Limb loss in snakes and whales also demonstrates the importance of paedomorphosis in the evolution of morphological novelties.
Having said that, however, it may be that peramorphic changes very early in development, such as an earlier onset of growth of specific morphological traits, might play as significant a role in the formation of morphological novelties as paedomorphic delays.
In addition, mating preferences in zebra finches are substantially influenced by early learning about visual characteristics [48], including morphological novelties [49] [51].
Morphological novelties also seem to be lacking in some of the other miniaturized, but hardly developmentally truncated, cyprinids, like Horadandia, Sawbwa, Microrasbora, and ' Danio' erythromicron.
These morphological novelties are mainly reflected in the size and shape of the upper lip.
Morphological novelties abound in the history of animal evolution but increase of complexity and acquisition of novelties are not homogeneously distributed across the phylogenetic tree of life.
The rasborine clade A is not only an ideal group to study the evolution of miniaturization among vertebrates, but also to investigate the evolution of morphological novelties.
While those miniature cyprinids that hardly show any developmental truncation generally lack morphological novelties, they are common in miniature, developmentally truncated cyprinids.
The genetic basis underlying these morphological novelties is not fully understood, but increasing sequence data is providing clues to these questions.
The characterization of the molecular changes that underlie the origin and diversification of morphological novelties is a key challenge in evolutionary developmental biology.
