Teeth evolved early in vertebrate evolution, and their morphology reflects important
specializations in diet and ecology among species. The toothless jaws (edentulism) in extant …

Several recent studies conclude that exceptions to Dollo's law are more common than used
to be thought. If the claims are true this would change our view on the role of developmental …

Determining the direction of past transitions between adaptive traits is one of the major
objectives of evolutionary biology. Insights can be gained from phylogenies, but violation of …

Stomata are key innovations for the diversification of land plants. They consist of two
differentiated epidermal cells or guard cells and a pore between that leads to an internal …

The evolution of snakes involved dramatic modifications to the ancestral lizard body plan.
Limb loss and elongation of the trunk are hallmarks of snakes, although convergent …

Gene degeneration or loss can significantly contribute to phenotypic diversification, but may
generate genetic constraints on future evolutionary trajectories, potentially restricting …

Abstract Classification of the Class Echinoidea is under significant revision in light of
emerging molecular phylogenetic evidence. In particular, the sister-group relationships …

Evolutionary simplification, or loss of complex characters, is a major theme in studies of body‐
form evolution. The apparently infrequent evolutionary reacquisition of complex characters …

Dollo's law of irreversibility states that once a complex structure is lost, it cannot be regained
in the same form. Several putative exceptions to Dollo's law have been identified using …

Numerous cases of evolutionary trait loss and regain have been reported over the years.
Here, we argue that such reverse evolution can also become apparent when trait expression …