Romer將原來Wiman所(suo)命(ming)名的(de)(de)Helopus重(zhong)新在1956年(nian)命(ming)名為盤足(zu)(zu)龍,同時提(ti)出一(yi)(yi)個(ge)盤族類(lei)的(de)(de)新亞科。到(dao)1934年(nian),楊鐘(zhong)健協(xie)同卞美年(nian)考察(cha)這個(ge)化(hua)石(shi)點,又采(cai)集一(yi)(yi)些破碎(sui)不全的(de)(de)骨(gu)骼,大多屬于盤足(zu)(zu)龍的(de)(de)一(yi)(yi)部(bu)(bu)分,而少部(bu)(bu)分則經過監(jian)定屬于獸(shou)腳(jiao)類(lei)恐龍以(yi)及劍(jian)龍類(lei)的(de)(de)背部(bu)(bu)突棘。盤足(zu)(zu)龍的(de)(de)頭骨(gu)一(yi)(yi)般與圓頂龍相比較,但較為低平。它具有(you)極(ji)為碩長的(de)(de)脖子。總共有(you)17個(ge)頸椎。頸椎體的(de)(de)神經棘很低,在肩部(bu)(bu)附近開(kai)叉(cha)很寬(kuan)廣。據推(tui)估這具師氏盤足(zu)(zu)龍體長達(da)到(dao)10到(dao)11公尺,是(shi)中國(guo)所(suo)正式(shi)命(ming)名的(de)(de)第一(yi)(yi)只蜥腳(jiao)類(lei)恐龍。
我國(guo)發(fa)現(xian)的(de)(de)(de)(de)早的(de)(de)(de)(de)巨龍(long)形類(lei)(lei)恐龍(long)是(shi)師氏盤(pan)足(zu)龍(long)(Euhelopus zdanskyi),同時這(zhe)還(huan)是(shi)在我國(guo)發(fa)現(xian)的(de)(de)(de)(de)第一(yi)只蜥腳(jiao)類(lei)(lei)恐龍(long),早在1921年(nian)奧地利古(gu)生物(wu)學(xue)(xue)(xue)家師丹斯(si)基(ji)(Otto Zdansky,1894—1988)在瑞典烏(wu)普薩拉大(da)學(xue)(xue)(xue)(Uppsala University)的(de)(de)(de)(de)古(gu)生物(wu)學(xue)(xue)(xue)家維曼(Prof Carl Wiman,1867—1944)的(de)(de)(de)(de)建議(yi)下前往中(zhong)(zhong)國(guo),在中(zhong)(zhong)國(guo)他(ta)(ta)有許多重(zhong)大(da)的(de)(de)(de)(de)發(fa)現(xian),比如:著名的(de)(de)(de)(de)古(gu)中(zhong)(zhong)華虎(Panthera palaeosinensis or "Felis (Panthera)" palaeosinensis),北京猿(yuan)人(Homo erectus pekinensis or "Sinanthropus pekinensis")以(yi)及三趾(zhi)馬動(dong)物(wu)群等都(dou)(dou)是(shi)他(ta)(ta)發(fa)現(xian)的(de)(de)(de)(de);在1922年(nian)到1923年(nian)師丹斯(si)基(ji)和(he)我國(guo)地質學(xue)(xue)(xue)家譚錫疇(chou)在山東(dong)省(sheng)蒙陰縣寧家溝的(de)(de)(de)(de)上侏羅統或(huo)下白堊(e)統的(de)(de)(de)(de)蒙陰組(Meng-Yin Formation)地層發(fa)現(xian)并挖掘(jue)了一(yi)些恐龍(long)化石(shi),其中(zhong)(zhong)包括獸腳(jiao)類(lei)(lei)牙齒和(he)劍龍(long)類(lei)(lei)的(de)(de)(de)(de)骨(gu)板,同時還(huan)有兩具不完整(zheng)的(de)(de)(de)(de)蜥腳(jiao)類(lei)(lei)恐龍(long)骨(gu)骼,師丹斯(si)基(ji)把(ba)自己發(fa)現(xian)的(de)(de)(de)(de)大(da)部分化石(shi)都(dou)(dou)送到瑞典的(de)(de)(de)(de)烏(wu)普薩拉大(da)學(xue)(xue)(xue)由維曼研(yan)究,這(zhe)兩具蜥腳(jiao)類(lei)(lei)恐龍(long)骨(gu)骼也是(shi)一(yi)樣(yang)。
維(wei)曼在(zai)(zai)仔細研究了師丹斯(si)基(ji)送來化石后(hou)將(jiang)它們命名(ming)(ming)為(wei)"Helopus" zdanskyi,屬(shu)名(ming)(ming)“Helopus”是希(xi)臘語“濕(shi)(shi)地(di)的(de)(de)(de)(de)腳”的(de)(de)(de)(de)意思(si),而種(zhong)名(ming)(ming)“zdanskyi”是紀念師丹斯(si)基(ji)發現(xian)了這(zhe)種(zhong)恐龍(long);不過在(zai)(zai)1956年羅(luo)默(Alfred Sherwood Romer,1894—1973)發現(xian)一(yi)屬(shu)鳥類(lei)已(yi)經先行占有了“Helopus”這(zhe)個屬(shu)名(ming)(ming),所(suo)后(hou)就被"Helopus" zdanskyi重新(xin)命名(ming)(ming)為(wei)師氏盤(pan)(pan)足龍(long)(Euhelopus zdanskyi),屬(shu)名(ming)(ming)盤(pan)(pan)足龍(long)(Euhelopus)的(de)(de)(de)(de)意思(si)是“出色的(de)(de)(de)(de)濕(shi)(shi)地(di)的(de)(de)(de)(de)腳”,我國的(de)(de)(de)(de)古生(sheng)物(wu)學家(jia)因為(wei)過去認(ren)為(wei)蜥腳類(lei)恐龍(long)的(de)(de)(de)(de)足部的(de)(de)(de)(de)只(zhi)顧和趾骨是散(san)開(kai),像盤(pan)(pan)子一(yi)樣(yang),所(suo)以(yi)翻譯為(wei)“盤(pan)(pan)足龍(long)”;同時羅(luo)默認(ren)為(wei)盤(pan)(pan)足龍(long)的(de)(de)(de)(de)特(te)征獨特(te),所(suo)以(yi)建立了一(yi)個新(xin)的(de)(de)(de)(de)亞科(ke)(ke)(ke)(ke)——盤(pan)(pan)足龍(long)亞科(ke)(ke)(ke)(ke)(Euhelopodinae),當時歸(gui)入(ru)腕龍(long)科(ke)(ke)(ke)(ke)(Brachiosauridae),后(hou)來也有人把盤(pan)(pan)足龍(long)亞科(ke)(ke)(ke)(ke)歸(gui)入(ru)圓(yuan)頂龍(long)科(ke)(ke)(ke)(ke)(Camarasauridae)或(huo)者(zhe)馬門溪龍(long)科(ke)(ke)(ke)(ke)(Mamenchisauridae)的(de)(de)(de)(de),我國一(yi)些老一(yi)輩的(de)(de)(de)(de)古生(sheng)物(wu)學家(jia)目前多同意盤(pan)(pan)足龍(long)亞科(ke)(ke)(ke)(ke)歸(gui)入(ru)圓(yuan)頂龍(long)科(ke)(ke)(ke)(ke);劍橋大(da)學的(de)(de)(de)(de)阿普徹奇(qi)(Paul Publication Upchurch)在(zai)(zai)1995年進一(yi)步提出了盤(pan)(pan)足龍(long)科(ke)(ke)(ke)(ke)(Euhelopodidae),并(bing)認(ren)為(wei)在(zai)(zai)中(zhong)國中(zhong)侏羅(luo)統到白堊系發現(xian)的(de)(de)(de)(de)大(da)量的(de)(de)(de)(de)長頸椎蜥腳類(lei)恐龍(long)都(dou)屬(shu)于這(zhe)一(yi)支系(Upchurch, 1995, 1998)。
但是威(wei)爾(er)遜(Jeff Wilson)和塞里(li)諾(Paul Sereno)等(deng)人(ren)認為(wei)盤(pan)(pan)足龍(long)的頸椎(zhui)神經弓和肩帶結構十分進步,所以應該屬于巨龍(long)形類(lei);而(er)峨嵋龍(long)(Omeisaurus)的頭骨(gu)(gu)(gu),掌骨(gu)(gu)(gu),腰帶和距(ju)骨(gu)(gu)(gu)的特征過于原(yuan)始,并(bing)不屬于新蜥腳類(lei)恐(kong)龍(long)(Neosauropod),和盤(pan)(pan)足龍(long)關系很遠(yuan),目前很多學者都同意這種說(shuo)法(Wilson et Sereno, 1998,1999,2000, Wilson, 2002,Ksepka et Norell, 2006),所以我們在這里(li)也把盤(pan)(pan)足龍(long)作為(wei)巨龍(long)形類(lei)恐(kong)龍(long)進行描述。
因為盤(pan)足龍(long)(long)(long)(long)(long)的(de)(de)化石(shi)只(zhi)(zhi)發(fa)現了(le)(le)頭骨,大部分頸(jing)椎(zhui),肩(jian)帶(dai),前肢(zhi),背椎(zhui),腰帶(dai)和(he)后肢(zhi)等,所以我(wo)們對它的(de)(de)了(le)(le)解也主(zhu)要是這些,至于尾巴的(de)(de)形(xing)態(tai)只(zhi)(zhi)能(neng)(neng)推測。盤(pan)足龍(long)(long)(long)(long)(long)的(de)(de)頭骨和(he)圓頂(ding)龍(long)(long)(long)(long)(long)的(de)(de)比(bi)較接近,都(dou)(dou)屬(shu)于比(bi)較粗(cu)壯(zhuang)而高(gao)的(de)(de)類型,而且鼻孔也很(hen)大,牙齒(chi)也都(dou)(dou)屬(shu)于粗(cu)壯(zhuang)的(de)(de)勺形(xing)齒(chi);但是盤(pan)足龍(long)(long)(long)(long)(long)的(de)(de)頭骨比(bi)圓頂(ding)龍(long)(long)(long)(long)(long)的(de)(de)要長(chang)一些。盤(pan)足龍(long)(long)(long)(long)(long)的(de)(de)頸(jing)椎(zhui)很(hen)長(chang),而且數量很(hen)多,有十七個,估(gu)計長(chang)度超(chao)過(guo)體長(chang)的(de)(de)一半;后部頸(jing)椎(zhui)的(de)(de)神經棘低,而且分叉。盤(pan)足龍(long)(long)(long)(long)(long)的(de)(de)肩(jian)帶(dai)很(hen)發(fa)達(da),肩(jian)臼窩很(hen)淺,中部形(xing)成(cheng)一個斜面,后肢(zhi)較短(duan),所以古生物(wu)學家推測盤(pan)足龍(long)(long)(long)(long)(long)的(de)(de)前肢(zhi)很(hen)可能(neng)(neng)很(hen)發(fa)達(da);因為前肢(zhi)很(hen)長(chang),所以盤(pan)足龍(long)(long)(long)(long)(long)不用把脖子抬得(de)太高(gao)就可以吃到高(gao)處的(de)(de)樹(shu)葉。
巨(ju)龍(long)(long)形(xing)(xing)類(lei)(lei)(Titanosauriformes)恐(kong)龍(long)(long)屬于蜥腳次亞(ya)目(Sauropoda)真(zhen)蜥腳類(lei)(lei)(Eusauropoda)新蜥腳類(lei)(lei)(Neosauropoda)大(da)鼻龍(long)(long)類(lei)(lei)(Macronaria),和圓頂龍(long)(long)科(ke)(Camarasauridae)是姐妹(mei)群(qun);巨(ju)龍(long)(long)形(xing)(xing)類(lei)(lei)主(zhu)要包括腕龍(long)(long)科(ke)(Brachiosauridae),盤足龍(long)(long)科(ke)(Euhelopodidae)和巨(ju)龍(long)(long)類(lei)(lei)(Titanosauria)。巨(ju)龍(long)(long)形(xing)(xing)類(lei)(lei)包括很多著名(ming)的(de)恐(kong)龍(long)(long),比如(ru)坦(tan)(tan)桑尼亞(ya)上侏羅(luo)統的(de)坦(tan)(tan)達古(gu)魯層(ceng)(Tendaguru Beds)地(di)層(ceng)發(fa)現的(de)布氏腕龍(long)(long)(Brachiosaurus (Giraffatitan) brancai or Giraffatitan brancai),我國(guo)山東省上侏羅(luo)統或(huo)下(xia)白(bai)堊統的(de)蒙陰(yin)組(Meng-Yin Formation)地(di)層(ceng)發(fa)現的(de)師氏盤足龍(long)(long)(Euhelopus zdanskyi),阿根(gen)廷下(xia)白(bai)堊統的(de)里約利邁河(he)組(Rio Limay Formation)地(di)層(ceng)發(fa)現的(de)阿根(gen)廷龍(long)(long)(Argentinosaurus),我國(guo)河(he)南省的(de)蟒川組(Mangchuan Formation)地(di)層(ceng)發(fa)現的(de)汝陽黃河(he)巨(ju)龍(long)(long)(Huanghetitan ruyangensis)等。
巨龍(long)形類的特征(zheng)包括沒有前(qian)眶(kuang)前(qian)孔;上(shang)頜骨(gu)(gu)(gu)(gu)(gu)與(yu)前(qian)上(shang)頜骨(gu)(gu)(gu)(gu)(gu)的接(jie)觸面(mian)呈(cheng)棒(bang)狀;齒骨(gu)(gu)(gu)(gu)(gu)的多面(mian)陡(dou)峭。前(qian)棘突板(ban);頸椎(zhui)(zhui)普遍被加長;背椎(zhui)(zhui)氣腔化;背椎(zhui)(zhui)和前(qian)部(bu)尾(wei)(wei)椎(zhui)(zhui)神經弓只比椎(zhui)(zhui)體略窄;前(qian)段的背肋(lei)寬廣,呈(cheng)板(ban)狀;中后(hou)(hou)部(bu)尾(wei)(wei)椎(zhui)(zhui)神經弓位于椎(zhui)(zhui)體的前(qian)面(mian);脈弧不分叉;中后(hou)(hou)部(bu)脈弧向后(hou)(hou)彎曲(qu)。肩臼窩向前(qian)腹側和內側傾斜;掌骨(gu)(gu)(gu)(gu)(gu)長超過脛骨(gu)(gu)(gu)(gu)(gu)的百分之四(si)十五(wu)以上(shang);第一指爪縮(suo)小或(huo)消失。股骨(gu)(gu)(gu)(gu)(gu)骨(gu)(gu)(gu)(gu)(gu)干近端三(san)分之一處側向突出翻(fan)轉;恥(chi)骨(gu)(gu)(gu)(gu)(gu)的坐骨(gu)(gu)(gu)(gu)(gu)關節面(mian)較為縱深;恥(chi)骨(gu)(gu)(gu)(gu)(gu)突前(qian)的腸(chang)骨(gu)(gu)(gu)(gu)(gu)板(ban)明顯(xian)高于其后(hou)(hou)的腸(chang)骨(gu)(gu)(gu)(gu)(gu)板(ban)等(Wilson, 2002,Upchurch et al., 2004,Wilson, 2005,Mo et al., 2006)。
巨(ju)(ju)龍(long)(long)(long)(long)形類(lei)(lei)早(zao)出現(xian)在(zai)中侏羅世(shi)或晚侏羅世(shi),不(bu)過進入白堊紀(ji)(ji)后才(cai)變得十分繁盛,而(er)且是白堊紀(ji)(ji),特別(bie)是晚白堊世(shi)主(zhu)要(yao)的(de)(de)蜥腳(jiao)類(lei)(lei)恐龍(long)(long)(long)(long)。近來對南方岡(gang)瓦(wa)納(na)(na)大(da)(da)陸(lu)和(he)(he)我國發現(xian)的(de)(de)巨(ju)(ju)龍(long)(long)(long)(long)形類(lei)(lei),特別(bie)是一(yi)些巨(ju)(ju)龍(long)(long)(long)(long)類(lei)(lei)的(de)(de)研(yan)究徹底掃除了比如“蜥腳(jiao)類(lei)(lei)進入白堊紀(ji)(ji)后逐漸被鳥臀類(lei)(lei)取代并(bing)滅絕”等(deng)人們過去(qu)對蜥腳(jiao)類(lei)(lei)的(de)(de)一(yi)系列錯誤認(ren)識,我們現(xian)在(zai)知道不(bu)僅(jin)僅(jin)是巨(ju)(ju)龍(long)(long)(long)(long)形類(lei)(lei),在(zai)白堊紀(ji)(ji)還有雷巴齊斯龍(long)(long)(long)(long)科(Rebbachisauridae)和(he)(he)叉背(bei)龍(long)(long)(long)(long)科(Dicraeosauridae)等(deng)很多其他的(de)(de)蜥腳(jiao)類(lei)(lei)恐龍(long)(long)(long)(long),而(er)且它們一(yi)直是南方岡(gang)瓦(wa)納(na)(na)大(da)(da)陸(lu)主(zhu)要(yao)的(de)(de)植食(shi)動物,并(bing)且其中一(yi)部(bu)分甚(shen)至可能侵入或者起(qi)源于北方勞亞大(da)(da)陸(lu),和(he)(he)鳥臀類(lei)(lei)競爭。國外的(de)(de)白堊紀(ji)(ji)的(de)(de)巨(ju)(ju)龍(long)(long)(long)(long)形類(lei)(lei)主(zhu)要(yao)分布在(zai)南方岡(gang)瓦(wa)納(na)(na)大(da)(da)陸(lu)的(de)(de)南美(mei)洲(zhou)(zhou)(zhou),印(yin)度,非洲(zhou)(zhou)(zhou)北部(bu),馬(ma)達(da)加斯加,澳大(da)(da)利亞和(he)(he)南歐,也有部(bu)分化石發現(xian)于北美(mei)洲(zhou)(zhou)(zhou)和(he)(he)俄(e)羅斯西(xi)伯利亞地區南部(bu)。
我國(guo)系統的(de)(de)(de)進(jin)行巨龍形(xing)類研究(jiu)起步較晚,一方面(mian)是因為早期(qi)(qi)發現的(de)(de)(de)材(cai)料較少,另一方面(mian)是過去國(guo)內的(de)(de)(de)分類體系和(he)(he)材(cai)料更新(xin)受到新(xin)研究(jiu)的(de)(de)(de)影響比較小,所(suo)以一些錯(cuo)誤的(de)(de)(de)觀點(dian)和(he)(he)陳舊的(de)(de)(de)認識沒有得到及時更新(xin);但(dan)是最近在我國(guo)的(de)(de)(de)吉(ji)林省(sheng)(sheng),遼寧省(sheng)(sheng),山西省(sheng)(sheng),河南省(sheng)(sheng),甘肅省(sheng)(sheng),廣西省(sheng)(sheng)和(he)(he)浙江省(sheng)(sheng)等地發現了一些巨龍形(xing)類的(de)(de)(de)材(cai)料,雖然(ran)這些材(cai)料也都(dou)大多并不完整(zheng),但(dan)是在一定程(cheng)度(du)上是我們(men)對(dui)了解巨龍形(xing)類的(de)(de)(de)起源和(he)(he)早期(qi)(qi)演化(hua)以及白(bai)堊紀時期(qi)(qi)東亞的(de)(de)(de)生態環境的(de)(de)(de)重(zhong)要的(de)(de)(de)材(cai)料。