MetacarpalMetacarpalUlnaUlnaHumerusHumerusRadiusStomach chambersIntestine0.7
pound6-7 pounds80-100 beats per minute60-90beats per minute60-100beats per minute(^24) pounds
Weight395 to 575 lbsHeight4.5 - 5.1 ft (shoulder)
530 to 785 lbs4.7 - 5.2 ft
MALE
FEMALE
Life span
20
-30 years
Brain
Metacarpal
Ulna
Humerus
Radius
Radius
vessels
Left ventricle wall
Right ventricle wall
Elastic vessels
Open valveClosed valve
Sivatheriinae
Sivatherium gigantium
Palaeomerycinae
(approximately 18 mya
)
Palaeotragus primaevus
Palaeotraginae
(2 mya)
Okapia
G. camelopardalis
(one million years ago)
Giraffe
Okapi
Okapia johnstoni
Six ancestors
No known changes
OKAPI Okapia johnstoni The okapi is the giraffe’s closest living relative.
lar walls to pump blood up to the head and then around the body. The thinner right ventricle pumps blood a short distance to the lungs. ADJUSTING FOR PRESSUREA network of elastic vessels ex-pands when the head is lowered, to prevent blood from flooding the brain, and constricts when the head is raised, to prevent quick depletion. When the head is lowered, valves in the veins close to prevent backflow of blood.
Like a cow, a giraffe has four stomach chambers. Food, mainly leaves, enters the first chamber; coarse bits are regurgitated and rechewed before passing through the other chambers and an 82-foot-long large intestine. THE POWER BASEAs giraffes grow, their leg bones thicken, narrowing the marrow cavity and supporting increasing weight. Bones are especially long and straight in the lower legs.
SMALL FAMILY TREEEarly giraffes coexisted with two other subfamilies: the massive sivatheres (now extinct) and the ungulate group that includes the okapi. Scientists first became aware of the okapi, which has a long tongue and legs proportioned like those of a giraffe, at the turn of the 20th century.
Like compression socks, tight skin aids circulation by squeezing blood vessels and helping regulate blood pressure.
MEASUREMENTS ARE AVERAGES.FERNANDO G. BAPTISTA, TAYLOR MAGGIACOMO, AND EVE CONANT, NGM STAFF; LAWSON PARKER; SHIZUKA AOKI; QINGYANG CHEN; TANIA VELINSOURCES: SARA FERGUSON AND JULIAN FENNESSY, GIRAFFE CONSERVATION FOUNDATION; BALTIMORE ZOO