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歷史

這(zhe)個部分脊椎的(de)保(bao)存狀況很(hen)差(cha)，但(dan)卻異常(chang)的(de)巨(ju)大和(he)寬，高(gao)度有(you)1.5米高(gao)，估計完整的(de)脊椎可達2.7米高(gao)。他(ta)于(yu)1878年把(ba)這(zhe)個標本(ben)運送給科(ke)普(pu)(pu)，而科(ke)普(pu)(pu)以此作為(wei)新種易碎雙腔(qiang)龍的(de)正模標本(ben)（編號(hao)AMNH 5777），并于(yu)同年8月公布(bu)。它的(de)名字(zi)是(shi)由古希(xi)臘文的(de)“fragillimus”而來，即“非(fei)常(chang)易碎”，意(yi)指神(shen)經弓的(de)椎板非(fei)常(chang)薄(bo)。從(cong)科(ke)普(pu)(pu)發(fa)(fa)掘時的(de)紀錄得知，這(zhe)個標本(ben)從(cong)發(fa)(fa)現(xian)圓頂(ding)龍的(de)礦(kuang)場南面(mian)的(de)山上被發(fa)(fa)現(xian)。科(ke)普(pu)(pu)指該位置(zhi)是(shi)屬于(yu)達科(ke)他(ta)組（Dakota Formation），年代為(wei)侏羅(luo)紀晚期，而在同一地層的(de)圓頂(ding)龍則是(shi)屬于(yu)莫(mo)里(li)遜組（Morrison Formation），年代可追溯至(zhi)晚侏羅(luo)紀的(de)提通階。一塊(kuai)巨(ju)大的(de)股骨化石亦在附(fu)近(jin)被發(fa)(fa)現(xian)，被估計可能也是(shi)屬于(yu)易碎雙腔(qiang)龍。

化石的疑問

當(dang)討(tao)論(lun)最大(da)的(de)(de)恐龍(long)時，一般都(dou)會忽略易(yi)碎(sui)雙腔龍(long)的(de)(de)巨大(da)骨骼，這是(shi)因(yin)由于不(bu)(bu)同的(de)(de)報告都(dou)指(zhi)其脊椎及股骨的(de)(de)下落不(bu)(bu)明(ming)，而嘗(chang)試尋(xun)找的(de)(de)計劃都(dou)失(shi)敗。于2006年，肯尼(ni)思·卡彭特（Kenneth Carpenter）指(zhi)出(chu)易(yi)碎(sui)雙腔龍(long)標(biao)本失(shi)蹤(zong)的(de)(de)可能原因(yin)：由于科普在(zai)其描述中指(zhi)該神(shen)經弓非常(chang)易(yi)碎(sui)，而當(dang)時并沒有使(shi)骨頭硬化(hua)(hua)及保存化(hua)(hua)石(shi)(shi)的(de)(de)相關技術(shu)；科普的(de)(de)對手，奧塞內爾·查利斯·馬什（Othniel Charles Marsh）在(zai)1880年代(dai)首次采用此一技術(shu)。而保有易(yi)碎(sui)雙腔龍(long)化(hua)(hua)石(shi)(shi)的(de)(de)石(shi)(shi)礦是(shi)嚴(yan)重(zhong)侵蝕的(de)(de)泥(ni)巖(yan)，使(shi)得(de)該化(hua)(hua)石(shi)(shi)容易(yi)被粉(fen)碎(sui)及形成小(xiao)型、不(bu)(bu)規則的(de)(de)碎(sui)片。所以，它可能在(zai)科普描繪完后就被粉(fen)碎(sui)了，所以科普的(de)(de)插圖(tu)(tu)就只有一個視(shi)圖(tu)(tu)，而不(bu)(bu)是(shi)一般的(de)(de)多(duo)個視(shi)圖(tu)(tu)。但是(shi)今天來看(kan)易(yi)碎(sui)雙腔龍(long)確實存在(zai)，還是(shi)有史以來最大(da)的(de)(de)動物。

尋找化石

1994年，有(you)科(ke)(ke)(ke)學(xue)家嘗試(shi)去找出(chu)(chu)易碎雙腔(qiang)(qiang)龍(long)的(de)(de)(de)(de)(de)(de)(de)原有(you)石(shi)(shi)(shi)礦(kuang)，當中(zhong)使用(yong)了(le)雷達來(lai)探(tan)測地下(xia)藏有(you)的(de)(de)(de)(de)(de)(de)(de)骨頭影像(xiang)。這個嘗試(shi)最后(hou)失(shi)敗，是由于化(hua)石(shi)(shi)(shi)化(hua)的(de)(de)(de)(de)(de)(de)(de)泥巖與周(zhou)邊(bian)的(de)(de)(de)(de)(de)(de)(de)巖石(shi)(shi)(shi)同一(yi)密度，以(yi)(yi)致(zhi)不能分辨出(chu)(chu)兩者。另(ling)一(yi)個地形研(yan)究指出(chu)(chu)藏有(you)化(hua)石(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)(de)地層(ceng)經(jing)已受嚴重(zhong)侵(qin)蝕，可(ke)(ke)能在發(fa)掘易碎雙腔(qiang)(qiang)龍(long)的(de)(de)(de)(de)(de)(de)(de)脊椎及股骨后(hou)，該地的(de)(de)(de)(de)(de)(de)(de)大部分的(de)(de)(de)(de)(de)(de)(de)骨骼已經(jing)侵(qin)蝕、消(xiao)失(shi)。由于易碎雙腔(qiang)(qiang)龍(long)化(hua)石(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)(de)特殊尺寸及神秘失(shi)蹤，科(ke)(ke)(ke)普(pu)(pu)的(de)(de)(de)(de)(de)(de)(de)原始描(miao)述就引(yin)來(lai)了(le)懷疑(yi)，有(you)些人更指科(ke)(ke)(ke)普(pu)(pu)可(ke)(ke)能是在量度上出(chu)(chu)現了(le)排(pai)版印刷之(zhi)誤。但是卡彭特指出(chu)(chu)科(ke)(ke)(ke)普(pu)(pu)的(de)(de)(de)(de)(de)(de)(de)文章充滿根(gen)據，也顯(xian)示他是一(yi)位出(chu)(chu)色的(de)(de)(de)(de)(de)(de)(de)古生(sheng)物學(xue)家。而(er)發(fa)現化(hua)石(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)(de)時間正好是化(hua)石(shi)(shi)(shi)戰爭，當時科(ke)(ke)(ke)普(pu)(pu)的(de)(de)(de)(de)(de)(de)(de)競敵奧塞內爾·查利斯·馬什（O.C. Marsh）卻從沒(mei)有(you)對易碎雙腔(qiang)(qiang)龍(long)提出(chu)(chu)懷疑(yi)。而(er)馬什亦曾(ceng)雇(gu)用(yong)偵探(tan)監視科(ke)(ke)(ke)普(pu)(pu)的(de)(de)(de)(de)(de)(de)(de)發(fa)現，可(ke)(ke)能對易碎雙腔(qiang)(qiang)龍(long)骨頭的(de)(de)(de)(de)(de)(de)(de)巨(ju)大有(you)了(le)確定(ding)。而(er)奧斯本、C.C. Mook、 John S. McIntosh等不同的(de)(de)(de)(de)(de)(de)(de)學(xue)者亦都接受科(ke)(ke)(ke)普(pu)(pu)的(de)(de)(de)(de)(de)(de)(de)資料。所以(yi)(yi)易碎雙腔(qiang)(qiang)龍(long)確實存在。

分類

科普將他的發現于1878年兩度公(gong)布于(yu)《美國博(bo)物(wu)學家》（The American Naturalist）期刊，并分類(lei)在新的(de)(de)(de)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)屬(shu)下(xia)。他把這個屬(shu)編(bian)入梁(liang)(liang)龍(long)(long)(long)科內，雖然(ran)只有(you)部分的(de)(de)(de)化石碎(sui)(sui)片，有(you)些學者(zhe)則將(jiang)它分類(lei)在梁(liang)(liang)龍(long)(long)(long)超科下(xia)，或是(shi)梁(liang)(liang)龍(long)(long)(long)科的(de)(de)(de)“分類(lei)未定屬(shu)”。雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)屬(shu)中(zhong)首先被(bei)命名(ming)(ming)的(de)(de)(de)種(zhong)是(shi)高雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)（正模標本(ben)AMHD 5764），是(shi)由科普(pu)于(yu)1877年(nian)發現。雖然(ran)只有(you)部分的(de)(de)(de)骨骼，但(dan)(dan)有(you)足(zu)夠特(te)征可以(yi)確定此屬(shu)的(de)(de)(de)一些特(te)征。高雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)的(de)(de)(de)化石較為完好(hao)，但(dan)(dan)就比易碎(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)為小。在1921年(nian)，奧(ao)斯本(ben)與(yu)C.C. Mook指出(chu)易碎(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)其實只是(shi)非常(chang)大的(de)(de)(de)高雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)，是(shi)高雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)的(de)(de)(de)異(yi)名(ming)(ming)；在1998年(nian)，John S. McIntosh也同意這個看法(fa)。但(dan)(dan)是(shi)卡彭特(te)指出(chu)，它們在脊椎的(de)(de)(de)構(gou)造上有(you)所差異(yi)，足(zu)以(yi)顯示它們是(shi)不同的(de)(de)(de)種(zhong)，或甚至不同的(de)(de)(de)屬(shu)。

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(yi)較(jiao)多(duo)了解的(de)(de)(de)(de)梁(liang)龍(long)(long)(long)(long)(long)(long)(long)科(ke)(ke)的(de)(de)(de)(de)骨頭作縮放比(bi)例。在科(ke)(ke)普(pu)(pu)原先(xian)的(de)(de)(de)(de)紀錄(lu)，他(ta)以(yi)此來估計(ji)易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)的(de)(de)(de)(de)股骨大(da)(da)小(xiao)(xiao)。科(ke)(ke)普(pu)(pu)發現(xian)在其(qi)(qi)他(ta)的(de)(de)(de)(de)蜥腳下(xia)目恐龍(long)(long)(long)(long)(long)(long)(long)，尤其(qi)(qi)是(shi)(shi)高(gao)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)及至(zhi)高(gao)圓(yuan)頂龍(long)(long)(long)(long)(long)(long)(long)，它們的(de)(de)(de)(de)股骨都是(shi)(shi)背部(bu)最(zui)高(gao)脊椎的(de)(de)(de)(de)兩(liang)倍高(gao)度，因(yin)而估計(ji)易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)的(de)(de)(de)(de)股骨為3.7米(mi)(mi)(mi)(mi)高(gao)，前(qian)腿5.75米(mi)(mi)(mi)(mi)長，后腿7.5米(mi)(mi)(mi)(mi)長，臀(tun)部(bu)高(gao)度為9.7米(mi)(mi)(mi)(mi)。但這些都是(shi)(shi)比(bi)較(jiao)保(bao)守的(de)(de)(de)(de)估計(ji)值，可能和(he)實(shi)際的(de)(de)(de)(de)體(ti)格(ge)大(da)(da)小(xiao)(xiao)有出入，或許比(bi)這小(xiao)(xiao)一些，或者(zhe)還(huan)要(yao)大(da)(da)很多(duo)。于1994年(nian)，葛瑞(rui)格(ge)利·保(bao)羅（Gregory S. Paul）利用(yong)相關的(de)(de)(de)(de)梁(liang)龍(long)(long)(long)(long)(long)(long)(long)作為參考，估計(ji)易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)的(de)(de)(de)(de)股骨大(da)(da)小(xiao)(xiao)為3.1到4米(mi)(mi)(mi)(mi)長。于2006年(nian)，卡彭(peng)特就(jiu)同(tong)樣利用(yong)梁(liang)龍(long)(long)(long)(long)(long)(long)(long)重(zhong)新評估易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)的(de)(de)(de)(de)股骨為4.3到4.6米(mi)(mi)(mi)(mi)。卡彭(peng)特嘗試就(jiu)整(zheng)頭易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)的(de)(de)(de)(de)體(ti)型(xing)作出評估，但發現(xian)梁(liang)龍(long)(long)(long)(long)(long)(long)(long)不同(tong)種(zhong)的(de)(de)(de)(de)體(ti)型(xing)差異，會(hui)影響其(qi)(qi)估計(ji)結果。假(jia)設(she)易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)與梁(liang)龍(long)(long)(long)(long)(long)(long)(long)有著同(tong)一的(de)(de)(de)(de)比(bi)例，它的(de)(de)(de)(de)體(ti)型(xing)就(jiu)是(shi)(shi)58米(mi)(mi)(mi)(mi)，與保(bao)羅在1994年(nian)的(de)(de)(de)(de)估計(ji)范圍（40到60米(mi)(mi)(mi)(mi)）吻合(he)。卡彭(peng)特也(ye)指出易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)的(de)(de)(de)(de)最(zui)小(xiao)(xiao)估計(ji)值，亦比(bi)其(qi)(qi)他(ta)蜥腳下(xia)目更為巨大(da)(da)，如超龍(long)(long)(long)(long)(long)(long)(long)（32.5米(mi)(mi)(mi)(mi)）、腕龍(long)(long)(long)(long)(long)(long)(long)科(ke)(ke)的(de)(de)(de)(de)波(bo)塞東龍(long)(long)(long)(long)(long)(long)(long)（34米(mi)(mi)(mi)(mi)）及泰坦巨龍(long)(long)(long)(long)(long)(long)(long)類的(de)(de)(de)(de)阿根(gen)廷龍(long)(long)(long)(long)(long)(long)(long)（35米(mi)(mi)(mi)(mi)），因(yin)此易(yi)(yi)(yi)碎(sui)(sui)(sui)雙(shuang)(shuang)腔(qiang)(qiang)龍(long)(long)(long)(long)(long)(long)(long)從體(ti)形上來講才是(shi)(shi)最(zui)大(da)(da)的(de)(de)(de)(de)恐龍(long)(long)(long)(long)(long)(long)(long)，也(ye)是(shi)(shi)史上最(zui)大(da)(da)的(de)(de)(de)(de)動物。

假設易(yi)(yi)(yi)碎雙(shuang)(shuang)腔龍(long)(long)(long)(long)相當瘦，但其體(ti)型(xing)大小卻使(shi)它依舊的(de)巨(ju)大。與長(chang)度相比，體(ti)重(zhong)更難去估計(ji)，因為(wei)要使(shi)用(yong)更為(wei)復雜的(de)方程式，比例上的(de)小型(xing)差(cha)異就會產生(sheng)很大的(de)誤差(cha)。以(yi)卡內基梁龍(long)(long)(long)(long)（Diplodocus carnegii）的(de)估計(ji)質量為(wei)120公噸(dun)，易(yi)(yi)(yi)碎雙(shuang)(shuang)腔龍(long)(long)(long)(long)的(de)體(ti)重(zhong)就可(ke)(ke)以(yi)是180---220噸(dun)。易(yi)(yi)(yi)碎雙(shuang)(shuang)腔龍(long)(long)(long)(long)體(ti)重(zhong)大于阿根廷龍(long)(long)(long)(long)的(de)100噸(dun)。近期,科學家們重(zhong)新(xin)研究估計(ji),發(fa)現(xian)易(yi)(yi)(yi)碎雙(shuang)(shuang)腔龍(long)(long)(long)(long)和近親梁龍(long)(long)(long)(long)關系較遠,而(er)和超龍(long)(long)(long)(long)迷惑龍(long)(long)(long)(long)更近,認(ren)為(wei)之前(qian)利(li)用(yong)梁龍(long)(long)(long)(long)估計(ji)易(yi)(yi)(yi)碎雙(shuang)(shuang)腔龍(long)(long)(long)(long)的(de)體(ti)型(xing)得(de)出(chu)來(lai)的(de)結論是不準確(que)得(de)。而(er)利(li)用(yong)超龍(long)(long)(long)(long)和迷惑龍(long)(long)(long)(long)估算后,得(de)出(chu)了新(xin)的(de)數據(ju)。體(ti)長(chang)可(ke)(ke)達到60---80米(mi)(mi)甚至以(yi)上，體(ti)重(zhong)190噸(dun)以(yi)上,這個(ge)顯然和這個(ge)巨(ju)型(xing)動物(wu)的(de)真實體(ti)重(zhong)更加符合(he)。目前(qian)科學家普(pu)遍認(ren)為(wei)，易(yi)(yi)(yi)碎最大個(ge)體(ti)可(ke)(ke)達60---80米(mi)(mi)長(chang)、臀高(gao)10米(mi)(mi)、頭高(gao)14-15米(mi)(mi)之間、體(ti)重(zhong)最重(zhong)220噸(dun)。