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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 7.', NUMBER 8 A REVIEW OF THE INTERRELATIONSHIPS OF THE CETACEA BY HERLUF WINGE [Transhited by Gerrit S. Miller, Jr.] (Publication 2650) CITY OF WASHINGTON riJBl.ISHED BY THE SMITHSONIAN INSTITUTION 1921 C^e Boti) <§a(timove (pnes BALTIMORE, MD., U. S. A. A RF.VIEW OF THE INTERRELATIONSHIPS OF THE CETACEA By HERLUF WINGE [Translated by Ge:rrit S. Miller, Jr.] In translating Doctor Winge's " Udsigt over Hvalernes indbyrdes " Slaegtskab (Vidensk. Medd. fra Dansk naturh. Foren., vol. 70, pp. 59-142, 1918) my aim has been to give the author's ideas as clearly and exactly as possible rather than to make smooth English sentences. I have been much aided by the kindness of Dr. Leonhard Stejneger, who has compared the entire MS with the original, making himself responsible in particular for the rendering of the adverbs ret, sikkert, vel, and vist, whose idiomatic shades of meaning present many difficulties to one whose acquaintance with Danish is limited to the printed language. Doctor V/inge has also examined the translation, expressed his approval of it, and made some useful suggestions for its improvement. I have added an index, a few bibliographical refer- ences, and in some instances the generic names which are correct according to the International Code of Nomenclature. Brackets are used to distinguish all additions to the original text.—G. S. M., Jr. ^ The Cetacea ' originated from the Hyccnodontidcc, the most primi- tive family of the Carnivora, by way of the most typically carnivorous members of the group such as Pterodon and Hycsnodon. The oldest known whales have such a great likeness to Hyccnodon and its nearest relatives that there can be no doubt about the relationship. Aquatic habits have given the cetaceans their special peculiarities and have caused their differentiation from the Hyaenodonts. As an inheritance from the highest Hyaenodonts, and as an indica- tion of relationship with exactly these animals, the most primitive whales retained a series of special peculiarities which the Hysenodonts had developed in the course of their differentiation from the insectiv- orous stage. They still had about the same dentition as the Hyaeno- donts. All the teeth were fitted for flesh eating; the incisors and canines were strong and hooked, the anterior cheekteeth strong, elongated, compressed, smooth-edged; the molariform cheekteeth, especially those of the upper jaw, had a peculiar form and all of them were nearly alike. In the upper molars the 4th and Sth cusps [paracone and metacone] were coalesced to form a trenchant longi- tudinal ridge, the ist and 2d cusps [parastyle and mesostyle] were reduced, the 3d cusp [metastyle] was a compressed ridge, and the ^ Notes are at end of paper, pages 47-93- Smithsonian Miscellaneous Collections, Vol. 72, No. 8 ;; 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 'J2 6th cusp [protocone] was reduced or absent. All of the upper molari- form teeth including the third premolar still had the inner root, though this was in process of reduction. All the teeth of the typical [eutherian] dentition were present, ii in each jaw [44 in all]. The jaws were elongated in harmony with the long, well-developed tooth- rows. The temporal fossa was very large, widened out by a powerful temporal muscle. It was bounded by a high sagittal crest, by a strong, backward-projecting occipital crest, and by an abruptly out- standing, posteriorly heavy processus zygomaticus squamce. In addition to these peculiarities the most primitive whales had two high characters which were perhaps inherited from the Hysenodonts at any rate they are to be found in the latter group, though less pro- nounced : a rather large supraorbital process, and a bony palate lengthened backward far under the posterior nares. Radical alterations have taken place during the change from Hysenodont-like carnivores to true whales. In many of the mam- malian groups there have arisen forms modified for life in the water but no other aquatic mammals are modified to the same degree as the cetaceans, nor has any other become so exclusively aquatic ; only to breathe do they raise the nose above the water in which they other- wise are hidden. The cetacea have used the tail as the chief implement of locomo- tion ; the hind limbs are put wholly out of service ; the fore limbs are scarcely used for much else than steering and balancing. The tail becomes enormous, long and thick, powerfully muscled. It is formed in agreement with the manner in which it is wielded: with strokes from side to side, or up and down, or with a sculling motion. Throughout most of its extent it becomes compressed, but at the tip it acquires a powerful, horizontal, caudal fin constructed of skin folds (not present in quite young embryos of recent cetaceans). At the front of its upper margin, in the region where the tail joins the back, there may occur a special erect skin fold in the form of a longitudinal crest, a dorsal fin. Most of the caudal vertebrse lose the atrophied appearance which they have in primitive mammals ; they acquire powerful centra, heavy, flat-outspread transverse processes, high dorsal arches with large, compressed spinous process, and articular processes which are distinct though not mutually fitting together. The ventral arches with the inferior spinous processes become so large that they approach the upper arches in size. Only the outermost caudal vertebrae, which lie almost inclosed in the caudal fin, retain the degenerate character. The tail has an influence on the —; XO. 8 INTERRELATIONSHIPS OF THE CETACEA WINGE 3 dorsal vertebras also. Its powerful muscles, which have their origin in part on the sacral and dorsal vertebrae, and are also in connection with the muscles of the back, widen their place along the spinal column and stimulate the vertebrae to increase in bulk. The sacral and lumbar vertebras come to resemble the largest, most anterior caudal vertebrae exactly, apart from the lower arches. On a few of the hindmost thoracic vertebrae, which in the ancestral forms are without, or as good as without, transverse processes, there grow out powerful transverse processes on a line with and similar to those of the lumbar vertebras (parapophyses, apparently corresponding to the lower section of the double, rib-bearing " transverse process " of the anterior thoracic vertebras, which supports the rib's capitulum but in reality they most probably correspond to the upper and lower sections combined), and on their tip they eventually bear the attach- ment surface for the rib. Apparently this surface may be either for the attachment of the tuberculum or of the capitulum or of the two coalesced, but in reality it is perhaps always for the two combined (or, more correctly, not separated). The transverse processes of the anterior thoracic vertebrae (diapophyses, the upper portion of the double "transverse processes"), which in the beginning are quite short, may eventually grow long, pushing far out to the side the articular surface for the rib's tuberculum which they bear at their extremity. On all the thoracic vertebrae the spinous processes finally become high and strong. The hind limb atrophies completely, and disappears. At length only quite insignificant parts of its skeleton are found, hidden deep under the skin, finally in the form of a mere little rod-shaped bone, a remnant of the pelvis.^ In small embryos the hind limb can, however, still be distinguished externally. The disappearance of the hind limb has a great influence on the vertebral column. No longer does a pelvic bone come in contact with any of the vertebrae. In consequence the sacral vertebras completely lose their peculiarities : their characteristic strength, their mutual firm connection, their robust transverse processes with flattened areas for the hip bones. They are formed exactly like the adjacent dorsal and caudal vertebras. The movements of the spinal column become changed in character. Bending of the column in the vertical plane, which depends especially on the movements of the hind legs, is reduced or abandoned, and as a result the differences in slant forward or backward—of the spinous processes as good as disappear. MISCELLANEOUS COLLECTIONS VOL. 4 SMITHSONIAN 'J2. SO that all the processes alike are directed upward. The zygapophyses become reduced and in large part lose their mutual articulations. The fore limb, which no longer comes in contact with the earth or bears any load, is changed into a flipper whose single function is that of striking against the water. The entire arm becomes an oar blade. it Of the fore limb's articulations the shoulder joint only is used ; retains its ball-and-socket structure. All the other articulations are held stiff. They degenerate, become flat and immovable, or are wholly effaced. Practically the only function of the upper arm is to support the forearm and hand. It becomes short and heavy. Its middle portion retains its terete form, but its lower end is com- pressed in agreement with the bones of the forearm. The radius and ulna become very simply-formed, compressed bones, losing muscle crests, sinew furrows and all pronounced articular sur- faces;, even the olecranon may wholly disappear. The mutual posi- tion of the two bones is somewhat altered, so that they eventually lie exactly fore and aft of each other. The hand is set somewhat supine, fore edge downward. The carpal bones become compressed, or more correctly flattened, pieces [like sections of a mosaic]. They are rather indifferent as to form and number, and are immovable. The folds of skin between the fingers are lengthened out to the finger tips ; and the hand stiffens. The claws disappear. The first and fifth fingers are somewhat inclined to be stunted, but the other fingers, particularly the second, tend to lengthen and to form new joints at their tips, so that the number of phalanges may increase far beyond the typical three.