Mammalogy Exam 1

What is mammology

the study of mammals

what are traits that distinguish mammals

- mammary glands
- homeothermic metabolism
- hair
- birth to live young
- synapsid skull
- 3 pairs of auditory ossicles

what is systematics

the system of organization

What is taxonmy

naming and classifying of species

What are synamorphies?

shared derived characters
classify by physical attributes

What is homolgy?

similarities resulting from common ancestry

What is homoplasy?

a character shared by a set of species but not present in their common ancestor

what is analogy ?

an anatomical structure that does the same function but the species are not related

What is adaptive radiation?

the evolution of many diverse species from a common ancestor

what is adaption

A trait that helps an organism survive and reproduce

what is biological adaption

hereditary modification of species structure that increases the probability of survival

What is pre-adaptation?

when an organism's existing trait is advantageous for a new situation

What is speciation?

Formation of new species

What are ecomorphs?

animals with a morphology adapted to a particular environment

what are characteristics of monotremes?

- oviparous
- produce milk and care for young
- lay eggs
- lower metabolism

what are the seven orders in metatheria?

1. Didelphimorphia (American oppsum)
2. Paucitubercuta (shrews and rats)
3. Microbiotheria (montio del monte)
4. dasyuromorphia ( tasmian devils, numbut)
5. paramelemorphia (bandicots)
6. notoryctemorphia (burrow moles)
7. diprotodontia (koala, wombats, kangaroos)

what are the characteristics of infraclass Eutheria?

- placental mammals
- most widely distributed
- viviparous
-higher metabolism
-more intelligent and social

what are the four suborders of eutheria ?

1. afrotheria
2.xenarthra
3. euarchontoglires
4. laurasiatheria

what are the seven orders of Afrotheria?

1. Tubulindenta ( aardvarks)
2. afrosoricidia ( tenrecs and golden moles )
3. eulipotyphia ( shrews, moles, hedgehogs, and gymnurs)
4. macroscelidea ( elephant shrews)
5. hyracoicea ( the hyraxs)
6. proboscidea ( elephants)
7. sirenia ( manatees and dugongs )

what are the orders of subclass xenartha ?

1. Cingulata (armadillos)
2. pilosa (sloths and ant eaters)
evolved in south america

what are the five orders of euarchontoglires ?

- originated in lauriasia
1. Rodentia ( rodents ( most diverse)
2. Lagamorphia ( rabits and harres)
3. Dermoptera (the colugos)
4. Scandentia (tree shrews)
5. primates (monkeys and apes)

what are the five extant orders of laurasiatheria ?

- originated from laurasia
1. Chiroptera (bats)
2. pholidota (pangolins)
3. carnivora ( cats, dogs, bears, lions)
4. cetatriodactyla ( even toed, pigs, dolphins)
5. perissodactyls ( odd toed, horses, rhinos)

What did mammals evolve from?

synapsids

when did synapsids diverge ?

the Carboniferous period

when did monotremes diverge?

monotremes diverged from therapsids in the early triassic

What are amniotes?

tetrapods that have a terrestrially adapted egg

what was the great extinction event ?

P-Tr

what period was the synapsid domination ?

permian period (290-208 mya)

what is the order of synapsids that gave rise to therapsids ?

Sphenacodontia

what are characteristics of therapsids?

- more advanced than synapsids
- dominated upper and middle permian
- diverged into 2 suborders ( animodontia and theriodontia)

what group of therapsids survived into the Triassic

theriodontia, more specifically cynodonts

what are characteristics of Cynodonts ?

survived into the jurassic
cynodonts shrank
gave rise to mammals

what are mammalian characteristics of Cynodonts:

1. Temporal fossa and zygotic arch increased in size
2. expansion of the Dentary and reduction in the other lower jaw bones
3. developed cheek teeth
4. reduction of the non-dentary lower jaw bones
5. the cranium increased in size
6. developed a secondary plate
7. developed nasal turbinates
8. reduction in lumbar limbs ( formed mammalian rib cage)
9. change in skulls attachment to the vertebral column
10. rotation of limbs under the torso

what are some features of cheek teeth

- double rooted
- had three cusps
- tricuspid
- chewing surface deemed occlusal surface

what is the diagnostic feature of mammals

is the jaw joint being composed of the dentary and squamosal bones

what are the advantages of a secondary plate

allowed the baby to nurse and breathe at the same time

what is the nocturnal bottleneck ?

direct effect on mammalian evolution, forced mammals to become nocturnal, vision became reduced, hearing and olfactory improved

what are mammalioformes:

mammal like animals , smaller than cynodonts
point of jaw articulation was the dentary and squamosal
quadrate and angular in the middle ear
gave rise to prototheria and metatheria

describe early prototherians:

- early monotremes
- dentary attached to squamosal
-angular and quadrate were in middle ear
-laid eggs with lethary shells
-pectoral/pelvic girdle more synapsid
- CLOACA

What are the basic monotreme characteristics:

- slender dentary
- small jugular and malar bone
- primitive pectoral girdle
- sprawling forelimbs

what are the two orders of subclass alotheria

Eutricodontia and Multicuberculta

characteristics of eutricodontia

small insectivores
named for their molars, 3 cusps arranged in a row

characteristics of multituberculates:

successful mesozoic group
originated in late Jurassic
very successful and called rodents of the mesozoic
elongated incisors
herbivorous

name Therian traits:

- lack inter-clavicle in pectoral girdle
- coracoid bones in pectoral girdle are absent
- have crurotarsal joint
- have tribosphenic molars

what are characteristics of Tribosphenic molars:

- named for 3 cusps arranged in a triangle

what are the 3 cones of tribosphenic molars

- paracone
-metacone
-protocone

lingual side

side of the tooth closest to the tongue

labile side

side of the tooth closest to the cheek

theodontic teeth

teeth attached to the jaw by roots in the socket

What kind of dentition do mammals have?

heterodont

heterdont dentition

teeth that have various shapes and purposes

what kind of teeth do platypus and echidna have?

monophydontic

what kind of teeth do elephants and manatees have?

polyphydontic

crown

above the gum line

root

below the gum line

what are the three layers of the tooth

1. enamel: outmost layer
2. dentine: major portion of each tooth
3. cementum: bone layer covering the root

what is the pulp cavity:

open space in the crown that contains blood vessels

what kind of roots do mammals have:

closed rooted teeth

orastema

space occurring bt the teeth

what are the types of mammalian teeth:

incisors, canines, premolars, molars

incisors

Teeth between the canines that are used for cutting.

canines

Teeth in front of the premolars that rip and tear food.
unicuspid and one root

Premolars

bicuspids
have two roots

molars

Back teeth that grind food
tricuspid

the trigonid side:

the shearing portion

the talonoid

the crushing / posterior

upper molar:

trigonid only

lower molars:

trigonid and talonoid

where is the protocone located

upper tooth lingual side
lower tooth labiel side

where is the paracone located

upper tooth anterior/labiel side
lower tooth on labiel side

where is the metacone located

upper tooth: posterior and labiel side
lower tooth: lingual side

what mammals were the splitting point between metatherians and eutherians?

- eomaia (oldest marsupial)
- juramaia (oldest placental)

what two eutherian groups survived after the cretaous period?

monotremes and multituberculate

what two factors drove adaptive radiation?

extinction of dinos and beak up of pangea

Quadrate Dentition

molars have an additional fourth cusp on the lingual (tongue) side called the hypocone, located posterior to the protocone.

Bunodont Dentition

animals with teeth that have worn, rounded surfaces (swine)

Hypsodont dentition

high crowned teeth
mammals that eat plants

Brachyodont teeth

Do not grow continually
low crowned

Zalambdont Dentition

molars having 3 cusps; form a "lambda shape"; missing the protocone

stylar shelf

A horizontal portion of the labial side of the tooth

Dilambdont Dentition

modified Zalambdont dentition; forms 2 "lambda shapes"
insectivores have these teeth

Lophodont teeth

Many herbivorous mammals

Cusps fuse to form elongated ridges called lophs.

Creates abrasive surface for grinding plants

**Variably shaped ridges**

Bilophodont Dentition

Refers to lower molars, in Old World monkeys, that have two ridges.

Secodont Teeth

Meet side to side like scissors
Carnivores
Ex: cats, dogs

dental formula

2-1-2-3
upper jaw teeth listed
32 teeth total, only 16 counted

Agenus

less than 32 teeth

supernumero

more than 32 teeth

Biogeography

Study of past and present distribution of organisms

species range

Geographic distribution of species.

what can species range distribution be explained by:

speciation, extinction, and continental drift

ecological biology

studies how organisms interact with their environment and other organisms

Historical biology

looks at changes that have occurred in a species range over time

Endemism/Endemic Species

species restricted to a single specific area

disjunct distribution

a gap in the range of related species or clades

Ecozone

region based on its ecological characteristics

what are the six broad regions:

nearctic, palearctic, neotropical, ethiopean, oriental, australian

Palearctic Region

largest terrestrial region
made up of europe, north africa, and the middle east
divided into east and west paleoarctic

Nearctic Region

North America
2 endemic families

Neotropical Region

The biogeographic region of the Southern Hemisphere that corresponds to South America
19 endemic species

Afrotropical Region

Africa
18 endemic families