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Mesozoic Era | Evolutionary Biotas | Terrestrial Paleozoic Ecosystems | Tetrapoda | Permo-Triassic tetrapods | Marine Reptiles

The following diagram is from Fig. 3. of Dr Robert T. Bakker's 1977 paper "Tetrapod Mass Extinctions - A model of the regulation of speciation rates and immigration by cycles of topographic diversity" in A. Hallam, ed. Patterns of Evolution as illustrated by the Fossil Record, Elsevier Scientific Publishing Company, Amsterdam, Oxford, New York, pp.439-68

Although subsequent research has modified some of the family rankings and stratigraphic correlations, the basic pattern remains.

Diversity of tetrapods, Early Triassic to Cretaceous. Standard marine stages are indicated by intitials in boxes at top. Families indicated as in Fig. 2. Biomass D for large herbivores for Triassic taken from Fig. 2; D calculated for a few large Jurassic and Cretaceous samples from the following formations: 1, Tendaguru (Kimmeridgian); 2, Morrison (Kimmeridgian/Tithonian); 3, Old Man (Campanian); 4, Lower Edmonton A (Campanian/Maastrichtian); 5, Lower Edmonton B (Maastrichtian); 6, Lance-Hell Creek-Frenchman (latest Maastrichtian).

Family abbreviations:

Marine Aquatics: A = henodontids; B = pachypleurosaurids; C = mixosaurids; D= placocheliids; E = nothosaurids; F = shastasaurids; 0 = pliosaurids; H = metriorhynchids; I= rhomaleosaurids; J = ichthyosaurids; K = plesiosaurids and cryptocleidids; L = stenopterygiids; M = teleosaurids; N = rhamphorhynchids; O = protostegids; P = mosasaurids; Q = cheloniids; R = toxocheliids; S = ichthyornids; T = hesperornids; U = elasmosaurids; V = polycotylids; W = ornithocheirids (pteranodontids); X = ornithodesmids.

Large Fresh-Water Aquatics: A =baenids; B = varanids; C = pelomedusids; D = dermatemyids; E = crocodylids; F = trionychids; G = pholidosaurids; H = goniopholids; I = glyptopids; J = emyids; K = champsosaurids.

Triassic fresh water aquatics shown here. The sampling of non-marine tetrapods during the first eight stages of the Jurassic is so poor that the records are not worth plotting on this compilation.

Large Terrestrial Herbivores: A = camarasaurids; B = diplodocids; C = stegosaurids; D = brachiosaurids; E = cetiosaurids; F = camptosaurids; G = hypsilophodontids; H = panoplosaurids; f = ceratopsids; J = iguanodontids; K = hadrosaurids; L = protoceratopsids; M = titanosaurids; N = pachycephalosaurids; 0 = euoplocephalids. Explanation of Triassic families here

Mesozoic Era| Evolutionary Biotas | Terrestrial Paleozoic Ecosystems | Tetrapoda | Permo-Triassic tetrapods | Marine Reptiles

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