Evolution of pinniped Carnivora with reference to other aquatic Mammalia - a case study of constructional morphology
Final Report Abstract
Despite the differences in anatomy and locomotion all extant Pinnipedia show the bracing principle of a terrestrial quadrupedal mammalian. Bracing of the trunk is brought about dorsally by the vertebral column combined with the epaxial muscles, ventrally by the thorax, the abdominal muscles and especially m. iliopsoas. In all Pinnipedia the hind limb is permanently flexed in the knee joint. A specialty of Phocidae is a proximally facing process on the talus which bears a plantar sulcus for the tendon of m. flexor hallucis longus. This tendon blocks the dorsal flexion of the pes in the ankle joint and, as a consequence the hind limbs no longer can support the body. The sternal- and pubical areas are support areas of the body and terrestrial locomotion is inch wormlike. Shock absorber is the blubber coat combines with the paired m. pectoralis with a m. pectoralis profundus reaching caudally to the pelvis, as well as the abdominal- and extrinsic muscles of the hind limbs. This makes Phocidae the most derived of all extant Pinnipedia. In Otariidae and Odobenidae the pelvis stands vertically during stance and gait to warrant a full plantar contact of the pedes despite the permanently flexed knee joint. Because of the shortness of the limbs with respect to the body the centre of gravity swings stronger laterally during terrestrial locomotion than in terrestrial quadrupedal mammals. Compensation movements of neck and head are necessary to balance the body during terrestrial locomotion. The pinniped pre-construction either was trunk flexible with short limbs or trunk stiff, both having a short tail. Such constructions today are found among extant Musteloidea. This would support the hypothesis of a monophyly of extant Pinnipedia. However, monophyly of the Pinnipedia cannot be finally validated by the applied method of constructional morphology.
Publications
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2008. Biomechanics of Pinniped Locomotion and Evolution. In: 6th Meeting of the European Association of Vertebrate Palaeontologists. EAVP Meeting, Spisska Nova Ves, pp. 23–26
Burkhardt, C., Frey, E.
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2009. Anatomical Peculiarities in Phoca (Mammalia: Pinnipedia) and their Consequences on Locomotion and Moving Options. In: 7th Annual Meeting of the European Association of Vertebrate Palaeontologists. EAVP Meeting, Shaker Verlag, Aachen, p. 16
Burkhardt, C., Frey, E.
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2010. Bracing system and locomotor mechanics in Phocinae (Carnivora, Mammalia). In: 8th Meeting of the European Association of Vertebrate Palaeontologists. EAVP Meeting, Aix-en-Provence, France, p. 21
Burkhardt, C., Frey, E.
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, 2011. Walking Like Caterpillars, Flying Like Bats – Pinniped Locomotion. In: 9th Meeting of the European Association of Vertebrate Palaeontologists. EAVP Meeting, Heraklion, Greece, pp. 33–34
Kuhn, C., Frey, E.
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2012. Walking like caterpillars, flying like bats—pinniped locomotion. Palaeobiodivers Palaeoenviron 92: 197–210
Kuhn, C., Frey, E.
