Christiane Helene Mendrez Institut de Paliontologie, Museum National d'histoire Naturelle, 8 rue de Buffon, Paris, France

Transcription

1 69 Palaent. afr., 17, A NEW SPECMEN OF PROMOSCHORHYNCHUS PLATYRHNUS BRNK 1954 (MOSCHORHNDAE) FROM THE DAPTOCEPHALUS-ZONE (UPPER PERMAN) OF SOUTH AFRCA by Christiane Helene Mendrez nstitut de Palintlgie, Museum Natinal d'histire Naturelle, 8 rue de Buffn, Paris, France ABSTRACT The mrphlgy f the skull f PrmJchrhynchuJ platyrhinuj (Mschrhinidae) frm the DaptcephalUJ-zne (Upper Permian) f Suth Africa) is described with special reference t the palate and psterir part f the skull. PrmJchrhynchUJ is cmpared with MOJchrhinUJ and cnsidered t be a vaild genus mainly differing frm MOJchrhinUJ in retaining a lnger snut, and in pssessing a mre primitive mrphlgy f the palatal plates f the premaxillae and vmers. PrmJchrhynchUJ als differs frm MOJchrhinUJ in having develped a sharp crijta chanalij and a fairly brad epipterygid. The cmpsitin f the Suth African Mschrhinidae is briefly discussed and is cnsidered temprarily as cnsisting f five genera: M JchrhinUJ (.1 = TigriJuchuJ). CerdPJ, PrmJchrhynchUJ and Hewittia. TigriJuchUJ and MOJchrhinuJ are prbably synnyms. RESUME La mrphlgie du crane de PrmJchrhynchuJ platyrhinuj (Mschrhinidae de la zne a Dap tcephaluj (Permien superieur) d' Afrique du Sud) est etudiee en insistant sur la descriptin du palais et de 'arriere crane. PrmJchrhynchUJ est cmpare a MOJchrhinUJ et cnsidere cmme un genre valable differant essentiellement de MOJchrhinUJ par la retentin d'un plus lng museau et d' une mrphlgie plus primitive des plaques palatales des premaxillaires et vmers. PrmschrhynchUJ differe egalement de MschrhinUJ par e develppement d'une crista chanalij aigue et d'un assez large epipterygide. La cmpsitin des Mschrhinidae sudafricains est discutee brievement et est temprairement cnsideree cmme cnstituee de cinq genres: MschrhinUJ (.?=TigrisuchUJ), CerdPJ, PrmschrhynchuJ et Hewittia. Tigrisuchus et MschrhinUJ snt prbablement synnymes. ZUSAMMENFASSUNG Die Mrphlgie des Schadels vn PrmJchrhynchus ptatyrhinus (Mschrhinidae aus der Daptcephalus Zne (Oberes Perm) vn Sudafrika) ist beschrieben mit besnderer Berucksichtigung des Gaumens und des hinteren Schadelteiles. PrmJchrhynchus wird mit MOJchrhinUJ verglichen, und fur eine selbstandige Gattung befunden. Sie ist hauptsachlich unterschieden vn MOJchrhinuJ durch die Beibehattung der langeren Schnautze, und det mehr primitiven Mrphlgie der Gaumenplatten der Pramaxillaren und der vmeren. PrmschrhynchUJ ist vn MOJchrhinUJ auch darin unterschieden dass sie eine scharfe crista chanalis entwickelt hat. Die Zusammensetzung der sudafrikanischen Mschrhinidae ist kurz behandelt und vrlaufig als aus funf Gattungen bestehend erachtet: MOJchrhinuJ, (? = TigriJuchUJ), Cerdps, Prmschrhynchus und Hewittia. TigrisuchUJ und MschrhinuJ sin sehr wahrscheinlich synnym. NTRODUCTON Prmschrhynchus platyrhinus is based n a snut (B.P.1. N. F.484/M.192) described by Brink 0954, pp , Fig. 2). A new skull and lwer jaw, almst cmplete, save fr the weathered skull rf, and nly slightly distrted (R.C. N. 116) has permitted a mre cmplete study f this genus. One ther specimen, represented by a snut, can als be included in this genus, s that ur knwledge f Prmschrhynchus is limited t three specimens. Material: A. Hltype: B.P.1. N. F.484/M.192: a snut including part f the interrbital regin, but la~ki.ng the rbital margins; the lwer jaw is mlssmg. Cllectin: Bernard Price nstitute fr Palaentlgical Research, Jhannesburg. Lcality: Wilgerbsch, New Bethesda (cllectr: J. W. Kitching). Hri7.0n: Frmer Cistecephalus zne (s.!.) (Upper Permian). Mre precisely the Daptcephalus zne, cf. Kitching (persnal cmmunicatin, 13/11/1973). B. Other Specimens: 1. R.C. N. 116: an almst cmplete skull with lwer jaw; the entire drsal surface f the skull and drs-ateral prtins f the cciput have been weathered away. Cllectin : Rubidge cllectin, Wellwd, Graaff-Reinet.

2 70 Lcality: Wellwd, Graaff-Reinet (cllectr: Hans Wessels). Hrizn: Daptcephalus zne. 2. G.S.P., K.C. N. R.85: a snut, which n the basis f external characters (the palate is nt cmpletely available) can be regarded as representing a prbable Prmschrhynchus. Cllectin: Gelgical Survey, Pretria, Keyser cllectin. Lcality: Ferndale, Graaff-Reinet (cllectr: Andre Keyser). Hrizn: Cistecephalus zne (5.1.), mre precisely the Daptcephalus zne, cf. Keyser (persnal cmmunicatin, 21/11/1973). Diagnsis: Prmschrhynchus is a msthrhinid which can be distinguished frm Mschrhinus by the fllwing features: (1) a mre slender snut, mre elngated in bth the precanine and pstcanine areas; (2) the nasals cnstricted at mid-length; (3) a brader epipterygid with a psterir apphysis mre ventrally lcated; (4) a clearer distinctin between the mastid and the quadrate prcesses f the pisthtic which are separated by a deep grve; (5) a premaxilla mre widely expanded n the palate, especially at the mid-ventral line; (6) a less prnunced anterir expansin f the vmer bth in length and breadth; (7) a sharp crista chanalis, which passes anterirly t the upper canines and is farther ventral t the anterir plate f the vmer than in Mschrhinus; (8) a wider psterir pening f the pst-tempral fssa; -(9) the greater develpment f intermediate and mastid prcesses f the squamsal; the frmer cvers the psterdrsal prcess f the pisthtic in anterir view and the latter cvers a large part f the mastid prcess f the pisthtic in ccipital view; (10) a greater participatin f the supra-ccipital in the margin f the framen magnum. The dentary f Prmschrhynchus differs frm that f M schrhinus in the fllwing characters: (1) the relatively slender bne is nt markedly cnstricted behind the canine; (2) the part f the dentary participating in the frmatin f the symphysis is separated frm the hrizntal ramus by a much less prnunced mentum angulatin, and the derttary is less thickened at this level; (3) the ascending ramus is relatively lnger and the gnial angle is smaller. The dental frmula f Prmschrhynchus is.!2 pc, C, 5-6 PC, it differs frm that t 4' C 6 -? ' Mschrhinus in the slightly greater number f pstcanines. DESCRPTON The skull f Prmschrhynchus platyrhinus (R.C. N. 116) is f medium size with a strngly built snut which is relatively lnger and less massive than that f Mschrhinus. The drsal sur- TABLE 1 The chief measurements (in mm) are: B.P.!' N. F.484/M.192 R.C. N. 116 C.S.P., K.C. N. R.85. Ttal length f the skull (recnstructed) 2. Maximum widlh (recnstructed) 3. Distance between the anterir brder f the premaxilla and the anterir rbital brder (recnstructed) Breadth f the snut at the level f its maximal cnstrictin (recnstructed) 5. Height f the snut at the same level (recnstructed) 6. Ttallenglh f the maxillary dentitin Ttal length f the pstcanine tth-rw Length f the anterir part f the palate, n the middle-line, between the anterir edge f the first incisr alvelar brder and the psterir edge f the medial part f the transverse prcesses Lenglh between this pint f the transverse prcesses and lhe psterir limil f the tubercula sphen-ccipitalia 10. Length, n the middle-line, f the palatal plate f the premaxilla Length f the anterir plate f the vmers, frm the premaxill-vmerine suture t its narrwest part (near the psterir end f the chanal pening) in the middle-line 12. Breadth f the vmer at the premaxill-vmerine suture 13. TOlal length f the dentary, frm drsal pint f the symphysis anterir t the incisrs t the psterir angle f the crnid prcess Length f the hrizntal ramus f the dentary frm the base f the symphysis t the gniac angle Length f the ascending ramus frm the gniac angle t the psterir angle f the crnid prcess apprx. 30 apprx. 26 (right) 16 (right) ,5 135 apprx. 100 apprx. 66 apprx. 39 apprx. 28 (right), 26 (left) 15,5 (right), 13,5 (left) , apprx. 25 apprx. 25 (right) apprx. 16 (right) apprx.

3 71 face f the skull is weathered; hwever the drsal surface f the snut f the type specimen (B.P.. N. F.484/M.192) is well preserved. The type specimen is used als fr the descriptin f the anterir part f the palate because this area in R.C. N. 116 is bscured by the presence f the lwer jaw. Nte n Figures: The skull f R. C. N. 116 being little distrted, the drawings crrespnd t recnstructins, allwing fr the asymmetry and the slight crushing f the psterir part f the skull. The palate f the type (B.P.. N. F.484/M.192) has been represented in an earlier article (Mendrez, 1973, Fig. 7). The drsal surface f the snut f R.C. N. 116 is recnstructed after the type.. SKULL A. Dermal Bnes 1. Drsal5uiface (Fig. 1 and P.. A) n the type specimen (B.P.. N. F.484/M.192) premaxillae, septmaxillae, maxillae, nasals and a small part f the prefrntal and frntal are preserved. The premaxillae (Pmx), f which the nasal prcesses are missing, are little expsed in anterir and lateral view. They are cvered by the septmaxilla (Smx) and the maxilla (Mx). The latter extends anterirly t the level f the furth incisr. V Prtf.mx.-smx_... (N) f.srb--?:,~~~~ f.pttemp f.pt:-parc pt.qpt ~-~ 1cm. Fig. 1 Prmschrhynchus plalyrhinus. RC. N. 116; drsal view (x ). Bc, basiccipital; Cr, crnid; De, dentary; Ec, exccipital; Epl, epipterygid;jmg, framen magnum;fpt.-parc, pterygparccipital framen;je. temp, fenestra tempralis;j.mx.-smx, maxill-septmaxillary fssa;j. parc. Op, parccipital fssa f the pisthtic;j.pttemp, psttempral fssa;j,srb, subrbital fssa (r subrbital vacuity); La, lachrymal; Mx, maxilla; (Na), impressin f the nasal; nar, nare; Op, pisthtic; rb, rbit; Part, prearticular; Pmx, premaxilla;pr.q.pl, quadrate prcess f the pterygid; Prl, prtic; Pt, pterygid; Sang, surangular; Smx, septmaxilla; Sc, supraccipital; Sq, squamsal; Tr, transversum; V2, ntch fr the maxillary branch f the trigeminal nerve; V3, ntch fr the mandibular branch f the trigeminal nerve; X, internal framen fr the hypglssal nerve.

4 72 A _pr.bspt.p.-bsph Op f.pt.prc 5 fe.oy q 0 ".T\GS. P pr p.-v. roo tub.sph:-oc" P ~ Prt.t.Pt Fig. 2.

5 73 Fig. 2 Prmschrhynchus platyrhinus. Re. N. 116; A: cmplete ventral view with lwer jaw in situ (x 1l; B : palate, with lwer jaw suppsed t have been remved (x ). Ang, angular; Art, articular; Bc, basiccipital; C, canine; Cr, crnid; De, dentary; CT. ch, crista chanalis; CT.v.-it.Pt, ventrintermediate crest f the pterygid; cr.v.-m.pt, ventr-medial crest f the pterygid; cr.v.-m. V, ventr-medial crest f the vmer; Ec, exccipital; Ept, epipterygid; fju, jugular framen; fmx.-p, maxill-palatine framen; fpt.-parc, pterygparccipital framen;f v.p., framen fr the vena palatina majr;f v, vmerine framen ;fe.v, fenestra valis;fe.pt.-de, pstdentary fenestra ;f.c.i, fssa fr the lwer canine;j.ipt, interpterygid fssa;j.srb, subrbital fssa (r subrbital vacuity); Jl, first upper incisr; ' first lwer incisr; 1 4, furth lwer incisr; P, fifth upper incisr; inc. prt, incisura prtica ;ju, jugal; 1.t.Pt, lateral lamina fthe pterygid ; l.r.ang, reflected laminaftheangular; Mx, maxilla;.ch, internal chanalpening;.e.c.c.i, external pening f the canal f the internal cartid; Op, pisthtic; P.-Bsph, para-basisphenid cmplex; Pal, palatine; Part, prearticular; PC, first upper pstcanine; pc;s, fifth upper pstcanine; pc, precanine; Pmx, premaxilla; pr.bsph.pt, basisphenid prcess fthepterygid;pr.bspt.p-bsph, basipterygid prcess fthe para-basisphenid ~mplex;pr.mas.op, mastid prcess f the pisthtic; pr.q.pt, quadrate prcess f the pterygid; pr.tr.pt, transverse prcess f the pterygid; Prt, prtic; Pt, pterygid; Sang, surangular; Spl, splenial; Sq, squamsal; sut.itv, intervmerine suture; Tr, transversum; t.r/.my, rf f the middle ear; tub.sph. -c, tuberculum sphen-ccipitale; V, vmer; V2, ntch fr the maxillary branch f the trigeminal nerve; V J, ntch fr the mandibular branch f the trigeminal nerve. The septmaxilla (Smx ) is well develped and has a brad psterir prcess extending between the maxilla and the nasal. The m axilla (Mx ) is highest at a pint ppsite t the middle f the nasals. Frm this pint the maxilla regularly slpes bth frward and backward. Therefre, the nasals appear cnstricted in the middle. n Mschrhinus the maxilla reaches its maximum height at the level f the psterir end f the septmaxilla and this height remains cnstant t the level f the prefrntal, s that the nasals d nt appear cnstricted. The snut f Prmschrhynchus is slightly cnstricted behind the canine; this is mre nticeable in the upper part f the maxilla. This character has nt been bserved in Mschrhinus. The maxilla f Prmschrhynchus participates in the frmatim f the subrbital bar nearly as much as the jugal and extended prbably as far as the psterir limit f the rbit (Fig. 3 and P.. B). n bth genera, a mid-sagittal ridge is present in the psterir part f the nasal and the frntal. 2. Occiput (Fig. 4 and P.. C). Only the basal part f the cciput, belnging t the endcranium, is preserved in R.C. N. 116 and is described belw. 3. Cheek (Fig. 3 and P.. A-B) The relatively narrw jugal (ju) is represented by its anterir and subrbital prtins. Only a small part f the psterir area f the squamsal (Sq) is bservable. Psterirly (Fig. 3 and P.. C) the squamsal cntributes greatly t the lwer margin f the pst-tempral fssa. Within the tempral fenestra (Fig. 5) the anter-ventral prcess f the squamsal (pr.a. -v.sq) is divided int tw, the rbust prtic prcess (pr.prt.sq ) and the slender epipterygid prcess (pr. ept.sq l. A similar subdivisin f the anter-ventral prcess has als been bserved in Mschrhinus and in the Whaitsiidae. The upper part f the quadratjugal (OJ, Fig. 2 and P.. A-C) is well preserved and is brad. t is separated frm the quadrate (Q) by the quadratequadratjugal framen f.q.-q;l. The ventral part f the quadratjugal is weathered. 4. Palate (Fig. 2 A,B and P.. B,C) The palate f Prmschrhynchus is less specialized than that f Mschrhinus, but shws a sharper crista chanalis (cr.ch ). The relative length f the snut is reflected n the palate. n Prmschrhynchus the distance between the psterir edge f the medial part f the transverse prcesses f the pterygid and the psterir limit f the tubercula sphen-ccipitalia (Tab. 1, N.9) equals nly 47% f the length f the anterir part f the palate in the mid-line, between the anterir edge f the first incisr alvelar brder and the psterir edge f the medial part f the transverse prcesses (Tab. 1, N.8). This rati is greater in M schrhinus in which it varies frm 61 % t 68%. n Mschrhinus, the measurements have been taken n the fur specimens in which the whle palate is available. The size f the specimen des nt seem t influence this rati. The palatal plate f the premaxilla (Pmx ) has apprximately the same anter-psterir le ngth bth medially and laterall y, wh e reas in Mschrhinus the lateral part f the plate is cnsiderably lnger than the medial part. Tgether with the maxilla, each premaxilla frms the rf f the fssa fr the lwer canine ([.C.i ). This fssa is nt therwise distinguishable frm the lng renifrm chanal pening (.ch ). The sharp crista chana/is extends frward n the maxilla and reaches the anterir edge f the chanal pening. n Mschrhinus this crest is blunt and tapers t terminate at the level f the canine. The vmers (V. Fig. 2B) are still well separated psterirly by a clear intervmerine suture (sut.itv ). The anterir and psterir plates are situated at the same level drsal t the crista chanalis. The anterir plate bradens anterirly but t a lesser extent than in Mscrhinus and is ar-shaped rather than fanshaped. The ventr-median crest (cr. v. -m. V l is very high and sharp. Tw vmerine framina f. vl are visible anterirly. The pterygids (Pt, Fig. 2A) extend anterirly t the level f the anterir brder f the subrbital fssa ([.srb ). They are remarkable because f the B.P.-G

6 74 Ept Sc Mx nr_.ms.op Bc --Q ~-----Oj ---_0 1cm. ' Fig. 3 PrmJchrhynchuJ platyrhinuj. Re. N. 116; left lateral view (x ). Ang, angular; Art, articular; Bc, basiccipital; C, canine; De, dentary; Ec, exccipital; Ept, epipterygid;fmx, maxillary framen; f ven, venus framen; fe.pt. -De, pst-dentary fenestra; f.mx. -Jmx, maxill-septmaxillary fssa;, first upper incisr; ' first lwer incisr, 1 2, secnd lwer incisr; S, fifth upper incisr; Ju, jugal; l.r.ang, reflected lamina f the angular; La, lachrymal; Mx, maxilla; (Na), impressin f the nasal; nar, nare; rb, rbit; Pal, palatine; Part, prearticular; PJr, prefrntal; pr.it.sp, intermediate prcess f the squamsal; pr.mas.op, mastid prcess f the pisthtic; PC, first upper pstcanine; PCs, fifth upper pstcanine; pc, precanine; Prt, prtic; ~ quadrate; OJ, quadratjugal; Sang, surangular; Smx, septmaxilla; Sc, supraccipital; Sq, squamsal. Ang prminence f the tubersity at the psterir end f the ventr-intermediate crest f the pterygid (cr. v. it.pt), and the very acute angle frmed between the transverse (pr.tr.pt) and the quadrate prcesses (pr. q.pt). The lateral lamina f the pterygid ([.t.pt) is very small. The psterir edge f the transverse prcess seems t be in cntinuity with the edge f the quadrate prcess, while the edge f the tubersity f the ventr-intermediate crest is cntinuus with the edge f the interpterygid fssa lf.ipt) (r "medial pterygid crest" accrding t Barghusen's nmenclature (1968, pp. 6 and 41 )). The lateral end f the cncave transverse prcess is strngly swllen. The pterygids f either side are clsely apprximated in frnt f the para-basisphenid keel (q.p. Bsph). The basisphenid prcess (pr.bsph.pt) extends anterirly a little farther than the external pening f the internal cartid canal (.e.e.c.i.). The lamina between the quadrate prcess and the basisphenid prcess is strngly cncave, brdered by the strng crest f the quadrate prcess. The maxilla (Mx. Fig. 2B) is swllen medially t the canine (C) and is bradly extended medially t the pstcanines (PC). n Mschrhinus, the cntributin f the palatine (Pal) is much greater at the level f the pstcanines. 0 n the type f Prmschrhynchus (B.P.1. N. F. 484/M.192), this part f the maxilla is marked by shallw parallel grves which crrespnd t the impressins f the lwer pstcanines ((PCi) in Mendrez, 1973, Fig. 7). n R.C. N. 116 there are six lwer pstcanines. n Prmschrhynchus the maxill-palatine framen lfmx.-p) is situated mre psterirly than in Mschrhinus. Relative t the psitin f the anterir plate f the vmer, the crista chana lis is situated mre ventrally than in Mschrhinus. The maxilla carries ne precanine, ne canine and five pstcanines. The anterir and psterir parts f the palatine (Pal) are relatively narrw and the latter des nt extend farther than the anterir brder f the subrbital fssa. The transversum (Tr, Fig. 2A,B) extends anterirly a little farther than the anterir brder f the subrbital fssa (f. srb). The crest f the transversum is separated frm the subrbital vacuity by a shrt narrw and flat flange. The brader psterir area is marked by a strng dimple. Psterirly the transversum des nt extend far and its limit remains drsal t the ventr-ateral swelling f the transverse prcess. n Mschrhinus the psterir limit f the transversum reaches the anterir limit f the swelling. B. Endcranium The mrphlgy f the para-basisphenid cmplex (P.-Bsph, Fig. 2) is typical f thercephalians. The basipterygid prcess (pr. bspt. P.-Bsph) is incmpletely cvered by the pterygid. The keel (q.p. B5ph), partly brken, des nt seem t have extended far ventrally. The tubercula sphen-ccipitalia (tub.sph. -c) are strng. The para-basisphenid cmplex, tgether with the basiccipital (Bc, Fig. 7),

7 75 f.mg, tub.prafl _f.pttemp, pr.q.op Fig.4 Prmschrhynchus platyrhinus. Re. N. 116; ccipital view (x 1). Ang, angular; Art, articular; Bc, basiccipital; cdy.c, ccipital cndyle; Ec, exccipital;fju, jugular framen;fmg, framen; (f.parc.op), parccipital fssa f the pisthtic; f.pttemp, psttempral fssa; lvje.v, 'lip' f the fenestra valis; Op, pisthtic; Part, prearticulr; P.-Bsph, para-basisphenid cmplex; pr.it.sq, intermediate prcess f the squamsal; pr.mas.op, mastid prcess f the pisthtic; pr.p.-op, pster-drsal prcess f the pisthtic; pr.q.op, quadrate prcess f the pisthtic; pr.q.pt, quadrate prcess f the pterygid; Q, quadrate; q.p.-bsph, k-eel f the para-basisphenid cmplex; Qj, quadratjugal; Sc, supraccipital; tt.rl.my, rf f the middle ear; tub.pratl, tubersity fr the articulatin with the pratlas. pr p.-d.prt.d.ept- Sc---- f.ve Prt----- pr.a.- d.prt-_. -L_.\.' pr.a.-v.prt V-- (ca.e?,t) lcq.<.b)-- pr.a;-v.epl rg.bas.prt"" ' Q.p.~Ptj v. fe.v pr.c.prt tub.sph.-c pr.q.pt '-' , Fig. 5 Prmschrhynchus platyrhinus. RC. N. 116; Anterir view f the psterir wall f the left tempral fssa (x 5/3). a.p.ept, psterir apphysis f the epipterygid; (ca.cb), brain cavity; (ca.ept), cavum epiptericum; fven, venus framen; f.pttemp, pst-tempral fssa; l.d.ept, drsal lamina f the epipterygid; lvje.v, 'lip' f the fenestra valis; Op, pisthtic; P.Nsph, para-basisphenid cmplex; Pa, parietal; pr.a.-d.prt, anter-drsal prcess f the prtic; pr.a.-v.ept, anterventral prcess f the epipterygid; pr.a.-v.prt, anter-ventral prcess f the prtic; pr.a.-v.sq, anter-ventral prcess f the squamsal; pr.c.prt, central prcess f the prtic; pr.ept.sq, epipterygid prcess f the squamsal; pr.it.sq, intermediate prcess f the squamsal; pr.p.-d.prt, pster-drsal prcess f the prtic; pr.p.-v.ept, pster-ventral prcess f the epipterygid; pr.prt.sq, prtic prcess f the squamsal; pr.q.pt, quadrate prcess f the pterygid; Prt, prtic; Pt, pterygid; Q, quadrate; q.p.-bsph, keel f the para-basisphenid cmplex; OJ, quadratjugal; rg.bas.prt, basal area f the prtic; Sc, supraccipital; Sq, squamsal; tub.sph.-c, tuberculum sphen, ccipitale; V, framen fr the facial nerve. 1cm.

8 76 frm apprximately ne third f the brder f the fenestra val is lfe.v). The epipterygid (Ept, Fig. 6) is much brader than that f Mschrhinus. The psterir apphysis, sel. uating the penings fr the maxillary (V2 ) and m(1 pdibular (V 3) branches f the trigeminal nerve, is psitined fairly lw, n the lwer half f the epipterygid. n cntrast, in Mschrhinus it is situated n the upper half. The pster-ventral prcess (pr.p.-v.ept) is very high. The cavum epiptericum (ca.ept, Fig. 5) is very brad in Prmschrhynchus. The tic bnes n Prmschrhynchus the prtic and pisthtic are distinguishable frm each ther. This cnditin has been bserved by Mendrez in a number f thercephalian families: ctidsuchidae (l972a, p. 201), Whaitsiidae, Pristergnathidae and Mschrhinidae (1974). t is prbably a general feature f the Thercephalians. The prtic (Prt, Fig. 7) is fairly well preserved. t shws the general thercephalian mrphlgical pattern (Ptmalestes excluded, which has an additinal prcess) as far as this is knwn. The basal area f the prtic (rg.bas) is in cntact with the para-basisphenid cmplex (P.-BsPh) and frms a third f the brder f the fenestra valis lfe.v). The anter-ventral prcess (pr.a.-v) is strng with ventral and lateral faces separated by a sharp crest. The framen fr the facial nerve (V) is situated psterirly t the later.al face. The incisura prtic (inc.prt) is narrw psterirly. The anter-drsal prcess (pr.a. -d) is psitined abve and slightly lateral t the anter-ventral prcess and has n sutural cntact with the epipterygid. The shrt pster-drsal prcess (pr.p. -d.prt) is in cntact with the squamsal (Sq) and the pisthtic (OP). The lng central prcess (pr.c.prt), brdered ventrally and drsally by grves, frms the medial half f the bar anterir t the pteryg-parccipital framen lfpt.-parc, Figs. 1 and 2). The squamsal frms the lateral half f this bar. The later-ventral prcess (pr.p. -v.prt, Fig. 2) is as lng as the central prcess. n drsal view, the suture between the prtic and the pisthtic runs laterally thrugh the anterir half f the pst-tempral fssa lf.pttemp). t then emerges anterirly t the parccipital prcess. n ventral view, the suture runs medially twards the fenestra valis where it cntinues ventrally n the drsal brder f the fenestra. The pisthtic (Op) als frms ne-third f the margin f the fenestra valis. ts drsal prcess (pr.p.-d.op, Fig. 4) is thin and elngated ; it is cmpletely cvered anterirly by the intermediate prcess f the squamsal (pr.it.sq, Fig. 5) in cntrast t the situatin bserved in Mschrhinus S.A.M. N. K. 118 (Mendrez, 1974, Figs. 6-7). The parccipital prcess is very strng and is marked ventrally by a very deep and narrw grve (tt.rl.may) separating the quadrate prcess (pr.q.op) frm the pr.c.prt V2---.p.Ept V3 pr.:-y.sq- Fig. 6 pr.~-y.ept 1cm. PrmJchrhynchuJ platyrhinu5. Re. N. 116; lateral view fthe right epipterygid (x 1/3). a.p _Ept, psterir apphysis f the epipterygid; f ven, venus framen; l.d.ept, drsal lamina f the epipterygid; Pa, parietal; pr.a. -v.ept, anter-ventral prcess f the epipterygid; pr.a. -v.prt, anter-ventral prcess f the prtic; pr.a. -v.sq, anter-ventral prcess f the squamsal; pr.c.prt, central prcess f the prtic; pr.ept.sq, epipterygid prcess f the squamsal; pr.p. -v.ept, pster-ventral prcess f the epipterygid; pr_prt.sq, prtic prcess f the squamsal; pr_q_pt, quadrate prcess f the pterygid; Prt, prtic; Sc, supraccipital, V2, ntch fr the maxillary branch f the trigeminal nerve; V3, ntch fr the mandibular branch f the trigeminal nerve. mastid prcess (pr.mas.op). n Mschrhinus this area is brad and shallw. The mastid prcess f Prmschrhynchus is slender, even taking int accunt the crushing f that area. The quadrate prcess (pr.q.op, Fig. 4) is mre massive. The pisthtic is marked ventr-anterirly by a triangular grve abve the fenestra valis int which the stapes prbably fitted. A lng and brad parccipital fssa lf.parc.op, Fig. 4) is fund n the drsal surface f the parccipital prcess. The supraccipital (Sc, Fig. 4) is damaged but what remains shws that it was tripartite, fairly high and brad. t participates bradly in the upper margins f the framen magnum lfmg). t is als well expsed in the tempral fssa (Figs. 1, 3 and 5). The exccipital (Ec, Fig. 4) is tripartite. ts lng and slender lateral prcess frms the rf f the jugular framen lfju). The tuberculum fr the articulatin with the pratlas (tub.pratl) is damaged but seems t have been large. The basiccipital (Bc) frms slightly mre than ne third f the ccipital cndyle. n drsal view it is visible psterirly, but mre anterirly, at the level f the framen magnum (m.mg), it is cvered by the united exccipitals. Tw internal framina fr the hypglssal nerve (X, Fig. 1) pen thrugh the exccipitals n each side. Ventrally, the basiccipital participates in the frmatin f the strng tuberculum sphen-ccipitale (tub.sph.-c, Fig. 2) tgether with the para-basisphenid cmplex. Of the fur

9 77 Fig. 7 inc.prtanterir pening (Fig. 5) f this fssa is frmed by the squamsal, the pisthtic and the prtic. The anterir pening is abut half the size f the psterir ne and is situated mre medially, s that the tw penings nly partly face ne anther. n cntrast, in the pristergnathid Ptmalestes the anterir pening is cmpletely medial t the.prc.op psterir pening and this latter is thus placed behind a sheet f the squamsal. Op _tt.rj.my 1cm. Prmschrhynchus platyrhinus. Re. N. 116; lateral view f the left prtic (x 5/3). Bc, basiccipital; d.n., drsal ntch; Ept, epipterygid; f. ven, venus framen; fe.v, fenestra valis; (f. parc.op), parccipital fssa f the pisthtic; inc.prt, incisure prtica; Op, pisthtic; P. -Bsph, parabasisphenid cmplex; pr.a.-d, anter-drsal prcess; pr.a.-v, anter-ventral prcess;pr.c.prt, central prcess f the prtic; pr.it.sq, intermediate prcess f the squamsal; pr.p.-d.prt, pster-drsal prcess f the prtic; pr.parc.op, parccipital prcess f the pisthtic; rg.bas, basal area f the prtic; Sc, supraccipital; tt.rl.my, rf f the middle ear; V, framen fr the facial nerve. bnes surrunding the fenestra valis, the basiccipita.l participates least in the frmatin f its margm. The quadrate (Q, Fig. 4) is psterirly damaged. t can be bserved in ccipital view and medial view. n additin, in drsal view the left quadrate is visible because the squamsal has weathered away. The squamsal prcess (pr.sq.qj has a shrt narrw and thick base which is visible in ccipital view. Mre drsally, it spreads laterally t frm a flange which meets the quadratjugal. This flange is cnvex psterirly. The pisthtic prcess appears fairly shrt, but the flr f the pisthtic-stapes fssa (f.p. -50 is widely expanded medially. The quadrate-quadratjugal framen Jq.-qj) is brad. C. Principal fssae and penings f the psterir part f the skull The interpterygid vacuity if.ipt, Fig. 2) is heartshaped with its anterir margin divided by the bulging f the ventr-medial crest f the pterygid (cr.v.-m.pt). ts lateral margins are frmed by the medial pterygid crests which cnverge almst t meet psterirly. The fenestra valis ife.v, Fig. 7) is brdered by fur bnes (as said abve): the prtic frms ne third, the pisthtic frms ne third and the parabasisphenid cmplex, alng with a minr cntributin frm the basiccipital, frms the remaining third f the brder. The psterir pening f the pst-tempral fssa (f.pttemp, Fig. 4) is brad and triangular-shaped; its brder is frmed by equal cntributins frm the squamsal and the pisthtic. The brder f the The parccipital fssa if.pare.op, Fig. 4) is almst as lng as the pst-tempral fssa. The anterir wall f the pteryg-parccipital framen Jpt. -pare, Figs. 1 and 2), which is frmed by the central prcess f the prtic and the prtic prcess f the squamsal is narrw in its vertical dimensin as in Msehrhinus. The framen magnum (Fig. 4) is brdered by the exccipitals and the supraccipital, which makes a greater cntributin than in Msehrhinus. The jugular framen (Fig. 4) is brdered by tw bnes: the exccipital and the pisthtic.. LOWER JAW (Figs. 3 and 8) The lwer jaw f Prmsehrhynehus is characterized by a lng dentary (De) f which the crnid prcess extends abve the level f the zygmatic arch. n' additin, the pster-ventral crner f the crnid prcess is separated by a shrt distance nly frm the squamsal. A. Membrane bnes The dentary's hrizntal ramus (Fig. 3) is relatively slender and des nt shw the drs-ventral cnstrictin which exists in Msehrhinus behind the canines. The crnid prcess is thick. The part f the dentary participating in the frmatin f the symphysis is separated frm the hrizntal ramus by a very slight angulatin. Psterirly the hrizntal ramus is separated frm the ascending ramus by a wide gniac angle. The lateral surface f the crnid prcess is marked by a slight grve anterir t the well-defined pst-dentary fenestra ife.pt.-de). Even if distrtin is taken int accunt, the dentary f Mschrhinus differs frm that f Prmsehrhynehus: the "mentum" area f Msehrhinus is much mre massively develped; n bth sides a thickening f the dentary bulges in a manner cmparable t that f the grgnpsians-thugh nt s prnunced and nt median. The ascending ramus is relatively shrter in Msehrhinus and is separated frm the hrizntal ramus by a greater angle. The rati between the length f the ascending ramus (Tab. 1, N. 14) and that f the hrizntal ramus (Tab. 1, N. 15) is apprximately 60% in Msehrhinus (B.P.1. N. F.2788/M.378) and apprximately 82% in Prmsehrhynehus (R.C. N. 116). These ratis are nly given as an indicatin, as lack f specimens precludes the study f variatin in either genus.

10 78 Fig. 8 Prmschrhynchus platyrhinus. Re. N. 116; medial view f the left mandible. Ang, angular; C, canine; Cr, crnid; De, dentary;je.pt.-de, pst-dentary fenestra; p first lwer incisr; 1 4, furth lwer incisr; Part, prearticular; PCp first lwer pstcanine; PC 6, sixth lwer pstcanine; Sang, surangular, Spl, splenial. The angular (Ang) and its reflected lamina have the typical thercephalian mrphlgy with its pattern f bulges and grves. The splenial (Spl, Figs. 2A and 8) is an elngated bne participating in the frmatin f the lwer part f the symphysis. ts psterir extent cannt be determined because it is brken slightly beynd the gniac angle. The crnid (Cr) is nly partially visible in the specimen examined, but is elngated anterpsterirly. The surangular (Sang) is als nly partly visible but its mrphlgy appears t cnfrm with the general thercephalian pattern. The prearticular (Part) is characterized by the height and the sharpness f the buttress linking its vertical lamina t its ventral plate which cvers the articular. B. Cartilage bne The area crrespnding t the articular S damaged t shw any details.. DENTTON t The upper dental frmula is identical in the type specimen (B.P.1. N. F.484/M.192) and the mre cmplete specimen f the Rubidge cllectin (R.C. N. 116): 51, pc, lc, 5PC. These tw specimens are almst identical in size. The specimen in the Keyser cllectin (C.S.P., K.C. N. R.85) which here is cnsidered as a prbable Prmschrhynchus has the fllwing dental frmula: 1 pc, 1 C, 6PC. This specimen is slightly smaller than the ther tw, s the number f pstcanines may be reduced during grwth, withut affecting the length f the pstcanine rw (Tab. 1, N. 7). The lwer dental frmula is 41, 1 C, 6PC. The greater number f pstcanines in the lwer jaw than in the maxilla is a very cmmn feature amngst the thercephalians. Very little can be said abut the teeth because they are damaged. Bth upper and lwer incisrs shw labial facets extending half f their length frm the tip. The fifth upper incisr is smaller than the thers, but still larger than the precanine which in turn is bigger than the pstcanines. The pstcanines seem t be simple cnes. The single upper canines, as preserved, are large. The mesi-distal diameter f each canine is slightly larger than the labi-buccal diameter. V. DSCUSSON Brink ( 1954, pp , Fig. 2) when creating the genus Prmschrhynchus nted tw pints f resemblance with Mschrhinus: a mid-sagittal ridge n the nasal and frntal and the dimensins f the external nares. He nted ne pint f dissimilarity: the different prprtins f the snut. He als cnsidered that Prmschrhynchus agrees with Mschrhynchus in its general prprtins and in the dimensins f the external nares. n additin, he cncludes that Prmschrhynchus had n lwer pstcanine but pssessed a palate "as far develped as in Whaitsia". He (p. 58) als cncluded that Prmschrhynchus "evlved frm Mschrhinus" and that "Whaitsia branched frm Prmschrhynchus fairly early and M schrhynchus much later". All the genera quted abve were included in the Whaitsiidae by Haughtn and Brink (1954, pp ) and Watsn and Rmer (1956, p. 70). n 1958 (p ), Brink divided the frmer family int Whaisiidae prper and Mschrhinidae. He then bserved that "the aberrant Whaitsia pricei" may turn ut t be a Mschrhynchus and this genus, with Prmschrhynchus, culd then be included in the Mschrhinidae. He included Ntaelurps in Ntsllasia, dubting the existence f any difference between this latter and Whaitsia. Cncerning the Suth African Whaitsiids, Kitching (1972, thesis, p. 69) states that: "the marked similarity in the skull mrphlgy, irrespective f minr individual variatins, has led the authr and thers t cnclude that the genera

11 79 Aneugmphius, Ntsllasia and Mschrhynchus represent grwth stages f the genus Whaitsia, as well as Whaitsia pricei and Whaitsia majr. The ther genera Therignathus and UN taelurps n based n single badly preserved specimens are als included in Whaitsia. t has been bserved in the field that UNtsllasia and N Whaitsia nrmally ccur in clse assciatin in the field r in the same hrizn ll. Mendrez (197 3b, in press and 1974) recgnizes nly ne valid genus fr the Whaitsiidae f Tanzania and Suth Africa: Therignathus, which has pririty ver Whaitsia and which, after further preparatin, shws all the essential characteristics f Whaitsia fr that part f the specimen which is preserved. Therignathus is cnsidered then as including Hyenasuchus as well as Alpecpsis, Aneugmphius, Mschrhynchus, Ntaelurps, Ntsllasia and Whaitsia (including W. pricei). The differences between the Whaitsiidae and the Mschrhinidae have been emphasized. n the Mschrhinidae, Kitching (1972, thesis, p. 70) des nt accept the validity f the genus "Prmschrhynchus platyrhinus, based n a distrted snut... " and cming"... frm the same hrizn and expsure n the slpes f Cmpassberg that had previusly yielded tw specimens f the genus Mschrhinus N He cncludes that "additinal preparatin t Prmschrhynchus platyrhinus, M schrhinus warreni and Cerdps burgheri has revealed that these specimens are juvenile stages f Mschrhinus kitchingi as well N (pssibly) as Hewittia. t has been shwn by Mendrez (1973, Fig. 7, in press) that the palate f the type specimen f Prmschrhynchus is very different frm that described by Brink but is clse t that f Mschrhinus thugh clearly distinguishable. The palate f the secnd specimen quted by Mendrez (id, Fig. 8) agrees with that f the type. Further study f the latter specimen gives additinal pints f cmparisn between M schrhinus and Prmschrhynchus and leads t the cnclusin that they are different genera. Mendrez (1974) has discussed als the cmpsitin f the Suth African Mschrhinidae, subtamily Mschrhininae which can be summarized as fllws: Mschrhinus is almst certainly synnymus with Tigrisuchus. Tigrisuchus is represented by the anterir half f the snut and shws a structure identical t that f Mschrhinus, hwever, the precanine frmula is uncertain. Cerdps is apparently very clsely related t Mschrhinus, but is mre lightly built if ne cmpares specimens f the same size belnging t these tw genera. The snut is much less massive and the subrbital bar and the pstrbital and zygmatic arches are mre slender. the precanine frmula is shrter. What is available f the palate cmpares favurably with that f Mschrhinus, but the part f it anterir t the canines is bstructed by the lwer jaw. Hewittia has been cmpared t Mschrhinus n the bais f Brink's dentitin 0958, pp , Figs ) in Mendrez (1974) wh cnclud-es that it is better t leave it as a separate genus since the type specimen is nw lst. CONCLUSON At present, the Suth African Mschrhinidae include five genera f which ne is very dubtful: Tigrisuchus which is prbably a synnym f Mschrhinus, if this can be prved Tigrisuchus has pririty. Of the fur ther genera, Prmschrhynchus appears t be the mst different frm Mschrhinus, n the ne hand, it has a relatively lnger snut, a larger palatal plate f the premaxillae and a narrwer anterir plate f the vmer, but, n the ther hand, it is mre advanced in having a brader epipterygid and a sharper crista chanalis. ACKNOWLEDGEMENTS am very grateful t Dr. S. H. Rubidge and his family fr the lan f the specimen f Prmschrhynchus (R.C. N. 116) and t the staff f the Bernard Price nstitute fr Palaentlgical Research-Dr. A. S. Brink, Dr. A. R.. Cruickshank, Dr. S. H. Haughtn and Dr. J. W. Kitching-fr prviding the facilities fr preparing the type specimen as well as R.C. N am specially grcatful t Dr. J. W. Kitching fr helping me in the preparatin f this latter specimen. wuld like als LO express my thanks t Dr. J. P. Lehman fr his advice and fr prviding the facilities fr munting the plates and making the drawings in the "nstitut de Palentlgie du Museum Natinal d'histire Naturelle de Paris". My thanks are als due t Melle J. Crapart wh made the drawings and plates and whse clse cllabratin and stimulating discussins helped imprve the quality f my bservatins. Dr. H. R. Barghusen has discussed pints with me and has helped with the English versin f this paper. Dr. S. H. Haughtn has agreed t revise this paper and am very grateful fr all their help. REFERENCES BARGHUSEN, H. R. (1968). The lwer jaw f cyndnts (Reptilia, Therapsida) and the evlutinary rigin f mammal-like adductr jaw muscle. Pstilla, 116, BRNK, A. S. (1954). On the Whaitsiidae, a family f Thercephalian mammal-like Reptiles. Trans. Ry. Sc. Afr., 34, ~--- (1958). Ntes n sme Whaitsiids and Mschrhinids. PaLaent. afr., 6,

12 80 HAUGHTON, S. H. and BRNK, A. S. (1954). A bibligraphical list f Reptilia frm the Karr beds f Africa. Palaent. fr., 2, KTCHNG,J. W. (1972). On the distributin f the Karr vertebrate fauna with special reference t certain genera and the bearing f this distributin n the zning f the Beaufrt beds. Ph.D. thesis, Witwatersrand University. (Type script, 127 pp, appendix 256 pp.) MENDREZ, Ch. H. (1973). Principales variatins du palais des thercephales. Cllques int Cent. natn. Rech. Scient. Paris 4-9 juin 1973 (in press). ----(1974). Etude du craned'un jeunespecimen de Mschrhinus kitchingi Brm 1920 (? Tigrisuchus Owen 1876) Thercephalia, Pristersauria, Mschrhinidae d' Afrique australe. Ann. S. Afr. Mus., 64, WATSON, D. M. S. and ROMER, A. S. (1956). A classificatin f Therapsid Reptiles. Bull. Mus. cmp Zl. Harv., 114,37-89.

13 Pmx,--... Smx--- (NL A \L_ \1- \~--- 5 \ pc- C.1--- C.S PC1~~. PC- 5 PC-_ 6-, ' M x - - Pmx-- Mx_ B -De -Sp\ P. c _.ch _V cr.v.-m.v Pal Ept Part Sq- PL_..-La... Tr -Ept - P -Pt - Sq g f.srb-- pr.tr.pt-- Ept- _ pr.q.ptq.p.-bsph Part-- -f.ipt -Ang --Part _rpr.bspt. P.-Bsph - Prt _Sq _1.r.Ang -OJ / : f.pt.-parc / O J P J Prt X Ec f.parc.op Bc Sc " "- " Prt 2cm. J Art. \ f ' E.JU fe.v Bc c P~Bsph f.pt.-pre Part i \ \ \ \ Sang 00

14 f.mx.-smx Mx La Pfr J,u. Ept Sc P.ll 00 "" Smx_ A B Pmx_ 11_- Ee Be ~- / / 12 / 14 Prt, Sc 'i c.s PC! pc9 Ept De La, i Ang, Sang Mx, fe.pt.-de l.r.ang - -Qj Q f.pare.op - Sq t:: ", Sang f.pttemp pr. prt.sq p~.e. Prt. \ pr.,\sq \,, f.mg Sc Qj-- Q--.~ " ~ '.1 Sang--- ~~ f De Sp" f.jul Be / h'-e Part Art. Pt / tub.sp. pr.q. B h pr.tr.pt f mx.- Pmx 5 _-1- q.p.- sp Pt pr.q. / Ee c pr.p.-d.op / La._ Ju --De _Sang _AnQ... Sq,pr.mas.Op ',pr.q.op ". \ Q \ Part \ \ \ Art Ang,, fe.pt.-de Ang, De, PC PCl C.s a, 2em.

15 Prt Ec Sc Ept Sc ~, xu Bc B C./, Bc X-~~_~! a~p.epl~. '. ' ~.c C ~>,"< _Ec f.'len,pt V2 _Op...' V3- t _-pr.c.prt pr.p. v.ept - - '...'.j,._.. _f.srb PL. i La A TL. _ f.pt.-parc -- pr.prt.sq pr.q.pt - - -, De - - f.pttemp pr.a7v.sq,... i.h q. r 0' \ De Ju e Sang Part \ pr.q.pt OJ,- P..ch_- Pal_ f.v.p f.srb- pr.tr.pt- - _f.v.p _ cr.v.-it.pt '--Tr - fo.ipt - - q.p.-bsph ParL Art- 0-- '. ' \ / \ \ \ Sq fe.v i \ Op \ Ec Bc \ tt.rl. my f.ju tub.sph.-c P.-Bsph Part -Sang ';;: OJ, \, " 0 Art, 2cm. 00 u

16 P.V 00 "" A De_ Sang f.mx Pmx Ang- Smx De "..Mx _Sq Sc Prf V2 \ X., Ec,... OP... f.pttemp_ a.p.ept -'-_ pr.p.-v.ept_ Sq-- " ---.~-~- l.d.ept - pr.a.-v.ept 8,, De C.s i Ang, 2cm. V3 pr.q.ept c f.pttemp.g tt.rl.my.g_ pr.mas.op.g_ / pr.q.op Q/ / ~tt / Part pr.tr.pt.g Ang Spl Cr Spl v PC s De pc1 pc C.S ~ \ 1- D~.dfi 4 \, Pmx ",1

17 85 Plate Prmschrhynchus platyrhinus. Re. N. 116; A: drsal view (x ); B: ventral view with lwer jaw in situ (x); C: ventral view f part f the palate, part f the right jaw remved alng a crack (x ). Ang, angular; Art, articular; Bc, basiccipital; C.i., lwer canine; C.s, upper canine; Cr, crnid; cr.v.-it.pt, ventrintermediate crest f the pterygid; cr. v.-m.pt, ventr-median crest f the pterygid; cr. v. -m. V, ventr-median crest f the vmer; De, dentary; Ec, exccipital; Ept, epipterygid;fju, jugular framen;fpt.-parac, pteryg-parccipital framen; f v.p., framen fr the vena platina majr;fe.v,fenestra valis;f.ipt, interpterygid fssa ;f.parc.op, parccipital fssa f the pisthtic; f.srb, subrbital fssa (r subrbital vacuity); Jl, first upper incisr; " first lwer incisr; 1 4, furth lwer incisr; S, fifth upper incisr; ju, jugal; l.r.ang, reflected lamina f the angular; La, lachrymal; Mx, maxilla; (Na), impressin frhe nasal;.ch, internal chanae pening; Op, pisthtic; P.-Bsph, para-basisphenid cmplex; Pa, parietal ; Pal, palatein; Part, prearticular; PC', first upper pstcanine; PCs, fifth upper pstcanine; PC 6, sixth lwer pstcanine; pc, precanine; Pfr, prefrntal; Pmx, premaxilla; p.bspt.p.-bsph, basipterygid prcess f the para-basisphenid cmplex ; Prt, prtic; pr.q.pt, quadrate prcess f the pterygid; pr.tr.pt, transverse prcess f the pterygid; Pt, pterygid; C6 quadrate; q.p.-bsph, keel f the para-basisphenid cmplex; OJ, quadrat-jugal; Sang, surangular; Smx, septmaxilla; Sc, supraccipital; Spl, splenial; Sq, squamsal; Tr, transversum; V, vmer; X, internal framen fr the hypglssal nerve. Plate Prmschrhynchus platyrhinus. Re. N. 116; A; left lateral view (x ); B: right lateral view (x ); C: ccipital view (X ). Ang. angular; Art, articular; Bc, basiccipital; C.s, upper canine; De, dentary; Ec, exccipital; Ept, epipterygid;jju, jugular framen;fmg, framen magnum;fmx, maxillary framen;fe.pt.-de, pst-dentary fenestra;f.mx. -smx, maxillseptmaxillary fssa; f.parc. Op, parccipital fssa f the pisthtic ;f.pttemp, pst-tempral fssa ; ', first upper incisr; " first lwer incisr; 1 2, secnd lwer incisr; 1 4, furth lwer incisr; J5, fifth upper incisr;ju, jugal; l.r.ang, reflected lamina f the angular; La, lachyrymal; Mx, maxilla; Op, pisthtic; Part, prearticular; PC', first upper pstcanine; PCs, fifth upper pstcanine; pc, precanine; Pfr, prefrntal; Pmx, premaxilla; pr.c.prt, central prcess f the prtic ; pr.it.sq, intermediate prcess f the squamsal; pr.mas. Op, mastid prcess f the pisthtic; pr.p. -d. Op, pster-drsal prcess f the pisthtic; pr.prt.sq, prtic prcess f the squamsal; pr.q. Op, quadrate prcess f the pisthtic; 6pr.q. Pt, quadrate prcess f the pterygid, pr.tr.pt, transverse prcess f the pterygid; Prt, prtic; Q; quadrate; OJ~ quadratjugal ; q.p. Bsph, keel f the para-basisphenid cmplex; Sang, surangular; Smx, septmaxilla; Sc, supraccipital; Spl, spenial ; Sq, squamsal; tub.sph. -c, tuberculum sphen-ccipitale. Plate Prmschrhynchus platyrhinus. Re. N. 116; A: ventral view, the skull being slightly tilted t shw the premaxillae (x ); B: drs-ateral view f the right tempral fssa (x ); C: drs-ateral view f the left tempral fssa (x 1). a.p.ept, psterir apphysis f the epipterygid; Ang, angular; Art, articular; Bc, basiccipital; cr. v. -it.pt, ventrintermediate crest f the pterygid; C.s, upper canine; De, dentary; Ec, exccipital; Ept, epipterygid ; f lu, jugular framen;fpt.-parc, pterygparccipital framen;fv.p., framen fr the vena palatina majr;fven, venus framen;j. v, vmerine framen; fe.v, fenestra valis; f.ipt, interpterygid fssa; f.pttemp, psttempral fssa; f.srb, subribtal fssa (r subrbital vacuity);ju, jugal; La, lachrymal;.ch, internal chanae pening; Op, pisthtic; P.-Bsph, parabasisphenid cmplex; Pal, palatine; Part, prearticular; Pmx, premaxilla; pr.a.-d.prt, anter-drsal prcess f the prtic; pr.a. v.ept, anter-ventral prcess f the epipterygid; pr.a.-v.sq, anter-ventral prcess f the squamsal ; pr.c.prt, central prcess f the prtic; pr.p.-v.ept, pster-ventral prcess f the epipterygid; pr.prt.sq, prtic prcess f the squamsal; pr.q.pt, quadrate prcess f the pterygidl pr.tr.pt, transverse prcess f the pterygid; Prt, prtic; Pt, pterygid; Q; quadrate; q.p.-bsph, keel f the para-basisphenid cmplex; OJ, quadratjugal; Sang, surangular; Sc, supraccipital; Spl, splenial; Sq, squamsal Tr, transversum; tt.rl.my, rf f the middle ear; tub.sph. -c, tuberculum sphenccipitale; V, vmer; V2, ntch f the maxillary branch f the trigeminal nerve; V), ntch fr the trigeminal n erve ; X, internal framen f the hypglssal nerve. Plate V Prmschrhynchus platyrhinus. Re. N. 116; A: anterir view (x ); B: laterial view f the right epipterygid (x 1); C: medical view f the left lwer jaw. a.p.ept, psterir apphysis f the epipterygid; Ang, angular; C.s, upper canine; C.i, lwer canine; cr. v. -it.pt.dt, ventrintermediate crest f the right pterygid; Cr, cracid; De, dentary; De.dt, right dentary; Ec, exccipital;jmx, maxillary framen;f.pttemp, pst-tempral fssa;f.pttemp.g, left psttempral fssa; ', first upper incisr; " first lwer incisr; 1 4, furth lwer incisr; P, fifth upper incisr; ju, jugal; l.d.ept, drsal lamina f the epipterygid; Op, pisthtic; Pad.dt, right palatine; Part, prearticular; PC', first upper pstcanine; PCs, fifth upper pstcanine; PC 6, sixth lwer pstcanine; pc, precanine; Pmx, premaxilla; pre.a.-v.ept, anter-ventral prcess f the epipterygid ; pr.mas.op.g, mastid prcess f the left pisthtic; pr.p.-v.ept, pster-ventral prcess f the epipterygid; pr.q.ept, quadrate prcess f the epipterygid ; pr.q.op.g, quadrate prcess f the left pisthtic; pr.tr.pt.g, transverse prcess f the left pterygid; Prt, prtic; Sang, surangular; Smx, septmaxilla; Sc, supraccipital; Spl, splenial; Sq, squamsal; Tr.g, left transversum; tt.rl.my, rf f the left middle ear; V2, ntch fr the maxillary branch f the trigeminal nerve: V), ntch fr the mandibular branch f the trigeminal nerve; X, internal framen fr the hypglsal nerve.