The Chordata Chapter 34

We’ve done some of this before …

Fig 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

Fig 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 Chordate characteristics

Figure 34.4b Subphylum Cephalochordata: the lancelet Branchiostoma

Figure 34.4a Subphylum Cephalochordata: lancelet anatomy The lancelet, Subphylum Cephalochordata, has all four chordate synapomorphies

Figure 34.9 A hagfish A skull of cartilage, but no jaw and no vertebrae, Class Myxini

Figure 34.7 Phylogeny of the major groups of extant vertebrates

Figure 34.9 A sea lamprey Lampreys, Class Pteromyzontida The first vertebrates lack jaws

Figure Cartilaginous fishes (class Chondrichthyes): Great white shark (top left), silky shark (top right), southern stingray (bottom left), blue spotted stingray (bottom right) Cartilaginous fishes, (class Chondricthyes): jaws, paired appendages, mineralized skeletons

Note: The BCOR 12 tutoring room (Sunday night from 7:30-9pm) has been changed to L/L A101 (not A161). Darlene will NOT be available this Sunday. HW is due this Sunday night at 11:59 p.m., as usual.

Why are humans considered members of the chordates when we have no notochord, pharyngeal slits, or muscular tail? A.Our mammalian ancestors show some of these traits. B.Other similar traits appear in humans. C.Our nerve cord has replaced the notochord. D.Embryonic humans have these traits. E.More than one of the above. Clicker Question

Fig 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 34.12a Ray-finned fishes (class Actinopterygii): yellow perch Ray-finned fishes (class Actinopterygii): lungs or lung derivatives Clade = Ostichtyes, the “bony fishes”

Figure Anatomy of a trout, a representative ray-finned fish

Fig 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 aquaticaquatic ostichthsostichths

Figure A coelocanth (Latimeria), the only extant lobe-finned genus The coelocanth (class Actinistia) first appeared in the fossil record in the Devonian

Figure Skeleton of Acanthostega, a Devonian tetrapod fish Transitional tetrapods -- feet in place but gills and tail with fin

Figure Amphibian orders: Newt (left), frog (right) Class Amphibia Clade = Tetrapods Synapomorphy: four walking legs

Figure “Dual life” of a frog (Rana temporaria)

Note: The Tri-Beta honors society will be having its regular intro bio tutoring sessions Monday and Tuesday after break, 6 - 8pm in Rowell 244. This is in addition to the regular Sunday sessions in Living and Learning.

Figure A hatching reptile Class Reptilia Clade: Amniotes Synapomorphy: the amniotic egg

Figure Amniotic egg Amnion: cushioning chamber for embryo Chorion: gas exchange to exterior Allantois: disposal sac Yolk sac: surrounds yolk

Figure A hypothetical phylogeny of amniotes

Figure Extant reptiles: Desert tortoise (top left), lizard (top right), king snake (bottom left), alligators (bottom right)

Figure A hypothetical phylogeny of amniotes

Archaeopteryx (150 mybp): feathered wings and powered flight, but retained ancestral characteristics such as teeth, clawed wings, and a long tail.

Figure A small sample of birds: Blue-footed boobies (top left), male peacock (top right), penguins (bottom left), perching bird (bottom right) Modern birds: endotherms with feathers of keratin, circa 10,000 species

Figure A hypothetical phylogeny of amniotes

Synapsid reptiles evolved into large carnivores and herbivores during the Permian period. Diversity was much reduced in the Permian -Triassic extinction.

Class Mammalia: amniotes that have hair and produce milk

Figure Hypothetical cladogram of mammals

Fig a (a) A young brushtail possum

Eutherians, the placental mammals: internal gestation

Figure A phylogenetic tree of primates

Figure Prosimians:Lemurs

Figure Upright posture predates an enlarged brain in human evolution

Fig 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