歷史
這個部分脊椎的(de)保存(cun)狀況很差,但卻異常(chang)(chang)的(de)巨(ju)大(da)和寬,高(gao)度有(you)1.5米(mi)高(gao),估計完(wan)整(zheng)的(de)脊椎可達2.7米(mi)高(gao)。他于(yu)1878年(nian)把這個標(biao)本運(yun)送給科普(pu),而科普(pu)以此作為新種易(yi)碎雙腔龍(long)的(de)正模標(biao)本(編號AMNH 5777),并于(yu)同年(nian)8月公(gong)布。它的(de)名字是由古希臘文的(de)“fragillimus”而來,即“非常(chang)(chang)易(yi)碎”,意指(zhi)神經弓的(de)椎板非常(chang)(chang)薄。從(cong)科普(pu)發(fa)掘時的(de)紀(ji)錄得知,這個標(biao)本從(cong)發(fa)現(xian)(xian)圓頂(ding)龍(long)的(de)礦場南面的(de)山上(shang)被(bei)發(fa)現(xian)(xian)。科普(pu)指(zhi)該位置是屬(shu)于(yu)達科他組(Dakota Formation),年(nian)代(dai)為侏羅紀(ji)晚(wan)期,而在同一(yi)(yi)地層的(de)圓頂(ding)龍(long)則(ze)是屬(shu)于(yu)莫里遜組(Morrison Formation),年(nian)代(dai)可追溯至晚(wan)侏羅紀(ji)的(de)提(ti)通階。一(yi)(yi)塊巨(ju)大(da)的(de)股骨化石亦(yi)在附近被(bei)發(fa)現(xian)(xian),被(bei)估計可能也是屬(shu)于(yu)易(yi)碎雙腔龍(long)。
化石的疑問
當(dang)討(tao)論最大的(de)(de)恐龍(long)(long)時,一(yi)般(ban)都(dou)(dou)會(hui)忽略易(yi)碎(sui)(sui)雙腔(qiang)(qiang)龍(long)(long)的(de)(de)巨大骨骼,這是因由于不(bu)同的(de)(de)報(bao)告都(dou)(dou)指(zhi)其(qi)脊(ji)椎及股骨的(de)(de)下落不(bu)明,而(er)(er)嘗試尋找的(de)(de)計劃都(dou)(dou)失(shi)敗。于2006年,肯尼思·卡彭特(Kenneth Carpenter)指(zhi)出(chu)易(yi)碎(sui)(sui)雙腔(qiang)(qiang)龍(long)(long)標本失(shi)蹤的(de)(de)可(ke)(ke)能(neng)原因:由于科普在(zai)其(qi)描述中指(zhi)該(gai)神經弓(gong)非常易(yi)碎(sui)(sui),而(er)(er)當(dang)時并沒有(you)(you)使骨頭硬化(hua)及保存化(hua)石(shi)的(de)(de)相關技術;科普的(de)(de)對(dui)手,奧塞內爾·查利斯·馬(ma)什(Othniel Charles Marsh)在(zai)1880年代首(shou)次采用(yong)此一(yi)技術。而(er)(er)保有(you)(you)易(yi)碎(sui)(sui)雙腔(qiang)(qiang)龍(long)(long)化(hua)石(shi)的(de)(de)石(shi)礦是嚴重侵蝕的(de)(de)泥巖,使得該(gai)化(hua)石(shi)容易(yi)被(bei)粉碎(sui)(sui)及形成(cheng)小型、不(bu)規(gui)則(ze)的(de)(de)碎(sui)(sui)片。所(suo)以(yi),它可(ke)(ke)能(neng)在(zai)科普描繪完后就被(bei)粉碎(sui)(sui)了(le),所(suo)以(yi)科普的(de)(de)插圖(tu)就只有(you)(you)一(yi)個(ge)視圖(tu),而(er)(er)不(bu)是一(yi)般(ban)的(de)(de)多個(ge)視圖(tu)。但是今天來看易(yi)碎(sui)(sui)雙腔(qiang)(qiang)龍(long)(long)確實(shi)存在(zai),還是有(you)(you)史以(yi)來最大的(de)(de)動物。
尋找化石
1994年,有科學家嘗(chang)試(shi)去找(zhao)出(chu)(chu)易(yi)碎(sui)(sui)(sui)(sui)雙(shuang)腔(qiang)龍(long)的(de)(de)(de)(de)原(yuan)有石(shi)礦,當中使(shi)用(yong)了雷(lei)達來(lai)探測地下藏有的(de)(de)(de)(de)骨(gu)頭影像。這個(ge)嘗(chang)試(shi)最后(hou)失(shi)(shi)敗,是(shi)由(you)于化石(shi)化的(de)(de)(de)(de)泥(ni)巖(yan)(yan)與周邊的(de)(de)(de)(de)巖(yan)(yan)石(shi)同(tong)一(yi)密度(du),以致不能分辨出(chu)(chu)兩者。另一(yi)個(ge)地形研究指(zhi)出(chu)(chu)藏有化石(shi)的(de)(de)(de)(de)地層經(jing)已(yi)受嚴重侵(qin)蝕(shi),可(ke)能在發(fa)掘易(yi)碎(sui)(sui)(sui)(sui)雙(shuang)腔(qiang)龍(long)的(de)(de)(de)(de)脊椎(zhui)及股骨(gu)后(hou),該地的(de)(de)(de)(de)大部分的(de)(de)(de)(de)骨(gu)骼(ge)已(yi)經(jing)侵(qin)蝕(shi)、消失(shi)(shi)。由(you)于易(yi)碎(sui)(sui)(sui)(sui)雙(shuang)腔(qiang)龍(long)化石(shi)的(de)(de)(de)(de)特殊(shu)尺寸(cun)及神秘失(shi)(shi)蹤(zong),科普(pu)的(de)(de)(de)(de)原(yuan)始描述就引來(lai)了懷疑(yi),有些(xie)人更指(zhi)科普(pu)可(ke)能是(shi)在量度(du)上出(chu)(chu)現(xian)了排版(ban)印刷(shua)之誤(wu)。但(dan)是(shi)卡彭特指(zhi)出(chu)(chu)科普(pu)的(de)(de)(de)(de)文(wen)章充(chong)滿根(gen)據,也(ye)顯示他是(shi)一(yi)位(wei)出(chu)(chu)色的(de)(de)(de)(de)古生物學家。而發(fa)現(xian)化石(shi)的(de)(de)(de)(de)時間正好是(shi)化石(shi)戰爭,當時科普(pu)的(de)(de)(de)(de)競(jing)敵(di)奧(ao)塞內爾·查利(li)斯(si)·馬什(shen)(O.C. Marsh)卻從沒有對(dui)易(yi)碎(sui)(sui)(sui)(sui)雙(shuang)腔(qiang)龍(long)提出(chu)(chu)懷疑(yi)。而馬什(shen)亦曾雇(gu)用(yong)偵探監視(shi)科普(pu)的(de)(de)(de)(de)發(fa)現(xian),可(ke)能對(dui)易(yi)碎(sui)(sui)(sui)(sui)雙(shuang)腔(qiang)龍(long)骨(gu)頭的(de)(de)(de)(de)巨(ju)大有了確定。而奧(ao)斯(si)本、C.C. Mook、 John S. McIntosh等不同(tong)的(de)(de)(de)(de)學者亦都接受科普(pu)的(de)(de)(de)(de)資(zi)料。所(suo)以易(yi)碎(sui)(sui)(sui)(sui)雙(shuang)腔(qiang)龍(long)確實存在。
分類
科普將他的發現于1878年兩度公布于《美國博(bo)物學(xue)家》(The American Naturalist)期刊,并分(fen)(fen)類在新(xin)的(de)(de)雙腔(qiang)龍(long)(long)屬下(xia)。他把這個屬編入梁(liang)龍(long)(long)科(ke)(ke)內(nei),雖然只(zhi)有部分(fen)(fen)的(de)(de)化石碎片(pian),有些學(xue)者(zhe)則將它(ta)分(fen)(fen)類在梁(liang)龍(long)(long)超科(ke)(ke)下(xia),或是(shi)(shi)梁(liang)龍(long)(long)科(ke)(ke)的(de)(de)“分(fen)(fen)類未定屬”。雙腔(qiang)龍(long)(long)屬中首先被(bei)命名的(de)(de)種(zhong)(zhong)是(shi)(shi)高雙腔(qiang)龍(long)(long)(正模標本(ben)AMHD 5764),是(shi)(shi)由科(ke)(ke)普于1877年發(fa)現。雖然只(zhi)有部分(fen)(fen)的(de)(de)骨骼(ge),但有足(zu)(zu)夠特征可以確(que)定此屬的(de)(de)一些特征。高雙腔(qiang)龍(long)(long)的(de)(de)化石較為完好,但就比易(yi)碎雙腔(qiang)龍(long)(long)為小(xiao)。在1921年,奧(ao)斯(si)本(ben)與C.C. Mook指出易(yi)碎雙腔(qiang)龍(long)(long)其實只(zhi)是(shi)(shi)非常大的(de)(de)高雙腔(qiang)龍(long)(long),是(shi)(shi)高雙腔(qiang)龍(long)(long)的(de)(de)異(yi)名;在1998年,John S. McIntosh也同(tong)意這個看法(fa)。但是(shi)(shi)卡彭特指出,它(ta)們在脊椎的(de)(de)構造(zao)上有所差異(yi),足(zu)(zu)以顯示它(ta)們是(shi)(shi)不同(tong)的(de)(de)種(zhong)(zhong),或甚至不同(tong)的(de)(de)屬。
體型
若要估計易碎雙腔龍的大小,就須假設它與梁龍科的相對比例相似,以較多了解的(de)(de)(de)(de)(de)(de)梁(liang)龍(long)(long)(long)(long)科(ke)的(de)(de)(de)(de)(de)(de)骨(gu)頭作(zuo)縮(suo)放(fang)比(bi)例。在(zai)(zai)科(ke)普原先的(de)(de)(de)(de)(de)(de)紀錄,他(ta)以此來估(gu)計(ji)易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)的(de)(de)(de)(de)(de)(de)股(gu)骨(gu)大(da)(da)小(xiao)。科(ke)普發現在(zai)(zai)其他(ta)的(de)(de)(de)(de)(de)(de)蜥(xi)腳下目(mu)恐龍(long)(long)(long)(long),尤其是(shi)(shi)高(gao)(gao)雙(shuang)腔(qiang)龍(long)(long)(long)(long)及(ji)至高(gao)(gao)圓頂龍(long)(long)(long)(long),它們(men)的(de)(de)(de)(de)(de)(de)股(gu)骨(gu)都是(shi)(shi)背部(bu)最高(gao)(gao)脊(ji)椎的(de)(de)(de)(de)(de)(de)兩(liang)倍高(gao)(gao)度,因而(er)估(gu)計(ji)易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)的(de)(de)(de)(de)(de)(de)股(gu)骨(gu)為(wei)(wei)(wei)3.7米高(gao)(gao),前腿5.75米長,后腿7.5米長,臀(tun)部(bu)高(gao)(gao)度為(wei)(wei)(wei)9.7米。但這些都是(shi)(shi)比(bi)較保守的(de)(de)(de)(de)(de)(de)估(gu)計(ji)值(zhi),可能和實(shi)際(ji)的(de)(de)(de)(de)(de)(de)體格(ge)大(da)(da)小(xiao)有(you)出入,或(huo)許比(bi)這小(xiao)一些,或(huo)者(zhe)還要大(da)(da)很多。于1994年,葛瑞格(ge)利(li)·保羅(Gregory S. Paul)利(li)用(yong)相關的(de)(de)(de)(de)(de)(de)梁(liang)龍(long)(long)(long)(long)作(zuo)為(wei)(wei)(wei)參考,估(gu)計(ji)易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)的(de)(de)(de)(de)(de)(de)股(gu)骨(gu)大(da)(da)小(xiao)為(wei)(wei)(wei)3.1到(dao)4米長。于2006年,卡(ka)彭(peng)特就(jiu)同(tong)(tong)樣(yang)利(li)用(yong)梁(liang)龍(long)(long)(long)(long)重新評估(gu)易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)的(de)(de)(de)(de)(de)(de)股(gu)骨(gu)為(wei)(wei)(wei)4.3到(dao)4.6米。卡(ka)彭(peng)特嘗試就(jiu)整頭易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)的(de)(de)(de)(de)(de)(de)體型(xing)作(zuo)出評估(gu),但發現梁(liang)龍(long)(long)(long)(long)不(bu)同(tong)(tong)種的(de)(de)(de)(de)(de)(de)體型(xing)差異,會影響(xiang)其估(gu)計(ji)結果。假設易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)與梁(liang)龍(long)(long)(long)(long)有(you)著同(tong)(tong)一的(de)(de)(de)(de)(de)(de)比(bi)例,它的(de)(de)(de)(de)(de)(de)體型(xing)就(jiu)是(shi)(shi)58米,與保羅在(zai)(zai)1994年的(de)(de)(de)(de)(de)(de)估(gu)計(ji)范圍(40到(dao)60米)吻合。卡(ka)彭(peng)特也(ye)指出易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)的(de)(de)(de)(de)(de)(de)最小(xiao)估(gu)計(ji)值(zhi),亦比(bi)其他(ta)蜥(xi)腳下目(mu)更為(wei)(wei)(wei)巨大(da)(da),如超龍(long)(long)(long)(long)(32.5米)、腕龍(long)(long)(long)(long)科(ke)的(de)(de)(de)(de)(de)(de)波塞東龍(long)(long)(long)(long)(34米)及(ji)泰坦巨龍(long)(long)(long)(long)類的(de)(de)(de)(de)(de)(de)阿(a)根廷龍(long)(long)(long)(long)(35米),因此易(yi)(yi)(yi)碎(sui)(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)從體形上來講才是(shi)(shi)最大(da)(da)的(de)(de)(de)(de)(de)(de)恐龍(long)(long)(long)(long),也(ye)是(shi)(shi)史(shi)上最大(da)(da)的(de)(de)(de)(de)(de)(de)動物。
假設(she)易碎(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)(long)(long)相當瘦,但其體(ti)(ti)(ti)(ti)型大小卻(que)使(shi)它(ta)依舊的(de)(de)(de)巨大。與長度相比,體(ti)(ti)(ti)(ti)重(zhong)(zhong)(zhong)(zhong)更(geng)難去(qu)估(gu)(gu)計(ji),因(yin)為(wei)要使(shi)用更(geng)為(wei)復雜的(de)(de)(de)方程式,比例上(shang)的(de)(de)(de)小型差(cha)異就(jiu)會產生很大的(de)(de)(de)誤(wu)差(cha)。以(yi)(yi)卡內基梁龍(long)(long)(long)(long)(long)(long)(Diplodocus carnegii)的(de)(de)(de)估(gu)(gu)計(ji)質量(liang)為(wei)120公(gong)噸,易碎(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)(long)(long)的(de)(de)(de)體(ti)(ti)(ti)(ti)重(zhong)(zhong)(zhong)(zhong)就(jiu)可(ke)以(yi)(yi)是(shi)180---220噸。易碎(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)(long)(long)體(ti)(ti)(ti)(ti)重(zhong)(zhong)(zhong)(zhong)大于阿根廷龍(long)(long)(long)(long)(long)(long)的(de)(de)(de)100噸。近期,科學家們(men)重(zhong)(zhong)(zhong)(zhong)新(xin)研究(jiu)估(gu)(gu)計(ji),發現易碎(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)(long)(long)和(he)近親梁龍(long)(long)(long)(long)(long)(long)關系(xi)較(jiao)遠,而(er)(er)和(he)超龍(long)(long)(long)(long)(long)(long)迷惑龍(long)(long)(long)(long)(long)(long)更(geng)近,認為(wei)之(zhi)前(qian)利用梁龍(long)(long)(long)(long)(long)(long)估(gu)(gu)計(ji)易碎(sui)雙(shuang)腔(qiang)龍(long)(long)(long)(long)(long)(long)的(de)(de)(de)體(ti)(ti)(ti)(ti)型得(de)出(chu)來的(de)(de)(de)結論是(shi)不準確得(de)。而(er)(er)利用超龍(long)(long)(long)(long)(long)(long)和(he)迷惑龍(long)(long)(long)(long)(long)(long)估(gu)(gu)算(suan)后,得(de)出(chu)了(le)新(xin)的(de)(de)(de)數據。體(ti)(ti)(ti)(ti)長可(ke)達(da)到(dao)60---80米甚(shen)至以(yi)(yi)上(shang),體(ti)(ti)(ti)(ti)重(zhong)(zhong)(zhong)(zhong)190噸以(yi)(yi)上(shang),這個(ge)顯然和(he)這個(ge)巨型動物的(de)(de)(de)真實體(ti)(ti)(ti)(ti)重(zhong)(zhong)(zhong)(zhong)更(geng)加(jia)符(fu)合。目前(qian)科學家普(pu)遍認為(wei),易碎(sui)最大個(ge)體(ti)(ti)(ti)(ti)可(ke)達(da)60---80米長、臀高10米、頭(tou)高14-15米之(zhi)間、體(ti)(ti)(ti)(ti)重(zhong)(zhong)(zhong)(zhong)最重(zhong)(zhong)(zhong)(zhong)220噸。