The phylogenetic tree / the evolution of animals


The order of things

Since the middle of the 18th century, scientists had described the variety of the animals, plants and unicellular organisms and had arranged them according to similarities, so that a system of graded similarities developed. It has the purpose to name the objects and to be able to communicate about them. It fulfills its purpose in spite of a considerable subjectivity about what one perceives as similar.  It results in shifting the systamatic order and in changing of names, often perceived as annoying. Within the limits of describing morphology and ordering systematics, the procedure is flawless in terms of scientific theory.

Haeckel – The reinterpretation of being and becoming

After Darwin’s book (1859) the question arose for scientists how they should explain the emergence of the variety of living beings by Darwin’s theory of descent. The solution appeared obvious by using what already existed, namely the system already established. This system must, so the conviction, reflect the course of evolution. Moreover, in the common thinking in progress and higher development, the simple creatures had to be regarded as the original ones and the more complexly built animals as the higher developed ones, and they must have emerged from the simpler ones. Ernst Haeckel, who stands for the Darwinism reception in the public like no other, spread with word and writing and excellent illustrations also this thinking.

If there is a lineage of animal species, it can be visualized in the form of the well-known family trees, and only a few years after Darwin’s book, Haeckel drew in his Anthropogenie (1874) the first phylogenetic tree of the animal kingdom, in which he also included man. All following phylogenetic tree drafts are based on the same working method.

One had reinterpreted a similarity order to the result of the course of evolution, –  untenable in the view of theory of science and an error running on long time.

Hennig – The formalization of the error

All of the following phylogenetic trees are based on the same working concept. It was formalized as Phylogenetic Systematics (Hennig 1950) and dominates the main stream of research today. It is thought to be evolutionary research, but is in reality not more than traditional systematics as introduced by Linnaeus in the 18th century and by Lamarck at the beginning of the 19th century as a hierarchical system and continued by today’s systematists. However, the experienced systematists know very well how subjectively such a system comes about and they refuse to interpret it as evolutionary process.  Phylogenetic systematics is „old wine in new bottles“ whose label is „phylogenetic“. In fact, the old mistake of Erst Haeckel is continued.

Break with Tradition

The course of evolutioncannot be explained by pointing out similarities. Like any historical process, it can only be determined by reconstruction.

With this principle, which is a matter of course in the historical sciences, Wolfgang F. Gutmann and some other scientists, most of them at the Senckenberg Research Institute, had reconstructed the main evolutionary lines and the body design of the primordial animal, from which all lines started.  The results could be summarized for the first time in 1992/93 as a poster-graph.

However, the new view met with rejection and found only little recognition, – it deviated too far from the traditional phylogenetic trees, and from the old method of comparative morphology by which they had been developed. The field remained with the Idealistic Morphology and – especially internationally – with Phylogenetic Systematics. The question of anagenesis, of transformation, was and is so far out of sight that work on it has been labeled „outside-science“ (see also chapter „On the History of the Frankfurt Theory“).

Modern time

Molecular genetic investigations of the different construction types of the Bilateria (bilaterally right/left symmetrical animals) brought a result, which was felt as revolutionary: the Ur-Bilaterian must have been metamerically segmened. As New Animal Phylogeny (Adoutte et. al. 1999, 2000, 2003) the result soon entered the textbooks of zoology. The New Animal Phylogeny overturned the traditional phylogenetic trees that had been established by the old method of Comparative Morphology

The compliance with the results of the Frankfurt research is striking as far as the evolutionary lines within the Bilateria are concerned. In addition, the Frankfurt research has additionally clarified the origin of the ur-bilaterian and the five non-bilateria – called the Deep Animal Phylogeny. In contrast, the results of molecular research on Deep Animal Phylogeny – twenty years after the success of the New Animal Phylogeny, (which is basically a New Bilateria Phylogeny), are still uncertain and in flux. The reason for this appears as a consequence of the from the method applied:

Molecular research works on the basis of Phylogenetic Systematics, which seeks dichotomous branchings, „sister groups“. However, according to the Frankfurt reconstructions, the six main evolutionary lines of the animal kingdom are independently descended from a single primordial body design. Accordingly, there are no sister groups among the six lineages of the Deep Animal Phylogeny.

The zoological results of the Frankfurt Organismic Theory: The Gallertoid-Hydroskeleton-Hypothesis

The primordial animal body construction of cells and gelatinous collagen fibers, called Gallertoid, arose by internal compartmentalization of a multinucleate cilia-bearing protozoan. From this basic type of animal body design, the six main evolutionary lines of the animal kingdom started: and we can show the gradual transformation of their body design.

Among the phylogenetic lineages of non-bilaterian animals, Trichoplax stands as a descendant of an early evolutionary stage of gallertoid development; the jellyfishes (Ctenophora) are the giants among the gallertoids; the sponges (Porifera) and the octocorals are still close to the sessile gallertoids permeated by canals, the other Coelenterata (Medusozoa and Anthozoa other than Octocorallia) are more evolved body designs, and the two types of Acoela are „bilaterian non-bilateria“.

The ur-bilaterian originated as a primordial coelomate with coeloms arranged bilaterally next to the intestinal tract. Two lineages separated early on, and their original names have been reinstated here. The Gastroneualia (main nerve cord is ventral – gaster-venter) (= so-called Protostomia) with the evolutionary lineages of Chaetognatha, Ecdysozoa, Annelida, Platyhelminthes, and Mollusca.

The second main line of the Bilateria are the Notoneuralia (=Deuterostomia), their main nerve cord runs dorsally (notos – back, dorsum) with the three lineages of Ambulacraria, the fossil Conodonta, and Chordata.

All figured in the graphic design and comprehensively described in the booklet “The Evolution of Animals” (Grasshoff 2021), English edition. Schweizerbart, Stuttgart.

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