Lecture 4- Diversity And Phylogeny Of Tetrapods

Question 1

List the subclasses and orders for the superclass Tetrapoda, class Amphibia

Answer 1

Class Amphibia:
> subclass Labyrinthodontia 
>>> order Icthyostegalia
>>> order Temnospondyli
>>> order Antracosaur

> subclass Lepospondyli

> subclass Lissamphibia
» order Anura
» order Caudata (urodeles)
» order Apoda (caelians)

Question 2

List the orders of the superclass tetrapoda, class Amphibia, Subclass Labyrinthodontia

Answer 2

> order Icthyostegalia
order Temnospondyli
order Antrhacosaur

Question 3

List the orders of the superclass Tetrapoda, class Amphibia, Subclass Lissamphibia

Answer 3

> order Anura
order Caudata (urodeles)
order Apoda

Question 4

List the subclasses and orders of the superclass Tetrapoda, class Reptilia

Answer 4

Class Reptilia
> subclass Anapsida
»> order cotylosauria
»> order Chelonia

> subclass Diapsida
>>> infraclass Euryapsida
>>> infraclass Lepidosauria
>>> infraclass Archosauria
>>>>> order Thecondonta
>>>>> order Pterosauria
>>>>> order Saurischia
>>>>> order Ornithischia
>>>>> order Crocodilia

> subclass Synapsida
» order Pelycosauria
» order Therapsida

Question 5

List the orders for the superclass Tetrapoda, class Reptilia, Subclass Anapsida

Answer 5

> order Cotylosauria

> order Chelonia

Question 6

List the infraclasses and the orders associated with each for the superclass Tetrapoda, Class Reptilia, subclass Diapsida

Answer 6

> infraclass Euryapsida
> infraclass Lepidosauria
> infraclass Archosauria
>>> order Thecondonta
>>> order Pterosauria
>>> order Saurischia
>>> order Ornithischia
>>> order Crocodilia

Question 7

List the orders for the superclass Tetrapoda, class Reptilia, subclass Synapsida

Answer 7

> order Pelycosauria

> order Therapsida

Question 8

List the subclasses for the superclass Tetrapoda, class Aves

Answer 8

> subclass Archaeornithes
> subclass Neornithes

Question 9

List the subclasses for the superclass Tetrapoda, class Mammalia

Answer 9

> subclass Prototheria
> subclass Theria

Question 10

List the classes associated with the superclass Tetrapoda

Answer 10

> class Reptilia
> class Amphibia
> class Aves
> class Mammalia

Question 11

Many sources refer to early Devonian Tetrapods as __________, which are usually replace with the amphibians?

Answer 11

> Labyrinthodonts

Question 12

Labyrinthodont-you of early tetrapods appeared during these time periods?

Answer 12

> late Devonian or early Carboniferous periods

Question 13

__________ are named for the complexly folded pattern of enamel seen in cross-sections of their teeth?

Answer 13

> Labyrinthodonts

Question 14

True or False: modern sources use the term “amphibian” to refer only to the three living classes of amphibians and have dropped the term labyrinthodont?

Answer 14

> true

Question 15

___________ are early Carboniferous tetrapods that were smaller than Labyrinthodonts and have differences in their vertebral column and teeth?

Answer 15

> Lepospondyls

Question 16

___________ appeared during the early Carboniferous period and are thought to have given rise to modern amphibians?

Answer 16

> Temnospondyls

Question 17

What is one of the best know of examples of an early Devonian tetrapod?

Answer 17

> Icthyostegalia

Question 18

What are the characteristics of Icthyostega (

Answer 18

> minute bony scales in skin

> tail with fin rays

> sensory canals with neuromas the cells

> external nostrils located far forward on lateral margins of upper jaws and separated from internal nostrils by a thin plate of bone

> in later tetrapods the external nostrils were located more dorsally, and the internal nostrils were more posteriorly, resulting in a well-defined nasal canal

Question 19

What are the characteristics of Lepospondyls?

Answer 19

> co-existed with Devonian tetrapods

> produced a wide variety of forms

> some forms had horn-like extensions on sides of head that supported skin flaps that may have served as hydrofoils for locomotion or may have been vascularized as gas exchange organ

> Lepospondyls became extinct without giving rise to additional groups

Question 20

Characteristics of early Devonian Tetrapods?

Answer 20

> probably aquatic (even later tetrapods required water for reproduction)

> probably spent most of time in water

> lungs were well developed and frequently used

> early tetrapods (including amphibians) probably retained fish-like scales, but later tetrapods in Permian developed tougher skin with bony plates and ossicles

> By Carboniferous, skulls of early tetrapods were heavily armored

> dorsal median opening in skull for pineal body

> notch at back of skull on either side for tympanic membrane
» New development, because no tympanic membrane existed in fishes or crossopterygians

> rod-like stapes attached to inside of tympanic membrane and inserted into a hole (fenestra ovalis) in the side of the braincase
» sound transmission system which transmitted sound waves to inner-ear mechanism just inside the brain case
» space occupied by the stapes between the braincase wall and the tympanic membrane was forerunner of the tetrapod middle ear cavity
» stapes itself was derived from the hyomandibular element (from the second gill arch) which was used to support the lower jaw in fishes

Question 21

True or False: descendants of early Devonian tetrapods included a variety of forms, most of which became extinct without giving rises to other forms

Answer 21

> true

Question 22

Temnospondyls are thought to have given rise to modern _______?

Answer 22

> amphibians

Question 23

Anthracosaurs appeared during late Devonian or early Carboniferous and co existed with _______?

Answer 23

> icthyostegids

|&raquo_space;> Anthracosaurs included the embolomeres (referred to later in discussion on vertebral column)

Question 24

These evolved from Anthracosaurs and anatomically are intermediates between early tetrapods and reptiles?

Answer 24

> seymouriamorphs

Question 25

These included a wide variety of forms and are thought to have given rise to modern amphibians?

Answer 25

> temnospondyls >>> arose during Mississippian period >>> dominant amphibian during Permian >>> best represented by Eryops (>>>> 6+ feet in length >>>>> heavily boned, thick skull >>>>> may have been an aggressive fish-eating animal that also preyed on other land animals

Question 26

Temnospondyls are best represent by the Eryops (

Answer 26

> 6+ feet in length > heavily boned, thick skull > may have been an aggressive fish-eating animal that also preyed on other land animals

Question 27

What are the characteristics of the caudates (urodeles) [modern amphibian]?

Answer 27

> name implies that they have a tail > includes modern salamanders > earliest salamanders is Karurus (

Question 28

What are the characteristics of the anurans [modern amphibian]?

Answer 28

> name implies that they lack a tail > includes modern frogs and toads > earliest frog ancestor is Triadobatrachus ( earliest known frog id Vieraella ( similar to modern frogs but vertebral column was longer and hind legs were shorter

Question 29

What are the characteristics of the apodans (caecilian)[modern amphibian]?

Answer 29

> name implies that they lack limbs includes modern caecilians > earliest caecilian is Apodops ( wormlike, externally segmented, burrowing, subterranean amphibians

Question 30

What are the relationships shared by the three modern orders (caudates, anurans, and apodans)?

Answer 30

``` > uncertainty as to whether the three modern orders belong to a single subclass or to two or three subclasses > all modern amphibians have pedicellate teeth, cylindrical vertebral centra, and two auditory ossicles, suggesting that they belong to a single subclass, but some workers think otherwise ```

Question 31

List the characteristics of the Seymouriamorphs.

Answer 31

> evolved from Anthracosaurs > represented by Seymouria (>> from Permian sediments from Seymour, Texas >>> structurally intermediate between early tetrapods and reptiles >>> deep, roofed dorso-lateral notch at back of skull >>> Labyrinthodont teeth >>> single occipital condyle (typical of Anthracosaurs) >>> reptilian-like vertebral column >>> centra constructed of two elements each an reptilian-like >>> limb bones similar to reptiles >>> may have laid reptilian-like eggs >>> most anatomical features definitely similar to Anthracosaurs

Question 32

Subclasses of reptiles are based on what?

Answer 32

> skull morphology

Question 33

Classification of the subclasses of reptiles is dependent upon what two features of the skull?

Answer 33

> classification depends on presence of holes (fenestrae) and intervening bony arches located on back sides of skull

Question 34

This term refers to the arch of the reptile skull?

Answer 34

> apsid

Question 35

These skull types have no additional opening other than nasal and orbital openings?

Answer 35

> anapsid (no arch) skulls

Question 36

These skull types have two additional openings aside from the nasal and orbital openings?

Answer 36

> diapsids (two arches) skulls

Question 37

These skull types have one additional opening aside from the nasal and orbital openings?

Answer 37

> synapsid skulls

Question 38

The term "________" has been used in older classification schemes and refers to a skull with one additional opening but is now thought to be a modified diapsid skull?

Answer 38

> euryapsid

Question 39

This subclass includes the cotylosaurs and chelonian (turtles)?

Answer 39

> anapsids

Question 40

True or False: it is now thought that turtles have a modified diapsid skull in which both openings have been lost. Therefore, turtles are probably not direct descendants of the cotylosaur?

Answer 40

> true

Question 41

List the characteristics of the cotylosaur (Didactomorph)?

Answer 41

> stem reptiles for all other reptiles > resembled seymourian tetrapods > may have been several feet in length > had considerable dermal armor > skulls more laterally flattened rather than dorsoventrally flattened as in amphibians > no additional skull openings >>> temporalis muscles are the major jaw-closing muscles and run between the medial side of the lower jaw and the lateral side of the braincase >>> additional openings would allow for more muscle expansion and a more powerful bite and more efficient chewing > earliest cotylosaurs were the captorhinids >>> first appear in Carboniferous period >>> relatively small (>> probably insectivorous

Question 42

______ are characterized by having two lateral cheek openings behind each orbit?

Answer 42

> diapsids

Question 43

Each of the lateral cheek openings, behind each orbit of the diapsids, are bounded by what?

Answer 43

> a bony bar (or arch)

Question 44

True or false: many diapsids have secondarily lost one or both of the bars that bind the lateral cheek openings behind their orbits?

Answer 44

> true >>> modern lizards have lost the lower bar >>> snakes have lost both bars

Question 45

The earliest diapsids appeared during what time period?

Answer 45

> upper Pennsylvanian

Question 46

Summarize the Lepidosauromorphs, an infraclass of the diapisids.

Answer 46

> include modern groups of reptiles: snakes, lizards, Sphenodon (

Question 47

Summarize the Archosauromorphs, and infraclass of the diapsids.

Answer 47

> include crocodilians, flying reptiles, dinosaurs (ornithischians and saurischians) and birds > also referred to as thecodonts because of teeth set into sockets

Question 48

What two groups of dinosaurs are classified according to their pelvic girdle?

Answer 48

> Ornithischians (bird-hipped dinosaurs) | > Saurischians (lizard-hipped dinosaurs)

Question 49

Summarize the Ornithischians (bird-hipped dinosaurs)

Answer 49

> tetraradiate pelvic girdle > include both quadrupedal and bipedal forms > include hadrosaurs, stegosaurs, Triceratops (

Question 50

Summarize the Saurischians (lizard-hipped dinosaurs)

Answer 50

> triradiate pelvic girdle > include both quadrupedal and bipedal forms > include Apatosaurs (

Question 51

The Lepidosaurs include three modern groups of reptiles, what are they?

Answer 51

> Sphenodon ( snakes | > lizards

Question 52

Summarize the Sphenodons (

Answer 52

> has a true diapsid skull and a primitive pectoral girdle > resembles a lizrd but is not a lizard > native to New Zealand

Question 53

These would be the flying reptiles?

Answer 53

> pterosaurs

Question 54

What are the characteristics of the flying reptiles (pterosaurs)?

Answer 54

> thin fold of skin extended between the trunk and the elongated fourth finger of each hand. (Different from pattern in birds) > appear fully developed in the upper Triassic and Jurassic > Rhamphorhynchus was a Jurassic pterosaur: >>> 2 feet in length >>> long tail with rudder-like flap of skin >>>hollow bones (similar to modern birds) >>> example of parallel evolution > early pterosaurs possessed sharp teeth (fish-eaters?) and were found near bodies of water > mostly adapted for soaring but some may have been capable of some power flight

Question 55

List some other diapsids

Answer 55

> crocodilians > phytosaurs >>> closely related to crocodilians but not ancestral to them > mosasaurs >>> marine reptiles > euryapsids >>> plesiosaurs and icthyosaurs

Question 56

True or False: birds are not placed in their own class?

Answer 56

> false | > birds are placed in their own class, Aves

Question 57

** Bird information **

Answer 57

> examination of the cladogram suggests that birds are most closely related to the saurischians

Question 58

** Bird information **

Answer 58

> the term "dinosaurs" (comprised of the ornithischians and saurischians) refers to a paraphyletic group, because it includes the ancestors of birds and dinosaurs but not include the birds

Question 59

Birds my be thought of as what?

Answer 59

> feathered dinosaurs

Question 60

The earliest bird-like fossils belonged to what genus?

Answer 60

> Archaeopteryx (

Question 61

What were the characteristics of the bird-like animals belonging to the genus Archaeopteryx (

Answer 61

> upper Jurassic > bony tail (birds have replaced bony tail with feathers) > separate fingers with claws (birds have reduced digits w/o claws) > teeth (birds lack teeth)

Question 62

What was an indication that Archaeopteryx was a bird, but not the first bird?

Answer 62

> later, better preserved fossils showing the presence of feathers

Question 63

** Bird information **

Answer 63

> there is a gap in the bird fossil record until the Cretaceous, when a few fossils of birds similar to moderns aquatic birds were found >>> Hesperornis (

Question 64

What is the current theory on the origin of birds?

Answer 64

> birds probably evolved from a bipedal archosaur (probably a saurischian) >>> this transition is not in the fossil record >>> neither is there any evidence as to why flight might have evolved >>>>> may have evolved as a means of thermal insulation >>>>> may have evolved as an insect-catching net >>>>> may have allowed for better pursuit of prey or escape from predation >>>>> may allowed early archosaurs to roost in trees at night

Question 65

** Synapsids information **

Answer 65

> synapsids include the pelycosaurs through the cynognathids in the cladogram

Question 66

** Synapsids information **

Answer 66

> members of this subclass appeared in the later Permian 310 to 280 million years ago

Question 67

Members of this subclass were reptile that bridged the gap between reptiles and mammals?

Answer 67

> synapsids

Question 68

What were the earliest synapsids?

Answer 68

> pelycosaurs

Question 69

Later synapsids are collectively referred to as the ________, which are more similar to mammals?

Answer 69

> therapsids

Question 70

** Synapsids information **

Answer 70

> transition from reptiles to mammals occurred between Permian and Triassic 230 to 180 million years ago

Question 71

What are the characteristics of the pelycosaurs (synapsids)

Answer 71

> generally only a few feet in length > NOT contemporary with dinosaurs > some had a large sail-like structure on their back >>> this structure was highly vascularized >>> thought to have been a thermoregulatory device

Question 72

What are the characteristics of the therapsids (synapsids)?

Answer 72

> make up a group of several clades > prosynosuchidae, thrinaxondontidae, and cynognathidae are the cynodont therapsids and are most mammal-like > Cynognathus (>> elbow and knee swung inward to toward the body >>> many features of the skull were more mammal-like >>> transition to mammal-like jaw articulation

Question 73

What mammalian characteristics are shared with advanced therapsids?

Answer 73

> secondary palate consisting of premaxillary, maxillary, and palatine bones > pterygoid bones solidly fused to braincase > enlarged dentary bone > differentiation of teeth into incisors, canines, and cheek teeth > considerable regional differentiation of ribs and vertebrae > legs pulled in > ilium extended forward > elongated sacrum > feet well-developed > jaw articulation pattern: >>> mammalian jaw articulation occurs between temporal bone and mandible >>> reptilian jaw articulation occurs between quadrate and articular bones >>> Triassic therapsid Diarthrognathous (>>>> has both patterns of jaw articulation

Question 74

List some mammalian characteristics

Answer 74

> live birth (except egg-laying mammals) > endothermy (homeothermy) > respiratory diaphragm > four-chambered heart with completely divided ventricle > neocortex >>> multiple layer of neurons covering cerebral lobes of brain > double occipital condyle > mandible consisting of a single bone (dentary) > bony secondary palate > loss of interclavicle (except in egg-laying mammals) > hair/ fur > possess mammary glands

Question 75

Earliest mammals were the ______?

Answer 75

> morganucodonts >>> late Triassic to early Jurassic >>> heterodont dentition with triconodont molars

Question 76

What are the two subclasses of mammals?

Answer 76

> prototheria | > theria

Question 77

Summarize the protheria, a subclass of mammals

Answer 77

> include egg-laying mammals---the monotremes---which lay shelled eggs and retain a reptilian cloaca > examples: duck-billed platypus and spiny anteater (restricted to Australia and New Guinea)

Question 78

Summarize the theria, a subclass of mammals

Answer 78

> include the marsupials (pouched mammals such as the possum and kangaroo) and the placentals > trituberculate molars

Question 79

The earliest known vertebrates were confined to what type of environment?

Answer 79

> an aquatic environment

Question 80

What advantages would there be for an aquatic animal to venture onto land?

Answer 80

> to find new environments when some existing ponds and freshwater environments are dried up > to tap into a new and abundant food source (insects)

Question 81

Terrestrial life requires solving what types of problems?

Answer 81

``` > desiccation > resistance to gravity > changes in organs for special senses > excretion of nitrogenous wastes > changes in reproduction ```

Question 82

Amphibians are subject to _______ when out of water for prolonged periods of time?

Answer 82

> desiccation

Question 83

What type of environment do amphibians require for reproduction?

Answer 83

> an aquatic environment

Question 84

True or False: most amphibians depend partially or entirely on their skin for gas exchange?

Answer 84

> true >>> most amphibians supplement gas exchange through the lungs with gas exchange through the integument >>> the integument must be kept moist to allow diffusion of respiratory gases and must be relatively thin and well vascularized >>> some amphibians, such as plethodontid salamanders, depend entirely on their integument for gas exchange and lack lungs >>>>> NOTE that to maximize surface area for gas exchange, these salamanders are small and very slender

Question 85

What changes in the pituitary gland occur to control desiccation occur when the amphibians are out of water?

Answer 85

> changes in the pituitary gland to secrete vasopressin (ADH = antidiuretic hormone) > this hormone affects the permeability of certain tissues and allows water that would otherwise be lost to the environment to enter tissue spaces and be retained > in humans, this hormone causes the kidneys to retain water and to reduce the amount of water lost as urine

Question 86

How do aquatic animals control for resistance to gravity when upon land?

Answer 86

> the body weight (mass) of aquatic animals is supported in part by the buoyancy of the water in which they live > Terrestrialism requires anatomical adaptations that resist the pull of gravity > some of these adaptations include: >>> more dorsal positioning of the vertebral column >>> considerable development of the pectoral and pelvic girdles and limbs >>> attachment of the pelvic girdle to the vertebral column >>> reduction in axail musculature in favor of an increase mass and complexity of the limb musculature

Question 87

Summarize the vertebral column in terms of the resistance of gravity required for terrestrialism for Devonian tetrapods.

Answer 87

> vertebral column consisted of a series of discs or rings, making up the centra of the vertebrae

Question 88

Summarize the vertebral column in terms of the resistance of gravity required for terrestrialism for early amphibians.

Answer 88

> vertebrae became transformed into a series of ligaments of interlocking bones with attachments for muscles and ligaments > vertebral column remained flexible in more aquatic vertebrates such as salamanders, but became less flexible in those tetrapods that became more dependent on limbs for locomotion >>> aquatic salamanders such as Necturus (>>>> use their trunk and tail for swimming >>>>> limbs are relatively small and more useful for walking on bottom of river or streams >>>>> buoyancy provides some support against gravity >>> more terrestrial amphibians such as frogs and toads have a more rigid vertebral column and depend on limbs for locomotion

Question 89

Summarize the changes in organs for special senses, such as the lateral line system, required for terrestrialism

Answer 89

> the lateral line system is extensively well developed in most aquatic organism such as fishes > this system allows the organism to detect electromagnetic waves in the water and is used extensively to find prey

Question 90

Summarize the changes in organs for special senses, such as the ear, required for terrestrialism.

Answer 90

> the ear of terrestrial vertebrates changed and became able to conduct sound waves in air rather than in the water > lagena formed the cochlea (discussed later in lecture)

Question 91

summarize the changes in special organs for special senses, such as the eye, required for terrestrialism

Answer 91

> evolution of the cornea allowed for coarse adjustment, while the lens allowed for fine adjustment