32. Vertebrates

Chordates

GNATHOSTOMES: SKELETAL FEATURES

Consider the evolution of protostomes and deuterostomes (this chapter): (1) Compare adaptations in protostomes and deuterostomes for living on land. (2) Recall that changes in the expression patterns of tool-kit genes in arthropods such as insects enabled a dramatic diversification of their segmented appendages and bodies. Design an experiment to test whether this concept applies to vertebrates.

A lamprey, a shark, a lizard, and a rabbit share all the following characteristics except
a. pharyngeal slits in the embryo or adult.
b. vertebrae.
c. hinged jaws.
d. a dorsal, hollow nerve cord.

 No. Annelids lack, for example, a post-anal tail. 

 No. Platyhelminthes (flatworms) lack, for example, pharyngeal gill clefts. 

This describes the group to which you belong.

If an animal has segments, bilateral symmetry, pharyngeal clefts, a post-anal tail, and deuterostomic development, it must be a member of the __________.

 No. Such pharyngeal clefts are one of the defining features of chordates. 

 No. All of these chordates are vertebrates. 

 No. A dorsal, hollow nerve cord is one of the defining features of chordates. 

 All of the listed responses are correct. 

 No. Only one of the choices is correct. 

They all share the basic chordate characteristics.

A lamprey, a shark, a lizard, and a rabbit share all the following characteristics except __________.

Bony Fish

Tetrapod origins and Amphibia

What trait(s) characterize the vertebrates?
a. vertebrae and a cranium
b. jaws and a spinal cord
c. bony endoskeleton
d. notochord and post-anal tail

There is some evidence that pharyngeal slits occur in certain species of echinoderms that appear early in the fossil record. If confirmed, what do these data suggest?
a. Echinoderms are chordates.
b. Pharyngeal slits were present in the earliest echinoderms and lost later.
c. Some lineages of echinoderms are more closely related to chordates than others.
d. Pharyngeal slits should not be used as a trait in phylogenetic analysis.

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

How is the opossum related to you? Select True or False for each statement.
T/F An opossum is an animal, but I am a human.
T/F An opossum is a mammal, but I am a human.
T/F An opossum is a marsupial, but I am a placental mammal.
T/F The opossum and I are both tetrapods.

In Figure 34.25, which of the following is the sister taxon to the archosaurs? 
(A) synapsids 
(B) crocodilians 
(C) turtles 
(D) lepidosaurs

PHYLUM – CHORDATA

Chordates - CrashCourse Biology #24

Short Video: Seahorse Camouflage

CLADOGRAM--11 GNATHOSTOMES

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

The illustration of the opossum skull shows that the ear bones are completely separated from the jawbone (as they are in all mammals). Pose a hypothesis to explain why this separation could be an adaptation that contributed to the radiation of mammals into diverse niches, including a nocturnal lifestyle.

Vertebrate Diversity: Amphibians

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

 No. Hagfish, lampreys, and cartilaginous fishes also have gills. 

 No. Gnathostomes have mineralized teeth. 

 pelvic and pectoral fins with bony supports 

 No. This is a feature of lobe-fins, and it provides evidence that this group may be ancestral to the tetrapods. 

 No. Sharks also possess a lateral line system. 

Consider the fate of a shark that stops swimming.

A feature of bony fish not found in sharks is __________.

To estimate the relative abundance of the major phyla, calculate how many named species of arthropods, mollusks, and nematode worms exist per named species of chordate (the phylum containing vertebrates, including humans; see Table 30.1). Do you think these calculations are likely to be underestimates or overestimates? Why? <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/b4e3951f2d0ca6eb-1677288493508.jpg" style="width: 300px;">

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

Evolution often results in the co-option of a preexisting structure for a new use. Cite three examples from this chapter to support this statement. Evolution can also result in the loss of a trait. Cite three examples from this chapter.

 No. Lampreys and hagfish are the oldest group of living vertebrates, but fossils indicate that earlier vertebrates existed. 

 No. Sharks evolved after conodonts, hagfish, and lampreys. 

 None of the listed responses is correct. 

 No. One of the other choices is correct. 

This group dates to about 500 million years ago.

Which of the following is among the earliest known vertebrates?

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

Vertebrates and tunicates share
a. jaws adapted for feeding.
b. a high degree of cephalization.
c. an endoskeleton that includes a skull.
d. a notochord and a dorsal, hollow nerve cord.

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

Researchers studied mice embryos as a model organism to determine whether the cells of the ear bones originated from the same embryonic cells as the cells that form the jaw in other vertebrates. Why would the researchers use mice instead of humans? Do the results from mice tell you something about your own ears? Why or why not?

True or false? Both echinoderms and vertebrates have endoskeletons. Explain.

"In the chordate phylogenetic tree below, fill in the shared derived character that defines each clade.
a. Notochord
b. Vertebral column
c. Jaws
d. Bony skeleton
e. Four limbs
f. Amniotic egg
g. Hairs"

 No. Although there are nerves associated with these suspension-feeding devices, this is not the best choice. 

 No. This is the wrong end of the animal. 

 No. Although there are skeletal structures associated with these suspension-feeding devices, this is not the best choice. 

Many suspension-feeding devices in many invertebrate chordates are associated with modifications of the throat.

Which of the following chordate characteristics contributes most to suspension-feeding devices in many invertebrate chordates?

Exploring Jawless and Cartilaginous Fish

Compare the adaptations of amphibians and reptiles for terrestrial life.

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

Analyze the morphological data shown here and write a hypothesis to explain the origin of mammalian ear bones. (The cynodont shown is one of many extinct synapsid amniotes that lived early in the lineage that gave rise to mammals.)

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

Gene expression patterns can be used to test hypotheses based on morphology. For example, the regulatory gene Bapx1 is expressed in the hinge of the developing lower jaw in fishes and reptiles. Where would you predict Bapx1 expression to occur in mammals?

Chordate Phylogeny | Evolution & Phylogeny 08 | Biology | PP Notes | Campbell 8E Ch. 43

Birds and mammals are both endothermic, and both have four-chambered hearts. Most reptiles are ectothermic and have three-chambered hearts. Why don’t biologists group birds with mammals? Why do most biologists now consider birds to be reptiles?

Some vertebrates do not have jaws.

Which of the following pairs is not a correct match?

Lecture 16 Origin of Jaws in Fish

A marine biologist has dredged up an unknown animal from the seafloor. Describe some of the characteristics that could be used to determine the animal phylum to which the creature should be assigned.

Tetrapods

 No. "Vivi-" means "live"; thus, viviparous animals bear "live" young; they do not lay eggs. 

 they have a tendency toward multiple births 

 No. The term does not refer to litter size. 

 they have a tendency toward single births 

 they maintain a constant body temperature 

 No. You would expect such a term to contain the suffix "-therm." 

 the young develop within the female's body 

Consider the meaning of the prefix "vivi-."

Some sharks are viviparous, which means that __________.

Which clade does not include humans?
a. synapsids
b. lobe-fins
c. diapsids
d. osteichthyans

Agnatha and the Evolution of a Jaw

 No. Although this statement is true, it is not the best choice. 

Two or more clusters of Hox genes

 Duplications of genes that produce signaling molecules and transcription factors 

 No. All of the other choices are correct. 

There is more than one defining difference between these groups.

Which of the following can be found in vertebrates but not in lancelets and tunicates?

Phylum Chordata

Lecture 25 Jaw Muscles in Early Tetrapods and Amphibians

EVOLUTION CONNECTION Living members of a vertebrate lineage can be very different from early members of the lineage, and evolutionary reversals (character losses) are common. Give examples that illustrate these observations, and explain their evolutionary causes.

 No. Large-scale commercial fishing seems to be causing most of the decline in sharks. 

 No. Birds do not seem to be as sensitive to these problems. 

 No. Turtles do not seem to be as sensitive to these problems. 

 No. Rodent populations do not seem to be as sensitive to these problems. 

This tetrapod group does not have amniotic eggs.

Habitat loss, the spread of a fungal disease, climate change, and pollution are causing severe population declines and extinction in __________.

 No. The lateral line system helps fish sense vibrations in their environment. 

 No. The operculum is not a sensory structure. 

 No. The swim bladder of bony fish plays a major role in adjusting buoyancy. 

 No. The operculum helps with obtaining 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. 

Consider the location of the operculum.

The operculum was an important adaptation for fish because it helps with __________.

A good scientific hypothesis is based on existing evidence and leads to testable predictions. What hypothesis did the paleontologists who discovered Tiktaalik test? What evidence did they use to predict where they would find fossils of transitional forms?

No. Archaefructus sinensis was an early flowering plant.

No. Coccosteus cuspidatus was a placoderm, a fishlike aquatic vertebrate.

No. Dushantuophyton was a marine alga.

No. Kimberella was a mollusc, only distantly related to angiosperms.

What characterizes amphibians?

Which of the following organisms is most closely related to the ancestor of modern amphibians?

Match each description on the left with the corresponding term on the right
Closest relatives of chordates



annelids
nematodes
sponges
arthropods
flatworms
cnidarians
molluscs
echinoderms
chordates<img src="https://lightcat-files.s3.amazonaws.com/problem_images/39508fdb959b07df-1672343333409.jpg" alt="" />

Phylum Chordata-Which animals belong?

Vertebrates

The Chordates

34.4 Gnathostomes

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

 No. None of these animals have or had jaws. 

 Conodonts, placoderms, and acanthodians 

Gnathostomes have jaws.

Which of the following sets of animals contains only gnathostomes?

The size and shape of the vertebrate skull can reveal a great deal about an animal’s lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don’t. Where did ear bones come from?

Analyze the morphological data shown here and write a hypothesis to explain the origin of mammalian ear bones. (The cynodont shown is one of many extinct synapsid amniotes that lived early in the lineage that gave rise to mammals.)


 No. Conodonts were jawless vertebrates restricted to aquatic environments. 

 No. Reptiles are well adapted to land, and they are not the most primitive terrestrial vertebrate. 

 No. Chondrichthyans are restricted to aquatic environments. 

 No. Mammals, which are found in both aquatic and terrestrial environments, are not the most primitive terrestrial vertebrates. 

Consider which of these groups is representative of the most primitive group of extant tetrapods.

The first vertebrates to live on land were __________.

The Incredible Diversity of Bony Fish

Subphylum  Vertebrata Overview

 No. Lampreys have a cartilaginous tube around their notochord; they qualify as vertebrates. 

 No. Sharks have cartilaginous vertebrae. 

 No. Frogs are amphibians; amphibians are vertebrates. 

The correct choice is an invertebrate.

A __________ is a chordate but not a vertebrate.

3840_Chapters 23: Chordata

Fish (Osteichthyes)

A Tail Of Four Feet: the evolution of tetrapod animals

Jawless Fish

Vertebrate Diversity: An Introduction

Pacific Lamprey Life Cycle

Basics of Bony Fishes (Most Fishes)  | Koaw Nature Lesson 3

 No. Although our ears have components of the nervous system, this is not the best choice. 

 No. The notochord does not contribute to the ear. 

Your middle ears are connected to your throat.

Which of the following chordate characteristics contributes most to the formation of your ears?

Gnathostomes

ANIMAL KINGDOM / Gnathostomata / Characters/BIOLOGY / ICSE  /ISC

HHMI BioInteractive: The Origin of Tetrapods

Why were the Tiktaalik fossils an exciting discovery for scientists studying tetrapod evolution?
a. They are the earliest frog-like animal discovered to date.
b. They show that tetrapods successfully colonized land much earlier than previously thought.
c. They have a roughly equal combination of fishlike and tetrapod-like characteristics.
d. They demonstrate conclusively that limbs evolved as lobe-fins dragged themselves from pond to pond during droughts.

 No. Turtles are reptiles, not amphibians. 

 No. Lizards are reptiles, not amphibians. 

 All of the specific listed responses are correct. 

 No. Only one of the choices is an amphibian; the other two choices are reptiles. 

 None of the specific listed responses is correct. 

 No. One of the choices is an amphibian. 

Some amphibians have tails and some do not.

Which of the following animals is an amphibian?

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