On the Traces of Cranial Veins in Saurischians and Ornithischians, As Well As Several Other Fossil and Recent Reptiles1

On the traces of cranial veins in Saurischians and Ornithischians, as well as several other fossil and recent reptiles1

By WERNER JANENSCH, Berlin with 5 Figures

1 Original citation: Janensch, W. 1936. Über bahnen von Hirnvenen bei Saurischiern und Ornithischiern, sowie einigen anderen fossilen und rezenten Reptilien. Paleont. Zeitschrift 18(3-4):181-198. Translated 2009 by J.A. Whitlock, University of Michigan. There are not many observations on the traces of veins on the braincases of fossil reptiles to be found in the literature. They cannot be noticable, since in the adult head the intracranial veinous system sends only a very few branches by the skull wall. If, however, foramina are interpretable as insertion places of veins, then their experiences over the ontogenetic development of the intracranial venous system must be considered in our interpretation. C. VAN GELDEREN (1924/25) stated very clearly how this occurs with the different sauropsids and thereby how important elements are backformed to a large extent. Since such evolutionary investigations—understandably—treats only the process of the container, but not or only in small measure the question of whether traces impress themselves into the fully developed bony braincase2, then the interpretation of questionable venous foramina is difﬁcult for the paleontologist

2 [Ed.]—Hirnkapsel-lit. cranium, here considered as ʻbraincaseʼ 182 Werner Janensch, and always afﬂicted with a fairly large measure of uncertainty. During the investigation in the collections of the Berlin Geological and Paleontological Institute and Museum of skull caps recovered from the sauropods from the Tendaguru layers of German East Africa it resulted that that certain morphologic details can probably be interpreted best as the traces of cranial nerves. I could use the results of the following investigations in the detailed representation of the skulls of the sauropods of the Tendaguru layers (1935).

Fig.1. Brachiosaurus brancai JANENSCH. Medial view of the right wall of the brain cavity (Cat. Nr. Y 1). 2/3 nat. size. d.e Foramen for the Ductus endolymphaticus, fe.ep Fenestra epioptica, fs.sa Fossa sub-arcuta, v.c.m Foramina and groove for the Vena cerebralis media, v.c.p Foramen for the Vena cerebralis posterior, lV-XII IV.-XII. Cranial nerves.

I begin with the the description of the sometimes very distinct vascular traces, which I believe to be attributable to the Vena cerebralis media. The preparation of the cranium of three genera of East African sauropods exposed a sulcus above the foramen trigemini which travels, in a more or less pronounced arc, upward from the rear wall. In the endocast3, the sulcus presents itself as accordingly formed, raised border or line. Such a sulcus was in the genera Brachiosaurus, Dicraeosaurus and Barosaurus.

3 [Ed.]—Hirnschädelausguß, here interpreted as ʻendocastʼ On the traces of cranial veins in Saurischians and Ornithischians, etc. 183

The traces are notably developed in three braincases of Brachiosaurus brancai JANENSCH. The sulcus has a length of approximately 3 cm, is several millimeters broad and ends both above and below in an approximately 3 mm broad foramen (Fig. 1). On two skulls the lower foramen perforates the wall of the braincase so near to the Foramen trigemini that only a plate of bone a few mm wide remains between them, and opens laterally; on the third skull the lower foramen is also closely placed above the Foramen trigemini in the wall of the brain cavity, but it does not reach the external wall but instead opens already into the upper wall of the Foramen trigemini.

Fig. 2. Barosaurus africanus (E. FRAAS). Medial view of the left wall of the brain cavity (Cat.-Nr. dd 316).2/3 nat. size. fe.ep Fenestra epioptica, fe.ov Fenestra ovalis, hy Groove for the hypophysis, p.oe Parietal opening, pp.l Postparietal opening, v.c.m. groove and foramina of the Vena cerebralis media, ve Vestibulum, I-XII I.-XII. Cranial nerves.

The upper foramen perforates the supraoccipital not far beneath its upper margin and opens on the external occipital surface4. It is not improbable that a foramen in the back wall of the upper temporal hollow, where the Parietal, Prootic, and Laterospenoid meet, represents the exit of a channel of the upper foramen, which branches within the supraoccipital. With Barosaurus africanus (E. FRAAS) the sulcus can be demonstrated in a large, nearly full-grown skull and a small skull (Fig. 2);

4 [Ed.]—Hinterhauptsfläche, lit. ʻposterior head surfaceʼ 184 Werner Janensch, it has a length of approximately 22 and 19 mm and is much more constricted and more sharply incised than in Brachiosaurus. The lower foramen could not be determined in the larger skull, in the smaller skull it is deeper, but it is assumed the lower end of the sulcus does not widen; also the opening on the external wall was recognizable over the foramen trigemini on one side. The upper foramen pierces with a funnel-shaped enlargement. In the large head, the opening of a 2 mm wide foramen is possible in the exposed sutural surface of the upper margin of the supraoccipital 3 cm distance from the median, perhaps also still farther laterally present for a branching canal. On the small skull, only one opening lies on the suture of the supraoccipital and the suture5 of the parietal is the same distance from the middle. The third genus Dicraeosaurus in the species D. hansemanni JANENSCH possesses a sharply incised sulcus of approximately 27 mm in length (s. W. JANENSCH 1935, fig. 135). At its upper end a small subovate pore penetrates into the thick brain cavity wall, down, 1/2 to 1 cm above the for. trigemini; the sulcus ends in an oblong pore. That the lateral openings of the pores can not be found, may be a consequence of conservation disturbance to the bottom, as it may be that they are always missing. Also with other sauropods, the sulcus and upper foramen come forwards, as F. V. HUENE (1906) first described in the skull of Megalosaurus bucklandi and Cetiosaurus oxoniensis PHILL. from Stonesfield. The endocast of Camarasaurus depicted by F. OSBORN 6 & C. MOOK (1921) shows a projection high above the foramen trigemini, likely corresponding to the foramen at the upper end of the sulcus in Brachiosaurus, although this is not self evident. An indentation is in the appropriate place in the wall of the brain cavity in Diplodocus (F. OSBORN, 1912, Fig. 16 and F. VON HUENE, 1914, Pl. 8, Fig. 3).A sulcus leading to this depression is not to be seen in these cases, based on their position I would however like to equate the indentations with the upper foramen with which the sulcus ends in the Tendaguru Sauropods. These cases mentioned from the literature were brought in connection with the saccus endolymphaticus, a view I cannot follow because of the lack of a local relationship with the ear capsule. With recent reptiles I have not found a description where the appropriate sulcus is indicated. I could determine, meanwhile,

5 [Ed.]—Spange, lit. ʻbuckleʼ or ʻhaspʼ

6 [Ed.]—Here and elsewhere, F. Osborn refers to H.F. Osborn On the traces of cranial veins in Saurischians and Ornithischians, etc. 185 that in a cut through the medial plane the skull of a Crocodilus niloticus from the Tendaguru area exhibits a 39 cm long (Nose-Condyle) sulcus in the same place as in the sauropods; it lies beside the dorsally running suture between the prootic and the laterosphenoid and is quite easily recognized. Their lengths amount to 7 mm on the right and 8 mm on the left. Also directly next to each other two small foramina are at the upper and and likewise a very small pore at the lower end, about 7 mm above the foramen trigemini, impressed into the skull wall under the margin of the laterosphenoids. A second smaller crocodile skull exhibited the sulcus also. In order to determine the meaning of the sulcus, I examined the alcohol preserved preparation of an average skull of Crocodylus americanus in the exhibition collection of the Berlin Zoologicial Museum7. It appears here that the contents of this sulcus are a tissue that cannot be recognized by the shape of the container. It is questionable to me whether the investigation of a fresh head would obtain a different result; nevertheless it would be very desirable, in order to ﬁnally clarify the question. Now the attempt is made to come to the solution of the question by comparing anatomical details coming from use of the zoological literature. The sulcus and associated foramina cannot be placed in a relationship with any cranial nerves under any circumstances. Also, the sulcus does not lead back to the Ductus endolymphaticus. Apart from the fact that the lower foramen would be inexplicable, the sulcus lies much too far away from the inner upper chamber; in Brachiosaurus I regard the foramen medially perforating the bony wall as the outlet of the D. endolymphaticus, according to its position as conditions of the inner ear clearly show. If, then, the only remaining possibility is to regard the sulcus and the foramina as a passage for blood vessels, then the arteries might be insufﬁcient for it. The lumen of the foramina of Brachiosaurus corresponding with powerful arteries with such a peculiar route is not likely based on conditions in living reptiles. If we regard the venous system of the head in reptiles, then it seems to me that the local relationship of the lower foramina of the sulcus to the foramen of the trigeminus,

7 I am very much obligated to thank Dr. AHL, the manager of the reptile department of the Berlin Museum, and the head preparator Mr. RICHTER, for friendly permission to study the mentioned preparation and for valuable support with the investigation 186 Werner Janensch, which is so particularly clear in Brachiosaurus, supplies the key for the interpretation. From H.L. BRUNNERʼs work on the head veins of reptiles (1907), it can be seen that the middle of the three cross-connections between the unpaired V. longitudinalis cerebri and the V. jugularis interna, the V. cerebralis media, leaves the brain cavity in lizards via the Foramen trigemini. A. DENDY's (1909) investigations in Sphenodon resulted, that the vein8 had a sack-like lateral enlargement medially in the Dura underlying the sinus longitudinalis, described as the sinus transversus, and some distance from the For. trigemini, an efferent vein sends out the extracranial part of the V. cerebralis media by means of a "slit-like" opening in the wall of the brain cavity. In Emys europaea on the other hand, as with Lacerta, according to BRUNNER, the V. cerebralis media goes out through the for. trigemini. The location of the foramina in question are directly above the for. trigemini and, in one skull even opening into the upper surface of the For. trigemini, in Brachiosaurus, in Barosaurus and Dicraeosaurus on the other hand it sits somewhat higher, this makes it quite probable to me that this is the opening by which the V. cerebralis media leaves the brain cavity. The sulcus ascending on the inner wall of the brain cavity from the foramen of the V. cerebralis media would represent the impression of the vein. In addition, an interpretation of the foramen present on the upper end results from conditions in the case of the lacertilians and Sphenodon. According to H.L. BRUNNER (1907), in Lacerta agilis the blood from the muscles of the occipital fossa, including the anterior parts of the mm. capiti cervicales and the rear dorsal section of the mm. temporales., ﬂows into the vena capitis dorsalis from the rear, and into the brain cavity between the parietal and the upper margin of the prootic. A. DENDY (1909) found accordingly with Sphenodon, two smaller openings over the lower opening in the sinus transversus, one of which he would like to see as the opening for the V. capitis dorsalis. Comparing the dorsal wall of the brain cavity in crocodile skulls with the dorsal brain of Crocodilus niloticus given by F. HOCHSTETTER (1906, Pl. 5, Fig. 33), we ﬁnd in the topography of the skull wall, in the area of the n. trigemini and the otic capsule, a visibly pronounced dorsal sinus. A strong branching of the sinus longitudinalis, which HOCHSTETTER calls the recessus lateralis, runs near there, where the upper end of the sulcus in in the braincase. From the sinus longitudinalis runs a strong offshoot, which HOCHSTETTER described as the recessus lateralis, where the upper end of the sulcus in the braincase is located. According to VAN GELDEREN (1924) the V. anastomotica

8 [Ed.]—the V. cerebralis media On the traces of cranial veins in Saurischians and Ornithischians, etc. 187 posterior, flowing into the V. cerebralis media, which is one that would cause an impression in the skull wall (=rec. lateralis =sinus transversus), is no longer present in the adult crocodile. Apparently, as I indicated above, in older crocodiles we find the sulcus from the youth stage, where the V. cerebralis media was bound before and in the sulcus sequestered, retained even after the vene disappeared. I would like to deduce as somewhat likely, based on the previous observations, that the bottom foramen serves to connect the V. cerebralis media with the V. jugularia interna, that the sulcus is the impression of the first vein, and that it associated with a vein from the occipital region through the upper foramen, probably the V. capitis dorsalis. The very consistent width of the two foramina and the sulcus in Brachiosaurus suggests that a vein of similar strength went through them. Whether this trail connects with the transverse sinus cannot be seen from the topography of the braincase walls. If the sulcus and foramina are very narrow, as in Dicraeosaurus, it is very likely that the continuous venous connection was degenerated, and perhaps no longer even functional. F. V. HUENE (1907/08) observed a corresponding sulcus on an endocast of Plateosaurus erlenbergensis, with the sublime name aquaeductus vestibuli. On the same pieces that I could investigate9, the previous sulcus is very pronounced, but perhaps elaborated too much by preparation. The medial entrance to the upper foramen is very clear, the bottom is unclear due to insufficient preservation. By contrast, the lateral output is very clear in the upper margin of the for. trigemini, while the posterior exit of the upper foramen is not visible. A foramen, which probably represents posterior output of the upper foramen is seen in the skull of Plateosaurus plieningeri (=Originally O. JAEKELʼs Pl. torgeri) from Halberstadt in the Berlin collection. It is located on the supraoccipital, about 11 mm under the upper margin and about 10 mm from the midline. Regarding the braincase, as illuminated by Skeleton No. 25 on display at the Berlin Museum, assigned by F. V. HUENE (1932) to P. quenstedti, the forward end of the bony braincase is present, even though accidentally crushed and the individual elements are not reliably identifiable.

9 I am very grateful to Dr. BERCKHEMER for his friendliness with the piece I went to investigate. 188 Werner Janensch,

The left external wall shows now here above the fairly narrow For. trigemini in this skull a separate opening, recognizable as the lower foramen for the V. cerebralis media. Likewise, the opening of the upper foramen in the posterior wall of the right supraoccipital is distinct. A very well preserved Plateosaurus braincase, which the head preparator Mr. E. SIEGERT in Halberstadt excavated and later prepared, allows the ratios of the sulcus and the foramina of the V. cerebralis media to be studied (Fig. 3). The front of the orbitosphenoid and the laterosphenoid shaped section is not preserved. The braincase closes anteriorly with a very broad sutural surface, the externally very ﬂat anterior margin of the Proticums10 is truncated. The upper foramen is broad, piercing the supraoccipital a considerable distance from the dorsal margin. Particularly on the left side it can be clearly seen, that the funnel- shaped sulcus extends down from the inner opening of the foramen in the anterior margin of Fig. 3 Plateosaurus sp. View of the brain cavity from the the front and slightly to the the skull, getting wider ventrally and ending in a right (from the point of view of the skull). 1/1 foramen above the wide For. trigemini, that is open nat. size. a.ba Arteria basilaris, fo.m. Foramen to the outer wall of the braincase due to the magnum, fs.sa Fossa subarcuta, opo Opisthotic, so Supraoccipital, v.c.m. Sulcus absence of the anterior end of the skull. and foramen for the vena cerebralis media, As for the images of the endocasts of the great V. and VI V. and VI cranial nerves carnivores Allosaurus (=Antrodemus) and Tyrannosaurus I see nothing that I would regard as the cast of the sulcus with any certainty. The pronounced, rising edge of Ceratosaurus (C.W. GILMORE; 1920, Pl. 36, Fig. 1, 2) above the foramen trigemini, however, could possibly correspond to the sulcus. Of the two strong, peg-like appendages on the endocasts of Allosaurus and Tyrannosaurus (H.F. OSBORN, 1912) above the foramen trigemini I believe the upper to be the foramen of the V. cerebralis media, and the lower to lead back to the fossa subarcuata. The fact that the canals open on the occipital area for Tyrannosaurus (H.F. OSBORN, 1912, Fig. 4)

10 [Ed.]—proticum, latin, meaning an anterior portico or doorway, almost the modern prootic On the traces of cranial veins in Saurischians and Ornithischians, etc. 189 and Allosaurus (F. V. HUENE 1914, Pl. 7, Fig. 3) and were drawn as venous foramina by those authors makes it quite likely to me that they are the rear outputs of the foramen of the V. cerebralis media or more correctly the V. capitis dorsalis. Their location—on top of the supraoccipital—is, at least concerning Tyrannosaurus, very similar to Brachiosaurus. Even the vascular channel, which, according to E.V. STROMER (1931, p. 5) pierced the rear wall of the skull in Carcharodontosaurus and caused very conspicuous, protruding cones in the endocast, I would like to equate with the top foramen of the sulcus. In a recent work the same author (1934, p. 47) suggests that the vessels passing through the channels may have serviced the large formations of hard bumps on the bone above it.

Fig. 4. Kentrurosaurus aethiopicus E. HENNIG. Medial view of the right wall of the brain cavity (Cat. No. St. 460). 2/3 Nat. size. d.e Foramen of the ductus endolymphaticus, fe.ep Fenestra epioptica, hy groove for the hypophysis, v.c.m. Sulcus and foramina of the vena cerebralis media, v.c.p. foramen of the vena cerebralis posterior, I-XII cranial nerves I-XII

It is very remarkable that even in the ornithischian Kentrurosaurus aethiopicus from the Tendaguru layers you will find a very strong sulcus in the same place as in the sauropods. I can only confirm E. HENNIGʼs (1924) indication that the pores at the top and bottom of the sulcus penetrate the skull wall. A look into the braincase shows a striking consistency with the conditions present in Brachiosaurus. Even in Kentrurosaurus the lower foramen sits close above the for. trigemini and opens to the lateral wall close to it (Fig. 4). The sulcus is incised in the wall in a weakly convex, 190 "Verner Janensch, ob190en h i n t e n , u m d a n n w i e d e r i n e i n F o Wernerramen Janensch,einzumÜnden. Der weitere Verlauf dieses oberen Kanales, der die Vena capitiR dorsalis enthalten haben dÜrfte, ließ sich an einer Schädelkapsel (Abb. 5), bei der sehr gÜalmostnstig d straight,as Dach arcdur ch fromein e then Q frontuerbr u toch theabg topetre nback,nt ist , tod u therch openinggering- of a foramen. The füfurthergige P rä courseparatio n ofa uf theklä re uppern. Es canal,ergab s ic takenh, da ß byde r thedurc h venaGes te capitisin aus- dorsalis, could be geenlightenedfüllte Kanal byin ad ebraincaser Schädelw (Fig.and n 5),ach withhint ean veryund zfavorableugleich et wtransverseas lateral break separated by eindringt und dann zu einer Gabelungsstelle führt, von der ein erweiterter Kminoranal n a preparation.ch hinten z ie Ith showedt und in that,einem byF oar a rock-filledmen nahe canaldem A inbg a theng skull,des it passes through Otheber rbackandes walldes andPro cates thesus samedes O timepisth oslightlyticum i laterally,n der H iandnterh thenaupts penetratesfläche to a bifurcation sipointch öf fleadingnet, und toe ian slightlyzweiter expandedin rechtem channelWinkel ltoate theralw rearärts openingabgeht u nind a foramen near the nach sehr kurzem Verlauf auf der Seitenwand der Hirnkapsel austritt. processus opisthoticum in the occipital area, and a . Daß diese beiden Kanalöffnungen secondzusamm e canalnhäng e movesn, hatt e laterallyauch be roffeit s at a right angle and afterE. H E aN N veryIG b shortei de r distanceUntersu c exitshung on the side of the dieser Schädelkapsel festgestellt, braincase. E. HENNIG, in his investigation of this ebenso auch erkannt, daß es sich braincase,nur um den K alreadyanal ei ne founds Blut ge thatfäße s these two channel openingshandeln k ö werenne. related, and also recognized that it couldO obnlydie beüb theer d echannelm Trigem ofin uas bloodauf- vessel. steigende erhabene Linie bei Igua- Fig. 5 XentruTOsaurus aethiopicus E. HENNIG. nodon, dWhetherie der v on theC. W raised. AND R lineEW S ascending over the AKentrurosaurusnsicht von obe naethiopicusauf den h E.in tHerENNIGen A.b - View from above on the posterior of the Trigeminus(1897, Taf .in 1Iguanodon6) abgebild, easte shownHirn- on the endocast by schnitt der Hirnkapsel , deren Dach an braincase, the roof is cut away along an höhlenausguß . erkennen läßt, oder einem etwa frontal verlaufenden Bruch C. W. ANDREWS (1897, pl. 16), or in Triceratops, (O. C. approximately anteroposteriorly directed bei Tricemtops (0. C. MARSH, 1896, abgetrennt ist (Kat.-Nr. St. 702). MARSH, 1896, pl. 77, fig. 4) can be traced back to the break (Cat. Nr. St. 702). 'l'af'. 77, Fig. 4) auf die besprochene vv.ca.d.ca.d CanalKanal ofd ether Vvenaena capitiscapitis dorsalis,dorsalis , linleftks filledals Ain,u srightfüllu withng , therec sulcushts als visibleFurche discussedFurche de rsulcusV. cereb r foral is theme dV.ia z cerebralisurück- media, I cannot sichtbar. judgezufüh withoutren ist, kknowledgeann ich ohn eofK theenn originaltnis pieces. der Originalstücke nicht beurteilen. It was here that a strange foramen was noted by C. CAMP (1930, p. 113, fig. 40) Es sei hier auf ein eigenartiges Foramen hingewiesen, das C. CAMP (while1930, describingS. 113, Fig. the40) phytosaurvon dem Ph Machaeroprosopus,ytosaurier Machaerop randosop udenoteds beschr easib ta velar foramen. uThend asupraoccipitalls ein Velarf o exhibitsramen b e az e pairichn e oft. perpendicularlyDas Supraoccip orienteditale wei sconicalt an concavities, from seiner oberen Endfläche ein Paar senkrecht gestellter, konischer Höhlungen which a foramen in the bone continues to run upward. CAMP believes that it is possible auf, von denen ein Foramen im Knochen weiter aufwärts verläuft. CthatAM Pthishä ltis eas fvascularür mögl ic foramenh, daß a n leadingdiesem toFo rtheam evelarn ein regionGefäß z orur V evenelar- to the Pineal gland. rTheegio ncourseoder a ofuc h thesezur Pforaminainealdrüs e withinverlie f the. D supraoccipitalser Verlanf diese sstillFo r hasame nsomes resemblance to ithenne rchannelhalb des S discussedupraoccipi t inal e thes h a differentt immerh i dinosaurs.n einige Ä h Anl isulcuschkeit m runningit dem downwards on the besprochenen Kanal der verschiedenen Dinosaurier. Eine vom Unterende lower end of the channel and a lower perforation of the side wall of the cranial cavity des Kanals abwärts verlaufende Furche und eine untere Durchbohrung daboveer Sei ttheenw Foramenand der H trigeminiirnhöhle wereüber dnotem namedFor. tri gbyem CinAMPi wi.r dOnv othen C openingsAMP of the foramen nonic ht thean g outerwallegeben. Ü ofbe r theetw a braincase,ige Offnun ge I n madedes Fo r noam e safens a uf conclusionsder Außen- based on CAMPʼS wrepresentations.and der Schädelkapsel vermag ich aus CAMP'S Darstellungen nichts On the traces of cranial veins in Saurischians and Ornithischians, etc. 191

These could be the foramina, which he illustrates at the suture between the supraoccipital and the tabulare (fig. 37). A homology between the foramina in sauropods and phytosaurs remains in any case questionable. Even in a family of distantly related reptiles, such as the cynodont Diademon, it seems, after a figure of M.S. WATSONʼS (1913, p. 12, fig. 1), a sulcus similar to that previously seen in dinosaurs, rising in a weak anteriorly curved bow above the for. trigemini and ending beneath in a large foramen, which WATSON assigns to a vein. It is quite likely that these are the channels for the V. cerebralis media. As long as no other, more likely interpretation is offered, I would like to apply the sulcus and the associated foramina in relation to the V. cerebralis media to the various reptiles discussed. Since evidence suggests it was present in such distantly related reptiles as saurischians, stegosaurians, crocodilians, and cynodonts, it was in any case a not unimportant element. An opening elsewhere, for which a connection with the Vena cerebralis anterior is proposed, is located in sauropods in the brain cavity in front of the margin of the orbitosphenoid. Among the existing foramina the exits for CN II and II are clearly marked, while that of CN IV is less clearly recognizable. In only one case, a small braincase of Barosaurus africanus, was a fairly narrow opening near the foramen for the Oculomotorius11, which I believe can be assigned to the Trochlearis12. The other small braincase of the same type is missing the upper narrower foramen, in this one the Oculomotorius is dorsally broadened and probably has the role of the upper included, so the Trochlearis is enclosed. In the same way, for example, in Sphenodon (J. GISI, 1907), both nerves exit through a shared cartilaginous opening. In the small skulls of Barosaurus an opening sits high above the foramen of the Oculomotorius, that is small and slit-like in the one skull and more extensive in the other, but is differently developed on the sides. A properly located foramen has been shown already in the year 1892 in the braincase of Triceratops, interpreted as brain anatomy by R. BURCKHARDT (1892) as the opening for the Vena cerebri anterior. This vein, after VAN GELDEREN (1924/25), is retained no longer in the adults of recent reptiles, in early developmental stages it pierces the skull in the eye region, among the birds the dorsal part is retained however.

11 [Ed.]—CN III

12 [Ed.]—CN IV 192 Werner Janensch,

For these highly-located foramen, the interpretation as one of the main nerves is in question. especially as a special foramen is also present, rightly sorted out as the Trochlearis by O. P. HAY (1909). That highly-placed foramen corresponds to, as I would like to assume, the Fenestra epioptica, which occurs in a similar position in the chrondrocranium13 of Chelone (H. FUCHS, 1915, pl. 1, 2) and is itself an extensive opening over the wide Fenestra optica and at the same time above the separate, narrow foramen of the Trochlearis found on the embryonic chondrocranium of Crocodilus biporcatus, as shown on the illustrations of K. SHIINO (1914). In an embryo of Chrysemis picta of 20 mm carapace length, C. VAN GELDEREN (1924, p. 581) found that the V. cerebralis anterior follows the aboral hemisphere margin to an opening in the bed of the superseptale and out. This opening is most certainly analogous to that opening designated the Fenestra epioptica by H. FUCHS; it lies above the opening for the Opticus and above and anterior to the Trochlearis. Later the V. cerebralis anterior disappears, as in all other fully investigated reptiles. Also on the chondrocranium of Sphenodon, a fenestra sits above the opening for the Opticus, in Lacerta E. GAUPP (1900, p. 472) notes that it is very large. This foramen is located in other places within sauropoda, except for Barosaurus africanus; in Dicraeosaurus hansemanni it is quite extensive. In some senses it is peculiarly developed in Brachiosaurus brancai. The fenestra is quite extensive and is apparently dorsoventrally elongate in shape. In two skulls a more or less clear division appears, since on the anterior margin a projection extends into the opening. It is not improbable, based on this apparent division, that the upper and lower sections had different purpose, in the sense that the Trochlearis issued from the lower, while the V. cerebralis anterior came out of the upper permanently or only in the early stages of development. Only this upper section can be considered the Fenestra epioptica. For these assumptions, it can be imposed that the lower extension of the Fenestra epioptica, attributed to nerve IV, can be 6-8 mm reaching up to the foramen of nerve III, so that in this region the exit for the Trochlearis may very well be.The third skull of Brachiosaurus shows, on the anterior margin of the foramen a notch on the upper end, approximately 6 mm deep, which is 13 mm wide continuing onto the

13 [Ed.—Knorpelcranium, lit. cartilaginous cranium On the traces of cranial veins in Saurischians and Ornithischians, etc. 193 front wall of the Orbitosphenoids; here the vein very well could be located. The attempted interpretation of the long opening in Brachiosaurus is the Oculomotarius, but this is a naturally hypothetical character. In the illustrations of braincases and endocasts given in the literature I can only in a few cases identify, which certainty, the Fe. epioptica, as with the picture of the braincase of Diplodocus in the Carnegie Museum 622/22, identified by W.J. HOLLAND (1924) as “possibly small foramen for vein”. In the form Camarasaurus H.F. OSBORN & C. MOOK (1921), above nerve III there is a fairly extensive elongate foramen, its greatest diameter increasing anteriorly. In the caption for plate 63 this is referred to as "pit and foramen of fourth cranial nerve and the cranial process at its base". According to the figure, it seems that this foramen is similar in its upper and lower sections to be the same as the openings in Brachiosaurus, it would be presumed that the upper part is the Fe. epioptica and the lower part represents the foramen for CN IV. The overall conformity agrees with the close relationship between these genera. Also in the South American sauropod Antarctosaurus wichmannianus there is a foramen located very high above the foramen of nerve III, a foramen assigned to nerve IV by V. HUENE (1933, pl. 28), which given its location seems to be the Fe. epioptica. In ornithischians the first example is the previously mentioned occurrence of the Fenestra epioptica in Triceratops. A second example is the stegosaurid from the Tendaguru layers, Kentrurosaurus aethiopicus. E. HENNIG (1925, fig. 3 d) in a skull of this genus refers a very deep-seat foramen, a significant distance from that of nerve IV and claims that it is nerve III, but cautiously admits that there is uncertainty in the openings for both nevers. Another Kentrurosaurus skull shows me, only after very detailed preparation on the wide foramen of the Oculomotorius the nearby Trochlearis and farther on a small opening, which I like to consider the Fenestra epioptica. As for a third cranial vein, the V. cerebralis posterior, it seems to me that it is often undetectable. In the sauropod Brachiosaurus it is found above and slightly in front of the rear, larger foramen of the two part Cranial Nerve XII, about the width of this foramen. 194 Werner Janensch,

A conveniently located break at one end of the skull enabled rock to fill in along that foramen, which was then prepared free. It appears that these fillings are irregular protrustions only a few mm long with small pointed ends. The wide foramen ends blind in the wall of the braincase after quite a short distance. It can be concluded that the tissue which ran here was obliterated and that the channel to the short external opening filled with bone tissue. This behavior is difficult to reconcile with a nerve or artery. In reptiles, the dorsal root of the hypoglossus is not fully developed, as noted for example in the embryonic stages of Crocodilus by K. SHIINO (1914). Speaking of the foramen as a lumen for a strong artery is just as inapplicable. It is much more probable that it is the action of a vein, because regression of cerebral veins during ontogeny is often significant. In Crocodilus, as in Sphenodon, chelonians, and Amphisbaena (C. VAN GELDEREN 1924, 1925), the V. cerebralis posterior goes through the posterior skull opening, in juvenile stages there is still a branch passing through the braincase wall, alongside the N. vagus. This branch is later completely obliterated. I found, however, in two skulls of Crocodilus niloticus near to and slightly behind the upper end of the For. jugulare a very clear, foramen shaped narrow cavity, closed-off at its base, proven by a tiny irregular bony edge. It lies perfectly in the place where, according to F. HOCHSTETTER'S (1906) description and illustration of the venous branch, for which this author has no specific designation, you would search for it. It is quite likely that this location shows a vestige of the foramen through which a branch of the V. cerebralis posterior went through the cranial wall. Then is it obvious to apply the same interpretation to the rudimentary foramen above nerve XII in Brachiosaurus, whose position deviates from Crocodilus only slightly in that it is somewhat farther from the For. jugulare. For the progress and development of the V. cerebralis posterior in Brachiosaurus, we can now conclude that, as with Crocodilus, in juvenile or embryonic stages a branch pierced the braincase near the caudal N. vagus, but was later completely rebuilt, and that probably a second, naturally undetectable, branch exits through the For. magnum. On the traces of cranial veins in Saurischians and Ornithischians, etc. 195

The fact that this foramen is caused by a vein has been previously discussed by F. V. HUENE. In the braincase of Cetiosaurus oxoniensis he examined (1906, here attributed to Megalosaurus bucklandi) are found two foramina for the two roots of the Hypoglossus and above these a venous foramina. The figure given by him shows the foramina in great agreement with Brachiosaurus. In the braincases of the sauropods Barosaurus africanus and Dicraeosaurus hansemanni, I could not discern the for. for the V. cerebralis posterior, but it is possible that they are unrecognizable as a result of preservation. For the previously described braincase of Plateosaurus from Halberstadt the foramen of V. cerebralis posterior is a fairly extensive, yet narrowly funnel-shaped, shot in the deep depression on the front of the internal opening of the posterior canal of Cranial Nerve XII, and sits nearly perpendicularly above the anterior canal, and is separated from the for. jugulare by a sharp ridge. In Tyrannosaurus, as seen in H.F. OSBORNʼS (1912, pl. 3) excellent figure, behind and higher than the For. jugulare there is a larger, anteriorly directed foramen, marked by OSBORN with a star; according to its location I ascribe it to the V. cerebralis posterior also, although naturally I cannot determine whether it ends blindly. Among the ornithischians we find very similar relationships, for example in the stegosaurian Kentrurosaurus for which E. HENNIG (1924) figured two foramina for the two roots of the Hypoglossus on the endocast, and above and a little behind the posterior root, a venous foramen. I can only confirm this observation, but I also found that this foramen, just like Brachiosaurus and Plateosaurus, ends blind after a few millimeters. The endocast of Claosaurus (=Trachodon) annectens depicted by O.C. MARSH (1896, pl. 77, fig. 3) also has three foramina, the venous hole above the anterior root of the Hypoglossus. In the braincases of the ornithopod Dysalotosaurus lettowvorbecki POMP. from the Tendaguru layers, the foramen of the V. cerebralis posterior is observable high above the posterior root of the Hypoglossus as a moderately large, funnel-shaped indentation. The foramen also ends blindly in this genus. Among the ornithischians, the discussed foramen has also been figured for Triceratops, by MARSH (1896, pl. 61, fig. 7); it sits here on the endocast obliquely behind and above the for. jugulare, diagonally and front of and above the foramen of the 196 Werner Janensch, posterior root of the Hypoglossus and also above a small foramen, which I want to assign to the anterior root of the Hypoglossus. R. BURCKHARDT (1892) indicated that the high foramen was the sensory root of the Hypoglossus, a view which is unsustainable because reptiles do not posses dorsal roots of the Hypoglossus, even in embryonic stages, as K. SHIINO (1924) recently noted in Crocodilus biporcatus. The same conditions of MARSHʼS figure are shown in the excellent view of the inner wall by O. P. HAY (1909, pl. 2, fig. 2). This figure also very well shows a narrow foramen, in the Ohrpyramid14 and also on the front end of the for. jugulare, and I believe that this can be explained as the outlet of the Ductus endolymphaticus. H. BURCKHARDT had distinguished this foramen as the V. cerebralis posterior. Finally, it is very remarkable that even in the cynodont Diademon D. M. S. WATSON (1913, fig. 1) found a foramen next to and above the posterior foramen for the Hypoglossus, which he could not determine but ascribed to a vein. It is certainly again the foramen of the Vene cerebralis posterior.

Abstract. 1. A sulcus in the inner cavity of the brain above the foramen trigemini, terminating at top and bottom in foramina, is the impression of the vena cerebralis media. 2. An opening above the shared foramen or the separate foramina of the Oculomotorius and Trochlearis, the Fenestra epioptica, from embryonic stage probably was the same opening for the Vene cerebralis anterior. 3. A foramen in the inner wall of the brain cavity above the canal or canals of the Hypoglossus, blind ended in the investigated cases, is a regressing branch of the Vena cerebralis posterior.

Literature.

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14 [Ed.]—probably in reference to the petrous portion of the temporal bone in mammals On the traces of cranial veins in Saurischians and Ornithischians, etc. 197

BURCKHARDT, R.,1892: Das Gehirn von Triceratops ﬂabellatus MARSH.—N. J. Min.1892, II, 71-72, 1 Abb. CAMP, C. L., 1930: A Study of the Phytosaurs with Description of new Material from Western North America.—Mem. Univ. California 10, 1-161,48 Abb., Taf.l-6 CASE, E. C., 1921: On an Endocranial Cast from a Reptile, Desmatosuchus spurensis, from the Upper Triassic of Western Texas.—Journ. Compar. Neurol. 33, 132 bis 140, 3 Taf. DENDY, A., 1909: The Intracranial Vascular System of Sphenodon.—Phil. Trans. Roy. Soc. B. 200. EDINGER, T., 1929: Die fossilen Gehirne.—Z. f. d. gesamte Anatomie, Abt.III, 28, 1-249, 203 Abb. FUCHS, H.: Über den Bau und die Entwicklung des Schädels der Chelone imbricata. 1915: 1. Das Primordialskelett des Neurocraniums und des Kieferbogens. In A. VOELTZKOW: Reise in Ostafrika in den Jahren 1903-1905. Stuttgart, 5, 1-325, Taf. 1-6, 182 Textf. GAUPP, E., 1900: Das Chondrocranium von Lacerta agilis. Ein Beitrag zum Verständnis des Amniotenschädels.—Anat. Hefte 15, 435-595, 5 Taf. VAN GELDEREN, C.: Die. Morphologie der Sinus durae rnatris 1924: 1. Teil. Z. f. d. ges. Anat. 1. Abt. Z. f. Anat. u. Entwieklungsgesch 73, 541-605, 38 Textf. München, Berlin 1924 1924: II. Teil. Ebenda 74, 432-508, 36 Textf. 925: III. Teil. Ebenda 75, 526-596, 31 Textf. GILMORE, C. W., 1920: A new Restoration of Triceratops , with Notes on the Osteology of the Genus.—Proc. U. S. Nat. Mus. 55, 97-112, Taf.3-9, 6 Abb. GISl, JULIA, 1907: Das Gehirn der Halteria punctata.—Zool. Jahrb. Abt. Anat. u. Ontog. 25, 71-234-, Taf. 3, 21 Textabb. HAY, O. P., 1909: On the Skull and the Brain of Triceratops, with Notes on the Braincases of Iguanodon and Megalosaurus.—Proc. U. S. Nat. Mus. 36, 95-108, Taf. 1-3. HENNIG, E., 1924: Kentrurosaurus aethiopicus, die Stegosaurier-Funde vom Tendaguru.— Palaeontogr. Suppl. VII, Reihe 1, 1, 101-2ä4, Taf. 11-14, 92 Abb. Stuttgart 1924. HOCHSTETTER, F.: 1906: Beiträge zur Anatomie und Entwicklungsgeschichte des Blutgefäßsystemes der Krokodile.—1906,1-139, Taf. 1-10, 37 Textf. in A. VOELTZKOW: Reise in Ostafrika in den Jahren 1903-1905. Stuttgart, E. Schweizerbart. HOLLAND, W. J., 1924: The Skull of Diplodocus.—Mem. Carnegie Mus. 9, 379-403, Textf. 1-11, Taf.40-43. VON HUENE, F. Frhr., 1906: Über das Hinterhaupt von Megalosaurus Bucklandi aus Stonesﬁeld. — N. J. Min. 1906, 1, 1-11, Taf. 1, 4 Abb. —, 1907—08: Die Dinosaurier der europäischen Triasformation, mit Berücksichtigung der außerellropäische.n Vorkommnisse.—Geol.-Paläont. Abh. Suppl.-Bd. 1, I-XII, 1-419, 351 Abb., Atl. m. 111 Taf. —, 1914: Über die Zweistämmigkeit der Dinosaurier, mit Beiträgen zur Kenntnis einiger Schädel.—N. J. Min. 37. Beil.-Bd., 577-589, Taf. 7-12. —, 1929: Los Saurisquios y Ornitisquios del Cretaceo Argentino.—Anal. Mus. La Plata 3, seI'. 2a, 1-196, 133 A~b., Atlas m. 44 Taf. Buenos Aires 1929. —, 1932: Die fossile R.eptil-Ordnung Saurischia, ihre Entwicklung und Geschichte. Monogr.Geol. u. Palaeont., SeI'. 1, Heft 4, 1-361, 42 Abb., Atlas mit 56 Taf. Leipzig 1932. 198 Werner Janensch,

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15 [Ed.]—[sic]