LAB #5




The mammalian skeleton serves four primary functions: 1) support, 2) protection, 3) attachment sites for muscles, and 4) leverage for movement.  Although similarities are found in skeletal morphology, shape, and structure between the various subgroups of mammals, many differences are noted as well.  These modifications are adaptations to more recently evolved, specialized lifestyles.  We will use the domestic cat skeleton as our model to learn the basic units of the skeleton.  The mammalian skeleton can be subdivided into two main regions, the axial skeleton and appendicular skeleton.  The axial skeleton is comprised of the vertebral column and ribs, whereas the appendicular skeleton consists of the appendages used for locomotion.  Except for the cetaceans (whales) and sirenians (manatees and sea cows), mammals are tetrapods and have four appendicular limbs, although the limbs of the marine carnivores (seals, sea lions, and walruses), cetaceans (whales), and sirenians (manatees and sea cows) are highly modified.  These modifications in the cetaceans and sirenians are so great that the hind limbs are vestigial and not externally visible.





The axial skeleton is the primary source of support for the body and transfers this weight to the appendages.  Additionally, by flexion and extension, the axial skeleton assists in movement.  The vertebral column of the axial skeleton has five main regions:  1) cervical, 2) thoracic, 3) lumbar, 4) sacral, and 5) caudal.  Examine the cat skeleton and locate these regions.  Where is the axial skeleton the most flexible?  Examine the different types of vertebrae on display.  You should be able to identify each type of vertebrae (i.e., cervical, thoracic, lumbar, sacral, and caudal) when disarticulated. 





The appendicular skeleton consists of the pelvic (hip) and pectoral (shoulder) girdles and their associated appendages.  Modern terrestrial vertebrates, especially mammals, have greater locomotor capabilities because of the rotation of the appendages beneath the body.  Use the diagrams on the following pages to learn the bones of the appendicular skeleton. The appendicular skeleton has been modified in the different groups of mammals for more specialized forms of locomotion.  These changes are useful when comparing the different lifestyles exhibited by mammals.  The most primitive form of locomotion is ambulatory (walking).  The ambulatory mammals are plantigrade in form and few modifications are noted in the metacarpals and metatarsals as the animals walk on the soles of their feet.  Plantigrade mammals may also run on their toes to lengthen their stride and thus increase speed.  Examples of plantigrade locomotion include humans, apes, bears, and raccoons. A few of the plantigrades are truly cursorial (running) in locomotion; these are mice and shrews. The other cursorial mammals are either digitigrade or unguligrade.  Animals are considered to be digitigrade when only the toes are in contact with the ground.  Digitigrade mammals often exhibit a reduction in number of toes and the metacarpals and metatarsals are elongated.  Mammals that rely on cursorial locomotion, either for feeding or predator avoidance, are often permanently digitigrade (e. g., Felidae and Canidae).  Ultimate modification of the limb structure for cursorial movement is found in the ungulates, especially those inhabiting the open plains and grasslands.  These animals are called unguligrade and the phalanges are elevated such that only the hooves contact the ground.  Greatest reduction of digits is found in horses, which run on a single digit.  Many other modes of locomotion are found in mammals.  You should learn the following terms and be able to use them when describing the lifestyles of mammals. 





Ambulatory -- walking (examples include: apes, bears, raccoons)

Amphibious -- spends time in both aquatic and terrestrial habitats (beaver, muskrat, otters)

Aquatic --living mostly in water, but can come onto land for some activities (seals)

Arboreal -- living in trees; may involve adaptations such as elongated limbs or a prehensile tail (New World monkeys)

Cursorial -- running (carnivores and ungulates)

Digitigrade -- running with only the digits touching the ground (carnivores)

Fossorial -- living underground, generally requires adaptations for digging tunnels or burrows in soil (moles, pocket gophers)

Glissant -- gliding (flying squirrels)

Graviportal -- walking on straight, pillar-like legs located directly beneath the generally heavy body (elephants, hippos)

Marine -- spending entire life in water, generally the ocean (whales)

Plantigrade -- walking or running on the soles of the feet (humans, raccoons)

Ricochetal -- jumping using only the hind legs for propulsion (kangaroos and kangaroo rats)

Saltatorial -- jumping using both the front and hind legs for propulsion (rabbits and hares)

Scansorial -- climbing (bears, squirrels, primates)

Unguligrade -- running with only the unguis or hooves touching the ground (ungulates)

Volant -- true flight (bats only)




Use the skeletal material provided in lab to learn the following bones and structures of the cat skeleton. 


 1.  Cranium                                                     19.  Pubis

 2.  Axis                                                           20.  Floating Rib

 3.  Cervical Vertebrae                                     21.  True Rib

 4.  Thoracic Vertebrae                                     22.  False Rib

 5.  Lumbar Vertebrae                                      23.  Xiphoid Process

 6.  Sacrum                                                       24.  Sternebrae

 7.  Ilium                                                           25.  Manubrium

 8.  Ischium                                                       26.  Phalanges

 9.  Caudal Vertebrae                                       27.  Metacarpals

10.  Fibula                                                        28.  Carpals

11.  Calcaneus                                                  29.  Ulna

12.  Phalanges                                                  30.  Radius

13.  Metatarsals                                                31.  Humerus

14.  Tarsals                                                      32.  Glenoid Fossa

15.  Head of Femur                                          33.  Spine

16.  Femur                                                       34.  Scapula

17.  Tibia                                                          35.  Atlas

18.  Patella                                                       36.  Mandible

























As you become familiar with the bones and structures, sketch and label the long bones, pelvic girdle, scapula, and vertebrae.  Be sure to label any features that help you identify the different bones and vertebrae types.  You will be expected to be able to identify a given vertebra to type (cervical, thoracic, lumber, sacrum, or caudal).  Additionally, you may be asked to identify some of the more conspicuously shaped bones from the cat, even when they are disarticulated from the skeleton.








Scapula                                                            Forelimb








Pelvic girdle                                                     Hindlimb








1st cervical vertebra                   2nd cervical vertebra                Typical cervical vertebra










Thoracic vertebra                                             Lumbar vertebra








Sacrum                                                             Caudal vertebra





ambulatory‑‑ambul:  walk

amphibious‑‑amphi:  on both sides;  bio:  life

appendicular‑‑append:  to hang

aquatic‑‑aqua:  water

arboreal‑‑arbor:  tree

atlas‑‑atla:  a giant bearing up the earth

axial‑‑axi:  an axle

axis‑‑axi:  an axle

calcaneus‑‑calcan:  heel

carpals‑‑carp:  wrist

caudal‑‑caud:  tail

caudal articular process‑‑caud:  tail;  artic:  a joint;  process:  projection

cervical‑‑cervi:  neck

cranial articular process‑‑crani:  the skull;  artic:  a joint;  process:  projection

cranium‑‑crani:  the skull

cursorial‑‑curso:  run or runner

dens‑‑dens:  dens, thick, compact

digitigrade‑‑digiti:  a finger or toe;  grade:  walk or step

femur‑‑fem:  high

fibula‑‑fibul:  a clasp, buckle or splint

fossorial‑‑fossori:  a digger

glenoid fossa‑‑glen:  a cavity or socket for a bone;  oid:  like;  fossa:  a ditch or trench

glissant‑‑gliss:  to glide

graviportal‑‑gravi:  heavy;  port:  to carry

hemal process‑‑hem:  blood;  process:  projection

humerus‑‑humer:  upper bone of arm

ilium‑‑ile:  the groin

ishium‑‑ischi:  the hip‑joint

lumbar‑‑lumb:  the loin

mandible‑‑mandib:  jaw bone

manubrium‑‑manubri:  a handle

metacarpals‑‑meta:  after;  carp:  wrist

metatarsals‑‑meta:  after;  tars:  ankle

patella‑‑patell:  a little dish

pectoral‑‑pector:  breast

pelvic‑‑pelv:  basin

phalanges‑‑phalang:  a bone of the finger or toe

plantigrade‑‑planti:  sole of the foot;  grade:  walk or step

pubis‑‑pubis:  the region of the pubes or the pubic bone

radius‑‑radi:  a spoke

ricochetal‑‑ricochet:  bouncing off of

sacral‑‑sacr:  sacrum

sacrum‑‑sacr:  comes from sacral bone which was offered up in sacrifices to gods

saltatorial‑‑saltator:  a leaper

scansorial‑‑scans:  to climb

scapula‑‑scapul:  the shoulder blade

spinous process‑‑spin:  a spine;  process:  projection

sternebrae‑‑stern:  breast or chest;  brae come from vertebrae

subunguligrade‑‑sub:  almost;  unguli:  nail or hoof;  grade:  walk or step

tarsals‑‑tars:  ankle

tetrapod‑‑tetra:  four;  pod:  foot

thoracic‑‑thorac:  breastplate

tibia‑‑tibi:  shin bone

transverse foramen‑‑trans:  across;  vers:  to turn, change;  foram:  an opening

transverse process‑‑trans:  across;  vers:  to turn, change;  process:  projection

ulna‑‑ulna:  the lower arm

unguligrade‑‑unguli:  nail or hoof;  grade:  walk or step

vertebrae‑‑vertebr:  a joint      (vert:  to turn)

volant‑‑vol:  to fly

xiphoid process‑‑xiph:  a sword;  oid:  like;  process:  projection





‑al‑‑relating to

‑ar‑‑pertaining to

‑ic‑‑belonging to, relating to

‑icular‑‑denotes means of or instrument of


‑ous‑‑full of or possessing qualities of

‑tory‑‑agent or doer of an action

‑us‑‑condition of





The goal for this lab is to learn to identify the skins of the mammals listed below.  Consult the list of external features that vary among different species of mammals that was included in the lab on common insectivores and rodents.  BEFORE you attend this lab, work on scientific and common names and some obvious features given in your field guide.





Didelphis virginiana

Eptesicus fuscus

Nycticeius humeralis

Scalopus aquaticus

Sylvilagus floridanus

Lepus californicus

Geomys bursarius

Glaucomys volans

Sciurus carolinensis

Perognathus sp.

Castor canadensis

Onychomys leucogaster

Ondatra zibethicus

Rattus norvegicus

Mus musculus

Erethizon dorsatum

Neotoma micropus