Mesozoic Vertebrates 1. Palaeogeographic context 2. Reptile phylogeny 3. Synapsids 4. Diapsids 5. Carrier’s Constraint 6. Dinosaurs

1. Palaeogeographic context CarboniferousTriassic Diverse forests Conifers Ice Pangaea Laurentia Gondwana

2. Reptile phylogeny Embryo Allantois Yolk Shell Hylonomus Synapsids Diapsids Anapsids Mammals, mammal-like reptiles Modern reptiles dinosaurs, birds Turtles

3. Synapsids Therapsids Late Carboniferous Late Permian Dimetrodon Kannemeyeria Pelycosaurs Therapsids Ectotherms - behavioural temperature control Pelycosaurs Sprawling gait Rigid spine Whiskers/ fur Partial endotherms Rigid spine Sprawling gait

4. Diapsids Dinosaurs Birds Archosaurs Pterosaurs Marine reptiles To modern reptiles Crocodiles Late Triassic Mid-Jurassic Late Carboniferous Permian

5. Carrier’s Constraint or, why Archosaurs were better Modern reptiles can either run or breath Synapsids used a rigid spine - wheelbarrow solution. Sprawling gait had low efficiency Archosaurs developed erect gait and upright posture. Both could sustain high metabolic rates

6a. Diapsids take over Herbivores Large carnivores Small carnivores Permian Triassic Jurassic Synapsids Archosaurs Dinosaurs Thecodonts Mammals

6b. Dinosaurs arrive Archosaurs Sauropods lizard-hipped. Vegetarians Evolved extremely large size, often in excess of 20 m in length and 50 tonness in weight. Theropods Late Triassic. All theropods were predators, including Tryannosaurus rex. Ornithischians bird hipped dinosaurs All herbivores, including armoured forms Iguanadonts and duck-billed dinosaurs. Highly modified teeth and jaws Birds Early Jurassic Ischium and pubis Ischium Pubis Illium