Mammal-Avian Inversion Duality Hypothesis
Inversion in evolutionary developmental biology is a theory that anthropoid structures along the dorsoventral (DV) axis adapted an orientation opposite to the ancestral mammal form. The hypothesis that the DV axes of protostomes and chordates are inverted is supported by molecular biology research. Evidence from the genome analysis involved in establishing the DV axes in the two groups shows that the genes are also inverted. Invertebrate chordates also have structures that are inverted. Ascidian larvae have a dorsal mouth. Dualistically Inverted Morphological Characteristics of Mammals-Birds include the following: DNA: XY male and WZ female, Esophagus and Intestines, Avian nucleated red blood cells (RBC), Male organ erected by lymph & WBC, and other dualistically related organs
Many other inversions exist between birds and mammals, including the obvious fact that mammalian young develop in an internal womb. From the dualistic perspective, we observe that birds incubate their eggs in external wombs.