Directed Evolution

Commentary on Wolfgang Schad's Archäopteryx lithographica – eine Mosaikform?
Elemente der Naturwissenschaft 100, 2014, P. 59-61 | DOI: 10.18756/edn.100.59


With the publication of the anatomical details of the prehistoric bird Archae- opteryx Wolfgang Schad laid in 1980 the foundations of work that eventually led to his dissertation on the transitional forms of the vertebrate groups. Other researchers had earlier noticed that, in these transitional forms, whereas the axial skeleton of head, vertebral column and trunk points to the ancestors, the limb skeleton points to the future of further evolution – just like in heterochrony which describes differential and distinguishable onsets of developmental impulses and their speeds. What was new in Schad’s work was his successful attempt to describe the ‘anomalies’ as resulting from the organism itself which integrates the past, present and future into a harmonic whole.

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