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 By the end of the Cambrian period, some 540 million years ago An astonishing variety of animals inhabited Earth’s oceans One of these types of animals 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 Figure There are approximately 52,000 species of vertebrates Which include the largest organisms ever to live on the Earth Concept : Chordates have a notochord and a dorsal, hollow nerve cord Vertebrates are a subphylum of 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 invertebrates A hypothetical phylogeny of chordates Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes Milk Amniotic egg Legs Lobed fins Lungs or lung derivatives Jaws, mineralized skeleton Vertebral column Head Brain Notochord Ancestral deuterostome Echinodermata (sister group to chordates) Urochordata (tunicates) Cephalochordata (lancelets) Myxini (hagfishes) Cephalaspidomorphi (lampreys) Chondrichthyes (sharks, rays, chimaeras) Actinopterygii (ray-finned fishes) Actinistia (coelacanths) Dipnoi (lungfishes) Amphibia (frogs, salamanders) Reptilia (turtles, snakes, crocodiles, birds) Mammalia (mammals) Figure Derived Characters of Chordates All chordates share a set of derived characters Although some species possess some of these traits only during embryonic development Muscle segments Brain Mouth Anus Dorsal, hollow nerve cord Notochord Muscular, post-anal tail Pharyngeal slits or clefts Figure Notochord The notochord Is a longitudinal, flexible rod located between the digestive tube and the nerve cord Provides skeletal support throughout most of the length of a . | Chapter 34 Vertebrates Overview: Half a Billion Years of Backbones By the end of the Cambrian period, some 540 million years ago An astonishing variety of animals inhabited Earth’s oceans One of these types of animals 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 Figure There are approximately 52,000 species of vertebrates Which include the largest organisms ever to live on the Earth Concept : Chordates have a notochord and a dorsal, hollow nerve cord Vertebrates are a subphylum of 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 invertebrates A hypothetical phylogeny of chordates Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods
