Presentation on theme: "Figure 20.1 Two models for the diversification of marine invertebrate life over the past 600 myr of good- quality fossil records. (a) The empirical model,"— Presentation transcript:
Figure 20.1 Two models for the diversification of marine invertebrate life over the past 600 myr of good- quality fossil records. (a) The empirical model, in which the data from the fossil record are plotted directly, and (b) the bias simulation model, in which corrections are made for the supposedly poor fossil record of ancient rocks. (Based on information in Valentine 1969; Raup 1972.)
Figure 20.2 The diversification of four groups of multicellular organisms during the Phanerozoic: (a) marine animals, (b) vascular land plants, (c) non-marine tetrapods, and (d) insects. All graphs show similar shapes, with a long initial period of low diversity, and then rapid increase since the Cretaceous. Geological period abbreviations are standard, running from Vendian (V) to Tertiary (T). (Based on various sources.)
Figure 20.3 Theoretical models for the diversification of life plotted as if for the last 600 myr (a) in the absence of major perturbation and (b) with two mass extinctions superimposed.
Figure 20.4 The history of family diversity of the three great faunas of marine animals, showing a Cambrian phase, a Paleozoic phase and a modern phase. The three phases add together to produce the overall pattern of diversification in Fig. 20.2a. Geological period abbreviations are standard, running from Vendian (V) to Tertiary (T). (Based on Sepkoski 1984.)
Figure 20.5 Sepkoskis three-phase coupled logistic model for diversification of animal life in the sea. (a) The family-level diversification curve for marine animals, showing the three evolutionary faunas from Fig. 20.4, each shaded differently. Numbers I to V are the five big mass extinctions, in sequence from left to right, Late Ordovician, Late Devonian, end- Permian, Late Triassic and Quaternary-Cretaceous. (b) The handover from the Cambrian to the Paleozoic fauna involved a shift in equilibrium diversity ; equilibrium diversity is achieved when origination (k s ) and extinction (k e ) rates match. (c, d) The coupled logistic model gives a simple representation of the broad outlines of the progress of the three evolutionary faunas 1, 2 and 3 (c), and perturbations, shown by vertical arrows, may be added to correspond to the mass extinctions (d). (Based on information in Sepkoski 1979, 1984.)
Figure 20.6 The evolution of the horses has been interpreted as a simple one-way trend towards large size, single toes and deep teeth. The reality is more complex: horse evolution has followed a branching pattern, and the line to the modern horses, Equus, was not preordained: notice the diversity of North American horses in the late Miocene and Pliocene. The evolutionary steps did not all occur in parallel: Merychippus was a grazing horse, with deep-rooted teeth, but retained a three-toed foot. (Based on MacFadden 1992, and other sources.)
Figure 20.7 A classic example of a radiation, the pattern of diversification of the placental mammals after the Cretaceous-Tertiary mass extinction. Mammals originated in the Triassic, and diversified at a modest rate during the Jurassic and Cretaceous. Modern placental superorders originated in the Late Cretaceous, and the orders began to diversify. Only after the dinosaurs had died out did the placental mammals really diversify and become abundant worldwide. (From Benton 2005.)
Figure 20.8 A classic example of competitive replacement? Articulated brachiopods were the dominant seabed shelled animals in the Paleozoic, whereas bivalves take that role today. It was assumed that the bivalves competed long term with the brachiopods during the Paleozoic, even in the Permian, and eventually prevailed. (a) A plot of the long-term fates of both groups shows a steady rise in bivalve diversity, and a drop in brachiopod diversity. However, brachiopods were also diversifying during the Paleozoic, although they were hard hit by the Permo-Triassic mass extinction (arrowed). (b) The bivalves managed to recover after the mass extinction event, while the brachiopods did not. Geological period abbreviations are standard, running from Vendian (V) to Tertiary (T). (Based on information in Gould & Calloway 1980.)
Figure 20.9 The diversification of life, with the timing of the 10 major biological advances indicated: 1, origin of life; 2, eukaryotes and the origin of sex; 3, multicellularity; 4, skeletons; 5, predation; 6, biological reefs; 7, terrestrialization; 8, trees and forests; 9, flight; 10, consciousness. The diversification of life is plotted for the whole of the past 4000 myr (a), and for the Phanerozoic (b). Geological period abbreviations are standard, running from Vendian (V) to Tertiary (T).