短吻贫齿龙_双孔亚纲_海龙目_的新材料及补充研究_英文_

短吻贫齿龙_双孔亚纲_海龙目_的新材料及补充研究_英文_ 第 48卷 第 1期 古 脊 椎 动 物 学 报 pp. 1 - 10 figs. 1 - 5 2010年 1月S IA T ICAVER TEBRA TA PALA 短吻贫齿龙 (双孔亚纲 :海龙目)的 )1 新材料及补充研究 331 324 3 佐藤环 刘 俊 李 淳 赵丽君 吴肖春 3 ) ( 杭州 310012通讯作者 1 浙江自然博物馆 ( )2 日本东京学艺大学 东京 184 - 8501 ( ) 3 中国科学院古脊椎动物与古人类研究所 北京 100044 ( )4 加拿大自然博物馆 渥太华 ON K1 P 6 P4 () 摘要 :记述了产自贵州关岭法郎组瓦窑段 上三叠统 短吻贫齿龙一新材料 。新标本头后骨 骼十分完整 ,使我们对该海龙的全身骨骼形态有了一个完整的认识 ,尤其是澄清了其肩带及 前 、后肢的解剖学特 征 。短吻 贫 齿 龙 牙 齿 稀 少 且 局 限 于 上 、下 颌 的 前 端 , 以 及 末 端 指 /趾 骨 ()爪 扁平等性状明 ,该种不是纯粹的肉食动物 。依据新材料 ,短吻贫齿龙在局部形态上存 ( )在个体变异 ,并确认后肢趾趾式 2 - 3 - 4 - 5 - 5 可作为该海龙的特征之一 。 关键词 :海龙目 ,贫齿龙 ,骨架 ,个体变异 ( ) 中图法分类号 : Q915. 864 文献标识码 : A 文章编号 : 1000 - 3118 201001 - 0001 - 10A NEW SKEL ETO N O F M IOD EN TO SAU RU S B R EV IS ( D IA PS ID A : THAL A TTO SA UR IA ) W ITH A FURTHER STUDY O F THE TA XO N 133 3 4 32ZHAO L i2J un L IU J un L I Chun WU X iao2ChunSA TO Tam ak i ( )1 Z hejiang M useum of N a tu ra l H istory H angzhou 310012 , Ch ina ( )2 Tokyo Gakugei U n iversity Tokyo 184 - 8501 , 4 - 1 - 1 N uku i2Kita2M ach i, Kogane i C ity, Jap an ( ) 3 Institu te of V ertebra te Pa leon tology and Pa leoan th ropology, C h inese A cadem y of S ciences B e ijing 100044 , Ch ina( )4 Canad ian M useum of N a tu re O ttawa ON K1 P 6 P4 , P. O. Box 3443 STN “D ”, Canada ( )3 Co rre spond ing au tho r: Zhao L 2J zlj881 @126. com; W u X2C xcwu@m u s2na tu re. ca A b stra c t A new tha la tto sau rian ske le ton from the Upp e r Tria ssic W ayao M em be r of the Fa lang Fo rm a2 tion, Guan ling a rea, Gu izhou P rovince, Ch ina can be refe rred to M ioden tosau rus brevis. The po stc ran ia l ske le ton of the sp ec im en is we ll2p re se rved and so comp le te tha t it is wo rthy to be de sc ribed. Th is new sp ec im en p rovide s a fu ll know ledge of the o steo logy of the tha la tto sau rian, e sp ec ia lly the ana tom y of the p ec to ra l gird le and bo th the fo re2 and h ind2lim b s. The p re sence of a few tee th re stric ted to the an te rio r end s of bo th the upp e r and lowe r jaw s and do rsoven tra lly fla ttened ungua l p ha lange s ind ica te tha tM. bre2 vis is no t a p u re ca rn ivo re. W ith new info rm a tion, som e ind ividua l va ria tion s a re recogn ized and the d ig2 ( ) ita l fo rm u la 2 - 3 - 4 - 5 - 5 of the p e s can be iden tified a s one of the d iagno stic fea tu re s fo r the tha l2 a tto sau rian. Key word s Tha la tto sau ria, M ioden tosau rus, ske le ton, ind ividua l va ria tion ) 1 中国科学院 、国家外国专家局创新团队国际合作伙伴资助 。 收稿日期 : 2009 - 03 - 12 1 In troduc tion ( ) The typ e of M ioden tosau rus b revis Cheng e t a l. , 2007; W u e t a l. , 2009 is a re la tive ly ( comp le te ske le ton bu t som e e lem en ts of the gird le s a re ob scu red due to po stmo rtem dam age e. ) g. , the scap u la, the ta il is m issing the po ste rio r th ird, and the zeugopod ium and m anu s /p e s of ( ) the fo re lim b s / h ind lim b s a re incomp le te. A new tha la tto sau rian ske le ton F ig. 1 wa s co llec ted from the sam e lowe r Upper Tria ssic W ayao Member of the Falang Fo rma tion in the Guanling a rea, Gu izhou P rovince, Ch ina. A lthough the sku ll of th is sp ec im en is p re se rved in ven tra l view , it is eviden tly refe rab le to M ioden tosau rus brevis on the ba sis of the com b ina tion of the fo llow ing fea tu re s: no mo re than six tee th in the p rem axilla, the sho rt snou t, the eden tu lou s m axilla, the op en and e longa te in te rp te rygo id vacu ity, the in te rna l ca ro tid fo ram en on the ven tra l su rface of the ba sisp heno id, and the in te rc lavic le becom ing m uch na rrowe r d ista lly than p roxim a lly. The new sp ec im en is so comp le te tha t it can be u sed to c la rify the ana tom y of the a rea s tha t a re no t we ll2p re se rved o r m issing in the typ e. The new sp ec im en ofM ioden tosau rus brevis is hou sed in Zhe jiang M u seum of N a tu ra l H isto2 ( ) ry ZMNH , w ith a ca ta logue num be r of ZMNH M 8742. It is a rticu la ted and ve ry comp le te ex2 cep t fo r the p a lm of the righ t fo re lim b and ta rsu s of the left h ind lim b. The sku ll is p re se rved in ven tra l bu t the po stc ran ia l ske le ton is m a in ly in la te ra l view s. The who le ske le ton is abou t 440 cm in to ta l length, w ith a p recauda l length of app roxim a te ly 181. 5 cm. ( )F ig. 1 The new ske le ton of M ioden tosau rus brevis ZMNH M 8742 The sku ll and m and ib le in ven tra l view and the po stc ran ia l m a in ly in la te ra l view 2 D e sc rip tion and comp a rison Sku ll an d m an d ib le The sku ll is sim ila r in length to tha t of the typ e, wh ich is ba sed on the length from the an te rio r m a rgin of the choana to the po ste rio r end of the occ ip ita l condyle ( ) 18. 2 cm in the new sp ec im en and 18. 4 cm in the typ e. The expo sed ven tra l su rface of the sku ll mo rp ho logica lly d iffe rs little from tha t of the typ e, and the m and ib le show s no sign ifican t ana tom ica l d iffe rence a s we ll. The nea rly in tac t sku ll fu rthe r ind ica te s tha t the in te rna l choana is sm a ll and ova l in ou tline; the two p te rygo id s do no t m ee t a long the m id line and the ir sligh tly cu rving m ed ia l m a rgin ind ica te s an op en and long vacu ity be tween them; and the in te rna l ca ro2 ()1期 赵丽君等 :短吻贫齿龙 双孔亚纲 :海龙目 的新材料及补充研究 3 ( ) A s in the typ e, the tid fo ram en is loca ted on the ven tra l su rface of the ba sisp heno id F ig. 2 . p a la ta l e lem en ts do no t have any tee th o r den tic le s on the ven tra l su rface. ( ) F ig. 2 A c lo se2up of the sku ll of M ioden tosau rus brevis ZMNH M 8742 in ven tra l view A bb revia tion s: cho. choana内鼻孔 ; ica. fo ram en fo r in te rna l ca ro tid a rte ry内颈动脉孔 ( ) F ig. 3 The 65 cauda l ve rteb rae of M ioden tosau rus brevis ZMNH M 8742 in la te ra l view A bb revia tion: c. cauda l ve rteb rae尾椎 A x ia l ske le ton The comp le te ve rteb ra l co lum n con sists of 105 ve rteb rae, of wh ich the re ( ) a re 13 ce rvica l, 25 do rsa l, 2 sac ra l, and 65 cauda l ve rteb rae F ig. 3 . The num be r of each ve rteb ra l sec tion of the p recauda l ve rteb ra l co lum n is sam e a s in the typ e. The po ste rio r do rsa l ve rteb rae a re ob scu red by the ove rlapp ing of the e lem en ts of the p e lvic gird le in the typ e, wh ich a re we ll expo sed in ZMNH M 8742. Mo rp ho logica lly, tho se do rsa ls a re no t d iffe ren t m uch from the an te rio r do rsa ls, w ith a neu ra l sp ine tha t is con stric ted a t the ba se. A s a who le, the re a re on ly a few size2re la ted d iffe rence s in the ve rteb ra l co lum n be tween the new sp ec im en and the typ e, of wh ich the mo st obviou s is in the sac ra l and first two cauda l ve rteb rae re la tive to the ( ) do rsa ls see Tab le 1 . The se m ay reflec t ind ividua l va ria tion s w ith in the tha la tto sau rian. Ta b le 1 M ea surem en ts of se lec ted e lem en ts of the type ( from W u e t a l. , 2009 ) an d ()the n ew spec im en ( ZM NH M 8742 in the secon d l in e) mm A xis C6 C9 D2 D12 S2 Ca2L ength of cen trum 30. 3 35. 8 35. 5 38. 8 38. 1 36. 1 43 26 ^ 34. 5 35 38 39. 5 42 40. 5 H e igh t of cen trum — 32. 5 34. 2 35. 5 32. 5 32. 9 37. 5 29. 5 34 33 34 34 45 43 H e igh t of who le ve rteb ra 49 74. 5 82. 4 85. 8 109 106. 9 108. 6 52. 5 70 81 85 — 122 128 M axim a l w id th of sp ine 46 18. 7 22. 2 30 34. 5 19. 5 22. 5 30 19. 5 25. 5 30 26 24. 5 24 H u R a U l Fe F i Ti3 3( ) L ength R 186 114 87 210. 6 96. 294. 5 — 110 — 210 131 1213 ()L 188 105 — — — 103 195 110 115 212 130 122 ( ) P roxim a l w id th R 62. 5 36 — 49. 2 28. 5 50. 5 68 42. 5 — 49. 5 28 48. 5()L 61. 9 37 33 — — — 67 43 40 48 29 50 3 ( ) D istal w id th R 45. 5 36. 8 80. 4 — — 68. 8 91 51 — 78 67 31()L 86 47. 2 36 — — — 95 51. 5 36 77 66 30 MC I MC II MC III MC VI MCV M T I M T II M T III M T IV M TV ( ) L ength R 47 59. 4 60 61. 5 52. 5 56. 4 68. 7 72. 5 — 63 45 42 50 60 55 50 64 68 72 67. 5 颈椎 ; Ca. caudal verteb rae尾椎 ; D. do rsal背椎 ; Fe. fem ur股骨 ; F i. fibu la腓骨 ; Hu. hu2 cervicalA bbreviations: C. m erus肱骨 ; MC. m etacarp al掌骨 ; M T. m etatarsal跖骨 ; Ra. radius桡骨 ; S. sacral荐椎 ; Ti. tib ia胫骨 ; U l. u lna尺骨. 3 p re se rved length o r expo sed w id th保存的长度或暴露的宽度 ; no t inc lud ing the odon to id p roce ss不包含齿突. ^ rd th The typ e ha s the first 47 cauda l ve rteb rae p re se rved, of wh ich, howeve r, the 3to 5and th th the 12and 13a re m issing. The re is no obviou s mo rp ho logica l d iffe rence in the first two cau2 da ls be tween ZMNH M 8742 and the typ e, w ith no chevron face ts a long the po ste roven tra l edge of the cen trum of the two cauda ls. Cauda l ve rteb rae 3 - 5 in the new sp ec im en a lso have a nea r2 ( ly ve rtica lly o rien ted neu ra l sp ine, a s in the first two. A s in the typ e, the neu ra l sp ine shown th ) ( by the imp re ssionof the 6cauda l sta rts to d irec t po ste rodo rsa lly to a grea te r degree in the ) fu rthe r po ste rio r cauda lsand the d ista l end of the neu ra l sp ine is na rrowe r than the ba se. It is th c lea r tha t the cauda l rib is su tu red bu t no t fu sed to the tran sve rse p roce ss un til the 8cauda l, th one mo re po ste rio r than in the typ e. The chevron sta rs to occu r from the 4cauda l ve rteb ra and ndis p re sen t th rough o the rs to the 62. ()1期 赵丽君等 :短吻贫齿龙 双孔亚纲 :海龙目 的新材料及补充研究 5 ( )F ig. 4 The p ec to ra l gird le and fo re lim b s of M ioden tosau rus brevis ZMNH M 8742 ( ) e lem en ts of the p ec to ra l gird le s in in te rna l view and the left hum e ru s in po ste rio r ven tra lA. view; B. the left rad iu s and u lna in po ste rio r view; C. the left m anu s in ven tra l view A bb revia tion s: avf. an te roven tra l flange前腹翼 ; c l. c lavic le 锁骨 ; cn. cen tra le中央腕骨 ; co. co raco id 乌喙骨 ; cof. co raco id fo ram en乌喙孔 ; h. hum e ru s肱骨 ; ic l. in te rc lavic le间锁骨 ; in. in te rm ed ium 中 st rd 间腕骨 ; ra. rad iu s桡骨 ; sc. scap ula肩胛骨 ; ul. u lna尺骨 ; un . l ulnare尺腕骨 ; I, III, V. the 1, 3,th st rd 5m e taca rp a l第一 , 第三和第五掌骨 ; 1, 3. the 1, 3d ista l ca rp a l第一和第三远侧腕骨 No d iffe rence is sign ifican t in the first 47 cauda l ve rteb rae be tween ZMNH M 8742 and the th typ e. A fte r the 47, the fu rthe r po ste rio r cauda l ve rteb rae still keep a sim ila r mo rp ho logy, ex2 cep t fo r the size reduc ing. They re ta in a na rrow , ta ll, and ob lique ly o rien ted neu ra l sp ine be2 fo re the la st cauda l. The la tte r is sligh tly d isp laced, w ith its an te rio r end po in ting backwa rd. It is abou t ha lf2sized and ha s no neu ra l sp ine a t a ll. st Two sac ra l rib s a re we ll2p re se rved in bo th the typ e and ZMNH M 8742. The 1show s little nd d iffe rence be tween the two sp ec im en s. Howeve r, the 2is rod2like and w ith bo th end s sligh tly ( ) exp anded in ZMNH M 8742 F ig. 5A . Th is rib ha s a d ista l end m uch b roade r than the p roxi2 ( ) m a l end in the typ e see fig. 7A , B in W u e t a l. , 2009 . Pec tora l g ird le A ll e lem en ts of the p ec to ra l gird le a re we ll expo sed excep t fo r the scap u2 () la in the typ e W u e t a l. , 2009 . The righ t scap u la is comp le te in ZMNH M 8742. It is cha rac2 ( ) te rized by a th in and b road an te roven tra l flange F ig. 4 . In con tra st to a p la te2like shap e seen in mo st o the r tha la tto sau rian s, the scap u la rem a in s a shaft a lthough ve ry sho rt. The do rsa l b lade of the scap u la doe s no t exp and m uch. In gene ra l, the scap u la is mo st comp a rab le to tha t of A n2 shunsau rus huangguoshuensis bu t the bone in the la tte r ha s a re la tive ly na rrowe r and ta lle r shaft ( ) ( see fig. 5 in L iu and R iepp e l, 2005 . The scap u la of Tha la ttosau rus a lexand rae see fig. 10A ) in N icho lls, 1999 is sligh tly dam aged bu t it show s the p re sence of the an te roven tra l flange. The scap u la of th is sp ec ie s even ha s an eviden t shaft w ith an exp anded do rsa l b lade, ve ry sim i2 la r to tha t of a te rre stria l rep tile. A sm a ll em baym en t ju st po ste rio r to the gleno id seen in the co raco id of the typ e is no t p re s2 en t in ZMNH M 8742. Th is is eviden tly an ind ividua l va ria tion in M ioden tosau rus b revis. The in2 te rc lavic le is p re se rved in exte rna l view in the typ e, wh ich is in in te rna l view in ZMNH M 8742. The in te rna l su rface of the in te rc lavic le is fla t and smoo th in mo st p a rt of the bone; it is strongly concave c lo se to the a rrowhead2like an te rio r end. Pe lv ic g ird le The ilium bea rs a nea rly stra igh t do rsa l b lade w ith a sligh tly b roadened d is2 () ta l tip in the typ e W u e t a l. , 2009 , un like the ilia in A skep tosau rus ita licus, and Endenna2 sau rus acu tirostris in wh ich the do rsa l b lade is mo re strongly cu rved po ste rio rly and d ista lly na r2 ( ) rowed see fig. 10 in M ülle r, 2005; fig. 6 in M ülle r e t a l. , 2005 . Howeve r, the righ t ilium of ( ) ZMNH M 8742 F ig. 5A show s tha t the shaft of the do rsa l b lade is cu rved po ste rodo rsa lly and ( d ista lly no t b roadened, a s in A nshunsau rus huangguoshuensis see fig. 6 in L iu and R iepp e l, ) 2005 , a lthough the shaft is no t a s strongly cu rved a s in A. ita licus, and E. acu tirostris. Th is is an ind ividua l va ria tion w ith in M ioden tosau rus brevis. () The righ t isch ium is nea rly comp le te in exte rna l view in the typ e W u e t a l. , 2009 . It wa s de sc ribed tha t the po ste rio rly d irec ted p roce ss wa s no t a s sha rp ly po in ted a s in mo st o the r tha la tto sau rian s such a s A nshunsau rus huangguoshuensis, A skeptosau rus ita licus, and Endenna2 sau rus acu tirostris. In ZMNH M 8742 , the we ll2p re se rved left isch ium show s a sim ila r mo rp ho2 ( ) see fig. 10 in L iu and R iepp e l, 2005 , w ith a po ste rio rly logy a s seen in A. huangguoshuensis ( ) d irec ted mode ra te p roce ss F ig. 5A . Th is p roce ss c lea rly d iffe rs from tha t of A. ita licus in ( wh ich it is m uch strong and con tinue s from the po ste rom ed ia l m a rgin of the bone see fig. 10 in ) M ülle r, 2005 and tha t of E. acu tirostris in wh ich it is p ronounced and ve ry sha rp , p ro jec ting ( ) po ste rio rly from a nea rly stra igh t po ste rio r m a rgin see fig. 8A in R ene sto, 1992 . It is obviou s tha t the en tire shap e of th is p roce ss in the typ e wa s ob scu red becau se of the dam age a long the m a rgin s of the bone. Fore l im b s Mo st e lem en ts of the zeugopod ium and m anu s a re e ithe r incomp le te o r d isa r2 () ( ticu la ted in bo th fo re lim b s in the typ e W u e t a l. , 2009 . The rad iu s in po ste rio r / ven tra l ) ( ) view and u lna in do rsa l / an te rio r view of the left side and the m anu s of the righ t side a re ( ) () we ll2p re se rved in ZMNH M 8742 F ig. 4B , C . A s p reviou sly de sc ribed W u e t a l. , 2009 , the new rad iu s d iffe rs little from tha t of A nshunsau rus huangguoshuensis [ bu t see A. w ushaensis ( ) the typ e sp ec im en, IV PP V 13782 o r the juven ile in fig. 5 in L iu, 2007 ] , w ith the d ista l ()1期 赵丽君等 :短吻贫齿龙 双孔亚纲 :海龙目 的新材料及补充研究 7 ( )F ig. 5 The p e lvic gird le and h ind lim b s of M ioden tosau rus brevis ZMNH M 8742 A. e lem en ts of the righ t p e lvic gird le and fem u r in m ed ia l view and e lem en ts of the left p e lvic gird le and fe2 ( ) m u r in la te ra l view; B. the righ t fibu la and tib ia and p e s in po ste rio r ven tra lview; C. the left fibu la and ( ) tib ia and p e s in po ste rio r ven tra lview s A bb revia tion s: a s. a straga lu s距骨 ; ca. ca lcaneum 跟骨 ; c r. cauda l rib尾肋 ; f. fem u r股骨 ; fi. fibu la 腓骨 ; fp u. face t fo r p ub is耻骨关节面 ; gl. gleno id po rtion of isch ium 坐骨髋臼部 ; il. ilium 肠骨 ; is. isch ium 坐骨 ; m em. m ed ia l m a rgin of isch ium 坐骨内缘 ; o tf. ob tu ra to r fo ram en闭孔 ; p dm. po ste rodo rsa lst th m a rgin of isch ium 坐骨后背缘 ; p u. p ub is耻骨 ; sr. sac ra l rib荐肋 ; ti. tib ia胫骨 . I, V. the 1, 5st th m e ta ta rsa l第一和第五跖骨 ; 1, 4. the 1, 4d ista l ta rsa l第一和第四远侧跗骨 end wh ich is sligh tly b roade r than the p roxim a l end. The la te ra l edge of the rad iu s is nea rly stra igh t and the u lna r edge is concave. The p roxim a l a rticu la r su rface is fla t whe rea s the d ista l a rticu la r su rface is convex. The expo sed righ t u lna is p roxim a lly incomp le te and the comp le te left one is exten sive ly () cove red by the ga stra lia in the typ e W u e t a l. , 2009 . The left u lna of ZMNH M 8742 show s tha t bo th end s of the bone a re sim ila rly exp anded. The shaft is nea rly symm e trica lly con stric ted a s in A nshunsau rus huangguoshuensis. The do rsa l su rface of the p roxim a l end is sligh tly con2 cave2convex and the ven tra l su rface of the bone is sligh tly concave. The ca rp a ls of the left side a re a rticu la ted and on ly the u lna re is cove red by the rib end in ( ) ZMNH M 8742 F ig. 4C . The re a re 7 ca rp a ls a s in A skep tosau rus ita licus and Endennasau rus acu tirostris. O f the ca rp a ls, the in te rm ed ium is the la rge st, w ith a rough ly rec tangu la r shap e; the cen tra le is the sm a lle st, w ith a shap e a symm e trica lly p en tagona l. Among the fou r d ista l st nd ca rp a ls, the 1and 2a re sim ila r in size and nea rly squa re in shap e; the d ista l ca rp a l 3 is b ig2 st nd ge r than the 1and 2ca rp a ls and w ith a shap e nea rly rec tangu la r; and the d ista l ca rp a l 4 is rdthe la rge st among the fou r d ista ls, w ith a shap e sim ila r to the 3. In the typ e, d ista l ca rp a l 2 is the sm a lle st and w ith an unu sua l shap e, wh ich m ay have been ob scu red by the ove rlap of the m e taca rp a ls. ( ) A s de sc ribed in W u e t a l. 2009 , the five m e ta ta rsa ls of ZMNH M 8742 show no sign ifi2 th ( ) can t mo rp ho logica l bu t length d iffe rence from tho se of the typ e F ig. 5C; Tab le 1 . The 4st rd th m e ta ta rsa l is the longe st and the 1is the sho rte st bu t mo st robu st. The 3and 5m e ta ta rsa ls nd nd a re sam e in length, and the 2is sligh tly sho rte r than the fo rm e r two. In the typ e, the 2m e ta2 th ta rsa l is longe r than the 5; once mo re, an ind ividua l va ria tion w ith in the taxon. The p ha langea l fo rm u la of the fo re lim b cou ld no t be e stab lished in the typ e becau se of the () d isa ssoc ia tion and incomp le tene ss of the p ha lange s W u e t a l. , 2009 . A cco rd ing to the a lmo st in tac t righ t p a lm of ZMNH M8742, the fo rm u la is 2 - 3 - 4 - 4 - 4, a s in A nshunsau rus huang2 () guo2shuensis L iu and R iepp e l, 2005 . The fo rm u la is e ithe r 2 - 3 - 3 - 4 - 3 o r 2 - 3 - 4 - 4 () - 3 in A skep tosau rus ita licus M ülle r, 2005 and 2 - 3 - 4 - 4 - 3 in Endennasau rus acu tirostris (( ) ) M ülle r e t a l. , 2005 and A nshunsau rus w ushaensis R iepp e l e t a l. , 2006 . The ungua l p ha2 ( ) lange s c law sa re do rsa l2ven tra lly fla t, ne ithe r b ila te ra lly comp re ssed no r sha rp ly cu rved a s in o the r a skep to sau ro id s. Th is ind ica te s tha t M ioden tosau rus b revis wa s no t a p u re ca rn ivo re. H in d l im b s The fibu la and tib ia a re incomp le te on bo th righ t and left side s in the typ e () ( W u e t a l. , 2009 , wh ich a re we ll2p re se rved in bo th h ind lim b s of ZMNH M 8742 F ig. 5B , ) ( C . In de ta il, the fibu la re sem b le s tha t of A nshunsau rus huangguoshuensis see fig. 12 in L iu ) and R iepp e l, 2005 mo re than o the r a skep to sau ro id s a lthough its shap e doe s no t change m uch among tho se taxa. It ha s a na rrow p roxim a l ha lf, wh ich is co lum n2like, and an eviden tly b road2 () ened d ista l ha lf, wh ich is fan2shap ed. In A skep tosau rus ita licus M ülle r, 2005 and Endenna2 () sau rus acu tirostris M ülle r e t a l. , 2005 , the d ista l po rtion doe s no t exp and a s m uch a s in ZMNH M 8742 o r A. huangguoshuensis. The tib ia show s a b roadened p roxim a l end and a na rrow d ista l end a s in o the r a skep to sau2 ro id s. It ha s a nea rly stra igh t la te ra l side and a concave fibu la r side. In de ta il, it is mo re sim i2 la r to tha t of E. acu tirostris in tha t the p roxim a l end exp and s to a grea te r degree when comp a red to tha t of o the r a skep to sau ro id s. (A ll ta rsa ls a re m issing excep t fo r one tha t wa s iden tified a s d ista l ta rsa l 5 in the typ e W u ) ( )e t a l. , 2009 . A s in A nshunsau rus huangguoshuensis see fig. 12 in L iu and R iepp e l, 2005 ( ) and A skeptosau rus ita licus see fig. 13B in M ülle r, 2005 , the re a re six ta rsa ls in ZMNH ( ) M 8742 , inc lud ing a ca lcaneum , an a straga lu s, fou r d ista l one s F ig. 5B , C . The a straga lu s is the la rge st among the ta rsa ls and irregu la rly hexagona l in ou tline. It is sim ila r to tha t of A. ita li2 cus, stou te r than tha t of A. huangguoshuensis. The ca lcaneum is the second la rge st and nea rly ( ) round in shap e a lthough five side s a re recogn izab le it is no t comp le te in the left p e s. Among ()1期 赵丽君等 :短吻贫齿龙 双孔亚纲 :海龙目 的新材料及补充研究 9 th the fou r d ista l ta rsa ls, the 4is the la rge st, ju st sligh tly sm a lle r than the ca lcaneum in size. It th th is irregu la rly quad rangle, a rticu la ting the 4and 5m e ta ta rsa ls d ista lly. The o the r th ree d ista l ta rsa ls a re a lso irregu la rly quad rangle; they con tac t the m e ta ta rsa ls 3 to 5. The one tha t wa s () iden tified a s d ista l ta rsa l 5 in the typ e W u e t a l. , 2009 shou ld be d ista l ta rsa l 4. A cen tra le ( ) seen in E ndennasau rus acu tirostris see fig. 7C in M ülle r e t a l. , 2005 is no t p re sen t in ZMNH M 8742. (M e ta ta rsa ls I - III and V a re p re se rved bu t d isa ssoc ia ted w ith one ano the r in the typ e W u ) e t a l. , 2009 . A ll five m e ta ta rsa ls a re we ll2p re se rved in bo th h ind lim b s in ZMNH M 8742. The th st ( ) longe st is the 4m e ta ta rsa l and the sho rte st is the 1see Tab le 1 . It is obviou s tha t m e ta ta r2 sa l V is longe r than m e ta ta rsa l II, wh ich is oppo site in o the r a skep to sau ro id s whe re the p e s is ( known. A cco rd ing to the left p e s, the length o rde r of the five m e ta ta rsa ls from the longe st to ) the sho rte stis m e ta ta rsa ls IV , III, V , II, and I. M e ta ta rsa l I is sho rte st a s in o the r tha la tto2 ( sau rian s bu t no t a s robu st a s in the la tte r, such a s A nshunsau rus huangguoshuensis see fig. 12 ) ( ) in L iu and R iepp e l, 2005 and A skep tosau rus ita licus see fig. 13B in M ülle r, 2005 . ()The p ha langea l fo rm u la of the h ind lim b wh ich wa s unknown in the typ e W u e t a l. , 2009 is 2 - 3 - 4 - 5 - 5. It d iffe rs from tha t of o the r a skep to sau ro id s, be ing 2 - 3 - 4 - 5 - 4 in A n2 () shunsau rus sp ec ie s L iu and R iepp e l, 2005; R iepp e l e t a l. , 2006 , 2 - 3 - 4 - 5 - 4 in Enden2 () nasau rus acu tirostris M ülle r e t a l. , 2005 , and 2 - 3 - 4 - 4 - 4 in A skeptosau rus ita licus () ( ) M ülle r, 2005 . A s in the fo re lim b, the ungua l p ha lange s c law sa re no t h igh ly cu rved and b ila te ra lly comp re ssed a s in o the r a skep to sau ro id s bu t do rsoven tra lly fla t a s in he rb ivo rou s rep 2 () tile s such a s ce ra top sian d ino sau rs W e ishamp e l e t a l. , 2004 . 3 D iscu ssion 3. 1 In d iv idua l va r ia t ion A lthough a num be r of comp le te ske le ton s of d iffe ren t tha la tto sau rian s have been de sc ribed / ( repo rted from the Tria ssic m a rine lim e stone of Ch ina see Cheng e t a l. , 2007; W u e t a l. , ) 2009 , ZMNH M 8742 is the be st one in view of bo th sc ien tific re sea rch and m u seum d isp lay becau se it is no t on ly so comp le te bu t a lso fu lly and beau tifu lly p rep a red by an exp e rienced techn ic ian team. The study of th is sp ec im en lead s u s to have a be tte r unde rstand ing of M ioden2 tosau rus brevis, e sp ec ia lly in the ind ividua l va ria tion of ce rta in struc tu re s. The mo st obviou s of tho se ind ividua l va ria tion s a re recogn ized in the co raco id, ilium , and ) m e taca rp a ls. The va ria tion s a re emp ha sized he re. 1 The co raco id ha s a na rrow em baym en t im 2 m ed ia te ly po ste rio r to the gleno id in the typ e. Th is is, a s p reviou sly de sc ribed, un ique w ith in the Tha la tto sau ria. The re levan t p a rt is we ll2p re se rved in bo th co raco id s of ZMNH M 8742. Howeve r, no such an em baym en t bu t a round edge of the bone is p re sen t, a s in o the r tha la tto2 ) sau rian s. 2 The iliac b lade is mo re stra igh t in o rien ta tion than in o the r tha la tto sau rian s and ha s ( ) a b roadened d ista l end in the typ e, wh ich wa s con side red by W u e t a l. 2009 a s one of d iag2 no stic fea tu re s of M ioden tosau rus b revis. The mo rp ho logy of the ilium in ZMNH M 8742 doe s no t m a tch the cond ition seen in the typ e bu t is sim ila r to tha t of the sp ec ie s of A nshunsau rus. nd ) 3 Bo th the typ e and ZMNH M 8742 a re sim ila r in size. In the typ e, the 2m e ta ta rsa l is longe r th th nd than the 5, wh ile the 5is longe r than the 2in ZMNH M 8742. In add ition to the afo rem en2 nd tioned va ria tion s, the 2sac ra l rib is mo rp ho logica lly d iffe ren t be tween the typ e and the new sp ec im en and the sac ra l and first two cauda l ve rteb rae show som e d iffe rence s in to ta l he igh t o r the sp ine w id th be tween the typ e and the new sp ec im en. 3. 2 Rev ised d ia gn o s is of M ioden tosa u ru s b revis ( ) Cheng e t a l. 2007 e stab lished a se t of d iagno stic cha rac te rs of M ioden tosau rus b revis ( ) ba sed on the study of the sku ll and m and ib le. L a te r, W u e t a l. 2009 em ended the d iagno sis of the sp ec ie s afte r the de sc rip tion of the po stc ran ia l ske le ton. N ew info rm a tion d rawn from ZMNH M 8742 ind ica te s tha t som e of the p reviou sly recogn ized d iagno stic cha rac te rs re la ted to ( ) the co raco id and the ilium va ry w ith in the taxon see aboveand som e fea tu re s from the lim b s ( ) such a s the p ha langea l fo rm u la of the p e sis un ique among the a skep to sau ro id s so fa r known. ) The refo re, the d iagno sis of M. brevis is fu rthe r revised a s: 1 stra igh t snou t ve ry sho rt, nea rly ( ) a s sho rt a s po st2snou t region from an te rio r edge of o rb it to po ste rio r edge of sku ll tab le ; ) ) 2 p re sence of a c re st a long the an te rio r th ird of do rsa l m id line of p rem axillae; 3 p rem axilla ) ) having six con ica l tee th; 4 m axilla eden tu lou s; 5 fron ta l fo rm ing an te rio r bo rde r of p inea l fo2 ) ram en; 6 p a rie ta l po sse ssing a slende r an te ro la te ra l p roce ss to w rap po ste ro la te ra l p roce ss of ) fron ta l; 7 den ta ry having no mo re than six con ica l tee th imp lan ted in the ro stra l po rtion; ) ) 8su rangu la r sudden ly b roaden s ven tra lly a t po ste rio r th ird of its length; 9in te rc lavic le becom 2 ) ing m uch na rrowe r d ista lly than p roxim a lly; and 10p ha langea l fo rm u la of p e s 2 - 3 - 4 - 5 - 5. ( A ckn ow ledgem en ts W e thank M r. D ing J in2Zhao and h is team of the IV PP In stitu te of V e r2 ) teb ra te Pa leon to logy and Pa leoan th ropo logy, B e ijingfo r the ir sk illfu l p rep a ra tion of the sp ec i2 m en. Zhao L i2Jun and Tam ak i Sa to a re gra tefu l to the F inanc ia l Sp ec ia l P ro jec t of Zhe jiang P rovince and Tokyo Gakuge i U n ive rsity fo r suppo rting the ir wo rk, re sp ec tive ly. X iao2Chun ( ) W u’s wo rk is suppo rted by the gran ts R S 34 of Canad ian M u seum of N a tu re and the CA S / SA FEA In te rna tiona l Pa rtne rsh ip P rogram fo r C rea tive R e sea rch Team s, Ch ina. L iu Jun and L i Chun a re suppo rted by NN SFC40772015. Referen ce s ) () () ( ) (Cheng Y N 程延年 , W u X C 吴肖春 , Sato T 佐藤环 , 2007. A new thalatto sau rian Rep tilia: D iap sidafrom the Upp er () ( ) Triassic of Gu izhou, China. V ert PalA siat 古脊椎动物学报 , 45 3: 246 - 260 ( ) ( ) L iu J , 2007. A juven ile sp ecim en of A nshunsau rus Rep tilia: Thalatto sau ria. 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