TABLE 1.

Parameter estimates of four bird phylogenies for the protracted birth model (pb, using likelihood) and the protracted birth–death model (pbd, using least squares)

Data set	Model	λ 1 = λ3 (Myr −1)	λ 2 (Myr −1)	μ 1 = μ2 (Myr −1)	GOF	τ (Myr )
Acanthiza	pb	0.47	0.04	0	– 7.89	5.16
	pbd	0.66	0.07	0.3	0.35	3.81
Cracidae	pb	0.96	0.12	0	1.13	2.31
	pbd	1.09	0.16	0.3	0.47	1.95
Myiborus	pb	0.48	0.89	0	– 2.71	0.89
	pbd	0.81	0.39	0.3	0.41	1.29
Toxostoma	pb	0.43	0.05	0	– 8.34	5.19
	pbd	0.65	0.06	0.3	0.24	3.98

Because the extinction rate cannot be estimated reliably (the goodness of fit [GOF] did not change over a wide range of extinction values), the reported value of 0.3 was set beforehand. Also shown are the corresponding values of the GOF statistic, i.e. maximum likelihood and least-ssquared distance, and the estimated average duration of speciation (τ).