2009/02/04 by Kenneth D. Angielczyk · 1 citation
Earth and Planetary Sciences · Environmental Science · Biochemistry, Genetics and Molecular Biology · #Evolution and Paleontology Studies #Species Distribution and Climate Change #Genetic diversity and population structure #Common descent #Mammal #Tree of life (biology) #Biology #Evolution of mammals #Evolutionary biology #Phylogenetic tree #Family tree #Zoology #Ecology #Genealogy #History
paper · pdf · doi:10.1007/s12052-009-0117-4
openalex publication_date 2009/02/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
The line of descent that includes all living mammals extends back in time over 300 million years. Many of the ancient relatives of mammals that fall along this line are very different in appearance from living mammals and are frequently mistaken for reptiles such as dinosaurs. This misconception is reinforced by the fact that these animals are often referred to as “mammal-like reptiles,” a term reflecting outdated methods for classifying organisms. In reality, these ancient mammal-relatives, known as synapsids, are more closely related to living mammals than they are to any reptiles. Evolutionary trees, which depict patterns of descent from common ancestors among organisms, are very useful for understanding why this is the case and for reconstructing the evolutionary histories of many of the unique characters found in mammals. Here, I provide an introduction to evolutionary trees and their implications for understanding the relationships between mammals, synapsids, and reptiles. This is followed by a review of synapsid diversity and a discussion of how evolutionary trees can be used to investigate when in synapsid history different mammalian characteristics first appeared.