But all living species are highly derived, being shaped by natural and sexual selection on evolutionary timescales to maintain adaptation to varying ecological niches.
The human CNS follows a pattern of development typical of all mammals, but certain neurodevelopmental features are highly derived.
Saurischians are known from specimens ranging from the Late Triassic to the present day, because, as will be seen, birds are highly derived saurischian dinosaurs.
A frequent criticism of the study of key model organisms such as fruit flies, mice and nematode worms is that these species are highly derived — that is, they contain many traits unique to them — and thus are unlike any distant ancestor.
The modified plastid genome architecture is a novel apomorphy that indicates that the Helicosporidia are highly derived green algae, more so than Prototheca spp. As such, they represent a promising model to study organellar genome reorganizations in parasitic protists.
Beardworms (pogonophorans) and spoonworms (echiurans) were previously separate phyla, but are now known to be highly derived Annelids (Lecointre and Guyader 2006).
One of the most surprising and near unbelievable developments is the finding that acanthocephalans, which have long been considered a separate phylum, may in fact be highly derived rotifers (Lecointre and Guyader 2006)!
The condition of the arteries in the head is highly derived.
The Tetraodontidae, known as pufferfishes, are highly derived euteleosts.
Zebrafish fin morphology is highly derived relative to other actinopterygians, sarcopterygians and chondrichthyans.
