Mammalogy Unit 1

Mammalogy

The study of mammals

Mammal Shared Features

Vertebrate

Endothermic

Coat of fur

Possess mammary glands

Give birth to live young (few exceptions)

Endothermic

Internal generation of body heat; aided by fur/hair

Vibrissae

Specialized hair

Aristotle

One of the earliest important figures in the study of mammalogy

Aristotle’s first classification scheme

Viviparous quadrupeds:

• Cloven hoofs

• Solid-hoofed

• others

Cetaceans

Humans

Galen

Famous Roman physician. Anatomist - discovered organ system (130-201 AD)

Mark Catesby

English explorer who documented animals in North America (1683 - 1749)

Georges Buffon

French explorer who documented animals in North America (1707 - 1788)

Carolus Linnaeus

Wrote Systema Naturae (1758) which established bases for modern taxonomy

Binomial Nomenclature

E.g. Homo sapiens

Lewis and Clark

1804: St. Louis to Pacific Ocean

First to report and describe many mammals

Zebulon Pike

1805: Tasked with finding the source of the Mississippi (failed).

Described many new mammals of the American Southwest

Fur Trade

Late 1700s - Early 1800s. Period of severe exploitation, crashed populations of many mammals. By the 1850s became almost nonexistent due to overexploitation.

Spencer Fullerton Baird

Wrote the General Report on North American Mammals (1859) (1823 - 1887)

C. Hart Merriam

Wrote North American Fauna. Developed techniques to identify mammals, including cranial traits and dentition. First president of the American Society of Mammalogists (1919) (1855 - 1942)

Joseph Grinnell

Established mammalogy as an academic discipline. Defined the niche. (1877 - 1939)

Biological Species Concept (BSC)

Species are distinct when reprod

Phylogenetic Species Concept (PSC)

Species are the smallest diagnosable cluster of individual organisms within which there is pattern of ancestry and descent

Subspecies

Group of organisms that can inbreed with others from another population

Phylogenetic Tree

A way to show relationships between organism through evolutionary time

Cladogram

A way to show relationships between organisms through their shared traits

Monophyletic Group

A group of species descended from one common ancestor.

Root

Most recent common ancestor of all species in a phylogenetic tree

Outgroup

Helps infer primitive states of in-group

Node

Represents a speciation event

Internal branch

A hypothesized ancestral species

Convergent Evolution

Some species may look similar, but are unrelated.

Edentata

Meaning “toothless”. Originally comprised of both families Cingulata and Pilosa until being found to be polyphyletic

Biogeography

The distribution of organisms

Causes of changes in species range

• Continental Dirft

• Rise of Landforms

• Ecological Constraints

• Extinction & Diversification

Pangaea

Supercontinent: 225 MYA Permian

Laurasia & Gondwanaland

Supercontinents: 200 MYA Triassic

Current Faunal Regions

• Nearctic

• Palearctic

• Neotropical

• Argentine

• Ethiopian

• Mediterranean

• Madagascan

• Australian

• Oriental

• West Indian

Vicariance

Geographic isolation of populations over time

Wallace’s Line

Discovered by Alfred Russell Wallace. Found going through Southeast Asia and Australia; species on either side of the line are fundamentally different from each other

The Great American Interchange

Panamanian isthmus rises out of the ocean during the Pleistocene, allowing for dispersal between the Americas

Bergmann’s Rule

An ecogeographic principle that states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments and species of smaller size are found in warmer regions

Allen’s Rule

Mammals in colder climates have shorter limbs than those in warmer climates

Chicxulub Crater

Apart of the modern day Yucatan Peninsula. The impact site of the meteorite that caused the K-2 extinction event 65 MYA.

Pennsylvanian Period

First appearance of synapsids 323 MYA

Triassic Period

First appearance of mammals 248 MYA

Paleocene Epoch

Adaptive radiation of metatherians and eutherians 65 MYA

Amniota

Common ancestor of mammals & reptiles.

Key Traits: amniotic sac, shelled egg

Cranium

Top part of a mammal skull

Mandible

The dentary bone

Heterodont Dentition

Different types of teeth for different purposes

Temporal Fossa

Opening for temporalis muscle to connect to dentary bone

Synapsida

Mammal-like reptiles (~320 MYA). Had one temporal opening behind orbit and heterodont dentition.

Eventually diverged intp Pelycosauria and Sphenacodontia, the latter would later diverge into Therapsida

Pelycosauria

Terrestrial herbivores and the largest land vertebrates during the Permian. ~280 MYA

Sphenacodontia

Dominant carnivore with an angular bone in their inner jaw, which would eventually become the middle ear in mammals. ~280 MYA

Mammalian ear bones

Malleus, Incus, Stapes

Zygomatic Arch

Allows for passage of jaw muscles

Temporalis

Jaw closing power

Masseter

Grinding force

Therapsida

Carnivores. Limbs went from being out to the side to being underneath their body. ~248 MYA

Cynodontia

Emerged from Therapsids during the Triassic. Developed a secondary palate, complex cheekteeth, cusps on the teeth, and 2 occipital condyle. Very mammal-like. 213 MYA

Secondary Palate

An adaptation that allows some mammals to breath more efficiently and retain moisture in the nasal cavity

Diphyodont

2 sets of teeth, including deciduous (milk teeth) and permanent

Thecodont

Teeth set in sockets called dental alveoli

Food Habits

• Insectivorous

• Carnivorous

• Herbivorous

• Omnivorous

Insectivorous Orders:

• Monotremata

• Notorctemorpha

• Pilosa

• Pholidota

• Tubulidentata

• Carnivora (aardwolfs)

• Eulipotyphla

• Chiroptera

• Cingulata

Procumbent

Forward pointing incisors, found in insectivores

Tactile Receptors

Structures that help insectivores find invertebrate food (Platpus bill, Eimer’s organ)

Eimer’s Organs

22 fleshy appendages that provide sensory input

Myrmecophagous

“Ant-eaters”. Has reduced and/or simplified (peg-like) teeth, enlarged salvary glands that has digestive enzymes and produce sticky secretions, and a long, sticky tongue.

Carnassials

Modified premolar, used for shearing

Papillae

Specialized hairs on tongue of felines used to scrape meat from carcass

Sanguinivorous

“Blood-eating”. Famously vampire bats. Have knife-like canines, small cheekteeth and a frooved tongue to lap up blood

Herbivorous Browsers and Grazers

• Cetartiodactyla

• Perissodactyla

• Diprodontia

• Pilosa

• Probos

Herbivorous Gnawers

• Rodentia

• Lagomorpha

Rumination

Digastric digestive system

Foregut Fermentation

Ruminants. Multi-chambered stomach

Rumen

Moistens food

Reticulum

Cud forms, regurgitated, enzymes digest

Omasum

Food swallowed 2nd time, kneeded

Abomasum

“True Stomach” of foregut fermenters

Hindgut Fermentation

Do not regurgitate food and absorbs nutrients in the small intestine. Less efficient but passes food rapidly. Must eat more.

Coprophagy

Feed on feces, which optimizes uptake of nutrients

Insectivores

Invertebrate eaters. Lack fibrous diet and have a fast digestion because fermentation is not required

Carnivores

Meat eaters. Have a short intestine and small cecum

Ruminant Herbivores

4-chambered stomach, large rumen and long small and large intestine.

Non-ruminant Herbivores

Simple stomach, but large stomach

Integument

Refers to skin, glands, hair, and epidermal derivatives. Plays a role in homeostasis, behavior and predation

Erector Pili

Muscles that make your hair stand up

Angora

Hair growth that is continuous

Definitive Hair Growth

Growing to a certain point before being shed

Pelage

Body hair

Awn

Guard hairs. Long and coarse

Underfur

Short, dense, fine fur underneath awn

Bristles

Long, angora growth for visual signaling

Disruptive Hair Coloration

Disorients predator

Crypsis Hair Coloration

Camouflages

Aposematic

Warning coloration

Scent Glands

Modified eccrine or apocrine glands that secrete pheromones for mate attraction. Can also be used for defense.

Mammary Glands

Used for milk production (lactation)

Distil Phalanx

End of a cats claw

Horn

Inner core of bone from frontal bone, outer layer is keratinized epidermal growth. These often grow continuously and can be found in both sexes

Antlers

Made entirely of bone, are branched, experience annual regrowth and are only in males (except caribou)

Ambulatory

Walking species