Vertebrate brain theory

2 Vertebrates and their classification

2.1. Basic characteristics of vertebrates

Vertebrates belong to the Chordata strain. They have a bilateral physique and are therefore also called Bilateria. Gerhard Roth, an internationally renowned evolutionary biologist and neuroscientist, considers the possibility that "there could be a common blueprint for a three-part brain for all bilaterias and their nervous systems or brains" (Gerhard Roth, "Wie einzigartig ist der Mensch", [48], page 147). According to Roth, the evidence for this is derived from the examination of developmental genes that determine the building plan of the body and the brain.

Hildebrand and Goslow describe in the work "Comparative and functional anatomy of vertebrates" [11] on page 28 the vertebrates as a substrain of the Chordata strain and give the following common characteristics (non-literal, abbreviated quotation):

• All chordatas have, at least in their early development, a chorda dorsalis. This is a supporting rod that usually originates from the dorsal wall of the archenteron. The vertebral column of vertebrates is a derivative of the chorda dorsalis.
• A second chordata feature is the dorsal hollow spinal cord (neural tube), which is formed by neurulation from the ectoderm.
• A third characteristic is the presence of a gill gut at least during early embryonic stages, but mostly also in adults.
• Another chordata feature is the closed blood vessel system with a ventrally located heart.
• The choral data tend to concentrate their main sensory organs in one head, which is called cephalisation. This is accompanied by bilateral symmetry and mobility.
• Chordata (with the exception of the urochordata) have a poststanal tail.
• Chordata (with the exception of urochordata) show metamerism or segmentation of certain body parts.

The vertebrates belong to the Chordata strain because they have a spinal column, a spinal cord, gills at the embryonic stage, a closed blood circulation with a ventrally located heart, a segmented body, a poststanal tail and a skull. In the latter, their main sensory organs are concentrated.

According to Roth, the chordatiere (chordata) comprise the following groups

• the tunicates (Urochordata)
• the skullless (cephalochordata)
• the cranial animals (craniata).

The group of craniatesincludes

• the hagfish (Myxinoidea)
• the vertebrates (vertebrata).

The animals of these groups have a head or skull (cranium). This contains the brain.

The vertebrates (Vertebrata) consist of

• the class of lampreys (Petromyzontida)
• of the large class of pine-bearing trees (Gnathostomata).

The pine-bearing (Gnathostomata) are divided according to Roth into

• the class of cartilaginous fish (Chondrichthyes)
• the class of bony fish (Osteichthyes)
• the amphibians (Amphibia)
• the mammals (mammalia)
• the Sauropsids, divided into reptiles (Reptilia) and birds (Aves).

Monograph of Dr. rer. nat. Andreas Heinrich Malczan

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