Paleozoic Era A) Cambrian A B) Ordovician B D C) Silurian C D) Devonian E) Carboniferous F) Permian E F The Cambrian explosion refers to the sudden appearance of many species of animals in the fossil record. The units of geologic time are listed are periods. 20
A better word than explosion would be adaptation Paleozoic Era: Cambrian Period or radiation. All current animal phyla share ancestry with species from this time. All of the animal fossils from this time are invertebrates many being mollusks and arthropods. The body parts that fossilize particularly well are shells (mollusks) and exoskeletons (arthropods). Brachiopods (Mollusk) Trilobites (Arthropod) 21
Supercontinent Pannotia In the image above, trilobites (1) live among many species that are not normally preserved. A typical Cambrian outcrop might produce only trilobites, brachiopods (2), mollusks (3), and crinoids (4). That is a tiny fraction of the full Cambrian biota, better represented by the roster of the Burgess Shale. That community includes sponges Vauxia (5), Hazelia (6), and Eifellia (7); brachipods Nisusia (2); priapulid worms Ottoia (8); trilobites Olenoides (1); other arthropods such as Sidneyia (9), Leanchoilia (10), Marella (11), Canadaspis (12), Helmetia (13), Burgessia (14), Tegopelte (15), Naraoia (16), Waptia (17), Sanctacaris (18), and Odaraia (19); lobopods Hallucigenia (20) and Aysheaia (21); mollusks Scenella (3); echinoderms Echmatocrinus (4); and chordates Pikaia (22); among other oddities, including Haplophrentis (23) Opabinia (24), Dinomischus (25), Wiwaxia (26), Amiskwia (27), and Anomalocaris (28). Can you identify the possible ancestor of vertebrates?22
Paleozoic Era: Continued evolution of aquatic invertebrates! Ordovician & Silurian Periods The evolution of the first vertebrates (fish)! The evolution of terrestrial invertebrates! Determine the events during these Periods that each figure represents. The evolution of plants (on land)! Oldest Land Animal Fossil (scorpion stinger, 350my) 23
Paleozoic Era: Devonian Period Laurasia and Gondwana The Devonian Period is also known as the age of fishes! The evolutionary advancement in Kingdom Plantae is the evolution of vascular tissue (ferns etc.)! This advancement increased the fitness of this group by allowing them to grow larger than Bryophytes (mosses etc.).? The evolutionary advancement in Phylum Arthropoda is flight (insects) allowing them to disperse far and wide! 24
Paleozoic Era: Devonian Period Acanthostega gunnari The evolutionary advancement in the vertebrate group is the ability to leave the water (legs & lungs, amphibians)! Tetrapod means 4 feet, and refers to all 4-limbed vertebrate animals (amphibians, reptiles, birds and mammals). The current understanding of how tetrapods evolved is that fish evolved legs and lungs to first help them survive shallow water habitats, then on land. 25
Paleozoic Era: Carboniferous & Permian Periods Supercontinent Pangea Anteosaurus was a large carnivore and probably weighed around 500-600Kg. The Early Permian apex predator Dimetrodon. A synapsid, mammal-like reptile. The Carboniferous Period got it's name from the vast forests of fern trees that covered the planet and fossilized as coal, which is primarily carbon. Four different evolutionary lines of reptiles arose at this time? What distinguishes them in the fossil record are the number of holes in their skull. The idea is that by the end of the Permian these evolutionary lines included reptile-like reptiles, aquatic reptiles (extinct), dinosaurs/birds, & mammal-like reptiles. Then... 26
Paleozoic Era: Permian Period The end-permian event that occurred 250 million years ago triggered an abrupt shift to the current dominance of higher-metabolism, mobile organisms (such as snails, clams and crabs) that actually go out and find their own food, and the decreased diversity of older groups of low-metabolism, stationary organisms (such as lamp shells and sea lilies) that filter nutrients from the water. The end Permian event was the largest mass extinction of all time! The extent of the event was the loss of 95% of aquatic species and about 70% of terrestrial species. The four possible causes are an asteroid/comet strike, supervolcano, release of gases from the ocean floor, a change in continental configuration, or all four! 27 This not only ended the Permian Period, but also the Paleozoic Era.
Mesozoic Era: Triassic Period Break-up of Pangaea starts. Following the Permian extinction, the species at the beginning of the Triassic Period were the survivors, including representatives of each major group. The pattern of evolution that followed was adaptive radiation into available niches vacated by extinction. The figure at left shows early Triassic protomammals. The evolutionary advancement in Kingdom Plantae was from reproduction with spores to pollen and seed production in gymnosperms (cone-bearing). Reproduction with pollen and seeds increased the fitness of these species by allowing reproduction without water, and seeds survive longer and can be dispersed farther from the parent plant. 28
Mesozoic Era: Jurassic Period The Jurassic Period is considered the age of reptiles due to dominance of dinosaurs. All the reptiles from this time were not dinosaurs, Pterosaurs, aquatic reptiles, turtles, tortoises, crocodilians, lizards and snakes were also around. The lower right figure is Archaeopteryx, and is also represented on the phylogenetic tree. It represents the dinosaur related group known as Class Aves (birds). The other major group were the mammals, surviving as small, nocturnal burrowers. 29
Mesozoic Era: Cretaceous Period The dominant terrestrial animals during the Cretaceous Period were dinosaurs. The lower left image shows ichthyosaurs, plesiosaurs and mosasaurs (not dinosaurs). The evolutionary advancement in Kingdom Plantae was from cones to flowers & fruit. This advancement increased the fitness of these species by using animals for pollination and seed dispersal. Evidence suggest a mass extinction at the end of the Cretaceous Period. This event also marked the end of the Mesozoic Era. 30