芒果视频下载

外形特征

秀頜龍是恐龍家族中小巧玲瓏的種類，它的成年個體從頭的前端到尾的末梢，全長75厘米，軀干部只有一只母雞那么大，無疑是恐龍家族中個體最小的成員。這種恐龍生活在侏羅紀，雖然其貌不揚,毫不引人注目，但是由于它與人們推測的鳥類祖先沾親帶故，反倒成為恐龍中最受專家學者們關注的對象。假如有人還盲目地認為恐龍都是龐然大物的話，它肯(ken)定是最好(hao)的反(fan)證。

秀頜龍的特征與腔骨龍差不多，肢骨中空，身體輕巧，后肢細長，口內長滿尖利的牙齒，身后拖著一條細長的尾巴。它是行動敏捷的動物，不僅善于快跑，而且擅長騰躍，爬樹也是它的絕活，它是侏羅紀一(yi)些小動物的天敵。

秀頜(he)龍(long)(long)(long)(long)是最小的(de)(de)(de)恐(kong)龍(long)(long)(long)(long)之一，可(ke)能(neng)只有(you)現(xian)在(zai)的(de)(de)(de)雞那么大。也有(you)人把(ba)它(ta)譯(yi)成美頜(he)龍(long)(long)(long)(long)。它(ta)在(zai)分類(lei)(lei)系(xi)統上屬(shu)于獸(shou)腳(jiao)類(lei)(lei)。對于獸(shou)腳(jiao)類(lei)(lei)中(zhong)各類(lei)(lei)恐(kong)龍(long)(long)(long)(long)的(de)(de)(de)演化(hua)關(guan)系(xi)，分類(lei)(lei)學家們有(you)著(zhu)(zhu)不(bu)同(tong)的(de)(de)(de)看法。美國古脊椎動物(wu)家盧卡斯(si)在(zai)他(ta)所(suo)著(zhu)(zhu)的(de)(de)(de)《恐(kong)龍(long)(long)(long)(long)》一書中(zhong)明確的(de)(de)(de)指出：現(xian)在(zai)大多數古生物(wu)學家都公認，角冠(guan)龍(long)(long)(long)(long)類(lei)(lei)是名為(wei)“聯尾(wei)龍(long)(long)(long)(long)類(lei)(lei)”的(de)(de)(de)恐(kong)龍(long)(long)(long)(long)在(zai)進化(hua)中(zhong)的(de)(de)(de)一個(ge)(ge)旁支。聯尾(wei)龍(long)(long)(long)(long)類(lei)(lei)包括前面提到的(de)(de)(de)獸(shou)腳(jiao)類(lei)(lei)中(zhong)的(de)(de)(de)肉(rou)食類(lei)(lei)與虛骨龍(long)(long)(long)(long)類(lei)(lei)，也可(ke)以說，聯尾(wei)龍(long)(long)(long)(long)類(lei)(lei)是指不(bu)包括角冠(guan)龍(long)(long)(long)(long)類(lei)(lei)的(de)(de)(de)獸(shou)腳(jiao)類(lei)(lei)。這(zhe)一類(lei)(lei)恐(kong)龍(long)(long)(long)(long)的(de)(de)(de)牙(ya)齒結(jie)構以及(ji)臀部形(xing)態，都非常(chang)像鳥。但(dan)這(zhe)并不(bu)是說，所(suo)有(you)的(de)(de)(de)聯尾(wei)龍(long)(long)(long)(long)類(lei)(lei)不(bu)屬(shu)于肉(rou)食類(lei)(lei)就屬(shu)于虛骨龍(long)(long)(long)(long)類(lei)(lei)。秀頜(he)龍(long)(long)(long)(long)，就是一個(ge)(ge)極好的(de)(de)(de)例子。

過去(qu)專(zhuan)家們都(dou)把秀頜龍(long)視為虛骨龍(long)類中(zhong)的一個成員，今(jin)天已(yi)改變了(le)看(kan)法。

研究發現

1861年(nian)，第一(yi)(yi)(yi)個秀(xiu)頜(he)(he)(he)龍(long)(long)(long)(long)的(de)(de)(de)(de)化石(shi)標(biao)(biao)本(ben)(ben)發現(xian)于始(shi)(shi)祖鳥化石(shi)產地德國(guo)巴(ba)伐利亞省索倫霍(huo)芬石(shi)板石(shi)石(shi)灰巖中(zhong)(zhong)(zhong)。它(ta)(ta)只有(you)(you)(you)70厘米長。小(xiao)軀體(ti)、大(da)(da)眼睛和(he)相對(dui)大(da)(da)的(de)(de)(de)(de)頭，證明它(ta)(ta)是秀(xiu)頜(he)(he)(he)龍(long)(long)(long)(long)的(de)(de)(de)(de)幼年(nian)個體(ti)。1972年(nian)，第二個秀(xiu)頜(he)(he)(he)龍(long)(long)(long)(long)的(de)(de)(de)(de)化石(shi)標(biao)(biao)本(ben)(ben)發現(xian)于法國(guo)南(nan)部，它(ta)(ta)比第一(yi)(yi)(yi)個標(biao)(biao)本(ben)(ben)大(da)(da)二分之(zhi)一(yi)(yi)(yi)。美國(guo)古脊椎(zhui)動物(wu)學的(de)(de)(de)(de)權威奧(ao)斯(si)(si)物(wu)羅姆1978年(nian)完成了(le)對(dui)秀(xiu)頜(he)(he)(he)龍(long)(long)(long)(long)所有(you)(you)(you)化石(shi)標(biao)(biao)本(ben)(ben)的(de)(de)(de)(de)研(yan)究(jiu)。他(ta)的(de)(de)(de)(de)研(yan)究(jiu)結果使人們(men)對(dui)這種(zhong)恐(kong)龍(long)(long)(long)(long)有(you)(you)(you)了(le)更深的(de)(de)(de)(de)了(le)解(jie)。秀(xiu)頜(he)(he)(he)龍(long)(long)(long)(long)身體(ti)結構輕(qing)巧，比大(da)(da)多數恐(kong)龍(long)(long)(long)(long)長得秀(xiu)氣。它(ta)(ta)有(you)(you)(you)修長而(er)(er)(er)靈活的(de)(de)(de)(de)脖子(zi)，短的(de)(de)(de)(de)前肢(zhi)(zhi)和(he)長的(de)(de)(de)(de)后肢(zhi)(zhi)，尾(wei)(wei)巴(ba)也(ye)較長。它(ta)(ta)的(de)(de)(de)(de)頭骨(gu)中(zhong)(zhong)(zhong)有(you)(you)(you)空(kong)洞(dong)，因(yin)而(er)(er)(er)變得較為輕(qing)巧。牙齒小(xiao)巧玲(ling)瓏，彎曲而(er)(er)(er)又非常(chang)尖銳，所有(you)(you)(you)下頜(he)(he)(he)的(de)(de)(de)(de)牙齒都長在眼窩之(zhi)前。秀(xiu)頜(he)(he)(he)龍(long)(long)(long)(long)的(de)(de)(de)(de)名稱就是指(zhi)(zhi)它(ta)(ta)有(you)(you)(you)秀(xiu)麗的(de)(de)(de)(de)頜(he)(he)(he)。它(ta)(ta)的(de)(de)(de)(de)前肢(zhi)(zhi)有(you)(you)(you)三個手指(zhi)(zhi)，只有(you)(you)(you)第一(yi)(yi)(yi)和(he)第二兩個手指(zhi)(zhi)可以(yi)彎曲，第三指(zhi)(zhi)只有(you)(you)(you)一(yi)(yi)(yi)個指(zhi)(zhi)節。它(ta)(ta)的(de)(de)(de)(de)恥(chi)骨(gu)呈靴子(zi)狀。這些特征既不(bu)出(chu)現(xian)在大(da)(da)型肉食龍(long)(long)(long)(long)類中(zhong)(zhong)(zhong)，也(ye)不(bu)出(chu)現(xian)在虛骨(gu)龍(long)(long)(long)(long)類中(zhong)(zhong)(zhong)，所以(yi)說它(ta)(ta)是最(zui)原(yuan)始(shi)(shi)的(de)(de)(de)(de)聯尾(wei)(wei)龍(long)(long)(long)(long)類。在德國(guo)發現(xian)的(de)(de)(de)(de)一(yi)(yi)(yi)具秀(xiu)頜(he)(he)(he)龍(long)(long)(long)(long)化石(shi)標(biao)(biao)本(ben)(ben)的(de)(de)(de)(de)腹(fu)腔內，曾找到過(guo)一(yi)(yi)(yi)個已經(jing)滅絕(jue)的(de)(de)(de)(de)小(xiao)蜥蜴。開始(shi)(shi)時曾誤認為是它(ta)(ta)的(de)(de)(de)(de)幼子(zi)，以(yi)為它(ta)(ta)是卵胎生(sheng)(sheng)的(de)(de)(de)(de)，經(jing)奧(ao)斯(si)(si)特羅姆教授(shou)研(yan)究(jiu)后才真(zhen)相大(da)(da)白：那是它(ta)(ta)生(sheng)(sheng)前的(de)(de)(de)(de)最(zui)后一(yi)(yi)(yi)頓美餐。