What is the most recent common ancestor of the zebra finch and the wallaby?
The correct answer and explanation is:
The most recent common ancestor (MRCA) of the zebra finch and the wallaby is a vertebrate that lived around 300 to 350 million years ago during the late Carboniferous to early Permian period. This ancestor would have been a small, early amniote, likely a reptile-like organism that gave rise to both the bird and the marsupial lineages.
Zebra finches (a type of bird) and wallabies (a type of marsupial) belong to different major groups in the animal kingdom. Birds are part of the class Aves, which evolved from theropod dinosaurs, while marsupials like wallabies are part of the class Mammalia. Despite the vast differences between these two species, they share a common evolutionary origin in the distant past, when amniotes first evolved.
Amniotes are a group of tetrapods (four-limbed vertebrates) that includes reptiles, birds, and mammals. The key evolutionary feature of amniotes is the development of an amniotic egg, which allowed them to reproduce on land without needing to return to water. This ancestor would have been one of the earliest vertebrates to adapt to terrestrial life, laying the groundwork for the evolutionary divergence of birds, mammals, and reptiles.
As the evolutionary tree branched, the ancestors of the zebra finch evolved into birds, while the ancestors of the wallaby evolved along the mammalian lineage. This common ancestor would have been a small, likely egg-laying creature that was among the first vertebrates to adapt to life on land, providing a crucial link between these two vastly different species.
In summary, the MRCA of the zebra finch and the wallaby lived about 300 to 350 million years ago and was an early amniote that set the stage for the later evolution of both birds and mammals.