美洲是否有過馬？
中國的一本什麼書上說：美洲有原始的馬（好像只有小狗大小）。為什麼沒有演化成現代的馬匹，這是一個謎。現在我們知道，這個謎底是：他們的知識太陳舊，又想當然。
美洲曾經有過馬匹，並且還是three to five species。大概是具體的分類有不同的意見，所以才有3到5個species的說法。
另外，在美洲，獅子、獵豹、駱駝，虎也是有的。但在第四紀期間，陸續滅絕了。許多還是在第四紀冰川已經結束了，氣溫回暖時期而滅絕的。許多動物和美洲的印第安人共同生活過。
至於滅絕的具體原因，各種假說都有。其中一個假說是：印第安人狩獵，把這些動物都滅絕了。有人用計算機模擬，斷定人類完全能滅絕那些動物。
印第安人基本上沒有金屬，靠石制的箭頭和原始的弓箭，幾乎不可能把那麼多種的動物都滅絕了。滅絕幾種，那還是有可能的。
下面是維基百科在Quaternary extinction event條目羅列的滅絕的動物一覽表。僅限於北美地區。當然，這些動物的滅絕的時間不是一致的，前後相去很寬的時間域。
這些滅絕的哺乳動物都有一個特點，就是體型很龐大。和被滅絕的Short-faced
Bear相比，今天的棕熊都是小玩意。
國家地理電視頻道上曾播放過介紹的片子，其中的觀點，只是許多假說中的某種說法罷了。
The megafaunal extinctions include
twelve genera of edible herbivores (H), and five large, dangerous
carnivores (C). North American extinctions included:
-
American horses,
(Equus, three
to five species) (H)
-
Yukon wild ass (Equus lambei) (H)
-
California tapirs (Tapirus californicus and Tapirus merriami)
(H)
-
Vero tapir (Tapirus
veroensis) (H)
-
Western camel (Camelops hesternus) (H)
-
North American llamas (Hemiauchenia)(H)
-
Deer (Cervidae, two genera) (H)
-
Pronghorn (Antilocapridae, two genera, one survived) (H)
-
Stag-moose (Cervalces scotti) (H)
-
Shrub-ox and Harlan's muskox (the Arctic Muskox survived) (H)
-
Ancient Bison (Bison
antiquus) (H)
-
Long-horned bison / Giant bison (Bison latifrons) (H)
-
Giant Beaver (Castoroides,
two species) (H)
-
Saiga (Saiga tatarica) (H)
-
Teratorns (C)
-
Pinckney's Capybara (Neochoerus
pinckneyi) (H)
-
Eremotherium and Nothrotheriops,
megatheriid ground sloths (H)
-
Megalonyx, a megalonychid ground sloth (H)
-
Paramylodon, a mylodontid ground sloth (H)
-
Glyptodonts (H)
-
Pampatheres (H)
-
Short-faced Bear (Arctodus simus, larger than the present Grizzly Bear) (C)
-
Florida Cave Bear (Tremarctos floridanus) (C)
-
Saber-toothed cat (Smilodon fatalis) (C)
-
Scimitar cat (Homotherium
serum) (C)
-
Giant polar bear (Ursus maritimus
tyrannus, it is possible that this giant relative of the
modern polar bear lived in North America) (C)
-
American lion (Panthera leo atrox, larger than the current
African Lion but probably a fairly recent immigrant through Beringia)
(C)
-
American cheetah (Miracinonyx, not a true cheetah, possibly
ancestral) (C)
-
Dire wolf (Canis dirus) (C)
-
Mammoth (Mammuthus), several species (H)
-
American mastodon (Mammut americanum) (H)
-
Flat-headed (Platygonus) & Long-nosed (Mylohyus) peccaries (H)
