The retinacula of artiodactyls bind tendons of the digital extensor muscles at the level of the carpus, and well‐developed palmar and digital annular ligaments bind the digital flexor tendons to the metacarpus and phalanges. The most unusual flipper shape is seen in humpback whales as they have longest flippers of any cetacean and the leading edge of the flipper is scallop shaped by the presence of large tubercles. A third triceps head, found only in Physeter, probably originated on the humerus, but its precise origin was unclear due to the condition of the specimen (Table 2). So the forelimb in all of these animals will have same bones: from proximal to distal the bones are-Humerus (remains attached to pectoral girdle), Radius and Ulna (in diagram shown as orange and white bones), Carpals (shown in yellow colour), Metacarpals, Phalanges. As the Physeter specimen did not have an attached scapula, this study cannot verify the muscular origin and, therefore, only tentatively describes this triceps head as originating from the scapula. Later diverging odontocetes lack musculature supporting digital movements and are unable to manipulate flipper curvature. Thewissen, Dr. C. Vinyard, A.L. How old was queen elizabeth 2 when she became queen? ... Cetacean ﬂ ippers function to stabilize the body and aid in turns ( Woodward et al., 2006 ). Intermediate between the forelimb morphologies seen in right whales and rorqual whales, the gray whale has a broad and elongated flipper. As WINGS, the bird wing and bat wing are analogous.They are similar to each other in function, performing as wings for flight, but have evolved differently. Extant cetaceans have a soft tissue flipper encasing the manus and acting as a hydrofoil to generate lift. Correlated with this reduced musculature, joints distal to the shoulder have reduced mobility (Louw, 1992). In contrast to the robust muscles found in all other mysticetes, antebrachial muscles of the humpback whale (Megaptera novaeangliae) displayed drastically reduced origins and insertions. When did organ music become associated with baseball? (Artiodactyla: Mammalia) Specifically, the distal limb is similar to monodontid, phocoenid, and delphinid odontocetes in having absent muscles or having tiny bellies and long, thin tendons (compared with flying birds, Louw, 1992). 3, 4) and listed in Table 3. Digital extensor tendons in the pygmy hippopotamus insert on the middle and distal phalanges (Campbell, 1936; Fisher et al., 2007), and a continuous synovial sheath would not allow any of these tendons to attach. Dashed lines indicate the assumed path of nerves that we were not able to trace. Extant cetaceans also lack both supinators and pronators, and it may be that the muscles controlling these movements were lost during the Eocene. A new Miocene baleen whale from the Peruvian desert. Alligator hindlimbs show high torsional loads during terrestrial locomotion, in sharp contrast to the bending or axial compressive loads that predominate in animals that use parasagittal limb movements. Inter state form of sales tax income tax? Over time, the limbs converged, becoming similar in form and function. based on osteological comparisons with extant marine mammals A similar arrangement is seen throughout the spe-cies, from the domestic cat and the medium-sized. (A forearm, however, is the part of the human arm or forelimb between the elbow and the wrist.). Figure 6. Because pressure is greatest on the leading edge of a hydrofoil, the musculocutaneous nerve may play a crucial role in detecting leading edge forces as the angle of attack (angle of the leading edge of the flipper) is changed. 2, 3) and Cuvier's beaked whale (Ziphius), two basal odontocetes, shared the mysticete‐like morphology of well‐developed antebrachial muscles with organized muscular bellies on both the dorsal and palmar surfaces of the flipper. Phylogenetic implications were supplemented with locomotor characteristics: relative swimming speed (Fish, 2002a, b, 2004; Woodward et al., 2006), and level of maneuverability (cruiser vs. agile, Benke, 1993; Fish, 2002a, 2004; Woodward et al., 2006). The belly of the flexor digitorum communis comes in direct contact with a large counter‐current heat exchanger in the axilla of bowhead whales (Balaena; Cooper, unpublished data), and contraction of the muscle may generate heat that could be cooled distally in the limb. Computed Tomography and Cross‐Sectional Anatomy of the Thorax of the Live Bottlenose Dolphin (Tursiops truncatus). Locomotion (Including Osteology and Myology). Muscle origins and insertions were recorded using nomenclature and forelimb orientations following the standard Nomina Anatomica Veterinaria (International Committee on Veterinary Gross Anatomical Nomenclature, 2005) terminology. 1; Table 2) was observed in mysticetes and the sperm whale (Physeter). Our data indicate this reduction is an autapomorphy. This helps the whale trap large amounts of prey. They are quite small compared to their counterparts in other animals, but they exist. Cetaceans immobilize the cubital joint and mostly immobilize the wrist and digits, develop hyperphalangy in the digits, and encase the limb in a soft tissue flipper. size. The tree shrew is small bodied, moves easily on the ground or in the trees, and has a flexible forelimb for these functions. Identification of the m. interosseus muscle group in Physeter was based on its location, attachments, and relationship to the digital flexor tendon in each digit. e. Indohyus shares an ancestor with modern whales. The median nerve sent motor branches to the digital flexor muscles, continued distally in the interosseous space between the radius and ulna, and further divided to form digital nerves that travel in the interdigital spaces. Laitman for helpful comments on this manuscript. 2). Odontocete taxa showed variation in antebrachial limb muscle morphology (Table 3). Extant ungulates display the primitive condition of well‐developed antebrachial muscles and tendons (Campbell, 1936; Fisher et al., 2005, 2007). Maintaining and modulating flipper stiffness is crucial for hydrodynamic efficiency. Alternatively, in the aerobatic maneuvers of spinner dolphins, before a jump, the dolphins will begin corkscrewing in the water, and the flippers are under hydrodynamic loads in the form of torques (Fish et al., 2006). m. flexor digitorum communis (fdc), m. flexor digitorum radialis (fdr), m. flexor carpi ulnaris (fcu). This unnamed muscle had a fleshy but small belly arising from the posteromedial aspect of the ulna, passed deep to the retinaculum, and fanned out over the connective tissue plate covering the carpus. Megaptera is the only mysticete that displays obvious antebrachial muscle reduction, similar to that seen in monodontid, phocoenid, and delphinid odontocetes. Morphology of the m. flexor carpi ulnaris is not included, as all taxa shared the same origin (olecranon process) and insertion along the pisiform cartilage. Otariids (fur seals and sea lions) have abundant forelimb muscles with complex pennation that allow for forelimb generated propulsion (English, 1976) while the hindlimbs aid in maneuvering (Gordon, 1983). Similarly, most cetaceans reduce or lack digit I and reduce digit V (Cooper et al., 2007). We report the pathways of the major terminal nerve branches of the brachial plexus in three cetacean species (two mysticetes, one odontocete) of varying ages. thanks Dr. P‐Y Daoust for access to specimens, and D. Hughes and G. Curtis for technical support. . The reduced triceps musculature of cetaceans is in strong contrast to that of the terrestrial artiodactyls (Table 4, Campbell, 1936; Dyce et al., 2002; Fisher et al., 2007), which typically have three to four functional triceps heads. The terms used to describe flipper orientation assume that the flipper is abducted 90 degrees away from the body and is rotated laterally so that its long axis lies in the horizontal plane (i.e., flat surfaces face up and down, the leading edge is blunt, and the trailing edge is thin). Cetacean Skeletons Demonstrate Ecologically Relevant Variation in Intraskeletal Stable Isotopic Values. These muscles gave rise to flattened tendons that were continuous with the connective tissue encasing each digit. This retention is in strong contrast to the significant reduction in muscle, motor nerve, and connective tissue structures. Also contrary to cetaceans, otariids retain abundant palmar musculature, including m. interossei, digital abductors and adductors, and in some specimens a single lumbrical (English, 1976). They see shapes clearly, recognize patterns on the sides of other cetaceans and can see when others in their pod have turned. Large bowhead and right whale ﬂ ippers are useful when the whale is turning at slow speeds. This palmar flexion is created by abundant antebrachial muscles with large muscular bellies, and robust tendons (see Howell, 1930b), a combination that affords large excursion compared with cetaceans. The antebrachial flexor and extensor muscles of the pygmy hippopotamus and domesticated pig act on the cubital joint, wrist, metacarpophalangeal, and interphalangeal joints (Fisher et al., 2007).