簡介:"鏟齒象的體型大小與現代大象大致相似,但是頭骨部位尤其是下顎骨與門齒,卻有相當大的差異。一般我們所知道的大象,不論是現生的亞洲象、非洲象,甚至也已經滅絕的猛獁象,其門齒都具有一對向上彎曲伸展的上門齒,下門齒則是退化。然而鏟齒象剛好相反,其上門齒退化,而下門齒卻逐漸發展成平鏟狀,下顎骨也呈寬扁狀並與下門齒相接合,形成一個約1公尺長的堅硬鏟子狀下巴。 如此特殊的結構,使得鏟齒象能夠很方便的生活在較淺的河流或沼澤中,並以水草為食,利用牠特有的鏟狀下門牙,將水草從河流或湖泊中鏟起,然後用長鼻與鏟齒下巴緊握住水草,扭轉並撕裂拔起,隨即送入口中。 鏟齒象曾在中新世分布在歐洲、非洲與亞洲一帶。如此特殊且高度特化的鏟狀牙齒的結構,顯然是為了其在沼澤中採食水草的生活方式。但是,當動物發展到高度特化之後,一旦氣候改變或環境變遷,很容易產生不適而無法存活。鏟齒象必須在有水草生長的環境才有食物的來源,並以此賴以為生。當氣候改變或地質變動,造成了河流消失或沼澤乾枯之後,鏟齒象就失去了食物供給,很快地也就死亡甚至絕滅了。化石脊椎長鼻目剷齒象Amebelodon had the body size of the modern elephant, but the skulls of these two, in particular, the jaw and incisor, are different. The elephants we know either existing or extinct have a pair of upper incisors pointing upward and the lower incisor became less prominent. Amebelodon , however, had more prominent lower incisors also pointing downwards and developing into the wide and flat shovel shaped tusk-incisors. Thus, a one-meter long scoop-like lower jaw was formed. This special structure enabled Amebelondon to live with the water and grass in the shallow rive or swamp. By using the shovel shaped lower incisor, Amebelondon was able to lift the grass, remove and curl the grass to the mouth. Amebelondon once distributed in Europe, Africa and Asia in Miocene and apparently, the shovel shaped tusk-incisors was modified due to the collection of water grass. On the other hand, after being highly evolved, animals have the difficulties to adapt to climate or environmental changes and thus, become extinct. Amebelondon needed to live nearby where water grass grown and when the climate change or geological movement dried up the livers and swamps, they lost the food supply and quickly came to the extinction."