I ,1 MEMOIRS OF THE CAKNEGIE MUSEUM. VOL. II. NO. 7. THE OSTEOLOGY OF PROTOSTEGA. By G. R. Wieland. The first mention of ancient gigantic marine turtles from America was made by Cope in 1871 in a letter to Professor J. P. Lesley containing an account of a journey in the valley of the Smoky Hill River in Western Kansas. This letter, as subse- quently published in the Proceedings of the American Philosophical Society,1 includes a preliminary notice of the huge Niobrara Cretaceous turtle, Protostega gigas. The type specimen was collected by Cope himself on a bluff near Butte Creek in the vicinity of Fort Wallace. It was secured in a more or less fragmentary condition after the manner of the vertebrate collecting of the earlier days of western exploration, for, in the more extended description given in the Cretaceous Vertebrata of the West, Cope says this fossil is made up of more than eight hundred separate fragments. The various parts of Protostega gigas (type), although mostly in situ, were con- siderably removed from their natural position. The original specimen is now in the collection of the American Museum of Natural History. It includes much crushed cranial elements with portions of the lower jaw, ten nearly free ribs, several verte- bra?, various. plastral elements, the shoulder girdle, a humerus, radius, and ulna, and several metacarpals and marginals, as well as parts of uncertain position. Owing, however, to the manner in which the ribs lay athwart the rather imperfect plastral plates, the latter were supposed to be dorsal, and to represent a very primitive con- dition of carapacial development with large fenestra. The radius and ulna were 1 Vol. XII., p. 175. 279 280 MEMOIRS OF THE CARNEGIE MUSEUM not distinctly recognized as such although clearly figured. Owing also to a palpable numerical error in the measurements of the cranium (" .50 M. = 24^ in.") the total length of the original animal was estimated at thirteen feet, and is so referred to in text-books ! The actual length is far less, as will clearly appear in the present description of a much completer cotype almost exactly the size of the original Cope specimen. This error was, however, in a sense prophetic, as some of the turtles of the related Dakotan genus Arckelon, discovered by the writer twenty-four years after the first Protostega, did actually reach, or possibly exceed, the enormous size of thirteen feet in length. Protostega remained a very vaguely known turtle until Baur 2 pointed out that it must in its main characteristics agree with the ( !heloniidae, and that the plates Cope supposed were dorsal must be plastral. That such was the fact was later more definitely shown by Hay,3 who figured the nuchal and hyo- and hypoplastron of another Niobrara specimen. The next contributions to our knowledge of the osteology of the Protosteginre were made by the writer, after his discovery of gigantic turtles east of the Black Hills in the Fort Pierre Cretaceous in the summer of 1895. In the communica- tions,4 which soon followed, the structure of the greater part of the carapace and plastron was made known from remarkably preserved specimens. All the larger limb bones were also determined and figured ; for the first time, indeed, in the case of any extinct sea-turtles of America. There immediately followed these papers the important contribution of Case,5 which, in addition to a careful discussion of the systematic position of Protostega, added more particularly to a knowledge of the cranial characters, as based on the description of various crushed, but otherwise well defined disarticulated elements. The pelvis was also made known. Further facts concerning the general cranial type in the Protosteginse were next given by the writer6 in a paper describing the splendid skull of Arckelon, now on exhibition in the Yale Museum. Later an attempt was made by Williston7 to restore tbe tarsus and give the organization of the bind Hipper of Protostega, and by 2 (a) "Die Systematische Stellung von Dermochelys Blainville," Biolog. Centratblatt, IX., 1889. (J) "On the Classification of the Testudinata," American Naturalist, XXIV., 1891). 3 " On Certain Portions of the Skeletion of Protostega gigas," Field Columbian Museum Publication, No. 7, 1895. '(«) " Arclulon ischyros, a New Gigantic Cryptodiran Testudinate from the Fort Pierre Cretaceous of South Dakota," Am. Jour. Science, December, 1895. (h) "The Protostegan Plastron," Ibid., January, 1898. 5 "On the Osteology and Relationships of Protostega,' ' Journal of Morphology, Vol. XIV. (This publication bears the date 1897, but did not appear until some time in June, 1898, its presumptively true date. ) b " The Skull, Pelvis, and Probable Relationships of the Huge Turtles of the Genus Arckelon from the Fort Pierre Cretaceous of South Dakota," Am. Jour. Sci , Vol. IX., April, 1900. T "On the Hind Limb of Protostega," Ibid., Vol. XIII., Apiil, 1902. WIELAND : THE OSTEOLOGY OK PROTOSTEGA 281 Wieland8 to show the carpal organization of Archelon ; but, as will be shown below, both these efforts are almost entirely in error. From the foregoing review of the slow progress of our knowledge of the Protostegimo it is seen that the third of a century which has elapsed since Cope's discovery of Protostega gigas has not sufficed to bring forth an entirely complete restoration of any single individual of these great sea-turtles. How welcome then has been the discovery during the past two years by Mr. Charles Sternberg in the Niobrara ( Vetaceous of Western Kansas of the nearly complete specimens of Protostega gigas which permit the present descrip- tion of the organization of the limbs, the most important of the parts yet unde- scribed, as well as the least likely to be recovered in complete form. For happily the elements of the first-secured and completer of these exceptional specimens, though somewhat crushed, were found altogether, or nearly, in their naturally articulated position, a condition imperatively necessary to a satisfactory description of the flippers. This rare fossil turtle was first briefly mentioned in Science by Professor Osborn9 as " * * * a complete skeleton of Protostega which lay on its dorsal surface with the fore limbs stretched out at right angles to the median line of the carapace, measur- ing six feet between the ungual phalanges." Afterwards it was secured for the Carnegie Museum by Mr. J. B. Hatcher, who, though he crowded the brilliant work, which might well have crowned the efforts of a long life, into a short one. leaves this ripe fruition mixed with a sorrow surely not lessened by the fact that the hardships of the plains of the Northwest and the Patagonian deserts had all too plainly left their mark upon him. Having expressed in conversation with Mr. Hatcher much interest in these more recent discoveries of Protostega, I was invited to make a study of the newly acquired material, this arrangement being concurred in by Dr. W. J. Holland, Director of the Carnegie Museum. But early in July, 1904, when I visited the Carnegie Museum for the purpose of doing this work, to my extreme sorrow I found, that, although 1 had a brief word from Mr. Hatcher shortly before, he was so seriously ill that there could be but little or no hope of his recovery. And indeed, as everyone feared, it was but a few days before he passed away. However, it was under such circumstances a relief to be busied, and Dr. Holland very kindly arranged for and furthered the initial study of the material on hand. Furthermore, during the past summer Dr. Holland has added to the collections first obtained much additional material, also collected by Mr. Sternberg, including 8 "Notes on the Cretaceous Turtles Toxochelyz and Archelon, with a Classification of the Marine Testudinates," Ibid., Vol. XIV., August, 1902. 9N. S., Vol. XIX., No. 470, p. 35, January, 1904. 282 MEMOIRS OF THE CARNEGIE MUSEUM one very important specimen, a large Protostega, represented by a quite complete cranium and lower jaw, accompanied by a humerus, radius, ulna, wrist, and palmar bones — all in place on the same slab. The acquisition of this specimen has been as timely as fortunate ; for it has removed all doubt as to the carpal and tarsal organization of Protostega, and made possible the avoidance of errors in the descrip- tion of the completer sjjecimen, most of the elements of which had been dissociated from their matrix, and the position of some of them rendered doubtful through the mistaken zeal of their collector. It will hence greatly simplify our description of the limb organization of Protostega as based on the free elements of the original and completer specimen, No. 1420, Carnegie Museum Catalogue of Vertebrate Fossils, if the more recently acquired and less complete Protostega with its parts in approxi- mately natural position, be considered first. Protostega gigas Cope (Cotype). Specimen No. 14.21 {Carnegie Museum Catalogue of Vertebrate Fossils). — This fine fossil is from the Niobrara Cretaceous of Hackberry Creek, Gove County, Kansas. The ex situ portions of the original skeleton, which had weathered out and were secured in more or less complete condition, include the left humerus, radius, ulna, Fig. 1. Protostega gigas. Carnegie Museum Specimen, No. 1421, from Niobrara chalk of Hackberry Creek, Gove County, Kansas. Superior view of skull with the lower jaw and a hyoid, the right anterior border of the carapace and most of the right fore flipper, all in nearly natural position and still partially imbedded as collected on a single slab of the chalk matrix. X s- Skull. — pm.% premaxillary ; in., maxillary ; n.o., external nares ; p.f., prefrontal ; Jr., frontal ; o., orbital border ; p., parietal ; s.o., snpraoceipital ; j., jugal ; q.j., quadratojugal ; sq., squamosal ; q., right quadrate. Lower Jaw. — rf., dentalium ; a., angular; or., surangular ; sp., splenial ; (h., hyoid). Carapace. — A'., portion of right ala of nuchal ; Cr., second rib ; lm., Sin., first and second marginalia. Flipper. — H., humerus; S., radius; U., ulna; r., radiale(?); i., intermedium; «/., uluare ; p., pisiform; 1-5, first to fifth carpalia respectively ; I.-V., first to fifth metacarpalia. WIELAND : THE OSTEOLOGY OF PROTOSTEGA 283 ulnare, radiale, and pisiform, with fragmentary phalanges, and many broken pieces of the plastron. The in situ portion consists of the right anterior part of the skele- ton, and was secured on a single slab of the chalk matrix, in which it still remains intact, as shown in the accompanying drawing, Fig. 1, by Mr. Prentice. It includes the following : the lower jaw in oblique inferior view, with the two larger hyoidal elements ; the skull in superior view, less the left squamosal and with the right quad- rate disarticulated and its anterior surface up ; the right humerus, radius, ulna, wrist, and palmar elements in superior view, and all in place, except the radiale which has slipped across to the posterior border of the wrist ; the right ala of the T-shaped nuchal with the first and second marginals, and the distal half of the second rib, all in place and resting over the proximal extremity of the humerus. Although the various bones are more or less crushed, after the manner of most fossils from the Kansas chalk, the contours are exceedingly good. In the skull, as simply crushed down in the vertical direction with little distortion of parts, there appear in clear preservation and united by distinct sutures the premaxillaries, maxillaries, prefrontals, frontals, postorbitals, and parietals, with the right squa- mosal, jugal, and quadrato-jugal. The cervicals have in some way been dissociated, but the skull lies in a normal position with respect to the anterior border of the carapace, from under which the right fore-flipper projects in the normal position, the hand being bent back pronately over the position of the third marginal, part of which appears in view. It will at once be seen what exceedingly satisfactory information is furnished by the present specimen, as compared with all other examples of Protostega hitherto found. The more important measurements afforded are the following : em. Lower jaw : Extreme length of ramus 37 Extreme length of median symphysis 16 Cranium : Extreme length (as crushed flat) measured from end of heak to posterior ex- tremity of occipital crest 58 Median length of narial opening 7.5 Greatest width of narial opening 5.5 Orbital border of the prefrontal 6 Antero-posterior length of orbit 12 Humerus: Length across head 31? Width of distal end 14 Radius : Length 19 UlDa: Length : 18 Carpalia : Width across the live carpalia in place 18 Metacarpalia : (Length of 1-5 resp.) ; 7( + or — ), 10.5, 12, 12.5, 10 ( + or — ) cm. The above cranial and hand measurements have not hitherto been obtained in Protostega, whence it is of interest to note, that, allowance being made for the crush- 284 MEMOIRS OF THE CARNEGIE MUSEUM ing of the specimens of the Niobrara chalk, no wide differences in proportion are evident on comparison with the much larger turtles of the genus Archelon from the Fort Pierre Cretaceous. The lack of coossification of the mandibular rami and especially the very low radial crest of the latter form will, however, serve to dis- tinguish it from the fossil before us. But of far greater interest than any question of generic values that may arise is the fact that the bones of the hand are, with the sole exception of the radiale, indisputably in place, the most striking fea- ture being the immense ulnare, and the sti'ong contact of the intermedium with the first carpale. With these remarks we may pass on, basing our main de- scriptions on the earlier secured and in some respects better specimen with its several elements freed from their matrix. Specimen No. 1420 (Carnegie Museum Catalogue of Vertebrate Fossih). — The present specimen of Protostega gigas is more nearly complete than any other as yet discovered. As originally imbedded in its matrix of chalk, nearly every ele- ment was present in an exactly or approximately natural position, and recovered as follows : 1. Portions of the skull, with the crushed lower jaw and two large and well preserved paired hyoids. 2. The 1st, 4th, 5th, 6th, 7th and 8th cervical, the dorsal, sacral, and eight anterior caudal vertebrae. 3. The nearly complete series of ribs, including the anterior pair of sacral ribs, also the neurals, and various marginals. 4. The left shoulder-girdle and proximal half of the humerus, with the right shoulder-girdle and complete front flipper in place, except the ungual phalanx of the fourth and the second phalanx of the fifth digit. 5. The pelvic girdle and hind limbs complete and in place, less only the fibu- lare (if ossified), the ungual phalanges of the right, fourth, and fifth digits and of the left fifth digit. 6. A nearly complete though very much crushed plastron. Unfortunately the collector of this surprisingly complete fossil, in an attempt to remove and separate the bones from their matrix of chalk, mis-marked some of them, and also made it virtually impossible to either replace more than a very few of the marginals, or to determine the outlines of any of the plastral elements with exact- ness. Hence it is not worth while, in view of the marked crushing undergone, to give figures of any of these parts now, although they will aid in the restoration. As will be evident to any student of the fossil vertebrates the removal of the fossil from its matrix in the absence of the necessary knowledge, training, and equipment, WI ELAND : THE OSTEOLOGY OF PROTOSTEGA 285 was ill advised. Such work is difficult enough in the best equipped labora- tories. However none of the hones of the limbs are broken, and Mr. Sternberg redeemed himself by discovering and securing in such excellent condition specimen No. 1421, as just related. The position of the following parts is independently determinable : 1. The fourth to the eighth cervical, the dorsal and sacral centra, with the proximal caudal vertebrae and most of the ribs as shown in part in Fig. 2. 2. The shoulder-girdles and elements of the fore-arm ; in particular (as can be determined by actual close articulation, or by such intervening matrix as the col- lector permitted in much too small part to remain), the intermedium, first carpale, metacarpale and its phalanges, and also carpalia 3-5. 3. The pelvic girdle and elements of the hind Hipper, in particular the inter- medio-centrale ami tarsaiia 1-3, ami ', and 5 (fused), as well as several metatarsals and phalanges. It should be stated here that it is claimed that, as figured, no element of either- Hipper is actually misplaced, although the extent of the crushing undergone makes it quite possible that in one or two instances dorsal surfaces have been mistaken for ventral ones, or vice versa, and that the ends of several phalanges may have been reversed. Withal it is deemed important to be thus explicit in giving the manner in which the accompanying text-figures and photographs have been obtained, before taking up more detailed description. (Because of the compression undergone it was not thought needful to figure either the lower jaw, cervicals, or caudals. The dorsal view of the carapace can better be given after the restoration now being made. I. The Carapace. (Fig. 2.) With the exception of the T-shaped nuchal and the marginals with dactylate interior borders so peculiar to the Protostegimc in distinction from all other known marine turtles, the main features of the carapace are very well represented in Fig. 2. The very thin, almost paper-like series of neuralia is present, though much crushed down on the underlying neural arches. The ribs are free through at least the distal two-thirds of their length. The first pair is comparatively slender, it not being clear as to whether, or not. their distal extremities rested on the lateral ala>- like expansions of the nuchal. The shield contour is, instead of elongate as once supposed, relatively broader than in either Thalassochelys or Ghelone, the ratio of the length of the dorso-sacral series to the breadth of the carapace being as three to four. 286 MEMOIRS OF THE CARNEGIE MUSEUM Fro. 2. Prutoslegit gigas. Carapace less the nuchal and the marginal series. Inner view. 1-10, the first to tenth ribs respectively ; s, the first sacral. Ten dorsal, the two sacral, and the first of the caudal centra are shown. (A trial drawing preparatory to mounting of specimen. About one-eighth natural size.) This greater breadth is quite characteristic of Cretaceous turtles, and a distinct ap- proach to a quite orbicular form like that of Li/toloma.w It is a form, moreover, that well accords with the powerful and widely expanded flippers now to be described. II. The Front Flipper. (Plates XXXI. and XXXII., with Figs. 3 and 4.) The shoulder-girdle of Protostega is robust but presents no strongly marked peculiarities, save the elongate coracoid which extended back to the pubis as in Eretmoehelys, but not either Chelone or the long-bodied Dermochelys. The 10 Wieland, "Structure of the Upper Cretaceous Turtles of New Jersey : Lytoloma," Amer. Jour. Sci., Vol. XVII.,' September, 1904. WIELAND : THE OSTEOLOGY OF PKOTOSTEGA 287 features of the humerus are, however, highly characteristic, as is shown more particularly in Figs. 3 and 4, which disclose certain approximations to the humerus of Dermochelys not so readily discernible in the figures hitherto pub- Fig. 3. Piolnslega gigas. Ental view of a large humerus. Actual length, 34 cm.