mammalian characteristics etc

mammalogy definition

study of mammals, or the animals in the class Mammalia, which is a taxonomic group of vertebrates

mammals in phylogenetic context

defined as all descendants from the most recent common ancestor of monotremes, marsupials, and placental mammals

reasons to study mammals

• food and other sources

• recreation (pets)/hunting

• disease (as reservoirs or vectors), or medical science (models for human diseases)

• conservation, which relates to human survival

the oldest known animal painting is approximately how old?

40,000 years old

first animals to be domesticated

goats and sheep for food; dogs for companionship

what accomplishment did galen have?

recorded dissections of various organisms; description of the musculoskeletal system of Barbary macaques was treated as definitive for human anatomy at its time; studied anatomy of circulatory system

what accomplishment did hippocrates have?

considered the father of medicine

aristotle and the scale of nature

early classification scheme that had man at the top, followed by mammals and cetaceans

mark catessby

one of the European explorers who began intensive collection of specimens and brought back to hoem country for further study

systema nature

published in 1735 by carolus linnaeus; used hierarchical classification; linnaeus came up with binomial nomenclature, using Genus followed by species

why was linnaeus’ systema naturae such an important contribution?

it was the basis for modern taxonomy and nomenclature

alexander von humboldt

foundation for the field of biogeography; first person to describe the phenomenon and cause of human induced climate change

lewis & clark

sent by thomas jefferson to explore territory of louisiana purchase; first to describe grizzly bear and black-tailed prairie dog

number of species of mammals that have been described?

about 6,500

where are undescribed species still likely found?

equatorial africa; indonesia/papua new guinea; south america

how we have come to mammals?

• fur trappers and traders

• whaling

• zoos: first for entertainment, then for conservation and research

• museums

spermaceti

waxy substance used in cosmetics, leather-working, and lubricants; obtained from head of whale

ambergris

used in perfume; a solid waxy substance from the digestive tract

domain

highest taxonomic rank of organisms; broken down into bacteria, archaea, and eukarya (which mammals are in)

kingdom

whittaker’s system: monera (prokaryotes); animalia; plantae; fungi; protista

kingdom animalia

• heterotrophic

• move

• big (many cells)

• no cell walls

• eukaryotes

• over 1,500,000 described species (most are invertebrates; about 1,000,000 are insects)

what is the lowest taxonomic level these organisms share with mammals?

kingdom

characteristics that unite phylum chordata

• notochord: develops into vertebral column/vertebra

• hollow dorsal nerve chord (DNC): develops into the central nervous system

• pharyngeal slits: develops into jaw and inner ear in terrestrial animals

• post anal tail: absent in humans and apes, although present during embryonic development (all mammals have this)

what animal is this?

lancelet, a primitive chordate

characteristics of subphylum vertebrata (craniata)

• well-defined cranium

• vertebrata

• bilaterally symmetrical

• closed circulatory system

breakdown of vertebrate species

• 60,000 total species

• about 15,000 amphibians and reptiles

• about 30,000 fish

• about 10,000 birds

• about 6,500 mammals

What is the lowest taxonomic level this organism shares with mammals?

subphylum vertebrata (craniata)

synapomorphy

an apomorphy (derived trait) shared by two or more taxa and is therefore hypothesized to have evolved in their most recent common ancestor

mammalian synapomorphies

• three ear bones: malleus, incus, and stapes (from outermost organ to innermost)

• presence of hair, which is dead keratin

• mammary glands for milk production

what is a synapomorphy?

a trait shared exclusively by the descendants and their common ancestor

mammalian synapomorphies

• ear ossicles

• presence of hair

• mammary glands

name domain, kingdom, phylum, sub-phylum, and class for mammals

eukarya, animalia, chordata, craniata (or vertebrata), mammalia (respectively)

crown group

the smallest clade that inclues all living members of a group and any fossils nested within it

stem group

set of extinct taxa that are not in the crown group but are more closely related to the crown group than to any other

mammalian characteristics of hard anatomy

• lower jaw made up of a single dentary on each side (the dentary is made of two bones) (reduction of bones leads to increased strength)

• three middle ear ossicles (bones); derived from the jaw bones of ancestors; include malleus, incus, and stapes

• dentary-squamosal articulation

• temporal opening of the skull

• double occipital condyles

• hard secondary palate

• heterodont dentition (not in all)

hard secondary palate

• keeps nasal cavity from collapsing when mouth is full of food

• allows for eating and breathing at the same time

characteristics of mammals in post-cranial skeleton

• thoracic ribs only (no lumbar or cervical ribs)

• diversified skeleton that is ossified, lighter, simplified, with limbs under body

• reduced shoulder girdle (only 1-2 bones)

• epiphyseal lines on long bones allows joint to remain stable while bone is growing

• calcaneous (heel bone) present: functions as lever for muscles in calf

• reduced number of phalanges

phalanges

bones that make up the fingers and toes; 2-3-3-3-3 found in most mammals

characteristics in mammals in soft anatomy

• complex integumentary structures: hair; sweat glands; sebaceous glands; true horns

• lactogenic (milk producing) via nipples, mammary slits (cetaceans), or mammary pores (monotremes)

• complex facial-dermal muscles: control over vibissae; allows babies to purse lips to nurse

• ear pinna: the ear flap

• enucleated red blood cells

• muscular diaphragm: aids in ventilation of the lungs

• no renal portal system

• four-chambered heart

• endothermic, homeothermic

examples of hair (dead keratin)

• unique to mammals

• scutes/scales in pangolin, true horn in rhinos; carapace in armadillo