What is a Cladogram?
A cladogram is a type of diagram that shows hypothetical relationships between groups of organisms based on their shared common characteristics. These characteristics are called synapomorphies and can be morphological, such as having fur or feathers, or molecular, such as having a certain DNA sequence or proteie. A cladogram resembles a tree with branches that indicate related groups and their common ancestors. The points where the branches intersect are called nodes and represent the hypothetical ancestors. A cladogram can be used to infer the evolutionary history and phylogeny of organisms or groups.
What is a Vertebrate?
A vertebrate is an animal that has a backbone or spinal column. Vertebrates are a major group of animals that include fish, amphibians, reptiles, birds, and mammals. Vertebrates are classified into different classes based on their characteristics, such as having jaws, limbs, scales, feathers, hair, or milk glands. Vertebrates are also characterized by having a complex nervous system, a closed circulatory system, and an endoskeleton made of bone or cartilage.
What is a Reptile?
A reptile is a type of vertebrate that belongs to the class Reptilia. Reptiles are cold-blooded animals that have scales or scutes covering their skin. Reptiles lay shelled eggs or give birth to live young. Reptiles include lizards, snakes, turtles, crocodiles, and dinosaurs. Reptiles are one of the oldest groups of vertebrates and have diversified into many forms and habitats over millions of years.
Based on this Cladogram, What Group of Vertebrates is Most Closely Related to Reptiles?
The cladogram below shows the relationships between some groups of vertebrates based on their synapomorphies. The root of the cladogram indicates the common ancestor of all vertebrates. The clades are the branches that indicate related groups and their common ancestors. The nodes are the points that indicate the hypothetical ancestors.
Based on this cladogram, we can see that the group of vertebrates that is most closely related to reptiles is birds. Birds belong to the clade Aves, which is nested within the clade Reptilia. This means that birds share a more recent common ancestor with reptiles than with any other group of vertebrates. Birds evolved from reptiles during the Mesozoic era, when dinosaurs were dominant. Birds have many characteristics that are derived from their reptilian ancestors, such as laying shelled eggs, having scales on their legs and feet, and having a single opening for excretion and reproduction (the cloaca)4. However, birds also have many characteristics that are unique to them or shared with other groups of vertebrates, such as having feathers, wings, a beak, and a high metabolic rate.
Conclusion
A cladogram is a useful tool to understand the evolutionary relationships between groups of organisms based on their shared common characteristics. A vertebrate is an animal that has a backbone or spinal column and belongs to one of the classes of fish, amphibians, reptiles, birds, or mammals. A reptile is a type of vertebrate that has scales or scutes covering its skin and lays shelled eggs or gives birth to live young. Based on a cladogram that shows the relationships between some groups of vertebrates based on their synapomorphies, we can conclude that the group of vertebrates that is most closely related to reptiles is birds. Birds belong to the clade Aves, which is nested within the clade Reptilia. Birds evolved from reptiles during the Mesozoic era and have many characteristics that are derived from their reptilian ancestors as well as many characteristics that are unique to them or shared with other groups of vertebrates.
