DURATION: ~500 million years before present
KEY ATTRIBUTE: Movement
KEY SPECIATION: Reptile / Vertebrate
KEY TISSUE TYPE: Mesoderm
KEY SENSE: Vision / Visual Processing
KEY HUMAN MOVEMENT DYNAMIC: Heterolateral
Animals are organisms which move. Movement is perhaps the single largest evolutionary leap, and required the development of specialized tissues for both movement (muscle tissue/Mesoderm) and tissues to figure out the how/where/why of action (nerve tissue/Ectoderm). These tissues overlay and are supported by the core endoderm, and in turn support the endoderm by enabling access to nutrients and opportunities to reproduce. Originally movement was extension and contraction(e.g.: how a snail moves), but rather quickly developed into free swimming movement, which can be considered movement along a line. Jellies are an example of early experiments in movement. Fish, amphibians and reptiles are much more advanced vertebrates that continue to operate within this constraint of linear movement.
More advanced (plane+) animals developed the basic format of movement with much more complex neurological and sensory mechanisms to “make sense” and to take advantage of their surroundings, and therefore animals dominated by foundational movement along the line dimension are considered here as primarily musculoskeletal.