Dinosaur demise did not jump start mammal evolution
You have heard it said that the mammals were small and undiversified during the time of the dinosaurs, but then after the dinosaurs became extinct the mammals blossomed tremendously in an ‘adaptive radiation’. Robert Carroll writes: ‘The extinction of the dinosaurs left vacant a broad range of adaptive zones that were subsequently occupied by therian mammals.’1
The notion of an adaptive radiation is considered to be based on the fossil record. However, the age distribution of fossils is partly based on circular reasoning.2-5 In other words, the finding of a dinosaur automatically places the rock containing the fossil into the Mesozoic, and mammalian fossils are always assumed to be Cenozoic. Similarly, the end of the Cretaceous is often defined as the last preserved dinosaur in a vertical sequence.6
A new article in Nature now claims that this evolutionary belief is a myth.7 Bininda-Emonds and others have constructed an evolutionary lineage of nearly all living mammals using DNA comparisons tied to fossil dates for the beginning of major lineages. They have called their results ‘supertrees’. The authors admit that using molecular data alone or fossil data alone sometimes gives conflicting results:
‘Molecular data and the fossil record can give conflicting views of the evolutionary past.’8
In the case of mammals, the fossil record favoured (or at least had favoured) an explosive increase in mammal diversification just after the Cretaceous/Tertiary (K/T) boundary, but the molecular data pushed most origins of the same orders back into the Late Cretaceous.8 The authors compiled a huge data set, and from the phylogenies they developed they were able to estimate diversification rates with time, all within the evolutionary paradigm of course.
Because their analysis is tied to the recent findings of many complex mammals in the Jurassic and Cretaceous,9,10 their diversity analysis showed an increase in diversity in the mid Cretaceous, 85 to 100 Ma, and in the early Eocene. In fact, nearly all the living orders of mammals had originated by 85 Ma.10 However, there was little or no change in diversity through the K/T boundary, as had been assumed for over 100 years. In fact, the few mammal groups that did diversify after the K/T boundary subsequently declined or died out.11 The graph leaves the evolutionists with a major question of mammal evolution:
‘What, then, was delaying the diversification of present-day mammals? Clearly, the priority is to identify why net rates of diversification remained low for so long after the major lineages became established.’11
It is interesting that their diversification graphs show the mammal diversification rate increasing to a maximum in the Miocene and then rapidly dropping to zero today.11 This implies that there is no evolution occurring in living mammals today, nor has there been in the recent geological past. Such a change is what we would expect in the post-Flood world—any changes that do occur are just the shuffling of genes within kinds. Because there is diversification of mammals up until the very late Cenozoic, the graph implies that the Flood/post-Flood boundary is in the very late Cenozoic based on this parameter, since any significant diversification rate in the rock record would likely represent burial characteristics in the Genesis Flood. The Flood interpretation of the diversification graph reinforces other evidence that the Flood/post-Flood boundary is in the very latest Cenozoic.12-14
- Carroll, R.L., Vertebrate Paleontology and Evolution, W.H. Freeman and Company, New York, p. 449, 1988. Return to text.
- Oard, M.J., The extinction of the dinosaurs, Journal of Creation 11(2):137–154, 1997; pp. 148–149. Return to text.
- Oard, M.J., End-Mesozoic extinction of dinosaurs partly based on circular reasoning, Journal of Creation 15(2):6–7, 2001. Return to text.
- Oard, M.J., Paleocene dinosaurs and the reinforcement syndrome, Journal of Creation 17(3):5–8, 2003. Return to text.
- Oard, M.J., Is the demise of the dinosaurs by a Yucatán impact a myth? Journal of Creation 18(1):6–8, 2004. Return to text.
- Fastovsky, D.E. and D.B. Weishampel, The Evolution and Extinction of the Dinosaurs, Cambridge University Press, Cambridge, UK, p. 385, 1996. Return to text.
- Bininda-Emonds, O.R.P., Cardillo, M., Jones, K.E., MacPhee, R.D.E., Beck, R.M.D., Grenyer, R., Price, S.A., Vos, R.A., Gittleman, J.L. and Purvis, A., The delayed rise of present-day mammals, Nature 446:507–511, 2007. Return to text.
- Bininda-Edmonds et al., ref. 7, p. 507. Return to text.
- Oard, M.J., Jurassic mammals more surprisingly diverse, Journal of Creation 21(2):10–11, 2007. Return to text.
- Bininda-Edmonds et al., ref. 7, p. 508. Return to text.
- Bininda-Edmonds et al., ref. 7, p. 510. Return to text.
- Holt, R.D., Evidence for a late Cainozoic Flood/post-Flood boundary, Journal of Creation 10(1):128–167, 1996. Return to text.
- Oard, M.J., Where is the Flood/post-Flood boundary in the rock record? Journal of Creation 10(2):258–278. Return to text.
- Oard, M.J., Defining the Flood/post-Flood boundary in sedimentary rocks, Journal of Creation 21(1):98–110, 2007. Return to text.