Figure 8 From: The brown adipocyte differentiation pathway in birds: An evolutionary road not taken Partial cladogram of the vertebrates. Taxa in which UCP1 are known to be present are indicated by a red dot. Those in which UCP1 is known to be absent are indicated by a black dot. The question mark indicates the span within the evolutionary history of the amniotes during which UCP1 and the capacity to produce functional brown fat was lost.Back to article page