Romer將原來Wiman所(suo)(suo)命(ming)名(ming)(ming)的(de)(de)(de)Helopus重新(xin)在(zai)1956年命(ming)名(ming)(ming)為盤足(zu)龍(long),同時提(ti)出一(yi)個盤族類的(de)(de)(de)新(xin)亞科。到(dao)(dao)1934年,楊鐘健協同卞(bian)美(mei)年考察(cha)這(zhe)個化(hua)石點,又(you)采集一(yi)些破(po)碎不全(quan)的(de)(de)(de)骨骼,大多(duo)屬于盤足(zu)龍(long)的(de)(de)(de)一(yi)部(bu)分(fen),而少部(bu)分(fen)則經過監定屬于獸腳(jiao)類恐(kong)龍(long)以及劍龍(long)類的(de)(de)(de)背部(bu)突棘(ji)。盤足(zu)龍(long)的(de)(de)(de)頭(tou)骨一(yi)般與圓頂龍(long)相比較,但較為低平(ping)。它具(ju)有極為碩長的(de)(de)(de)脖子。總共有17個頸椎。頸椎體的(de)(de)(de)神經棘(ji)很低,在(zai)肩部(bu)附(fu)近開叉(cha)很寬廣。據推估這(zhe)具(ju)師氏盤足(zu)龍(long)體長達到(dao)(dao)10到(dao)(dao)11公尺(chi),是中(zhong)國所(suo)(suo)正式命(ming)名(ming)(ming)的(de)(de)(de)第一(yi)只蜥腳(jiao)類恐(kong)龍(long)。
我國(guo)(guo)發(fa)(fa)現的(de)(de)早(zao)的(de)(de)巨龍(long)(long)形類(lei)(lei)(lei)恐(kong)(kong)龍(long)(long)是(shi)師氏盤足龍(long)(long)(Euhelopus zdanskyi),同(tong)時這還(huan)是(shi)在(zai)(zai)(zai)我國(guo)(guo)發(fa)(fa)現的(de)(de)第一只(zhi)蜥腳(jiao)類(lei)(lei)(lei)恐(kong)(kong)龍(long)(long),早(zao)在(zai)(zai)(zai)1921年奧地(di)利古(gu)(gu)生(sheng)物學家師丹(dan)斯基(ji)(Otto Zdansky,1894—1988)在(zai)(zai)(zai)瑞(rui)典烏普薩(sa)拉(la)(la)大(da)(da)學(Uppsala University)的(de)(de)古(gu)(gu)生(sheng)物學家維曼(Prof Carl Wiman,1867—1944)的(de)(de)建議下前往中國(guo)(guo),在(zai)(zai)(zai)中國(guo)(guo)他(ta)有許多重大(da)(da)的(de)(de)發(fa)(fa)現,比如:著(zhu)名的(de)(de)古(gu)(gu)中華虎(Panthera palaeosinensis or "Felis (Panthera)" palaeosinensis),北京猿人(ren)(Homo erectus pekinensis or "Sinanthropus pekinensis")以及三(san)趾(zhi)馬動物群等都是(shi)他(ta)發(fa)(fa)現的(de)(de);在(zai)(zai)(zai)1922年到1923年師丹(dan)斯基(ji)和(he)我國(guo)(guo)地(di)質學家譚錫疇在(zai)(zai)(zai)山東省蒙(meng)陰縣寧家溝的(de)(de)上侏羅統或下白堊(e)統的(de)(de)蒙(meng)陰組(zu)(Meng-Yin Formation)地(di)層發(fa)(fa)現并(bing)挖掘了(le)一些恐(kong)(kong)龍(long)(long)化石,其中包括獸(shou)腳(jiao)類(lei)(lei)(lei)牙齒(chi)和(he)劍(jian)龍(long)(long)類(lei)(lei)(lei)的(de)(de)骨板,同(tong)時還(huan)有兩(liang)具(ju)不完整的(de)(de)蜥腳(jiao)類(lei)(lei)(lei)恐(kong)(kong)龍(long)(long)骨骼,師丹(dan)斯基(ji)把自己發(fa)(fa)現的(de)(de)大(da)(da)部(bu)分(fen)化石都送到瑞(rui)典的(de)(de)烏普薩(sa)拉(la)(la)大(da)(da)學由(you)維曼研究,這兩(liang)具(ju)蜥腳(jiao)類(lei)(lei)(lei)恐(kong)(kong)龍(long)(long)骨骼也(ye)是(shi)一樣。
維曼在仔(zi)細研究了(le)師(shi)丹(dan)斯(si)基送來(lai)(lai)化(hua)石后(hou)將(jiang)它們命名(ming)為(wei)(wei)"Helopus" zdanskyi,屬(shu)名(ming)“Helopus”是希臘(la)語“濕(shi)地(di)的(de)腳”的(de)意思,而(er)種名(ming)“zdanskyi”是紀念(nian)師(shi)丹(dan)斯(si)基發現了(le)這種恐(kong)龍(long)(long)(long);不過(guo)在1956年羅(luo)(luo)(luo)默(Alfred Sherwood Romer,1894—1973)發現一(yi)屬(shu)鳥類已經先行占有(you)了(le)“Helopus”這個屬(shu)名(ming),所(suo)后(hou)就被"Helopus" zdanskyi重新命名(ming)為(wei)(wei)師(shi)氏盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)(Euhelopus zdanskyi),屬(shu)名(ming)盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)(Euhelopus)的(de)意思是“出(chu)色的(de)濕(shi)地(di)的(de)腳”,我國(guo)的(de)古生物學家因(yin)為(wei)(wei)過(guo)去認為(wei)(wei)蜥(xi)腳類恐(kong)龍(long)(long)(long)的(de)足部的(de)只顧和趾骨是散開,像(xiang)盤(pan)(pan)(pan)(pan)子一(yi)樣,所(suo)以翻譯為(wei)(wei)“盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)”;同時羅(luo)(luo)(luo)默認為(wei)(wei)盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)的(de)特(te)征獨特(te),所(suo)以建(jian)立了(le)一(yi)個新的(de)亞(ya)(ya)科(ke)(ke)(ke)——盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)亞(ya)(ya)科(ke)(ke)(ke)(Euhelopodinae),當(dang)時歸(gui)(gui)入(ru)腕龍(long)(long)(long)科(ke)(ke)(ke)(Brachiosauridae),后(hou)來(lai)(lai)也有(you)人把盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)亞(ya)(ya)科(ke)(ke)(ke)歸(gui)(gui)入(ru)圓(yuan)頂龍(long)(long)(long)科(ke)(ke)(ke)(Camarasauridae)或者馬門溪龍(long)(long)(long)科(ke)(ke)(ke)(Mamenchisauridae)的(de),我國(guo)一(yi)些老一(yi)輩的(de)古生物學家目前多同意盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)亞(ya)(ya)科(ke)(ke)(ke)歸(gui)(gui)入(ru)圓(yuan)頂龍(long)(long)(long)科(ke)(ke)(ke);劍橋(qiao)大學的(de)阿(a)普徹奇(Paul Publication Upchurch)在1995年進一(yi)步提出(chu)了(le)盤(pan)(pan)(pan)(pan)足龍(long)(long)(long)科(ke)(ke)(ke)(Euhelopodidae),并認為(wei)(wei)在中國(guo)中侏羅(luo)(luo)(luo)統到(dao)白堊系(xi)發現的(de)大量的(de)長頸椎(zhui)蜥(xi)腳類恐(kong)龍(long)(long)(long)都屬(shu)于這一(yi)支系(xi)(Upchurch, 1995, 1998)。
但是(shi)威爾遜(Jeff Wilson)和(he)塞里諾(Paul Sereno)等人認為盤足(zu)龍(long)的(de)頸椎神經弓(gong)和(he)肩帶結構十分進步(bu),所以(yi)(yi)應該屬(shu)于(yu)巨龍(long)形類(lei)(lei);而(er)峨嵋龍(long)(Omeisaurus)的(de)頭骨(gu),掌骨(gu),腰帶和(he)距骨(gu)的(de)特征過于(yu)原始,并不(bu)屬(shu)于(yu)新蜥腳類(lei)(lei)恐龍(long)(Neosauropod),和(he)盤足(zu)龍(long)關系很遠,目前很多(duo)學者都同意這種說法(fa)(Wilson et Sereno, 1998,1999,2000, Wilson, 2002,Ksepka et Norell, 2006),所以(yi)(yi)我(wo)們在(zai)這里也把盤足(zu)龍(long)作為巨龍(long)形類(lei)(lei)恐龍(long)進行(xing)描述。
因為盤足(zu)龍(long)(long)的(de)(de)(de)(de)(de)化石只(zhi)發(fa)(fa)現(xian)了頭(tou)骨,大部分頸(jing)椎,肩(jian)帶(dai)(dai),前肢,背椎,腰帶(dai)(dai)和后肢等(deng),所(suo)以我們對它的(de)(de)(de)(de)(de)了解也(ye)主要是這些,至于尾巴的(de)(de)(de)(de)(de)形態(tai)只(zhi)能推測。盤足(zu)龍(long)(long)的(de)(de)(de)(de)(de)頭(tou)骨和圓(yuan)頂龍(long)(long)的(de)(de)(de)(de)(de)比(bi)較接近,都屬于比(bi)較粗(cu)壯而(er)高的(de)(de)(de)(de)(de)類型,而(er)且鼻孔也(ye)很大,牙齒(chi)也(ye)都屬于粗(cu)壯的(de)(de)(de)(de)(de)勺形齒(chi);但(dan)是盤足(zu)龍(long)(long)的(de)(de)(de)(de)(de)頭(tou)骨比(bi)圓(yuan)頂龍(long)(long)的(de)(de)(de)(de)(de)要長(chang)一些。盤足(zu)龍(long)(long)的(de)(de)(de)(de)(de)頸(jing)椎很長(chang),而(er)且數量很多(duo),有十七(qi)個,估計(ji)長(chang)度超(chao)過體長(chang)的(de)(de)(de)(de)(de)一半;后部頸(jing)椎的(de)(de)(de)(de)(de)神經(jing)棘低,而(er)且分叉。盤足(zu)龍(long)(long)的(de)(de)(de)(de)(de)肩(jian)帶(dai)(dai)很發(fa)(fa)達(da)(da),肩(jian)臼窩很淺,中部形成(cheng)一個斜(xie)面,后肢較短(duan),所(suo)以古生物學家推測盤足(zu)龍(long)(long)的(de)(de)(de)(de)(de)前肢很可(ke)能很發(fa)(fa)達(da)(da);因為前肢很長(chang),所(suo)以盤足(zu)龍(long)(long)不用把脖(bo)子抬得太高就可(ke)以吃(chi)到高處的(de)(de)(de)(de)(de)樹葉。
巨龍(long)(long)(long)(long)形類(Titanosauriformes)恐(kong)龍(long)(long)(long)(long)屬(shu)于蜥腳(jiao)次亞目(Sauropoda)真(zhen)蜥腳(jiao)類(Eusauropoda)新蜥腳(jiao)類(Neosauropoda)大鼻龍(long)(long)(long)(long)類(Macronaria),和(he)圓頂龍(long)(long)(long)(long)科(ke)(Camarasauridae)是姐妹群;巨龍(long)(long)(long)(long)形類主要(yao)包(bao)括(kuo)腕龍(long)(long)(long)(long)科(ke)(Brachiosauridae),盤足龍(long)(long)(long)(long)科(ke)(Euhelopodidae)和(he)巨龍(long)(long)(long)(long)類(Titanosauria)。巨龍(long)(long)(long)(long)形類包(bao)括(kuo)很多著名(ming)的(de)(de)(de)恐(kong)龍(long)(long)(long)(long),比(bi)如坦桑尼亞上(shang)侏羅統(tong)(tong)的(de)(de)(de)坦達古魯層(ceng)(Tendaguru Beds)地(di)(di)層(ceng)發現的(de)(de)(de)布氏腕龍(long)(long)(long)(long)(Brachiosaurus (Giraffatitan) brancai or Giraffatitan brancai),我國山東省(sheng)上(shang)侏羅統(tong)(tong)或下(xia)白堊統(tong)(tong)的(de)(de)(de)蒙陰組(zu)(Meng-Yin Formation)地(di)(di)層(ceng)發現的(de)(de)(de)師氏盤足龍(long)(long)(long)(long)(Euhelopus zdanskyi),阿根廷(ting)下(xia)白堊統(tong)(tong)的(de)(de)(de)里約利邁河(he)組(zu)(Rio Limay Formation)地(di)(di)層(ceng)發現的(de)(de)(de)阿根廷(ting)龍(long)(long)(long)(long)(Argentinosaurus),我國河(he)南省(sheng)的(de)(de)(de)蟒川組(zu)(Mangchuan Formation)地(di)(di)層(ceng)發現的(de)(de)(de)汝(ru)陽黃河(he)巨龍(long)(long)(long)(long)(Huanghetitan ruyangensis)等(deng)。
巨龍(long)形(xing)類的(de)(de)(de)特征包括沒有前眶前孔;上頜(he)骨(gu)(gu)與前上頜(he)骨(gu)(gu)的(de)(de)(de)接觸面呈棒狀;齒骨(gu)(gu)的(de)(de)(de)多面陡峭。前棘突(tu)板;頸椎(zhui)(zhui)(zhui)(zhui)(zhui)普遍被加(jia)長;背椎(zhui)(zhui)(zhui)(zhui)(zhui)氣腔(qiang)化;背椎(zhui)(zhui)(zhui)(zhui)(zhui)和前部(bu)尾椎(zhui)(zhui)(zhui)(zhui)(zhui)神(shen)經(jing)弓(gong)(gong)只比椎(zhui)(zhui)(zhui)(zhui)(zhui)體(ti)(ti)略(lve)窄;前段的(de)(de)(de)背肋寬廣,呈板狀;中(zhong)后(hou)(hou)部(bu)尾椎(zhui)(zhui)(zhui)(zhui)(zhui)神(shen)經(jing)弓(gong)(gong)位于椎(zhui)(zhui)(zhui)(zhui)(zhui)體(ti)(ti)的(de)(de)(de)前面;脈(mo)弧(hu)不分叉;中(zhong)后(hou)(hou)部(bu)脈(mo)弧(hu)向(xiang)后(hou)(hou)彎曲。肩臼窩(wo)向(xiang)前腹側(ce)和內側(ce)傾斜;掌(zhang)骨(gu)(gu)長超過脛(jing)骨(gu)(gu)的(de)(de)(de)百分之(zhi)四(si)十五以上;第一指(zhi)爪(zhua)縮小或消失(shi)。股骨(gu)(gu)骨(gu)(gu)干近端三分之(zhi)一處側(ce)向(xiang)突(tu)出翻(fan)轉;恥骨(gu)(gu)的(de)(de)(de)坐(zuo)骨(gu)(gu)關節面較為縱深;恥骨(gu)(gu)突(tu)前的(de)(de)(de)腸(chang)骨(gu)(gu)板明(ming)顯高于其后(hou)(hou)的(de)(de)(de)腸(chang)骨(gu)(gu)板等(Wilson, 2002,Upchurch et al., 2004,Wilson, 2005,Mo et al., 2006)。
巨龍(long)形(xing)(xing)類(lei)(lei)(lei)早出現(xian)(xian)在中侏(zhu)羅(luo)世(shi)或(huo)晚侏(zhu)羅(luo)世(shi),不(bu)過(guo)進入白堊(e)(e)紀(ji)后才變得十分繁盛,而且(qie)是(shi)白堊(e)(e)紀(ji),特別(bie)(bie)是(shi)晚白堊(e)(e)世(shi)主(zhu)(zhu)要的(de)(de)(de)蜥(xi)腳(jiao)(jiao)類(lei)(lei)(lei)恐龍(long)。近來對南(nan)(nan)方(fang)岡瓦(wa)納大(da)陸和(he)我(wo)國發現(xian)(xian)的(de)(de)(de)巨龍(long)形(xing)(xing)類(lei)(lei)(lei),特別(bie)(bie)是(shi)一(yi)(yi)些巨龍(long)類(lei)(lei)(lei)的(de)(de)(de)研究徹底掃除了(le)比如(ru)“蜥(xi)腳(jiao)(jiao)類(lei)(lei)(lei)進入白堊(e)(e)紀(ji)后逐漸(jian)被鳥(niao)臀類(lei)(lei)(lei)取代并滅絕”等人(ren)們(men)過(guo)去對蜥(xi)腳(jiao)(jiao)類(lei)(lei)(lei)的(de)(de)(de)一(yi)(yi)系列錯(cuo)誤認識,我(wo)們(men)現(xian)(xian)在知道不(bu)僅(jin)僅(jin)是(shi)巨龍(long)形(xing)(xing)類(lei)(lei)(lei),在白堊(e)(e)紀(ji)還有(you)雷巴齊斯龍(long)科(ke)(Rebbachisauridae)和(he)叉背龍(long)科(ke)(Dicraeosauridae)等很多其他的(de)(de)(de)蜥(xi)腳(jiao)(jiao)類(lei)(lei)(lei)恐龍(long),而且(qie)它們(men)一(yi)(yi)直是(shi)南(nan)(nan)方(fang)岡瓦(wa)納大(da)陸主(zhu)(zhu)要的(de)(de)(de)植食(shi)動物,并且(qie)其中一(yi)(yi)部分甚(shen)至可能(neng)侵入或(huo)者(zhe)起源于北方(fang)勞亞(ya)大(da)陸,和(he)鳥(niao)臀類(lei)(lei)(lei)競爭(zheng)。國外(wai)的(de)(de)(de)白堊(e)(e)紀(ji)的(de)(de)(de)巨龍(long)形(xing)(xing)類(lei)(lei)(lei)主(zhu)(zhu)要分布(bu)在南(nan)(nan)方(fang)岡瓦(wa)納大(da)陸的(de)(de)(de)南(nan)(nan)美(mei)洲,印(yin)度,非(fei)洲北部,馬達加斯加,澳(ao)大(da)利亞(ya)和(he)南(nan)(nan)歐,也有(you)部分化石發現(xian)(xian)于北美(mei)洲和(he)俄羅(luo)斯西(xi)伯(bo)利亞(ya)地區南(nan)(nan)部。
我(wo)國系統的(de)(de)(de)進行巨(ju)龍(long)形(xing)(xing)類研究(jiu)起步(bu)較晚(wan),一(yi)(yi)方(fang)面是(shi)因為早期(qi)發現的(de)(de)(de)材(cai)(cai)料(liao)(liao)較少,另一(yi)(yi)方(fang)面是(shi)過去(qu)國內的(de)(de)(de)分類體系和(he)材(cai)(cai)料(liao)(liao)更新(xin)受到新(xin)研究(jiu)的(de)(de)(de)影響比(bi)較小,所以(yi)(yi)一(yi)(yi)些(xie)錯(cuo)誤(wu)的(de)(de)(de)觀點和(he)陳舊的(de)(de)(de)認識沒(mei)有得到及時(shi)更新(xin);但(dan)(dan)是(shi)最近在我(wo)國的(de)(de)(de)吉林省(sheng)(sheng)(sheng),遼寧省(sheng)(sheng)(sheng),山(shan)西(xi)省(sheng)(sheng)(sheng),河南(nan)省(sheng)(sheng)(sheng),甘肅省(sheng)(sheng)(sheng),廣西(xi)省(sheng)(sheng)(sheng)和(he)浙江省(sheng)(sheng)(sheng)等(deng)地發現了(le)(le)一(yi)(yi)些(xie)巨(ju)龍(long)形(xing)(xing)類的(de)(de)(de)材(cai)(cai)料(liao)(liao),雖然這些(xie)材(cai)(cai)料(liao)(liao)也都大多并不完整,但(dan)(dan)是(shi)在一(yi)(yi)定(ding)程度上是(shi)我(wo)們對了(le)(le)解巨(ju)龍(long)形(xing)(xing)類的(de)(de)(de)起源和(he)早期(qi)演(yan)化以(yi)(yi)及白堊紀時(shi)期(qi)東亞的(de)(de)(de)生態環(huan)境的(de)(de)(de)重(zhong)要(yao)的(de)(de)(de)材(cai)(cai)料(liao)(liao)。