Comparative Comparative AnatomyAnatomy

Higher AmniotesHigher Amniotes

Note Set 4Note Set 4

Chapter 3Chapter 3

Characteristics of BirdsCharacteristics of Birds

Feathers presentFeathers present HomeothermicHomeothermic Single occipital Single occipital

condylecondyle Scales on legs Scales on legs

and feetand feet

Figure 6.1

Flier and Flightless BirdsFlier and Flightless Birds

ArcheopteryxArcheopteryx- - gliderglider

sternumsternum

Figure 6.2: (a) Archaeopteryx (b) pigeon.

ClassificationClassification

Modern birds- Subclass NeornithesModern birds- Subclass Neornithes Ancient birds- Subclass Ancient birds- Subclass

ArcheornithesArcheornithes Passeriformes- Largest order of Passeriformes- Largest order of

birdsbirds Birds arose in mid-Jurassic Period Birds arose in mid-Jurassic Period

(ca. 175 mya)(ca. 175 mya)

MammalsMammals

Mammals arose in mid-Triassic PeriodMammals arose in mid-Triassic Period Cenozoic- age of mammalsCenozoic- age of mammals

Quaternary and TertiaryQuaternary and Tertiary Synapsid lineage began with Synapsid lineage began with

pelycosaurs, which therapsids pelycosaurs, which therapsids succeededsucceeded

Therapsids gave rise to mammalsTherapsids gave rise to mammals

Figure 6.3.

TherapsidsTherapsids

Synapsid skullsSynapsid skulls Possess hair and mandiblePossess hair and mandible Heterodont dentition Heterodont dentition Fusion of two bonesFusion of two bones Single lower jaw bone (dentary)Single lower jaw bone (dentary)

Evolution of ReptilesEvolution of Reptiles

1. Reduction in 1. Reduction in number of bones number of bones

2. Fusion of bones2. Fusion of bones

In reptiles, articular bone articulates with In reptiles, articular bone articulates with quadratequadrate

In mammals, dentary articulates with In mammals, dentary articulates with squamosalsquamosal

Figure 6.4: Mandible cladogram.

Evolution of Mammalian Evolution of Mammalian JawJaw

Articular of Articular of lower jaw and lower jaw and quadrate of quadrate of upper jaw and upper jaw and skull become skull become middle ear middle ear bones: maleus, bones: maleus, incus and stapesincus and stapes

Figure 6.5: Jaw and middle ear bone evolution.

Middle Ear BonesMiddle Ear Bones

Articular and quadrate evolved from 1Articular and quadrate evolved from 1stst visceral visceral archarch

Stapes evolved from hyomandibular of 2Stapes evolved from hyomandibular of 2ndnd arch arch Eustachian tube from 1Eustachian tube from 1stst pharyngeal pouch pharyngeal pouch

Figure 6.6: Origin of middle ear bones; adult (left) and embryo (right).

Figure 6.7: Skeletal Derivatives of Pharyngeal Arches.

Phylogeny of MammalsPhylogeny of Mammals

Oviparous- egg Oviparous- egg layerslayers Therapsids and all Therapsids and all

birdsbirds Viviparous- give birth Viviparous- give birth

to live youngto live young Most mammalsMost mammals

Ovoviviparous- retain Ovoviviparous- retain eggs in body and eggs in body and give birth to live give birth to live youngyoung Many fish and reptilesMany fish and reptiles

Figure 6.8: major categories of living mammals .

Placental TypePlacental Type

Therians diverged into the Therians diverged into the metatheria (marsupials) and metatheria (marsupials) and eutheria (placental mammals) orderseutheria (placental mammals) orders

Metatheria- yolk sac placentaMetatheria- yolk sac placenta Eutheria- true placenta Eutheria- true placenta

chorioallantoic placentachorioallantoic placenta

Characteristics of Characteristics of MammalsMammals

HairHair Single dentary boneSingle dentary bone

Fused to form mandible in primatesFused to form mandible in primates Sweat glandsSweat glands

Mammary glandsMammary glands HomeothermsHomeotherms Enucleated RBCEnucleated RBC

Figure 6.9: Eutheria (placenta mammals) phylogeny

Orders in Class Orders in Class Mammalia Mammalia

Infraclass Ornithodelphia:Infraclass Ornithodelphia: Monotremata- egg layersMonotremata- egg layers

Infraclass Metatheria:Infraclass Metatheria: Marsupialia- marsupium presentMarsupialia- marsupium present

Infraclass Mammalia:Infraclass Mammalia: Artiodactyla- Even-toed ungulatesArtiodactyla- Even-toed ungulates Perissodactyla- Odd-toed ungulatesPerissodactyla- Odd-toed ungulates Rodentia- Largest groups of placental Rodentia- Largest groups of placental

mammalsmammals Primates- catarrhine (Old World monkeys Primates- catarrhine (Old World monkeys

and humans) and platyrrhine (New World and humans) and platyrrhine (New World monkeys)monkeys)

Suborder Anthropoidea Suborder Anthropoidea -Infraorder Platyrrhini-Infraorder Platyrrhini

-Infraorder Catarrhini-Infraorder Catarrhini

Two infraorders distinguished Two infraorders distinguished

by nose form by nose form

Platyrrhines Platyrrhines Nostrils flare to sidesNostrils flare to sides Flat noseFlat nose Wide septumWide septum New World monkeys and marmosetsNew World monkeys and marmosets

Catarrhines Catarrhines Nostrils point straight downNostrils point straight down Narrow septumNarrow septum Old World monkeys, apes, and humansOld World monkeys, apes, and humans

(a)

(b)

Figure 6.10: Platyrrhine (a) and catarrhine (b).

Literature CitedLiterature Cited

Figure 6.1- Figure 6.1- http://www-rohan.sdsu.edu/~rhmiller/chordates2/Chordates2.htmhttp://www-rohan.sdsu.edu/~rhmiller/chordates2/Chordates2.htm

Figure 6.2, 6.3, 6.4, 6.7, & 6.8- Kent, George C. and Robert K. Carr. Figure 6.2, 6.3, 6.4, 6.7, & 6.8- Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.2001.

Figure 6.5- http://www.mun.ca/biology/scarr/QA_vs_DS_jaw.htmFigure 6.5- http://www.mun.ca/biology/scarr/QA_vs_DS_jaw.htm

Figure 6.6- Figure 6.6- http://www.med.unc.edu/embryo_images/unit-ear/ear_htms/ear01http://www.med.unc.edu/embryo_images/unit-ear/ear_htms/ear013.htm3.htm

Figure 6.9- http://tolweb.org/tree?Figure 6.9- http://tolweb.org/tree?group=Eutheria&contgroup=Mammaliagroup=Eutheria&contgroup=Mammalia

Figure 6.10- http://anthro.palomar.edu/primate/prim_4.htmFigure 6.10- http://anthro.palomar.edu/primate/prim_4.htm