Comparative Anatomy Higher Amniotes Note Set 4 Chapter 3

Characteristics of Birds Feathers present Homeothermic Single occipital condyle Scales on legs and feet Figure 6.1

Flier and Flightless Birds Archeopteryx- glider sternum Figure 6.2: (a) Archaeopteryx (b) pigeon.

Classification Modern birds- Subclass Neornithes Ancient birds- Subclass Archeornithes Passeriformes- Largest order of birds Birds arose in mid-Jurassic Period (ca. 175 mya)

Mammals Mammals arose in mid-Triassic Period Cenozoic- age of mammals Quaternary and Tertiary Synapsid lineage began with pelycosaurs, which therapsids succeeded Therapsids gave rise to mammals Figure 6.3.

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

Evolution of Reptiles 1. Reduction in number of bones 2. Fusion of bones In reptiles, articular bone articulates with quadrate In mammals, dentary articulates with squamosal Figure 6.4: Mandible cladogram.

Evolution of Mammalian Jaw Articular of lower jaw and quadrate of upper jaw and skull become middle ear bones: maleus, incus and stapes Figure 6.5: Jaw and middle ear bone evolution.

Middle Ear Bones Articular and quadrate evolved from 1st visceral arch Figure 6.6: Origin of middle ear bones; adult (left) and embryo (right). Articular and quadrate evolved from 1st visceral arch Stapes evolved from hyomandibular of 2nd arch Eustachian tube from 1st pharyngeal pouch

Figure 6.7: Skeletal Derivatives of Pharyngeal Arches.

Phylogeny of Mammals Oviparous- egg layers Therapsids and all birds Viviparous- give birth to live young Most mammals Ovoviviparous- retain eggs in body and give birth to live young Many fish and reptiles Figure 6.8: major categories of living mammals .

Placental Type Therians diverged into the metatheria (marsupials) and eutheria (placental mammals) orders Metatheria- yolk sac placenta Eutheria- true placenta chorioallantoic placenta

Characteristics of Mammals Hair Single dentary bone Fused to form mandible in primates Sweat glands Mammary glands Homeotherms Enucleated RBC

Figure 6.9: Eutheria (placenta mammals) phylogeny

Orders in Class Mammalia Infraclass Ornithodelphia: Monotremata- egg layers Infraclass Metatheria: Marsupialia- marsupium present Infraclass Mammalia: Artiodactyla- Even-toed ungulates Perissodactyla- Odd-toed ungulates Rodentia- Largest groups of placental mammals Primates- catarrhine (Old World monkeys and humans) and platyrrhine (New World monkeys)

Suborder Anthropoidea -Infraorder Platyrrhini -Infraorder Catarrhini Two infraorders distinguished by nose form Platyrrhines Nostrils flare to sides Flat nose Wide septum New World monkeys and marmosets Catarrhines Nostrils point straight down Narrow septum Old World monkeys, apes, and humans (a) (b) Figure 6.10: Platyrrhine (a) and catarrhine (b).

Literature Cited Figure 6.1- http://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. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001. Figure 6.5- http://www.mun.ca/biology/scarr/QA_vs_DS_jaw.htm Figure 6.6- http://www.med.unc.edu/embryo_images/unit-ear/ear_htms/ear013.htm Figure 6.9- http://tolweb.org/tree?group=Eutheria&contgroup=Mammalia Figure 6.10- http://anthro.palomar.edu/primate/prim_4.htm