National Geographic UK - 10.2019

Metacarpal

Metacarpal

Ulna

Ulna

Humerus

Humerus

Radius

Stomach chambers

Intestine

0.7

pound

6-7 pounds80-100

beats per minute

60-90

beats per minute

60-100beats 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