Mammals

The Tell-Tale Hair

The Tell-Tale Hair

Mammals use hair for protection, concealment, waterproofing, buoyancy, behavioral signaling, sensory function, and thermal insulation and to maintain a high, constant body temperature in all climates

Other Unique Mammalian Traits

middle ear bones mammary glands diaphragm placenta teeth

Highly Developed Nervous System Evolution from Synapsids

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Origin and Evolution of Mammals

Skull structures, especially teeth

Therapsids

upright limbs positioned beneath the body rather than on the sides as in lizards and reptiles. Body changes in the skull and mandibular adductor muscles allowing a variety of herbivores and carnivores to form

Cynodonts

evolved features that supported an active lifestyle and higher metabolic rates. Enhanced jaw musculature Secondary bony Important to mammal evolution because it allows young to breathe while suckling.

Early Mammals

Diphyodont

Jaw and Ear Bones Hair and Mammary Glands Diversification of Mammals Continued Diversification

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Integument and Its Derivatives

Generally thicker thin epidermis that is protected by hair and a thicker dermis?

Types of Hair

Hair follicle is an epidermal structure, but lies deep in dermis of skin.

Functions of Hair Periodic Molting Horns and Antlers

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Integumentary Glands

all derived from epidermis. Sweat glands

Scent Glands

marking territory, warning, and defense signals.

Sebaceous Glands

are usually associated with hair follicles

Mammary Glands

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DIVERSITY IN FEEDING

heterodont dentition?

Dentition

Mammals have four types of dentition: Incisors Canines Premolars Molars

Sets of Teeth

have one deciduous set (temporary) are Replaced by a permanent set incisors, canines, and premolars are deciduous compared to molars?

Mammalian Feeding Specializations

Insectivores short intestinal tract pointed teeth

Herbivores

Herbivores? have reduced or absent canines

Ruminants

large four-chambered stomach and long tract for increased fermentation and digestion: rumen re-chewed reticulum omasum abomasum

Carnivores

High protein diet cecum may be absent or reduced.

Omnivores

both plants and animals Many carnivores will switch to fruits, berries, etc. when normal food sources are scarce. store food

FLIGHT

Bats are true flyers a niche not occupied by birds. Gliding and flying may have evolved independently in many mammalian groups.

Echolocation

ultrasonic frequencies 10 pulses per second, increasing to 200 pulses when prey is detected.

Bats and Their Food Bat Diversity

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HUMAN EVOLUTION

The Descent of Man, and Selection in Relation to Sex few human fossils had been found but recent DNA and abundant fossil evidence has strongly vindicated Darwin’s beliefs of common ancestry.

Primate Features

grasping fingers, flat fingernails, and forward-pointing eyes small, nocturnal creatures First group was the lemurs and lorises, which were traditionally called prosimians. Second group was the tarsiers and apes, which were also called simians or anthropoids.

Simians

Three major simian groups: • New World monkeys • Old World monkeys • The apes

Old World monkeys differ from New World monkeys in the lack a grasping tail,

Apes

larger cerebrum, more dorsal scapula and the loss of tail. Hominids include all apeshominins are all hominid fossils placed closer to humans than to chimpanzees.

The First Humans and the Origin of Bipedalism

Human jaws are less robust and have smaller canines foramen magnum Shorter pelvic bones, S-shaped vertebral column

Sahelanthropus tchadensis

ventral foramen magnum to indicate bipedal human.

Ardipithecus

long limbs, fingers, toes, and bipedal

Australopithecus

slightly larger than a chimpanzee. sexually dimorphic

Other Australopithecines

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Australopithecus sediba and Paranthropus robustus

skull crests, heavy jaws, and large back molars.

Genus Homo Migration and Descendants Modern Humans

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Homo neanderthalensis

Homo neanderthalensis replaced H. heidelbergensis in Europe while Homo sapiens moved into Africa between 300,000 to 200,000 years ago.

H. neanderthalensis was more robust, with heavy muscles and adapted to the cold and had similar brain size of modern humans

Homo sapiens

out of Africa about 200,000 years ago Speech was possible for both H. sapiens and H. neanderthalensis