Mammology exam 1 lectures 1-4

Which characteristics are present at some stage in all mammals?

Lactogenic ability, hair, and endothermy

Which group do mammals belong to?

SubPhylum Vertebrata

Endothermy is a trait shared by:

Mammals and some other animals

: The Latin root "Mamma" refers to:

Teat or breast

True or False: All mammals are endothermic throughout their entire life.

False

True or False: All endothermic animals are mammals.

False

True or False: There are over 6,800 recognized species of mammals.

True

Name three defining characteristics of mammals.

Hair (hirsute), lactogenic (milk-producing), endothermy (warm-blooded)

List any five examples of mammals.

Humans, dogs, whales, kangaroos, platypus

What does the Latin root of "Mammalia" refer to, and why is it significant?

It refers to "teat" or "breast", highlighting the milk-producing glands unique to mammals.

What are homologous structures?

Structures with a common evolutionary origin, but not necessarily the same function, behavior, or structure.

What are analogous structures?

Structures with similar function in different organisms, but not derived from a common ancestor.

Homologous structures are defined as:

Similar in origin, regardless of function or appearance

: Analogous structures are:

Similar in function, but evolved independently

Which method involves comparing antigen-antibody reactions to infer evolutionary relationships?

Comparative Immunology

True or False: Morphological data used to build phylogenetic trees is always quantitative.

False

True or False: Homologous traits may not necessarily serve the same function.

True

True or False: RFLP and AFLP are methods for analyzing molecular genetic data.

False — It measures genetic similarity

What is the difference between homologous and analogous structures?

Homologous structures share a common evolutionary origin but may serve different functions.Analogous structures perform similar functions but evolved independently, without a shared ancestry.

Name four types of data that can be used to construct phylogenetic trees.

Genetic data, morphological data, ecological traits, behavioral traits

Define Diastema

a space separating teeth of different functions, especially that between the biting teeth (incisors and canines) and grinding teeth (premolars and molars) in rodents and ungulates.

What is Pangaea?

An ancient supercontinent

The movement of Earth's landmasses over time is called:

Continental drift

Vicariance is best defined as:

Geographic isolation caused by natural barriers

Define plate tectonics.

Plate tectonics is the theory that Earth's crust is made up of large geological plates that move over the asthenosphere.

How do vicariance and dispersal differ in terms of species distribution?

Vicariance involves passive separation of populations due to emerging physical barriers, while dispersal involves the active or passive movement of organisms to new areas.

Why is Alfred Wegener important in the context of biogeography?

He proposed the theory of continental drift, which helped explain the current distribution of species across continents.

Why is it important to understand historical continental positions in mammalogy?

To gain insight into mammalian evolution and diversification

What geological feature helped shape mammalian biogeography by allowing species to move between continents?

Land bridges

Vicariance is better understood when we:

Understand how and when continents split or merged

How does understanding historical continental positions help in the study of mammalian evolution?

It provides context for how and when species were isolated (vicariance) or able to move between regions (dispersal), helping explain patterns of diversification and current distributions.

What two processes must be considered when interpreting current mammalian biogeography, and how are they influenced by continental movement?

Vicariance and dispersal; continental drift can isolate populations (vicariance) or create connections like land bridges that allow movement (dispersal).

Around 500 million years ago, a major evolutionary milestone occurred. What was it?

Appearance of animals with hard shells in large numbers

What geological evidence from 450 million years ago supports the idea that Gondwana had equatorial regions?

Warm-water limestone and salt deposits

Which group of vertebrates first appeared around 425 million years ago?

Jawed fishes

The Devonian Period is often called the:

Age of Fishes

What major climate event was occurring around 650 million years ago, prior to the start of the Paleozoic Era?

Around 650 million years ago, Earth was experiencing a major ice age, meaning the global climate was cold. This was during the time of the ancient supercontinent Pannotia, before the Paleozoic Era began.

Describe the significance of the appearance of hard-shelled animals during the early Paleozoic.

Around 500 million years ago, during the early Paleozoic, animals with hard shells appeared in great numbers for the first time. This marks a major evolutionary development because hard shells provided protection from predators, improved fossilization potential, and were a key feature in the Cambrian Explosion, a period of rapid diversification of animal life.

describe a corridor in terms of dispersal?

A pathway connecting similar habitats that facilitates easy movement of species

The Bering Land Bridge is most associated with which geologic time period?

Pleistocene

What type of dispersal route is most likely influenced by chance events?

Sweepstakes route

Define the term filter zone in the context of dispersal and give an example of how it might function in nature.

A filter zone is a type of dispersal pathway that connects different regions and habitats, but unlike a corridor, it selectively allows certain species to pass through while restricting others. This is often due to environmental conditions that only some organisms can tolerate or navigate.

Explain how transoceanic rafting may have contributed to the distribution of primates and rodents in the Western Hemisphere.

Transoceanic rafting is a type of sweepstakes route, where organisms cross large water bodies—usually by accident—on floating vegetation or debris. This method of dispersal is highly unpredictable and relies on luck.

Describe two barriers to dispersal and explain how they might affect species differently depending on their ecology.

Oceans: Large bodies of saltwater prevent most terrestrial animals from crossing. However, marine or flight-capable species may be less affected, and some small mammals might cross via rafting.

Mountains: High elevations and cold temperatures act as physical and climatic barriers. Species adapted to lowland tropical environments may be completely restricted, while those with wider thermal tolerance or climbing abilities may navigate them more successfully.

How did corridors during the Miocene facilitate dispersal between the Oriental and Ethiopian realms?

During the Miocene, corridors—which are paths connecting similar habitats—allowed relatively easy movement of species between the Oriental and Ethiopian realms.

What was the climate like during the Early Carboniferous Period (350 million years ago)?

Warm and wet

What evolved or radiated rapidly during the Early Carboniferous?

Insects

What major geological event occurred during the Late Carboniferous Period (300 million years ago)?

Formation of the supercontinent Pangaea

What group(s) of vertebrates were present during the Early Carboniferous Period?

Amphibians and primitive reptiles

Which major crisis occurred at the end of the Paleozoic Era (Late Permian Period, ~250 million years ago)?

Permo-Triassic Crisis

The Permo-Triassic Crisis was associated with which of the following?

Worldwide glaciation and warming

Approximately what percentage of marine species were wiped out during the Permo-Triassic extinction event?

96%

What major geological change began during the Early Triassic period?

Breakup of Pangaea and creation of a seaway between Laurasia and Gondwana

. What biological pattern followed the Permo-Triassic extinction during the Early Triassic?

Diversification of life, including dinosaurs and early mammals

The slow breakup of Pangaea during the Early Triassic likely led to which evolutionary process for land animals?

Vicariance, where populations became geographically isolated

Which of the following statements accurately reflects the impact of the Permo-Triassic extinction?

It was the greatest extinction in Earth's history, wiping out 96% of marine species

What geological event contributed to higher sea levels during the Late Cretaceous?

Formation of new rifts in ocean basins

During the Late Cretaceous, which two continents were still connected?

North America and Europe

What type of mammals were widespread during the Late Cretaceous?

Multituberculates

In terms of mammalian biogeography during the Late Cretaceous, which statement is correct?

Marsupials were found in North America, dispersing southward

define Synapomorphy

A trait that is shared by two or more taxa (shared derived trait)

Define Sympleisiomorphy

A shared ancestral character state

What major events happened at the K/T boundary

Extensive mountain building (Rockies pushed up for the 2 nd time); Inland seas dryingo Flowering plant radiation and 2 nd insect radiationo General blossoming of life (mammals just taking off), but then an asteroid impact• Massive extinctions from dust cloud darkening of Earth• Or volcanos, crude oil & soot• Or microbes (and maybe dinosaurs were already in decline)

What are the effects of glaciers

Kettle lakes, Ice dams, Pluvial lakes during pluvial periods

Cool with high rainfall & low evaporation•

Many pluvial lakes now dry

Define Species pump

ecological or evolutionary mechanisms that promote rapid speciation. Often due to changing environmental conditions such as climate shifts, sea level changes, or tectonic activity.

Explain the river barriers and marmosets

Molecular data on Amazonian marmosets corresponds with current taxonomy based largely on morphology. Both indicate a strong role of rivers as barriers and their role in diversification of marmosets.

What is a mammal

Domain Eukarya

Kingdom Animalia

Phylum Chordata

Craniata

SubPhylum Vertebrata, Tetrapoda,

Mammalia

Amniote Egg

Membrane with a semi-permeable shell allowing for gas exchange with the environment. Contains yolk for nutrition and a membrane to store waste

What does Synapsida include

Both non-mammalian and mammalian forms.

What is the major early group of Synapsida?

Pelycosauria

What family within Pelycosauria includes Dimetrodon?

Family Sphenacodontidae

During what period did Pelycosaurs live?

Permian Period (Paleozoic Era; ~300-250 million years ago)

Name the three major subgroups of Therapsida.

Dinocephalia, Anomodontia, Theriodontia

When did Dinocephalia and Anomodontia appear?

Late Permian Period (Paleozoic Era)

When did Theriodontia first appear?

Early Triassic Period (Mesozoic Era; ~250-205 mya)

: Which subgroup of Theriodontia is especially important in mammal evolution?

Cynodontia

When did Cynodontia first appear?

Mid Triassic Period (Mesozoic Era)

What family within Cynodontia is noted in this material?

Family Galesauridae

List 4 Hard anatomy of mammals

Lower jaw in single bone on each side (= dentary bone)

Dentary-squamosal jaw articulation. 3 middle ear ossicles (= malleus, incus, and stapes)

Tympanic bone present

Explain Synapsida

Small and agile

Severed ties to water

Amniote egg

Permian: dominant

Triassic: top predators

Explain Pelycosauria

Paraphyletic

Many were large

Dominated early Permian

terrestrial faunas

Extinct end of Permian

What are therapsids?

Advanced synapsids that show evolutionary trends toward mammal-like characteristics.

What do therapsids represent in synapsid evolution?

A transitional group showing traits that lead to true mammals.

What change occurred in the temporal opening of therapsids?

It became enlarged to allow for stronger jaw muscles.

What is the significance of the lower temporal bar in therapsids?

It supports the skull and allows for attachment of larger jaw muscles.

What do sagittal crests and zygomatic arches indicate in therapsids?

Stronger jaw musculature and more complex chewing.

Where is the jaw joint positioned in therapsids?

In line with the occiput, indicating a shift toward mammalian jaw structure

What dental feature is seen in therapsids that is more mammal-like?

Enlarged upper canines, heterodonty, and diphyodonty.

What is the significance of a hard secondary palate in therapsids?

It allows for breathing while chewing, a trait found in mammals.

What is a deep acetabulum, and why is it important?

A deep hip socket that allows for better limb articulation and support.

What skeletal feature was lost in therapsids, aiding flexibility?

Loss of lumbar ribs

What happened to the tail in therapsids?

It became shorter, a trend seen in mammals.