October 30, 2019 | Jerry Bergman

Did Evolving Fish Cry “Land Ho!” and Walk onto Land?

 

New Study Does Little to Solve How Sea Creatures Could Have Evolved into Land Creatures

by Jerry Bergman, PhD

In the world of animals, a great chasm exists between aquatic and terrestrial creatures. Consequently, to imagine the changes required to go from a body designed for breathing and navigating in water to one enabling an animal to breathe air and move on land is regarded by Darwinists as one of the most profound evolutionary transitions that ever occurred.[1] Not only is the origin of the limbs a major issue, but the transition from fins to limbs “is one of the critical events in the history of vertebrates.”[2] Specifically, evolutionary theory requires evidence of the transition from lobe-finned fish to tetrapod life forms. Evolutionists assume this transition occurred about 400 million Darwin years ago in the Devonian Period. No evidence exists to fill in this major gap, but a new study titled “Early tetrapods had an eye on the land” hints at some progress.[3] How promising are these new findings?

Terminology Ground Rules

In the area of fish-to-tetrapod evolution, terminology is a problem, thus must be discussed. Tetrapod means “four feet” and includes all species that have four feet. Humans are called tetrapods by some, but because we walk on two legs, we are correctly called bipeds. Some evolutionists also include as tetrapods animals that don’t have four feet because they believe all land animals, living and extinct, were descended from the last common ancestor of tetrapods. Examples include the snake, even though it has no limbs, because evolutionists commonly claim it once had limbs, therefore is a tetrapod. No evidence exists to support this idea.[4] Also, the extinct swimming reptile called an ichthyosaur is called a tetrapod, even though it did not use its limbs to walk on land, because its ancestors are believed by evolutionists to have been tetrapods. Birds, too, are called tetrapods even though they walk on two legs, because they are believed to have evolved from tetrapod dinosaurs. The University of California website titled “Evolution” claims that all “animals are tetrapods because they descend from the tetrapod ancestor … even if they have secondarily lost their ‘four feet.'”[5] When used this way, the term “tetrapod” becomes not only confusing but meaningless. It violates the taxonomic rules of creationist Carolus Linnaeus, the father of taxonomy. This definition of tetrapod—even from an evolutionary framework—is meaningless if carried back far enough. It’s not unlike calling primates “bipedal” even if they walk on all fours or knuckle-walk, because of the assumption they evolved into bipedal humans.

To be consistent, we will use the term tetrapods to refer only to animals that actually walk on four feet, and not on animals whose ancestors were assumed to once having walked on four feet, or animals believed in the past to have evolved into tetrapods from fish.

Why Would a Marine Animal Evolve into a Land Animal?

Theories about why fish evolved into land animals include the ‘drying pond’ hypothesis. This was proposed to explain “selection pressures” behind the transition. Fish with traits that helped them to survive the set of new conditions caused by their habitat drying out drove the survivors to became progressively better adapted to terrestrial conditions during prolonged episodes of drought. As we will show, this just-so-story lacks both anatomical as well as fossil evidence.

The Problem of Tetrapod Evolution

Little evidence supports the notion that some transitional marine animal moved to live on dry land, as evolution predicts. Living in a gravity-neutral aqueous environment and moving to a terrestrial environment requires the invention of very strong legs, strong enough to support the animal’s entire weight. A transitional form, even with partly evolved legs, could not have held its midsection off the ground until its limbs eventually evolved long and strong enough to support its weight. Thus, until this evolution was complete, one should expect to find evidence that they dragged their bellies on the ground. One study of all known trackways by the leading authority of the fish-to-tetrapod transition theory, Professor Jennifer Clack, does not provide any evidence that they dragged their bellies on the ground.[6]

Clack also admitted, “The question of where tetrapods evolved is even more difficult to answer than that of when.”[7]  And Michael Denton noted after a full century and a half of research, “. . . the gap between the tetrapod limb and the fin remains.”[8] In a paper in Nature, Fröbisch and Witzmann admit that the

scientific investigations into how vertebrates transitioned from water to land is like reading a good crime novel. We have a range of suspects, patchy evidence and a lot of unanswered questions. And to complicate matters, this transition from finned fish to four-limbed creatures (tetrapods) is a ‘cold case’ from nearly 400 million years ago.[9]

Tetrapod fossil finds from the Devonian period have markedly increased recently. Still, however, the “fossil record consists mostly of tantalizing fragments.”[10] Fröbisch and Witzmann commented on the most recent attempts by announcing confidently, “Early tetrapods had an eye on the land: Fossil finds that can provide clues about how aquatic vertebrates evolved into land dwellers are elusive. But the ancient bones of a newly discovered species of tetrapod now provide some crucial missing evidence.”

Specifically, the new fossil announced in Nature by Beznosov et al. contains the “lower jaw, pectoral girdle, external dermal bone pattern of the snout region,” they say, adding their interpretation: “the absence of gular plates and the relative size of the orbits are all tetrapod-like.” But then, assuming that these other parts belong to the same creature, they go on to say they are not typical of a tetrapod. Why are they intent on drawing a connection between these non-typical tetrapod parts to insist that the creature is transitional between lobe-finned fishes and tetrapods? Ockham‘s Razor (i.e., “the simplest answer is to be preferred”) would advise calling it another tetrapod variety. Variations on a theme are common in the living world. Given the degraded condition of the bone fragments, other interpretations are also possible. They do not even consider their specimen, called Parmastega, to be a transitional form:

Parmastega gives us the earliest detailed glimpse of a tetrapod: an aquatic, surface-skimming predator, just over a metre in length, living in a lagoon on a tropical coastal plain. Parmastega is phylogenetically the least-crownward of all of the non-fragmentary tetrapods, but it is not necessarily representative of the primitive conditions for the group. The slightly earlier Elginerpeton—which was also probably aquatic and was even larger than Parmastega (Extended Data Fig. 4)—had well-ossified girdles and limb bones, as well as a distinctive head shape with a narrow snout. Moreover, the trackway record shows that tetrapods originated at least 20 million years before Parmastega, and the very existence of the trackways—which implies weight-bearing limbs, even if the prints were made in water—points to these forms having well-ossified postcranial skeletons. Together with the evidence for considerable morphological homoplasy among Devonian tetrapods, this hints at a tangled and still-unknown early history for limbed vertebrates.

The new analysis of one example of a Devonian era tetrapod fossil collected in 1947 consists only of  both lower jaws, partial palate, premaxillae and maxillae, with a natural mold of parts of the shoulder girdle.[11] The authors describe it as “numerous isolated bones and some articulated skull regions.” But as far as can be determined from the fossil fragments found, the creature is a tetrapod, not a fish trying to evolve into a tetrapod. The fragments clearly are from tetrapods.[12] As the authors admit, all of those fragments indicate that “tetrapods had been in existence for about 30 million years.” [13] No clear evidence exists that they were marine animals evolving into tetrapods. The inference is indirect, based on evolutionary assumptions.

Sign at Wyoming Dinosaur Center debunking earlier ideas about tetrapod evolution, before claiming Tiktaalik a “fish-a-pod” candidate. Photo by David Coppedge.

 

The new fossil remains analyzed by Beznosov et al., reviewed by Fröbisch and Witzmann, include 183 skeletal fragments which the researchers grouped together to comprise what they estimate were 132 individual animals collected during excavations from 2002 to 2012. An examination of the fragments shown in Nature illustrates the problem of assembling these pieces correctly. I fail to see any indications these fragments link marine sea creatures and tetrapods. The only thing the evolutionists relied on was that a number of limb bones give evidence of being weight-bearing. Bones that would show clear evidence of transitions from fish to tetrapods were not in evidence. As the article’s authors admits, “The known diversity of tetrapods of the Devonian period has increased markedly in recent decades, but their fossil record consists mostly of tantalizing fragments.”[14]

Many Radical Changes Required to Evolve From a Fish to a Land Animal

Evolving an aquatic animal into a tetrapod is, they confess, a chasm because of scores of radical changes that would be required. The transition from an aquatic, lobe-finned fish to an air-breathing amphibian had to be a major, fundamental event in the evolutionary history of the vertebrates. It would have required numerous adaptations within the overall body plan, both in form and in function. Consider just a few:

  1. Modification of the vertebral column to a thicker, stronger backbone to prevent the body from sagging under its own weight.
  2. Strong, sturdy limbs that could support and transport its body while out of water.
  3. Limbs with arms, and hands with digits (now standardized at five).
  4. A delicate integumentary system, modified from one designed to live in water. On land, it would be prone to desiccation, so it would need mechanisms to mitigate dehydration.
  5. A middle ear to connect to the piscine inner ear, allowing amplification of sound transmitted in air instead of water.
  6. Jaw bones reconstructed for herbivorous and carnivorous diets on land.

Summary

Fröbisch and Witzmann describe the Beznosov paper as a very partial, tentative story.

The P. aelidae fossils offer a treasure trove of information that could help to disentangle some of the complex evolutionary changes that took place when vertebrates made the transition from aquatic to terrestrial life. This discovery also reminds us that much still remains to be learnt in the next gripping chapter of this detective story.[15]

The existence of a “next gripping chapter of this detective story” is based on their firm belief that the evolutionary transition from aquatic to terrestrial life occurred. That’s why they believe more evidence will be uncovered if they just keep looking. In reality, the P. aelidae fossils do little to disentangle the “complex evolutionary changes that [supposedly] took place when vertebrates made the transition from aquatic to terrestrial life.”[16]


References

[1] Long JA, Gordon MS 2004. “The greatest step in vertebrate history: a paleobiological review of the fish-tetrapod transition”. Physiology Biochemical Zoology. 77 (5): 700–19.

[2] Joyce Pieretti, Andrew R. Gehrke, Igor Schneider, Noritaka Adachi, Tetsuya Nakamura, and Neil H. Shubin. 2015. Organogenesis in deep time: A problem in genomics, development, and paleontology. PNAS , 112 (16) 4871-4876. April 21.

[3] Nadia B. Fröbisch and Florian Witzmann, 2019. “Early tetrapods had an eye on the land.” Nature. 574 October 24. P. 494.

[4] Jerry Bergman 2009. “Evidence for the Lack of Snake Evolution.” CRSQ. 45(4): 258-268, Spring.

[5] The origin of tetrapods. https://evolution.berkeley.edu/evolibrary/article/evograms_04

[6] Clack, Jennifer A. 1997. “Devonian tetrapod trackways and trackmakers; a review of the fossils and footprints.” Paleogeography, Palaeoclimatology, Paleoecology. 130 (1–4): 227–250.

[7] Clack, Jennifer. 2012. Gaining Ground: the origin and evolution of the tetrapods, 2nd  edition. Indiana U Press, p. 128.

[8] Denton, Michael. 2016. Evolution: Still a theory in crisis. Seattle, WA: Discovery Institute Press, p. 159.

[9] Nadia B. Fröbisch and Florian Witzmann, 2019. “Early tetrapods had an eye on the land.” Nature. 574 October 24. P. 494.

[10] Pavel A. Beznosov, Jennifer A. Clack, Ervīns Lukševičs, Marcello Ruta & Per Erik Ahlberg. 2019. Morphology of the earliest reconstructable tetrapod Parmastega aelidae. Nature 574: 527–531. October 31

[11] Clack, J. A., Ahlberg, P. E., Blom, H. & Finney, S. M. 2012. A new genus of Devonian tetrapod from North-East Greenland, with new information on the lower jaw of IchthyostegaPaleontology 55(1): 73–86.

[12] Ibid.

[13] Ibid.

[14] Beznosov et al., page 530.

[15] Fröbisch & Witzmann. 2019.

[16] Ibid.


Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology at several colleges and universities including for over 40 years at Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored, are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.

(Visited 255 times, 1 visits today)

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.