Table 2. Comparison of vertebrates arriving before and after the K-T boundary.

Question, Null Hypothesis, and Interpretation	Pearson’s Chi SquareValue, df, P	Fisher’s ExactTest P
Does vertebrate class representation of arrivals change from before to after the K-T boundary?
H0: There is no change in vertebrate class representation of clade ancestors arriving before vs. afterthe K-T boundary. Reject. Conclusion: Following the K-T boundary, there was an increase inthe percentages of mammalian and avian clade arrivals.	34.999, df = 4, P<0.001	<0.001
Are these changes reflected in the Late Quaternary and extant fauna profiles?
H0: There is no difference in the age of clades represented in the Late Quaternary or extant faunasby vertebrate class. Reject. Conclusion: The younger clades represented in the Late Quaternaryand extant faunas of Madagascar are primarily birds and mammals.	34.159, df = 4, P<0.001	<0.001
Does clade age affect extinction?
H0: There is no difference in the percentages of vertebrate clades arriving before or after theK-T boundary that have become extinct. Reject. Conclusion: Clades arriving during the Mesozoicare far more likely to be extinct today than those arriving during the Cenozoic.	35.695, df = 1, P<0.001	<0.001
Among vertebrates present during the Mesozoic, does likelihood of extinction vary by class?
H01: There is no difference in survival of Mesozoic fishes vs. tetrapod clades. Reject. Conclusion:Fishes are more likely than tetrapods to have survived.	4.523, df = 1, P = 0.03	0.05
H02: There is no difference in survival of Mesozoic tetrapod clades by class. Fail to reject.	1.716, df = 3, P = 0.633	0.8