Title：
The Type of the Theropod Spinosaurus aegyptiacus nov. gen., nov. spec.

Three km north of Gebel el Dist, thus in the plain at the base of the Bahar”je Valley and in the deepest layer "7 p" (Stromer 1914, p. 28 and 29, fn. 1), out of a small hill, from a whitish-gray to yellowish, clayey, gypsum-free sandstone, below a cover of 30 cm ferruginous sandstone and 1 m of hard clay, in Spring 1912, the collector Markgraf excavated a number of remains, lying closely together, of a large theropod, namely the two mandibular rami without the posterior ends with a few teeth in situ, a ? left angular, a little piece of the left upper jaw, over a dozen individual teeth or tooth crowns, two cervical, seven dorsal, two and a half sacral, and one anterior caudal vertebrae, many incomplete ribs and lateral gastralia.


All these remains of brownish to gray color could be prepared out well, but in the washing many fell apart into many pieces, which had to be glued back together again with difficulty, and unfortunately many broken pieces became lost. Already in the stone much was deformed and shattered due to crushing, also the remains lay confusedly mixed. The skull seems to have been present, but due to its surficial deposition has been almost completely weathered away, since clearly the upper jaw piece shows the unmistakable character of weathering of a bone found on the surface and also the posterior ends of the mandibular rami, traversed by very many cracks, as well as the two cervical vertebrae, somewhat weathered especially in front, indicate a completely superficial disposition.


Of the girdle and extremity bones nothing at all has been found, so the skeleton would have been buried in an incomplete condition. In any case the soft parts were destroyed and with this the articulation of the individual bones was lost; many teeth, whose attachment was in part loosened on account of the replacement teeth pushing in, thereby fell out with their roots and all were confusedly mixed, thrown about either by scavengers or by flowing water. However, further transport of the remains, which show no trace of rolling and on which often very thin and fragile bone elements were perfectly preserved, certainly did not occur. Then in the stone the remains have suffered through compression, which clearly was more likely produced by displacement on account of the leaching of gypsum and salt than by tectonic processes.


Based on their position and preservation the remains belong to one individual, only the proportions in the sacral and caudal vertebrae make difficulties for this view, as is yet to be discussed in the description of these parts. In any case the jaws, teeth, and dorsal vertebrae suffice to characterize the form as new, which I will describe completely in the following, being sufficiently in contrast to all hitherto known dinosaurs.


Only the dentary and splenial are preserved in natural articulation on both mandibular rami in a length of over 75 cm, and there is also perhaps an isolated left angular. The symphysis end is complete, the posterior part though is penetrated by very many cracks and at the edges is in part incomplete. On the right ramus it has apparently so considerably retained its natural form, but on the left it has been somewhat flattened from the side, since here the wall of the jaw canal for Meckel's cartilage is very thin. On the right ramus near the 5th alveolus there is present laterally a small pathologic thickening of the bone, clearly as the result of a healed wound. The bone sutures are in large part not certainly determinable due to the many cracks. The teeth, present only partially in situ, will be described separately at the end.


The sharp and almost straight anterior edge of the mandible descends ventrally and very little posteriorly in a length of 10 cm, the long ventral edge, preserved on the right in a length of 72 cm, continues for a stretch of about 15 cm straight posteriorly, but then it forms an arch, smoothly convex dorsally, whose highest point lies approximately below the 13th alveolus and whose posterior end, as far as is preserved, turns very gradually ventrally. The edge is in the middle and largest part broadly rounded, but narrower far forward and back, so that it becomes sharp-edged about 60 cm posterior to the anterior end.


The upper end is preserved 66 cm long on the left, 62 cm on the right. It forms an arch, dorsally convex up to the 6th alveolus, concave from there to the 12th, and then it clearly ascends posteriorly, just barely convex dorsally. On account of this the mandible is rather high anteriorly Ð up to 13.5 cm between the 3rd and 4th alveoli Ð but at the 7th alveolus only 9 cm, at the 15th already 15.5 cm and even, 10 cm behind this, 19 cm; it is thus relatively long and low and first becomes gradually high posteriorly. The breadth of the upper edge measures 5 cm between the 3rd and 4th alveoli, barely 3.5 cm at the 7th, and only 2.5 cm at the 15th, i.e., the thickness of the jaw ramus decreases gradually toward the rear, which corresponds only in part with the changed size of the teeth. Medially along the alveoli follows a raised keel, which is sharp up to the 4th, but then becomes flattened and finally high and convex, and which rises above the alveolar part anteriorly by about 1 cm, then barely around 0.5 cm, but in the region of the 12th alveolus around 1.5 cm. It is provided with a longitudinal furrow directly laterally to the alveoli and is rough up to the 5th alveolus, then becomes smooth, and then proceeds, becoming gradually narrower and finally sharp, up to the posteriormost preserved part.


The smooth lateral side of the mandible is flat up to the 6th alveolus, then somewhat arched, especially in the lower third; behind the 15th alveolus it is arched here only, while clearly flat in the upper part. Along and also somewhat behind the anterior edge and along the upper edge up to the 6th tooth are present numerous small foramina, then to below the 15th alveolus in a flat channel, which extends 3-5 cm below the edge, still further in mostly larger irregular intervals. In   Dryptosaurus incrassatus Cope according to Lambe (1904, Pl. 3) the distribution of these foramina is quite similar, but they are also still numerous in the posterior part below the alveolar rim; in Tyrannosaurus in contrast they are, according to Osborn (1912, Pl. 1), not present at the anterior rim.


The medial side would have been on the whole originally almost completely flat. Up to 3-4 cm behind the anterior edge it is rough, apparently on account of a not tight and very short symphyseal union, then completely smooth. A furrow, which would correspond to the so-called Meckel's furrow of Tyrannosaurus   (Osborn, 1912, Fig. 18 and 20), is certainly not present. About 12 cm from the front and 2.5 cm from below a small foramen appears to occur, above which the inner side on both sides is somewhat crushed in; the inner wall of the jaw canal is here thus apparently especially weak. 41 cm from the front and 1 cm above the convex ventral edge is a longitudinally oval fenestra of the canal for Meckel's cartilage, 13.5 cm in length and up to almost 6 cm in height, whose middle occurs below the gap between the 14th and 15th alveoli.


Here also the borders of the bones are clear, which in comparison with those of Tyrannosaurus (Osborn, 1912, p. 22, Fig. 18) are easily understandable. Just as there the splenial (= operculare) at the lower edge of the fenestra forms a dagger-shaped point toward the front up to its middle, then the lower edge of this bone continues sharp-edged toward the back parallel to and a little below that of the dentary, but finally somewhat dorsally to at least 17 cm behind the fenestra. The well preserved posterior border of the splenial on the left mandibular ramus is very sharp, thin and weakly convex anteriorly and ascends dorsally and moderately anteriorly to a somewhat right-angled rounded upper corner, which occurs 14 cm behind the 15th alveolus. From here the thin upper edge seems to run rather straight anteriorly and moderately ventrally to about 7 cm in front of the fenestra, and from this anterior end on the lower edge runs horizontally posteriorly up to the anterior border of the fenestra. The course of this last border is yet uncertain, since longitudinal crack lines are confused with it. A supradentary seems to me not to be present, although somewhat in the position of the suture of the bone discerned by Osborn (1912, p. 24) in Tyrannosaurus, 2-3 cm under the alveolar border of the dentary on the right and left ramus, fracture lines run parallel to it. For the exclusion of a presplenial, as Lambe (1914, p. 11 and 15, Pl. 3 and 5) would have found in Dryptosaurus, there occurs here scarcely a clue.


On the outer side of the lower jaw the lower posterior end of the large long dentary is clearly not preserved, yet by comparison with Tyrannosaurus (Osborn, 1912, Pl 1) very little would have been broken off on the right ramus, so that it may have been in its entirety somewhat over 80 cm long. A part of the upper posterior edge is, especially on the right ramus, well preserved as a straight, thin, but rounded edge, which is drawn out from back to front and moderately upward to the 15th alveolus; 9 cm from this however it appears to run jaggedly upward, to reach the upper edge of the jaw 6.5 cm behind it. Consequently, from the surangular on the right mandibular ramus there would still be preserved a small little piece of the upper edge. Supposing this latter is correct, then the upper edge of the dentary would be 60 cm long and on the assumption of similar length ratios as in Tyrannosaurus the now missing posterior part of the lower jaw would be yet over 60 cm, the total length of the mandible thus would be over 120 cm. It must indeed be remarked that if the dentary of Tyrannosaurus is relatively much higher than in the present form, then also its proportions could have been very different. In any case, to me, the length of the dentary and the small lateral upswing of its posterior part still preserved on the right ramus seem to prove that the two mandibular rami diverged little from the short symphysis on, and that they belonged to an animal with a longer and narrower snout.


It is noteworthy how thin and weak the posterior ends of the dentary and splenial are. In this region Meckel's cartilage must have formed the most essential connection of the anterior half, so strong anteriorly in its bony parts, and the posterior half of the jaw.


Only with the greatest reservation can I interpret as a component of this posterior half, perhaps the left angular, an asymmetrically constructed, flat and elongated bone, which in its preservation and according to the place where it was found belongs just here. It is incomplete at the end, at least 25 cm long, at one end somewhat over 8 cm high, at the other broken end 5 cm high, but in the middle scarcely 4 cm high, here at the lower edge 0.8 cm thick, at the upper edge and at the higher end very thin, at the other end under 0.6 and over 0.2 cm thick. The upper edge is correspondingly sharp, especially in the higher half of the piece, likewise also clearly so was the edge at the end of this, at which it is scarcely much broken off, while it cannot be said how much is missing at the other end. The lower edge, finally, is rounded and in contrast to the higher end becomes too sharply keeled and bowed a little toward the inside.