Chordates and Vertebrate Characters Flashcards Preview

Comparative Vertebrate Anatomy > Chordates and Vertebrate Characters > Flashcards

Flashcards in Chordates and Vertebrate Characters Deck (77):
1

At some time in their life, what characters do chordates and vertebrates possess?

1. Pharyngeal wall with bilaterally symmetrical pharyngeal pouches and pharyngeal slits
2. Mid-dorsal, hollow nerve cord
3. A single, mid-dorsal supportive rod, the notochord
4. A muscular postanal tail at some stage in life
5. An endostyle (perhaps a precursor to the thyroid gland) or thyroid gland

2

Chordate and vertebrate characters that are shared with a variety of invertebrates or absent in some chordates.

6. A segmented body in part; i.e., metamerism
7. A coelom or true body cavity
8. Bilateral symmetry
9. Sense organs and nervous system concentrated in the head; i.e., cephalization; a distinct brain

3

What is phylogeny?

The course of evolution

4

Dendrograms

A graphical representation of phylogeny with branching patterns of evolutionary lines

5

What traits are used to construct dendrograms?

To construct this we might use both primitive or ancestral characters (plesiomorphic characters) as well as derived characters (apomorphic characters)

6

plesiomorphic characters

primitive or ancestral characters

7

apomorphic characters

derived characters

8

synapomorphies

shared derived characters

9

cladistics

A way to classify organisms via recognizing clades to construct cladograms. Cladistic analyses of the vertebrates might not use terms such as Subphylum, Class, Infraclass etc.

10

Clades

all organisms in a lineage plus the ancestors they have in common

11

Cladograms are based on what?

Cladists construct cladograms based only on unique derived characters (apomorphies) and shared derived characters (synapomorphies). Cladograms should graphically show monophyletic lineages.

12

What is a monophyletic lineage?

Lineages that include an ancestor and all its descendants, but only its descendants.

13

paraphyletic group

A paraphyletic group does not include the common ancestor and all its descendants, a monophyletic group does. Excluding birds from the reptiles makes the reptiles paraphyletic. Artificial taxa.

14

polyphyletic group

A polyphyletic group is based on nonhomologous characters, so lumping birds and mammals due to being warm blooded would be polyphyletic. Paraphyletic and polyphyletic groups are artificial taxa.

15

What are considered deuterostomes and share common patterns of development?

echinoderms (starfishes, sea cucumbers, urchins, etc.), hemichordates and chordates

16

protochordates

hemichordates, urochordates, and cephalochordates--they share some or all of the chordate characteristics and were among the earliest chordate like animals

17

Hemichordata

solitary or colonial marine animals that share some of the chordate characters. Lack a notochord and post-anal tail, hence called hemi- or half chordate. Most common are acorn worms. In addition to being deuterostomes,- the hemichordate larva is very similar to the echinoderm larva. Another group of hemichordates, pterobranchs, filter feeds by waving its arm in the water; these are similar to the primitive echinoderms.

18

Chordata

united by the five synapomorphies outlined before

19

Urochordata/Tunicata

Most are sea squirts. Adult sea squirts bear little resemblance to chordates, but their larvae have muscular tails, pharyngeal slits, dorsal hollow nerve cord, notochord, and an endostyle2. Adult sea squirts are found on rocks and pilings in the marine habitat. They filter feed through the pharyngeal slits.
2. Some forms have a post-anal tail

20

Cephalochordata

Small fish-like marine animals, possess all obvious chordate characters, best known by amphioxus, spends most of its time buried in mud. These pre-vertebrates suspension (filter) feed using cilia to produce a current drawing food in the mouth and out the pharyngeal slits.

21

Evolution of the Chordates

The most widely accepted theory of chordate ancestry is that the echinoderms, hemichordates and chordates diverged from a common lineage about 600 million years ago. Today we see offshoots from a common lineage, not direct descendants.

22

Evidence of the evolution of chordates

•Echinoderms and chordates are deuterostomes that share similarities of cleavage, and mesodermal and coelomic formation.
•The echinoderm larva is similar to the hemichordate larva.
•Primitive echinoderms were sessile, filter feeding animals that fed by means of ciliated tentacles called lophophores.
•One type of pterobranch (hemichordate) has a single pharyngeal slit.
•The hemichordates share some of the chordate characteristics while chordates have the five synapomorphies

23

What is the likely evolutionary scenario?

One type of hemichordate, the pterobranchs, are similar to primitive echinoderms, so both may have come from primitive sessile arm-feeder3. These evolved into sedentary, pharyngeal pouch bearing, filter feeding animals. The acorn worm, a hemichordate, is an offshoot of this.
The sedentary, gill bearing prevertebrate supposedly had a free swimming larval stage. The larval tunicate is an offshoot of this. The adult tunicate does not look anything like it though. Progenesis (peramorphosis) 4, accelerated development of the reproductive organs relative to the rest of the body results in reproductive maturity of the larval stage, resulting in a & primitive, free swimming chordate that produced amphioxus (cephalochordate) as an offshoot5, and went on to produce a primitive marine filter feeding vertebrate.
This pre-vertebrate fish-like animal was a suspension feeder that used cilia to move water into the mouth and out the pharyngeal slits.

24

Craniata

have a braincase of some form and vertebrae

25

Agnathans

(without jaws) fishes, they lacked jaws but used a muscular pump to produce a food-bearing water current. Evidence of an early fish-like chordate is the extinct Haikouella discovered in China. It apparently has all the chordate characters and looks similar to amphioxus.
The oldest ancestors to craniates are recently discovered fossils offish-like animals found in China.

26

Myxiniformes

hagfishes are agnathous- eel-like, scaleless, single nostril, no true jaws or girdles, scavengers, one semicircular duct

27

Vertebrata

NA

28

Petromyzontiformes

lampreys are agnathous - eel-like, scaleless, single nostril, poor eyes, no true jaws or girdles, predaceous on live fish, only two semicircular canals. Ammocoetes larva of the lamprey is similar to the primitive hypothetical vertebrate body plan.
Early fish-like vertebrates evolved in marine waters (500m years) and, subsequently, radiated mostly in fresh waters. These agnathous fishes use a muscular pump to produce a Current to capture food, as opposed to the ciliary pump of earlier forms.

29

Conodonts

a group of small jawless fishes of uncertain ancestry

30

ostracoderms

(shell skin) - this term refers to a paraphyletic group of extinct fishes, most were small -1 foot length - had no bony jaws, one or two nostrils, no true teeth, some had no girdles or appendages whereas others had structures homologous to pectoral fins, probably filter feeders, some were pelagic others benthic. Many had thick dermal bony armor covering them; marine or estuarine. Included in this group are heterostracans, anaspids, thelodonts, galeaspids, osteostracans etc.

31

Gnathostomata

Jaw bearing fishes
The most important advance to the remaining fishes was the evolution of jaws from gill arches, allowing them to utilize a great deal more food types. Now these jawed vertebrates can catch and manipulate food with their jaws. This separates the agnathous or jawless fishes from the jaw bearing fishes (Gnathostomes). The development of true paired fins (pectoral and pelvic fins) also allowed a great deal of motility in these fishes, allowing them to radiate into many niches.

32

Placodermi

(plate skin) - There is disagreement as to whether acanthodians, placoderms or sharks were the first jawed fishes, our text considers placoderms to be the first. Fresh water (at first) and marine fishes from few inches to over 20 ft. in length. Heavy bony armor anteriorly with a distinct hinge between the cranial and trunk bones. Most were predators. They had upper and lower jaws and paired appendages. All extinct. Exact ancestry is unsure but appear related to sharks.

33

Chondrichthyes

cartilaginous fishes (mostly marine) share a common ancestor with the bony fishes.

34

Elasmobranchii

(plate-gills) - more prevalent in the past. They primarily have cartilaginous skeletons, anatomically heterocercal tail in which the vertebral column courses into the upper lobe, dermal denticles or placoid scales, no swim bladders; males have claspers for internal fertilization. Includes ancestral and living sharks, rays, and skates.

35

Elasmobranchii

(plate-gills) - more prevalent in the past. They primarily have cartilaginous skeletons, anatomically heterocercal tail in which the vertebral column courses into the upper lobe, dermal denticles or placoid scales, no swim bladders; males have claspers for internal fertilization. Includes ancestral and living sharks, rays, and skates.

36

Holocephali

(all head) - chimaeras or rat fishes. Cartilaginous fishes as well, but have external gill slit covered by a fleshy operculum - deep water living; males have a head clasper for copulation. Probably derived from predecessors of modern sharks.

37

Acantnodii

(spine form) - These fishes were small with prominent fin spines, lived mostly in freshwater; some were plankton strainers, others were predators. They are related to bony fishes and are all extinct.

38

Osteichthyes

These bony fishes appeared in freshwater and radiated in the marine and fresh waters. All have a bony endoskeleton. Classification is debatable - There was an early split between the two groups of osteichthyes, the ray-finned fishes (Actinopterygii) and the fleshy-finned fishes (Sarcopterygii).

39

Actinopterygii

(ray-finned fishes) Membranes of the fin are supported by bony rays. Dominant subclass of fishes with two main lines of evolution, the Chondrostei and the more recent Neopterygii.

40

Chondrostei

Only living chondrosteans include the sturgeon and paddlefish

41

Neopterygii

More ancestral neopterygians include the gars and bowfin (Amia). The most advanced and successful neopterygians are the teleosts (Teleostei) which encompass over 30,000 species. The latter are the dominant group of fishes today.

42

Sarcopterygii

(fleshy paired fins with an internal bony pattern seen in all subsequent vertebrates) - Sarcopterygians had internal nostrils, muscular fleshy-lobed paired fins and heavy scales. Included in this group are the Actinistia (coelacanths including Latin America) and a group called rhipidistians which includes the lungfishes Dipnoi found in Africa, S. America and Australia.

43

Actinistia

coelacanths including Latin America

44

sarcopterygian rhipidistian

the extinct sarcopterygian rhipidistian lineage that gave rise to the first amphibians. These transitional extinct vertebrates are sometimes called "labyrinthodonts

45

labyrinthodonts

they have a characteristic grooved teeth. The earliest "labyrinthodont" amphibians were very similar to their rhipidjstjan fish relatives. Had dermal scales, fish-like tails, and similar skulls.

46

Amphibia

All amphibians are still tied to the water for respiration, existence and reproduction. Have moist skin, no amnion or chorion, no true claws, thin cornified layer in the skin, one sacral vertebra, tympanum for sound reception, and they cannot regulate their body temperature internally (poikilothermic exotherms)

47

poikilothermic exotherms

cannot regulate their body temperature internally

48

Two key characters resulted in their ability to live on land

1. Respiration by means of lungs
2. Development of limbs for walking

49

Gymnophiona

(formerly Apoda) - caecilians which are wormlike burrowers without limbs or girdles, having dermal scales lying within the annuli that encircle the body.

50

Urodela

salamanders; "newts" are aquatic salamanders of one family

51

Anura

frogs and toads

52

Amniotes

because of their embryonic membranes (LIST)

53

Reptilia/Reptilomorpha

- First vertebrates to be free of the aquatic environment. Have epidermal scales, dry skins, no external mucous glands, at least two sacral vertebrae, single occipital condyle, true claws, but still no internal way to regulate their body temperature within narrow limits. Most lay eggs that have embryo in embryonic membranes: amnion, chorion and allantois. This is the amniote or cleidoic egg. Because of egg which prevents desiccation, internal fertilization is necessary.

54

Testudines

turtles (however recent molecular work suggests turtles are diapsids

55

Diapsida

two fenestra in the skull. Includes:
Ichthyosaurs & Plesiosaurs
Lepidosauria

56

Ichthyosaurs & Plesiosaurs

aquatic reptiles that are extinct

57

Lepidosauria

Scaly reptiles

Sphenodontidae
Squamata

58

Sphenodontidae

the tuatara of New Zealand - ancestral lizard.

59

Squamata

1. Iguania - iguana, chameleons and lizards
2. Gekkota – geckos
3. Amphisbaenia - worm-lizards (legless, burrowing);
4. Serpentes – snakes

60

Archosauromorpha

Ruling reptiles. Includes:
a. Crocodilians - crocodiles, alligators, etc.;
b. Pterosauria - gliding reptiles;
c. Ornithischia or "bird-like" dinosaurs - based on bird-like pelvis - herbivores.
d. Saurischia or "reptile-like" dinosaurs - based on pelvic structure – carnivorous and herbivorous dinosaurs + Aves

61

Crocodilians

crocodiles, alligators, etc.;

62

Ornithischia

"bird-like" dinosaurs - based on bird-like pelvis - herbivores

63

Saurischia

"reptile-like" dinosaurs - based on pelvic structure – carnivorous and herbivorous dinosaurs + Aves

64

Aves

came from a saurischian therapod. One of the earliest bird remains are those of Archaeopteryx which had three fingers on the hand with claws, a dinosaur-like pelvic girdle, a long tail with feathers, teeth, a small bony sternum or breastbone, and abdominal ribs. One group of living birds called "ratites", includes ostrich, emus, rheas, cassowaries and kiwis, which are flightless. The barbs on their feathers do not interlock like other birds.

65

Neornithes

Modern birds. Neornithes. Neornithes are generally characterized by true flight, feathers, lightweight bones, air sacs, modified lung, only a left ovary and oviduct usually, high body temperature that can be regulated within narrow limits i.e. homeothermic endotherms, lack of a urinary bladder, teeth absent etc. About 8,500 species in 32 orders. Three orders are:
Pelecaniformes - tropic birds, pelicans, cormorants, frigate birds, etc.
Falconiformes - condors, hawks, eagles, falcons
Passeriformes - perching birds, including over 4,000 species of song birds

66

homeothermic endotherms

high body temperature that can be regulated within narrow limits

67

Pelecaniformes

tropic birds, pelicans, cormorants, frigate birds, etc

68

Falconiformes

condors, hawks, eagles, falcons

69

Passeriformes

perching birds, including over 4,000 species of song birds

70

Synapsida

"mammal-like" reptiles; have single temporal fenestra.

71

Therapsids

Ancestral to mammals

72

Mammalia

Mammals evolved from the therapsid reptiles, now are most diverse class of terrestrial vertebrates. Unique features include mammary glands, sweat and sebaceous glands, three ear bones, squamosal-dentary jaw joint, and anucleate adult red blood cells. They are homeothermic endotherms.

73

Homeothermic Endotherms

LOOK UP

74

monotremes

include the duckbilled platypus and spiny anteater (Echidnas) in Australia and New Guinea. These lay large reptilean-like eggs, have poorly developed mammary glands with no nipple, more limited tooth replacement, have a cloaca, abdominal testes, and little ability to maintain constant temperature.

75

Theria

bear live young, have diagnostic molar teeth, and have well developed mammary glands. They are divided into two groups metatheria and eutheria

76

Metatheria

which includes the marsupials - most in Australia; short intrauterine development and don't form a true placenta; most have well developed marsupium

77

Eutheria

which are the true or placental mammals having a chorioallantoic placenta.