A marked optical notch in some later thylacocephalans may be a derived feature, yet shield structures are highly likely to be convergent, and the plesiomorphic condition is difficult to infer.
However, the starting topography for DC is unusual in Drosophila, as the amnioserosa is a secondarily derived structure that never covers the embryo proper (Schmidt-Ott, 2000).
Interestingly, in red algae, which are close relatives to the green plants (Figure S1), the presence of an actin contractile ring and furrowing have been reported [29], suggesting that the plant phragmoplast is a very derived structure.
The pancreas is an endoderm derived structure that produces precursors of digestive enzymes and blood glucose regulating enzymes.
Should this turn out to be the case it would be rather interesting since it would be a case where one derived structure theory from an inconsistency without awareness of the inconsistency.
But they are derived structures that are universal enough in the Archaea to provide compelling independent arguments that exclude the root of the TOL from within the Archaea.
CFA is indeed useful for evaluating a theoretically derived structure.
Whilst the bundle of GT 1a is based on a fully computational derived structure, the bundle of GT 5a is based on NMR spectroscopic data.
The midbody is a structure derived from the spindle midzone that contains proteins indispensable for cytokinesis [78].
