Transitions in the evolution of synapsid tails

哺乳动物在陆地脊椎动物中在许多方面都是独一无二的，从它们的运动姿势到它们的生态形态多样性。独特特征的进化组合开始于上石炭世的古生物进化。一个被称为Synapsida的谱系，今天被定义为哺乳动物加上它的茎谱系，并起源于305 Ma，当它们最早的化石出现时（可能更早于315 Ma，但这取决于Protoclepsydrops作为Synapsida的确定成员的有效性）。

Mammals are unique among land vertebrates in a number of respects, from their locomotory posture to their ecomorphological diversity. The evolutionary assembly of unique traits began following the evolution of the amniotes, which occurred in the upper Carboniferous. One lineage of the amniotes, referred to as Synapsida, is today defined as Mammalia plus its stem-lineage, and originates by 305 Ma, when their earliest fossils occur (potentially earlier at 315 Ma, but this is conditional on the validity of Protoclepsydrops as a definitive member of Synapsida).