Table of Contents
Why is Reptilia not a monophyletic group?
Reptiles (such as crocodiles, lizards, snakes, and turtles) are not monophyletic, because the group does not include birds, which are also descendants of the most recent common ancestor of crocodiles,lizards, snakes, and turtles.
What is an example of a paraphyletic group?
The ancestral species of this group is thus also the ancestor of one or more other groups. The perhaps most compelling example for a paraphyletic group are the Reptilia (turtles, tuataras, lizards and snakes, crocodiles plus dinosaur-like reptiles), the lineage which also gave rise to the birds.
What is an example of a polyphyletic group?
Polyphyletic groups are formed when two lineages convergently evolve similar character states. An example of a polyphyletic group is bats and birds: both have wings, but they have evolved separately.
Why is the class Reptilia considered paraphyletic?
The class Reptilia, as traditionally defined, is paraphyletic because it excludes birds (class Aves) and mammals. Alternatively, reptiles are paraphyletic because they gave rise to (only) birds. Birds and reptiles together make Sauropsids, a clade of Amniota that is the sister group of the clade that includes mammals.
Why the class Reptilia is not a valid taxon unless the birds are included?
Linnaean class Reptilia is not a clade because it does not include modern birds. Because it leaves this descendant group out, the class is paraphyletic. Cladistic analysis shows that many traditional taxonomic groups do form valid clades.
Why is class Reptilia not a clade?
The traditional group Reptilia – things like lizards, crocodiles, snakes, tortoises plus many extinct groups – is not a true clade, because the common ancestor of all those animals also gave rise, at different points, to mammals and birds.
What is a monophyletic taxon?
Loosely, a monophyletic taxon is one that includes a group of organisms descended from a single ancestor , whereas a polyphyletic taxon is composed of unrelated organisms descended from more than one ancestor.
What is a monophyletic group example?
An example of a monophyletic group is one that is comprised of humans, apes, and new world monkeys, as they share the most common recent ancestral group, which is the old-world monkeys.
What are polyphyletic groups?
A polyphyletic group or assemblage is a set of organisms, or other evolving elements, that have been grouped together based on characteristics that do not imply that they share a common ancestor that is not also the common ancestor of many other taxa (of course, if “life” is monophyletic, then any set of organisms …
What does a polyphyletic group contain?
What is Paraphyly with example?
Like for example in class Reptilia as conventionally delineate, are paraphyletic since it excludes the two groups of its descendants, the class Aves and class Mammalia wherein birds are descended from dinosaurs of which classified as reptiles and mammals from mammal-like reptiles. …
What is monophyletic taxon?
In modern usage, a monophyletic taxon is defined as one that includes the most recent common ancestor of a group of organisms, and all of its descendents [as in (a)].