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Lecture Biology: Chapter 34 - Niel Campbell, Jane Reece

Chapter 34 introduce to vertebrates. This chapter list the derived traits for: chordates, craniates, vertebrates, gnathostomes, tetrapods, amniotes, birds, mammals, primates, humans; describe the trends in mineralized structures in early vertebrates; describe and distinguish between Chondrichthyes and Osteichthyes; describe an amniotic egg and explain its significance in the evolution of reptiles and mammals;. | Chapter 34 Vertebrates Overview: Half a Billion Years of Backbones Early in the Cambrian period, about 530 million years ago, an astonishing variety of animals inhabited Earth’s oceans. One type of animal gave rise to vertebrates, one of the most successful groups of animals. The animals called vertebrates get their name from vertebrae, the series of bones that make up the backbone. There are about 52,000 species of vertebrates, including the largest organisms ever to live on the Earth. Are humans among the descendants of this ancient organism? Figure 34.1 Are humans among the descendants of this ancient organism? Concept 34.1: Chordates have a notochord and a dorsal, hollow nerve cord Vertebrates are a subphylum within the phylum Chordata. Chordates are bilaterian animals that belong to the clade of animals known as Deuterostomia. Two groups of invertebrate deuterostomes, the urochordates and cephalochordates, are more closely related to vertebrates than to other invertebrates. Phylogeny of living chordates Lobed fins Legs Amniotic egg Milk Jaws, mineralized skeleton Lungs or lung derivatives Vertebral column Head Notochord Common ancestor of chordates ANCESTRAL DEUTERO- STOME Echinodermata (sister group to chordates) Chondrichthyes (sharks, rays, chimaeras) Cephalochordata (lancelets) Urochordata (tunicates) Myxini (hagfishes) Petromyzontida (lampreys) Mammalia (mammals) Actinopterygii (ray-finned fishes) Actinistia (coelacanths) Amphibia (frogs, salamanders) Dipnoi (lungfishes) Reptilia (turtles, snakes, crocodiles, birds) Chordates Craniates Vertebrates Gnathostomes Lobe-fins Osteichthyans Tetrapods Amniotes Figure 34.2 Phylogeny of living chordates Derived Characters of Chordates All chordates share a set of derived characters. Some species have some of these traits only during embryonic development. Four key characters of chordates: Notochord Dorsal, hollow nerve cord Pharyngeal slits or clefts Muscular, post-anal tail Chordate characteristics Dorsal, . | Chapter 34 Vertebrates Overview: Half a Billion Years of Backbones Early in the Cambrian period, about 530 million years ago, an astonishing variety of animals inhabited Earth’s oceans. One type of animal gave rise to vertebrates, one of the most successful groups of animals. The animals called vertebrates get their name from vertebrae, the series of bones that make up the backbone. There are about 52,000 species of vertebrates, including the largest organisms ever to live on the Earth. Are humans among the descendants of this ancient organism? Figure 34.1 Are humans among the descendants of this ancient organism? Concept 34.1: Chordates have a notochord and a dorsal, hollow nerve cord Vertebrates are a subphylum within the phylum Chordata. Chordates are bilaterian animals that belong to the clade of animals known as Deuterostomia. Two groups of invertebrate deuterostomes, the urochordates and cephalochordates, are more closely related to vertebrates than to other invertebrates. .