Chapter 34: Origin of Vertebrates

Tiktaalik had a combination of fishlike and tetrapod-like characteristics. Which were the tetrapod-like characteristics?

-A neck -Interlocking ribs -Flat head with eyes on top Tiktaalik had characteristics of both fish (scales, fins, and fin rays) and tetrapods (flat head, eyes on top, strong interlocking ribs, and a neck). These characteristics would have enabled it to survive both in and out of water, like amphibians and reptiles today.

The phylogenetic tree shown here displays the major clades of chordates. Which statements about the phylogenetic tree are true?

-Mammals and turtles are more closely related than are lungfishes and sharks. -Birds and ray-finned fishes have a notochord and jaws. -Rays and frogs have vertebrae. -Descendants of organism (d) have limbs with digits. -Organism (a) is a common ancestor of all chordates.

Why have we NOT found examples in the fossil record of every animal that ever lived on Earth? -Many fossils remain buried. We can only find them when they are exposed by erosion or excavation. -It is just a matter of time before we find them all. Rocks contain the history of all life, if you know where to look. -To become a fossil, an animal must be quickly and completely buried in ash or sediment before it has a chance to decompose. -To become a fossil, an animal must remain buried for thousands or millions of years until it (and the layer around it) turns to rock.

-Many fossils remain buried. We can only find them when they are exposed by erosion or excavation. -To become a fossil, an animal must be quickly and completely buried in ash or sediment before it has a chance to decompose. -To become a fossil, an animal must remain buried for thousands or millions of years until it (and the layer around it) turns to rock.

Which evidence supports the hypothesis that four-limbed animals came from fish? -The fossil record shows more and more tetrapod-like fish before the appearance of tetrapods about 365 million years ago. -Both fish and four-limbed animals are vertebrates. -Fish and four-limbed animals have very similar embryos. -Fossil evidence shows there have always been four-limbed animals on Earth. -DNA analysis shows that fish are tetrapods' closest relatives.

-The fossil record shows more and more tetrapod-like fish before the appearance of tetrapods about 365 million years ago. -Both fish and four-limbed animals are vertebrates. -Fish and four-limbed animals have very similar embryos. -DNA analysis shows that fish are tetrapods' closest relatives.

Research confirms that Neanderthal DNA makes up about ____ of the modern human genome.

4 %

Which of the following is a tetrapod? -A mammal -A reptile -A fish -A bird -An amphibian

A mammal A reptile A bird An amphibian Mammals, amphibians, reptiles and birds are all tetrapods. Their limbs are built with the "one bone, two bones, many bones, digits" arrangement Dr. Shubin describes in the film.

________ are early vertebrates that lacked jaws, had large eyes, and had mineralized dental tissues. A. Conodonts B. Placoderms C. Acanthodians D. Lampreys E. Hagfishes

A. Conodonts

Which of the following correctly lists probable ancestors of modern humans from the oldest to the most recent? A. Sahelanthropus, Australopithecus, Homo B. Homo, Sahelanthropus, Australopithecus C. Australopithecus, Sahelanthropus, Homo D. Homo, Australopithecus, Sahelanthropus E. Sahelanthropus, Homo, Australopithecus

A. Sahelanthropus, Australopithecus, Homo

Vertebrates and tunicates share A. a notochord and a dorsal, hollow nerve cord. B. jaws adapted for feeding. C. a high degree of cephalization. D. an endoskeleton that includes a skull.

A. a notochord and a dorsal, hollow nerve cord.

All species of New World monkeys are __________. A. arboreal B. solitary C. nocturnal D. ground dwelling E. oviparous

A. arboreal All New World monkeys and many Old World monkeys live their lives in the trees.

Basal chordates are animals called the ________. A. cephalochordates B. Myxini C. urochordates D. actinopterigii E. Petromyzontida

A. cephalochordates

Included among the modern groups of apes are __________. A. gibbons, orangutans, gorillas, chimpanzees, and bonobos B. tarsiers and gorillas C. lemurs and lorises D. chimpanzees and monkeys E. Old World monkeys and New World monkeys

A. gibbons, orangutans, gorillas, chimpanzees, and bonobos The modern groups of apes include gibbons, orangutans, gorillas, chimpanzees, and bonobos.

Tiktaalik is an important fossil find because ________. A. it has both fish and tetrapod characters B. it has fins with digits C. None of the listed responses are correct D. it was found in North America E. it has ray fins

A. it has both fish and tetrapod characters

Some sharks are viviparous, which means that __________. A. the young develop within the female's body B. they have a tendency toward single births C. they have a tendency toward multiple births D. they lay eggs E. they maintain a constant body temperature

A. the young develop within the female's body Some sharks are viviparous, which means that their young develop within the female body after hatching from eggs in the uterus.

Except for modern ethnic groups in ______, the majority of humans appear to have traces of Neanderthal DNA in their genome.

Africa

All chordates share a set of derived characters during at least some part of their life.

All chordate embryos exhibit four derived characters: a notochord; a dorsal, hollow nerve cord; a muscular, post-anal tail; and pharyngeal slits or clefts. In many chordates, these characters develop into different structures or are reduced in form as the animal continues its development. For example, the pharyngeal slits develop into gill slits in aquatic vertebrates, and a jointed skeleton forms around a reduced notochord in most vertebrates.

Which of the following statements about deuterostomes is false? -All deuterostomes exhibit radial symmetry in their bodies. -All deuterostomes are triploblastic and have three tissue layers. -All deuterostomes have a coelom. -All deuterostomes have a similar pattern of early embryonic development.

All deuterostomes exhibit radial symmetry in their bodies. This statement is false; in the deuterostome lineage, only adult echinoderms exhibit radial symmetry.

Most members of which of the following groups are most closely associated with a wet or moist environment? -Dinosaurs -Pterosaurs -Birds -Mammals -Amphibians

Amphibians Amphibians typically have a water-permeable skin that does not easily resist drying. Thus, amphibians tend to be found in moist environments.

Which of the following could be considered the most recent common ancestor of living tetrapods? A. an early ray-finned fish that developed bony skeletal supports in its paired fins B. a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates C. a salamander that had legs supported by a bony skeleton but moved with the side-to-side bending typical of fishes D. an armored, jawed placoderm with two pairs of appendages

B. a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates

Humans and the loris share many traits that probably evolved in our early primate ancestors, including __________. A. opposable big toes B. a thumb that is relatively mobile and separate from the fingers C. an arboreal way of life D. bipedalism (upright walking) E. culture

B. a thumb that is relatively mobile and separate from the fingers All primates have such thumbs. Anthropoids have a fully opposable thumb; that is, they can touch the ventral surface (fingerprint side) of the tip of all four fingers with the ventral surface of the thumb of the same hand.

The adaptation that freed vertebrates from water for reproduction and allowed them to radiate into diverse terrestrial environments was the __________. A. bony appendage B. amniotic egg C. lateral line system D. operculum E. placenta

B. amniotic egg

The adaptation that freed vertebrates from water for reproduction and allowed them to radiate into diverse terrestrial environments was the __________. A. placenta B. amniotic egg C. lateral line system D. bony appendage E. operculum

B. amniotic egg The amniotic egg allows for reproduction and development within a structure that provides moisture, food, waste storage, and gas exchange.

Which clade does not include humans? A. synapsids B. diapsids C. osteichthyans D. lobe-fins

B. diapsids

Derived chordate characteristics include all of the following except a _______. A. dorsal, hollow nerve cord B. dorsal, solid nerve cord C. pharyngeal slits D. notochord E. post-anal tail

B. dorsal, solid nerve cord

Derived mammalian characteristics include all of the following except _______. A. mammary glands B. ectothermy C. differentiated teeth D. four-chambered heart E. hair or fur

B. ectothermy

Primates known as anthropoids include all of the following groups except ________. A. Old World monkeys B. lemurs C. New World monkeys D. gorillas E. humans

B. lemurs

DNA was isolated from Neanderthal ____ and sequenced so that it could be compared to modern human DNA.

Bone Fragments

Which of the following statements is the most inclusive description of descent with modification? A. Natural selection leads to the evolution of similar features in independent evolutionary lineages. B. Similarity between two species results from genetic drift in small populations. C. A trait present in an ancestral organism is modified by natural selection over time in descendants of that ancestor. D. Similarity between two species results from convergent evolution.

C. A trait present in an ancestral organism is modified by natural selection over time in descendants of that ancestor. Evolution is a process of descent with modification: Characteristics present in an ancestral organism are altered in its descendants over time as they face different environmental conditions. One result of descent with modification is that related species can have characteristics that have an underlying similarity yet different functions. Descent with modification occurring in different evolutionary lineages may result in species in each of those lineages having characteristics that function similarly yet are not due to common descent as those species have independently adapted to similar environmental conditions.

Which of the following animals is an amphibian? A. None of the listed responses are correct. B. All of the listed responses are correct. C. Caecilian D. Lizard E. Turtle

C. Caecilian Although, because of their legless bodies, they may be mistaken for snakes, which are reptiles, caecilians, are amphibians.

Which of the following pairs is NOT a correct match? A. Aves, canary B. Mammalia, kangaroo C. Gnathostomata, hagfish D. Osteichthyes, perch E. Chondrichthyes, great white shark

C. Gnathostomata, hagfish Gnathostomes are jawed vertebrates. A hagfish is an agnathan, a jawless vertebrate.

Habitat loss, the spread of a fungal disease, climate change, and pollution are causing severe population declines and extinction in __________. A. turtles B. rodents C. amphibians D. birds E. sharks

C. amphibians Amphibians are susceptible to all of these circumstances.

As hominins diverged from other primates, which of the following appeared first? A. the making of stone tools B. an enlarged brain C. bipedal locomotion D. reduced jawbones

C. bipedal locomotion

Which of the following is among the earliest known vertebrates? A. lampreys B. hagfish C. conodonts D. sharks E. None of the listed responses is correct.

C. conodonts Conodonts are among the earliest known organisms that are considered to be vertebrates.

A lamprey, a shark, a lizard, and a rabbit share all the following characteristics except __________. A. a dorsal, hollow nerve cord B. All of the listed responses are correct C. hinged jaws D. pharyngeal clefts in the embryo E. vertebrae

C. hinged jaws The lamprey is jawless; all the other listed animals have jaws.

The gill flap, or operculum, was an important adaptation for fish because it helps with __________. A. sensing vibrations in the water B. underwater reproduction C. maintaining a supply of oxygen D. adjusting buoyancy E. sensing chemicals in water

C. maintaining a supply of oxygen Water is drawn into the mouth, through the pharynx, and out between the gills by movement of the operculum and contraction of muscles surrounding the gill chambers.

Analysis of mitochondrial DNA and Y chromosomes of modern humans has led most researchers to agree that __________. A. Homo sapiens settled in the New World approximately 75,000 years ago B. the common ancestor of Homo sapiens was a Neanderthal C. modern humans emerged from Africa D. Homo sapiens has many common ancestors E. Homo sapiens evolved from H. erectus in several parts of the world

C. modern humans emerged from Africa Older species (perhaps H. ergaster or H. erectus) gave rise to newer species, such as H. heidelbergensis and ultimately H. sapiens, which migrated from Africa.

All mammals __________. A. complete their embryonic development in the uterus B. bear live young C. nourish their offspring through mammary glands D. All of the listed responses are correct. E. None of the listed responses is correct.

C. nourish their offspring through mammary glands Mammary glands that produce milk are as distinctively mammalian as hair.

Primates are distinguished from other mammals by __________. A. long tails used for balance, stereoscopic vision, and opposable thumbs B. stereoscopic vision, mammary glands, and single births C. opposable thumbs, nails, and good depth perception D. eutherian reproduction, opposable thumbs, and good depth perception E. fur, claws, and small litters

C. opposable thumbs, nails, and good depth perception Arboreal adaptations that distinguish primates from other mammals include opposable thumbs, nails rather than claws, eyes on the front of the head (giving good depth perception), and small litters.

Which of the following chordate characteristics contributes most to suspension-feeding devices in many invertebrate chordates? A. dorsal, hollow nerve cord B. muscular, post-anal tail C. pharyngeal slits or clefts D. notochord E. None of the listed responses is correct.

C. pharyngeal slits or clefts Derivatives of the pharyngeal slits contribute to suspension-feeding devices in many invertebrate chordates.

Living vertebrates can be divided into two major clades. Select the appropriate pair. A. the chordates and the tetrapods B. the urochordates and the cephalochordates C. the cyclostomes and the gnathostomes D. the marsupials and the eutherians

C. the cyclostomes and the gnathostomes

In the phylogenetic tree shown, which of the following are shared ancestral characters for members of the turtle-leopard group? A. vertebral column; amnion B. hinged jaws; amnion C. vertebral column; four limbs D. four limbs; hair

C. vertebral column; four limbs A shared ancestral character is a character that is not unique to a particular group, having originated in an ancestor of that group. For members of the turtle-leopard group, the phylogeny shows that a vertebral column, hinged jaws, and four limbs are all shared ancestral characters, having originated before the turtle-leopard group diverged from other lineages shown in the tree. In contrast, a shared derived character is an evolutionary novelty that is unique to a particular group; in the phylogeny shown here, an amnion is a shared derived character for the turtle-leopard group.

Which of the following can be found in vertebrates but NOT in lancelets and tunicates? A. duplications of genes that produce signaling molecules and transcription factors B. neural crest C. two or more clusters of Hox genes D. All of the listed responses are correct. E. None of the listed responses is correct.

D. All of the listed responses are correct. All of these are characteristics found in craniates but not lancelets or tunicates.

_________ best explains the similarities between Australian marsupials and placental mammals (eutherians) in other parts of the world. A. Founder effect B. Adaptive radiation C. Bottleneck effect D. Convergent evolution E. Natural selection

D. Convergent evolution

Which of the following groups represents the most basal lineage of vertebrates? A. Amphibians B. Sharks C. None of the listed responses are correct D. Cyclostomes E. Conodonts

D. Cyclostomes

________ are extinct species that are more closely related to humans than to chimpanzees. A. Bonobos B. Gibbons C. Lorises D. Hominins E. Orangutans

D. Hominins

What was the earliest hominin to have an enlarged brain (relative to body size)? A. Australopithecus afarensis B. Homo erectus C. Homo neanderthalensis D. Homo habilis E. Ardipithecus ramidus

D. Homo habilis The brain of this species was intermediate in size between that of Australopithecus afarensis and that of Homo sapiens.

Which of the following chordate characteristics contributes most to the formation of your ears? A. Muscular, post-anal tail B. None of the listed responses are correct C. Notochord D. Pharyngeal slits or clefts E. Dorsal, hollow nerve cord

D. Pharyngeal slits or clefts In mammals, derivatives of the pharyngeal slits contribute to the development of portions of our ears.

Which of the following sets of animals contains only gnathostomes? A. Sharks, hagfish, and whales B. Hagfish, bass, sharks, and frogs C. Lampreys, conodonts, and hagfish D. Rays, turtles, pigeons, and tune E. Conodonts, placoderms, and acanthodians

D. Rays, turtles, pigeons, and tune

Which of the following correctly lists probable ancestors of modern humans from the earliest to the most recent? A. Australopithecus, Ardipithecus, Sahelanthropus, Homo B. Homo, Sahelanthropus, Ardipithecus, Australopithecus C. Sahelanthropus, Ardipithecus, Homo, Australopithecus D. Sahelanthropus, Ardipithecus, Australopithecus, Homo E. Homo, Ardipithecus, Australopithecus, Sahelanthropus

D. Sahelanthropus, Ardipithecus, Australopithecus, Homo

A feature of bony fish not found in sharks is __________. A. pelvis and pectoral fins with bony support B. mineralized teeth C. a lateral line system D. a swim bladder E. gills

D. a swim bladder A swim bladder, an aid in the maintenance of buoyancy, is a characteristic of most bony fish.

The first vertebrates to live on land were __________. A. reptiles B. chondrichthyans C. conodonts D. amphibians E. mammals

D. amphibians Amphibians, though tied to water for reproduction, include species that are, otherwise, entirely terrestrial.

Which of the following traits distinguishes hominins from other apes? A. an enlarged brain (relative to body size) B. the use of tools C. the use of fire D. bipedalism (upright walking) E. the absence of a tail

D. bipedalism (upright walking) Early hominins and members of the genus Homo, but no apes are or were bipedal.

Which of the following is an archosaur group? A. lizards B. snakes C. tuataras D. crocodiles E. None of the listed responses is correct.

D. crocodiles Crocodiles belong to an archosaur lineage that reaches back to the late Triassic.

Which of the following characteristics is NOT shared by extant birds and extant reptiles? A. scales containing keratin B. pharyngeal clefts in the embryo C. amniotic eggs D. endothermic metabolism E. vertebrae

D. endothermic metabolism Birds are endothermic, but extant reptiles are ectothermic. There is much debate over whether some groups of extinct reptiles, such as the dinosaurs, were endotherms or ectotherms

Based on the highlighted (white) branches in the phylogenetic tree shown, which of the following labels refers to a paraphyletic group? A. plants B. Archaeplastida C. red algae D. green algae

D. green algae A monophyletic group consists of an ancestral species and all of its descendants. Examples of monophyletic groups in this phylogenetic tree include red algae, plants, charophytes, chlorophytes, and the supergroup Archaeplastida. In contrast, a paraphyletic group consists of an ancestral species and some, but not all, of its descendants. In this tree, green algae are a paraphyletic group, because they consist of chlorophytes, charophytes, and their common ancestor, but not plants, which are also descended from the same common ancestor.

Unlike eutherians, both monotremes and marsupials A. are found in Australia and Africa. B. lay eggs. C. lack nipples. D. have some embryonic development outside the uterus.

D. have some embryonic development outside the uterus.

A _____ is a chordate but not a vertebrate. A. lamprey B. sea star C. shark D. lancelet E. frog

D. lancelet Lancelets are cephalochordates and, throughout their life, retain the notochord as the primary support of the appendicular skeleton.

The opossum is an example of a(n) __________ mammal. A. monotreme B. oviparous C. eutherian D. marsupial E. placental

D. marsupial Opossums, like all marsupial mammals, keep their nursing young in an external pouch.

Sharks that retain their fertilized eggs in the oviduct, where the eggs develop into young, are called ________. A. oviparous B. viviparous C. amniotes D. ovoviviparous E. None of the listed responses are correct

D. ovoviviparous

_______ belong to a group of bipedal saurischian dinosaurs. A. Crocodiles B. Geckos C. Snakes D. Lizards E. Birds

E. Birds

Sharks and rays belong to the clade ________. A. Sarcopterygii B. Tiktaalik C. Osteichthyes D. Actinopterygii E. Chondrichthyes

E. Chondrichthyes

If an animal has segments, bilateral symmetry, pharyngeal clefts, a post-anal tail, and deuterostomic development, it must be a member of the __________. A. Annelida B. Mollusca C. Arthropoda D. Platyhelminthes E. Chordata

E. Chordata Chordates are deuterostomes that have four anatomical structures appearing at some time in development: a notochord, a hollow dorsal nerve cord, pharyngeal clefts, and a muscular post-anal tail.

__________ arose very early in hominid evolution; __________ evolved more recently. A. none of the listed responses are correct B. Large brains; prominent brow ridges C. Upright posture; forward-looking eyes D. Large brains; upright posture E. Upright posture; large brains

E. Upright posture; large brains Various human characteristics, such as upright posture and large brains, did not evolve in unison. Different features evolved at different rates, with erect posture leading the way.

Derived amniote characteristics include all of the following except ___________. A. the amnion B. the yolk sac C. the chorion D. the allantois E. embryonic membranes

E. embryonic membranes

Animals that are classified as vertebrates and have rudimentary vertebrae are the ______ and the ______. A. tunicates; hagfishes B. hagfishes; lancelets C. lancelets; tunicates D. lampreys; placoderms E. hagfishes; lampreys

E. hagfishes; lampreys

The three lineages of the Sarcopterygii include the coelolcanths, lungfishes, and ________. A. acanthodians B. Osteichthyes C. Chondrichthyes D. placoderms E. tetrapods

E. tetrapods

The fact that tunicates have only 9 sets of Hox genes while lancelets and all other chordates have 13 sets of Hox genes indicates that ____________. A. the tunicate is a basal chordate B. lancelets evolved from tunicates C. None of the listed responses are correct D. the tunicate larva is still evolving E. the tunicate larva is using different set of genetic controls the that of the other chordates

E. the tunicate larva is using different set of genetic controls the that of the other chordates

Which structure is not an innovation that occurred during vertebrate diversification? -Amniotic egg -Bone -Jaws -Exoskeleton

Exoskeleton Exoskeletons are present in groups other than the vertebrates, including some in the protostome lineage.

True or false? An organism that is radially symmetric has many well-developed head regions.

False An organism that is radially symmetric does not have a well-developed head region.

The Neanderthal DNA discovered in Homo sapiens is best explained by ____.

Gene Flow

Which structure can be used for feeding and gas exchange? -Endoskeleton -Dorsal nerve cord -Pharyngeal gill slit -Notochord

Pharyngeal gill slit A pharyngeal gill slit is an opening into the throat that can be used for feeding and gas exchange.

Which of the following is a characteristic of all chordates at some point during their life cycle? -Jaws -Vertebrae -Post-anal tail -Four-chambered heart

Post-anal tail

Which of the following statements would be most acceptable to most zoologists? -Recent work in molecular systematics supports the hypothesis that lancelets are the basal clade of chordates. -The extant lancelets are the immediate ancestors of the fishes. -The first fossils resembling lancelets appeared in the fossil record around 10 million years ago. -Lancelets do not swim in the same way that fishes do.

Recent work in molecular systematics supports the hypothesis that lancelets are the basal clade of chordates.

Mating is believed to have taken place between modern humans and Neanderthals in ____ about 70,000 years ago.

The Middle East

Which of the following statements about vertebrates is true? -The development of an amniotic egg and internal fertilization allowed vertebrates to reproduce away from water. -The development of more efficient surfaces for gas exchange in reptiles stimulated expansion into terrestrial habitats. -Birds are more related to mammals than to dinosaurs. -All vertebrates have jaws with which to catch their prey.

The development of an amniotic egg and internal fertilization allowed vertebrates to reproduce away from water. Reptiles and their descendants reproduce on land via an amniotic egg, which prevents the embryo from drying out.

Which characteristics define a chordate? -The presence of a well-developed circulatory system -The presence of four specific morphological traits -The development of an anus from the blastopore -The ability to live on land

The presence of four specific morphological traits. Chordates are defined by the presence of four morphological traits: a notochord, a dorsal nerve cord, pharyngeal gill slits, and a tail behind the anus.

How did the great transition from fish to tetrapod occur?

The transition occurred gradually over time, so there are many intermediate for

Which characteristic distinguishes echinoderms from the other two deuterostome lineages? -Their ability to move -Their body plan -Their habitat -The presence of an endoskeleton

Their body plan Echinoderms exhibit a unique body plan characterized by an endoskeleton and a water vascular system.

Why did Shubin and Daeschler search in the Canadian arctic for fossil evidence of the transition from fish to tetrapods?

They hypothesized that the transitional fossils were in sedimentary rocks older than 365 million years ago, when the first tetrapods appear in the fossil record.

What kind of habitat did tiktaalik live in?

Tiktaalik lived in a warm, freshwater swamp. When tiktaalik lived and became fossilized, its location was closer to Earth's equator, where warm, freshwater habitats were abundant. Over time, continental drift moved the pieces of Earth's crust (and all the fossils in the rocks above them) to different locations.

What is a transitional fossil? -Transitional fossils were poorly adapted to their environments. -Transitional fossils only existed for a short period of time. -Transitional fossils have features that are intermediate between ancestors and descendants. -A transitional fossil is in the middle of a direct lineage stretching from ancient forms to organisms alive today.

Transitional fossils have features that are intermediate between ancestors and descendants. Species descend from other species. The fossil record includes fossils of animals with features that are intermediate, or transitional, between those of earlier and later species.

Lancelets and tunicates are two groups of chordates. Classify each statement as applying to lancelets, tunicates, both lancelets and tunicates, or neither.

Tunicates and lancelets are two groups of chordates. Both possess the four derived characters of chordates during their development. However, whereas adult lancelets retain all four of these characters, adult tunicates retain only one (pharyngeal slits). Lancelets swim by contracting a series of muscles located along the side of the notochord, which results in a motion similar to the swimming motion of fishes. Larval tunicates are mobile, using their tail muscles and notochord to propel themselves through the water; adult tunicates are sessile or float with the current. Adult lancelets and tunicates use their pharyngeal slits to filter suspended food particles from the water.