This study dissected a single specimen and cannot address whether this finding is a common morphology. A whale embryo in early stages of development b. Description of the skeleton of the fossil beaked whale Messapicetus gregarius: searching potential proxies for deep-diving abilities. It is possible that Megaptera has reduced muscular control over the manus, which would further isolate force generation to the glenohumeral joint. E,L: Humpback whale (M. novaeangliae). All taxa retained a triceps humeral head (m. triceps brachii, caput laterale). The taxonomic diversity of this database allows for phylogenetic interpretations of the evolution of antebrachial muscles and tendons. Enter your email address below and we will send you your username, If the address matches an existing account you will receive an email with instructions to retrieve your username, I have read and accept the Wiley Online Library Terms and Conditions of Use, The fossil record and evolutionary relationships of the genus, Investigations on the osteology and the functional morphology of the flipper of whales and dolphins (Cetacea), The role of phylogenetic analysis in the inference of unpreserved attributes of extinct taxa, The comparative myology of the forelimb of the hippopotamus, pig, and tapir, Evolution of digit reduction and hyperphalangy in the cetacean manus, The sirenian shoulder and forelimb‐a study of variation and function, Anatomy of the current and potential blood sampling sites in the Florida manatee (, Observations on underwater locomotion and flipper movement of the humpback whale, Functional anatomy of the hands of fur seals and sea lions, Structural correlates of forelimb function in fur seals and sea lions, Biomechanical perspective on the origin of cetacean flukes, Balancing requirements for stability and maneuverability in cetaceans, Structure and mechanics of nonpiscine control surfaces, Hydrodynamic design of the humpback whale flipper, Dynamics of the aerial maneuvers of spinner dolphins, Fore limb myology of the pygmy hippopotamus (, Comparative morphology of the forelimb skeleton in some Odontoceti (Mammalia, Cetacea), Morphological support for a close relationship between hippos and whales, Origin of whales from early artiodactyls: hands and feet of Eocene Protocetidae from Pakistan, The morphology of the brachial plexus with a note on the pectoral muscle and its tendon twist, Behavior and ecology of the Florida manatee (. 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. Brownell to L.N.C., the San Diego State University Biology Department Student Travel Grant to L.N.C, a NOAA Prescott Stranding Grant to J.S.R., and an NSF grant to A.B. Flipper movements were observed in the pilot whale (Globicephala) based on video footage of captive whales swimming at low speeds (see Werth, 1987). Deep water foragers, such as beaked whales, have an indentation in the body wall where the flipper tucks in (Mead, 1989). Those taxa that retain well‐developed muscles and tendons have the potential to actively adjust flipper stiffness and fine‐tune its shape. . These muscles gave rise to flattened tendons that were continuous with the connective tissue encasing each digit. Extant ungulates display the primitive condition of well‐developed antebrachial muscles and tendons (Campbell, 1936; Fisher et al., 2005, 2007). Cetaceans have undergone an anatomical trade‐off that has allowed them to evolve a rigid limb that may be more easily tucked against the body in deep water foragers (beaked whales), or capable of assisting high speed turns without deforming in shallow water foragers (dolphins). Results were compared with published descriptions of both artiodactyls and secondarily aquatic vertebrates. However, their skulls particularly in the ear region, which is surrounded by a bony wall strongly resemble those of living whales and are unlike those of any other mammal. The shoulder joint retains the standard ability for circumduction, the cubital joint moves during each paddle (Fish, 2004), and the wrist retains some mobility (Dart, 1974). These first whales, such as Pakicetus, were typical land animals. 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. Thehind limbs of the walrus are the major source of aquatic propulsion; the forelimbs are used for manoeuvring as well as for propulsion. Flexor tendons exhibited divergent fibers along the cranial and caudal surfaces to envelope interphalangeal joints and insert on each phalanx. Cetaceans lack proximal sesamoid bones, so the attachments of the m. interosseus muscle in Physeter would not be expected to be completely congruent with that of terrestrial mammals. also thanks L. Fajardo and Dr. J. Harper for literature assistance. This great length is achieved by elongated metacarpals, phalanges, and interphalangeal cartilages in addition to the standard cetacean presence of hyperphalangy (Cooper et al., 2007). Extant cetaceans have a soft tissue flipper encasing the manus and acting as a hydrofoil to generate lift. These data were then integrated to address the hydrodynamic performance There was no well‐defined pattern of superficial fibers wrapping around deep fibers to form a sleeve or manica flexorius, or digital annular ligaments, both typical of terrestrial artiodactyls (Table 4). The flipper of Megaptera is of special interest as it displays many unique attributes. Please check your email for instructions on resetting your password. Our data indicate this reduction is an autapomorphy. Extensor tendons adhere more closely to the underlying connective tissues, and lack such distinct synovial structures. They use their pectoral fins to dance together, sweeping beautiful arcs in the ocean, dancing and singing their haunting songs. Hilary M. Clayton, Henry Chateau and Willem Back. These flippers can grow to lengths of about 15 feet, which is abo\൵t 1/3 of the whale’s total length. 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. Distal to the carpus, it divides into thick ribbons that overlie each phalanx. f. Indohyus has some characteristics in common with modern whales. The most unusual flipper shape is seen in humpback whales as they have longest flippers of any cetacean. The surprising ease with which the flipper deformed was probably due to the lack of a thick connective tissue encasing the limb (as in the thick dermal layers of Orcinus and Physeter), and the maintenance of cartilaginous interphalangeal joints (Lee, 1978), which may allow a greater range of mobility. When did organ music become associated with baseball? is best predicted by taxonomic distribution and is not a function of body. The shovellike paw comprises almost half the length of the limb. based on osteological comparisons with extant marine mammals No gross evidence of a flexor muscle was found in Orcinus. 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. Forelimbs retain only three muscle groups: triceps (only the scapular head is functional as the humeral heads are vestigal), and antebrachial extensors and flexors. 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. Figure 6. Manipulation of the Megaptera limb before dissection showed it was extremely mobile with the manus able to flex and extend more than any other cetacean. Sensory branches of the musculocutaneous and ulnar nerves may be crucial for gathering hydrodynamic loading information on the flipper. Anat Rec, 290:1121–1137, 2007. Cynthiacetus peruvianus In Physeter, a scapular head (caput longum) of the triceps sent a tendinous band distally to the olecranon to fuse with the tendo flexor carpi ulnaris (Fig. Typical two‐headed m. triceps brachii in a dissected gray whale (Eschrichtius) forelimb, a scapular and humeral head inserting on the olecranon process of the ulna.
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