Devonian of Arctic Canada that represents an intermediate between fish with fins and tetrapods with limbs, and provides unique insights into how and in what order important tetrapod characters arose.”
A Devonian tetrapod-like fish and the evolution of the tetrapod body plan | Nature
But is there any reason that Tiktaalik couldn't be representative of the transtition between between non-tetrapod vertebrates (fish) such as
Panderichthys, known from fossils 380 million years old, and early tetrapods such as
Acanthostega and
Ichthyostega, known from fossils about 365 million years old?
As I said in #422, a mix of characteristics between fish and tetrapods, is not necessarily conclusive evidence of a transitional form. Amphibians/semiaquatic animals that exist today typically have a mix of characteristics between fish and tetrapods, and go through metamorphosis as they transition from one stage to another of its life cycle. Tiktaalik can possibly be an extinct amphibian that died at a specific stage of its life cycle. Many explanations are possible, especially that Tiktaalik’s hind fin bone
was never found. You may hypothesize as you wish but its only theories with no conclusive evidence. Again, evidence suggest that four-legged vertebrates existed 18 million years before Tiktaalik.
The 375 mya Tiktaalik with a mix of characteristics can be an extinct amphibian/semiaquatic animal and to a great extent similar to China giant salamander which is an amphibian that exist today.