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Locomotory capabilities in the Early Cretaceous ichthyosaur Platypterygius australis based on osteological comparisons with extant marine mammals

  • MARIA ZAMMIT (a1), BENJAMIN P. KEAR (a2) and RACHEL M. NORRIS (a3)

Abstract

Reconstructing the swimming capabilities of extinct marine tetrapods is critical for unravelling broader questions about their palaeobiology, palaeoecology and palaeobiogeography. Ichthyosaurs have long been the subject of such investigations because, alongside cetaceans, they are one of the few tetrapod lineages to achieve a highly specialized fish-like body plan. The dominant locomotory mode for the majority of derived, post-Triassic ichthyosaurs is hypothesized to have been caudal fin-driven propulsion. Limb-based swimming has however been suggested for some highly autapomorphic forms, such as the Cretaceous genus Platypterygius, which has a remarkably robust humeral morphology and exceptionally broad paddle-like limbs. To evaluate this atypical lifestyle model, we conducted a comprehensive comparative osteological assessment of Platypterygius in relation to extant marine mammals, whose analogous skeletal frameworks provide a structurally compatible selection of alternate propulsive strategies. Based on a proxy exemplar of the most completely known species, P. australis from the Early Cretaceous of Australia, the propodial shape, absence of functional elbow/knee joints, tightly interlocking carpals, hyperphalangy and extreme reduction of the pelvic girdle are most similar to cetaceans as opposed to pinnipeds or dugongs. There is no obvious structural consistency with aquatic mammals that use sustained forelimb-driven swimming. The exceptionally broad fore-paddle (a product of hyperdactyly) and extensive humeral muscle insertions might therefore have had a cetacean-like role in enhancing manoeuvrability and acceleration performance. We conclude that, despite its atypical features, P. australis was most likely similar to other ichthyosaurs in using lateral sweeps of the tailfin to generate primary propulsive thrust.

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Author for correspondence: maria.zammit6783@gmail.com

References

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Abel, O. 1909. Cetaceenstudien. I. Mitteilung: Das Skelett von Eurhinodelphis cocheteuxi aus dem Obermiozän von Antwerpen. Sitzungsberichte der Kaiserlickeh Akademie der Wissenschaften, Wien 118, 241–53.
Alexander, R. M. 1975. The Chordates. Cambridge: Cambridge University Press, 480 pp.
Bardet, N. & Fernández, M. 2000. A new ichthyosaur from the Upper Jurassic lithographic limestones of Bavaria. Journal of Paleontology 74, 503–11.
Baur, G. 1887. Über den Ursprung der Extremitäten der Ichthyopterygia. Jahresberichte und Mitteilungen des Oberrheinischen geologischen Vereines 20, 1720.
Berta, A. & Sumich, J. L. 1999. Marine Mammals: Evolutionary Biology. San Diego, California: Academic Press, 494 pp.
Best, R. C. & da Silva, V. M. F. 1993. Inia geoffrensis . Mammalian Species 426, 18.
Blake, R. W. 2004. Fish functional design and swimming performance. Journal of Fish Biology 65, 1193–222.
Buchholtz, E. A. 2001 a. Swimming styles in Jurassic ichthyosaurs. Journal of Vertebrate Paleontology 21, 6173.
Buchholtz, E. A. 2001 b. Vertebral osteology and swimming style in living and fossil whales (Order: Cetacea). Journal of Zoology, London 253, 175–90.
Buchholtz, E. A. & Schur, S. A. 2004. Vertebral osteology in Delphinidae (Cetacea). Zoological Journal of the Linnean Society 140, 383401.
Camp, C. L. 1976. Vorläufige Mitteilung über große Ichthyosaurier aus der oberen Trias von Nevada. Sitzungsberichte der Österreichischen Akademie der Wissenschaften, Mathematischnaturwissenschaftliche Klasse, Abteilung I 185, 125–34.
Cooper, L. N. & Dawson, S. D. 2009. The trouble with flippers: a report on the prevalence of digital anomalies in Cetacea. Zoological Journal of the Linnean Society 155, 722–35.
Cooper, L. N., Dawson, S. D., Reidenberg, J. S. & Berta, A. 2007. Neuromuscular anatomy and evolution of the cetacean forelimb. Anatomical Record 290, 1121–37.
Druckenmiller, P. S., Hurum, J. H., Knutsen, E. M. & Nakrem, H. A. 2012. Two new ophthalmosaurids (Reptilia: Ichthyosauria) from the Agardhfjellet Formation (Upper Jurassic: Volgian/Tithonian), Svalbard, Norway. Norwegian Journal of Geology 92, 311–39.
Druckenmiller, P. S. & Maxwell, E. E. 2010. A new Lower Cretaceous (lower Albian) ichthyosaur genus from the Clearwater Formation, Alberta, Canada. Canadian Journal of Earth Sciences, 47, 1037–53.
English, A. W. M. 1976. Limb movements and locomotor function in the California sea lion (Zalophus californianus). Journal of the Zoological Society, London 178, 341–64.
English, A. W. M. 1977. Structural correlates of forelimb function in fur seals and sea lions. Journal of Morphology 151, 325–52.
Feldkamp, S. D. 1987. Foreflipper propulsion in the California sea lion, Zalophus californianus . Journal of Zoology, London 212, 4357.
Fernández, M. S. 1997. A new ichthyosaur from the Tithonian (Late Jurassic) of the Neuquén Basin, northwestern Patagonia, Argentina. Journal of Paleontology 71, 479–84.
Fischer, V., Masure, E., Arkhangelsky, M. S. & Godefroit, P. 2011. A new Barremian (Early Cretaceous) ichthyosaur from western Russia. Journal of Vertebrae Paleontology 31, 1010–25.
Fish, F. E. 2004. Structure and mechanics of nonpiscine control surfaces. IEEE Journal of Oceanic Engineering 29, 605–21.
Harrison, R. J. & King, J. E. 1965. Marine Mammals. London: Hutchinson and Co. Limited, 192 pp.
Hildebrand, M. 1974. Analysis of Vertebrate Structure. New York: John Wiley & Sons, 710 pp.
Howell, A. B. 1929. Contribution to the comparative anatomy of the eared and earless seals (genera Zalophus and Phoca). Proceedings of the United States National Museum, 73, 1142.
Husar, S. L. 1977. Trichechus inunguis . Mammalian Species 72, 14.
Jaekel, O. 1904. Eine neue Darstellung von Ichthyosaurus . Zeitschrift der Deutschen Geologischen Gesellschaft 56, 2634.
James, P. B. S. R. 1974. An osteological study of the dugong Dugong dugon (Sirenia) from India. Marine Biology 27, 173–84.
Kear, B. P. 2003. Cretaceous marine reptiles of Australia: a review of taxonomy and distribution. Cretaceous Research 24, 277303.
Kear, B. P. 2005. Cranial morphology of Platypterygius longmani Wade, 1990 (Reptilia: Ichthyosauria) from the Lower Cretaceous of Australia. Zoological Journal of the Linnean Society 145, 583622.
Kear, B. P. & Zammit, M. 2013. In utero foetal remains of the Cretaceous ichthyosaurian Platypterygius: ontogenetic implications for character state efficacy. Geological Magazine, 151, 7186.
King, J. E. 1983. Seals of the World. Oxford: Oxford University Press, 154 pp.
Klima, M., Oelschläger, H. A. & Wünsch, D. 1980. Morphology of the pectoral girdle in the Amazon dolphin Inia geoffrensis with special reference to the shoulder joint and movements of the flippers. Zeitschrift fur Säugetierkunde 45, 288309.
Kolb, C. & Sander, P. M. 2009. Redescription of the ichthyosaur Platypterygius hercynicus (Kuhn 1946) from the Lower Cretaceous of Salzgitter (Lower Saxony, Germany). Palaeontographica Abteiling A 288, 151–92.
Maisch, M. W. & Matzke, A. T. 2000. The Ichthyosauria. Stuttgarter Beiträge zur Naturkunde Serie B (Geologie und Paläontologie) 298, 1159.
Massare, J. A. 1988. Swimming capabilities of Mesozoic marine reptiles: implications for method of predation. Paleobiology 14, 187205.
Massare, J. A. 1994. Swimming capabilities of Mesozoic marine reptiles: a review. In Mechanics and Physiology of Animal Swimming (eds Maddock, L., Bone, Q. & Rayner, J.), pp. 133–49. Cambridge: Cambridge University Press.
Massare, J. A. & Sharkey, S. J. 2003. Centrum shape in sharks: not a good analog for ichthyosaurs. Paludicola 4, 2736.
Maxwell, E. E. & Kear, B. P. 2010. Postcranial anatomy of Platypterygius americanus (Reptilia: Ichthyosauria) from the Cretaceous of Wyoming. Journal of Vertebrate Paleontology 30, 1059–68.
Maxwell, E. E., Zammit, M. & Druckenmiller, P. S. 2012. Morphology and orientation of the ichthyosaurian femur. Journal of Vertebrate Paleontology 32, 1207–11.
McGowan, C. 1972. Evolutionary trends in longipinnate ichthyosaurs with particular reference to the skull and fore fin. Life Sciences Contributions, Royal Ontario Museum 83, 138.
McGowan, C. 1992. The ichthyosaurian tail: sharks do not provide an appropriate analogue. Palaeontology 35, 555–70.
McGowan, C. 1996. The taxonomic status of Leptopterygius Huene, 1922 (Reptilia: Ichthyosauria). Canadian Journal of Earth Sciences 33, 439–43.
McGowan, C. & Motani, R. 2003. Ichthyopterygia . In Handbook of Paleoherpetology, Volume 8 (ed. Sues, H.-D.). München: Verlag Dr. Friedrich Pfeil, 175 pp.
M'Coy, F. 1867. On the occurrence of Ichthyosaurus and Plesiosaurus in Australia. Annals and Magazine of Natural History 19, 355–6.
Motani, R. 1999. On the evolution and homologies of ichthyopterygian forefins. Journal of Vertebrate Paleontology 19, 2841.
Motani, R. 2002. Swimming speed estimation of extinct marine reptiles: energetic approach revisited. Paleobiology 28, 251–62.
Ortega-Ortiz, J. G., Villa-Ramírez, B. & Gersenowies, J. R. 2000. Polydactyly and other features of the manus of the vaquita, Phocoena sinus . Marine Mammal Science 16, 277–86.
Osburn, R. C. 1903. Adaptation to aquatic, arboreal, fossorial and cursorial habits in mammals. I. Aquatic adaptations. American Naturalist 37, 651–65.
Riess, J. 1986. Fortbewegunsweise, schwimmbiophysik und phylogenie der ichthyosaurier. Palaeontographica Abteilung A 192, 93155 (in German).
Romer, A. S. 1956. Osteology of the Reptiles. Chicago: University of Chicago Press, 772 pp.
Seeley, H. G. 1874. On the pectoral arch and fore limb of Ophthalmosaurus, anew ichthyosaurian genus from the Oxford Clay. Quarterly Journal of the Geological Society of London 30, 696707.
Thewissen, J. G. M., Cohn, M. J., Stevens, L. S., Bajpai, S., Heyning, J. & Horton, W. E. Jr. 2006. Developmental basis for hind-limb loss in dolphins and origin of the cetacean bodyplan. Proceedings of the National Academy of Sciences of the United States of America 103, 8414–8.
Thewissen, J. G. M. & Taylor, M. A. 2007. Aquatic adaptations in the limbs of amniotes. In Fins into Limbs (ed. Hall, B. K.), pp. 310322. Chicago: University of Chicago Press.
von Huene, F. 1922. Die Ichthyosaurier des Lias und ihre Zusammenhänge. Monogaphien zur Geologie und Paläontologie, 1. Verlag von Gebrüder Borntraeger, Berlin, VIII + 114 pp.
von Huene, F. 1923. Lines of phyletic and biological development of the Ichthyopterygia. Bulletin of the Geological Society of America 34, 463–8.
Wade, M. 1984. Platypterygius australis, an Australian Cretaceous ichthyosaur. Lethaia 17, 93113.
Wade, M. 1990. A review of the Australian Cretaceous longipinnate ichthyosaur Platypterygius (Ichthyosauria, Ichthyopterygia). Memoirs of the Queensland Museum 28, 115–37.
Webb, P. W. 1977. Effects of median-fin amputation on fast-start performance of rainbow trout (Salmo gairdneri). Journal of Experimental Biology 68, 123–35.
Webb, P. W. 1984. Form and function in fish swimming. Scientific American 25, 5870.
Webb, P. W. & Keyes, R. S. 1981. Division of labor between median fins in swimming dolphin (Pisces: Coryphenidae). Copeia 1981, 901–4.
Zammit, M. 2010. A review of Australasian ichthyosaurs. Alcheringa 34, 281–92.
Zammit, M., Norris, R. M. & Kear, B. P. 2010. The Australian Cretaceous ichthyosaur Platypterygius australis: a description and review of postcranial remains. Journal of Vertebrate Paleontology 30, 1726–35.

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