THE LIFE OF MAMMALS 
THE AGE OF MAMMALS 
(CENOZOIC, OR TERTIARY AND QUATERNARY.) 
WESTERN LAKE BASINS and CHARACTERISTIC MAMMALS 
THE TERTIARY FORMATIONS ARE REPRESENTED IM | IN THE SEOIMENTS OF THESE LAKES 
WESTERN AMERICA BY A GERIES OF DEPOSITS | WERE BURIED THE REMAINS OF MANY 
FoR THE BOTTOMG OF SUCCESSIE | GF THE ANIMALS WHIEH LiveD AROUND 
FR ATER A FOTAL THICKNESS | THEIR, f , 
16 IeiNeanty ‘e800 TeeT PEQUINING PROGABLY | DF THE GUGCESENNE SPECIES WHICH 
WREE MILLION YEARS TO FoRM. | IMHABITED THE LAKE REGION 
PERIODS] LAKE BASINS [RUCK CHARACTERISTIC MAMMALS 
MESS 
[ELEFHANTS. LAST MASTODONS 
RECENTano| 0 = is f LAST GRoU Pee 
PLEISTOCENE} "EQUUS ano MEGALONYX ACCES TAPING OoUs eaters tenes 
“PLIOCENE | BLANCO ano PALO DURO |1S0 ian Ts CMs gw 0 wa 
fe MASTODONS TRUE MORNLESS RHINOCERDSES| 
LOUP FORK 400) Last onEGDONTS CAMELS THREE TOLD HORSES| 
DEER. FIRST PRONG-WOHN ANTELOPES 
150 [TRUE Noes aunoctaoat newer cams 
ert ele 
DEEP RIVER 
MIOCENE 
HORNLESS ano TWIN HORNED RHINOCEROSES 
LAST ELOTHERES oReODONTS 
CAMELS. PRIMITIVE DEER 
soormTs DOGS wolves roxes ci 
{ CATS \SABRE-TOOTH TIGERS) 
JOHN DAY 
(OREGON NEVADA) 
WVOPOTAMIDS. PRoTOCERAS ECCCARIE 
Uist cHeaoonTS. Doug =i CATS riser ecarcs 
FLO} THERES. Cures owners 
ITE RIVER nce Toco MeOH 
OLIGOCENE ay he Een ee tooo) exon RaWOCEROSES AMYNCOS 
OMT ts 
FIRST TRUE HORWLESS | RHINOCEROSES 
aot 
PRIMITIVE RKIMOCEROSES i AMYNODOXTS| 
TTTANGTHERES ELOTHERES, creooonrs 
Tima cast 7 OREOGONTS TAPINS 
HL rORB A EMaiee Parvin RODENT 
LAST UINTATHERES, coo xe cacooeats miacis: 
UINTATHERES 
iT (uence 
PRIMITIVE RHINOCEROSES (HYRACHYUS) 
rf FINST ELOTHERES |ACKANODON 
2o0g|tARGE CREOOONTS (MESONYX 
CATE earmoyt4 wt 606 URE wc cronens| 
BRIDGER 
Q (WYOMING. UTAH) 
LAST PRIMITIVE GROUND SLOTHS 
bwvsanres. aooce19, wate, LAST TILLODONTS 
LAST CORYPHODONS. FIRST UINTATHERES. 
IND RIVER 
EOCENE | W'S Bool, 
YOMING 
MOTHERES, LAST CONDYLARTHS| 
ORSKS (PROTOROMIPPUS! PRIMATES 
MODENTS, BATS, THLLODONTS 
Q 
tT 
AMBLYPODS CORYPHODON 
CONOYLARTHS |PHENACODUS) 
HAST FOUH TUED HORSES [HYRACOTHERIUM 
EMODON) 
Ccunvaw mooren aniaacs} 
2000|raimates (MONKEYS cm LEMURS 
CNEODONTS v« PRIMITIVE CARKIVORES 
[RESEMBLING CATS. 00GS s+ BEARS) 
rinst ROOENTS 
TiWLODONTS INSECTVORES 
PRIMITIVE GROUND SLOTHS 
conoviaatus PHEwacoo 
300 EREODONTS.— PRIMITI 
awe 
COENT, 
Conor PRIMITIVE" WOOFED MASMALe 
PUERCO 500 |SREOOONTS cx PRIMITIVE CARNIVORES 
& 
N 
we 
R 
Q A be 
S LARAMIE 5000 
ne 
S cRETACEOUS}: | 
¥ | 
Sy | 
on shore were rep- 
tiles, covered with 
a leathery or 
scaly hide, and 
having cold blood. 
Now when a kind 
of small crea- 
ture arose among 
them whose skin 
sprouted hairs 
instead of scales, 
it seems to have 
profited so much 
by this novelty 
that nature en- 
larged and = im- 
proved on the 
model. Its great 
advantage was in 
the warmth of 
the new covering, 
which as it be- 
came perfected in- 
duced a_ steadily 
increasing warmth 
of blood, and this 
promoted activity, 
AGE OF MAMMALS. 
Museum chart prepared 
by Prof. H. A. Osborn 
and Dr. W. D. Mat- 
thew. By permission 
of the American Mu- 
seum of Natural 
History, New York. 
