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Diversity and Endemism of the Benthic Seamount Fauna in the Southwest Pacific

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Diversity and Endemism of the Benthic Seamount Fauna in the Southwest Pacific letters to nature an exclusively to predominantly hei livorous~~ In overall A. morphology the dentition most closely resembles that of some We thank B. Rakotosamimanana. RasOakaramanana, P. Wright, B. Andriamihaja, the the omithischian dinosaurs, particularly stegosaurs and ankylosaurs, staff of the Institute for Conservationof Tropical Environments, the villagers of Berintra, and all expedition members for assistance with Beld work V. Heisq. and which are also generally regarded as herbivore~~~,~~.there are no J. Still, Holstein for assistance with specimen preparation; B. Demes, C Forster, N. Rybcrynski modem crocodylian analogues with which to compare the potential and S. Zehr for discussion; and the NSF for funding. function of Simosuchus' unique skull and dentition, and the suggestion of an herbivorous diet is speculatively based on dental Correspondence and requests for materials should be addressed to G.AB. comparisons with non-crocodylian reptiles. Given the cranial and dental specializations as well as the small size of the adult Sitnosuchirs, it can be assumed that Simosuchus did not bring down large prey. It is still plausible, however, that the diet may have consisted of arthropods, other invertebrates and potentially ................................................................. small vertebrates such äs frogs. Similarities with ankylosaurid dinosaurs are not limited to dentition. Other features of Simusuchus appear to be convergent Diversity and endemism of the with those of ankylosaurs, such as the broad compact body, extensive dorsal and ventral shielding, bony protettion of the benthic seamount fauna skull above the supratemporal fenestrae .and orbits, and a deep the southwest Pacific cranium with a broad, short snout. A crocodyliform convergent in upon an omithischian dinosaur is intriguing in lightof the apparent Bertrand Richer de Forges+t,J. Anthony KoslowSg & G. C. B. Poo& absence of the latter from the Late Cretaceous of Madagascar. 0 .. *Centre IRD de Noumea, BPA5, 98848, Noumea Cedex, New Caledonia .I Received 8 February;accepted 13 April 2000. $ CSIRO Marine Research, GPO Box 1538, Hobart, Tnsmania 7001, Atrsfralia Victoria, 1. , Langston,W. inBiologyo~tlreRrptiliaVol.4(edsGans.C. &Panons,'T. S.) 263-284 (Academic, New §Museum of 71 Victoria Crescent, Abbotgord, Victoria 3067, Australia York. 1973). t These authors contributed equally to this work 2. Ruxoni,C Sobrereptilescreticcos del Uruyay (Urugriaysuclt~~na',~,n. g. n. sp.) ysus relaciones .............................................................................................................................................. con los notossúquidor de Patagonia. Bol Inst. Geolog. PeTf: Umg~uy19,3-64 (1932). 3. ~ Knuse.D. W.~t~l.TheLatcCretaceousvertebrarehunaofMadagas~:implicationsforGondwan~ Seamounts comprise a unique deep-sea environment, character- paleobiogeography. GSA Today 9,l-7 (1999). ized by substantially enhanced currents and a,fauna that is 4. Brochu,C. A. Closureofneurocentnlsuturesduringcmwdilianontogeny:implications formpity dominated by suspension feeders, such as corals'-? The potential assessment fossil archossurs. J. Vértebr.Paleonto% 16.49-62 (1996). J. 5. Pol, D. Basal mesoeucrocodylianrelationships: new dues to old conflicts. Víebr. Paleonîol. 19 importance of these steep-sided undersea mountains, which are (suppl. 3). 69A (1999). generally of volcanic origin, to ocean biogeography and diversity J. 6. Bonaparte. F. Losvertebrados fosiles de la formacion Rio Colorado, de la ciudad de Neuquen y was recognized over 40 years ago', but this environment has Cercanias, Cretacico Superior, Argentina. Rev. Mus. Argcnr. Cienc. Nat. 4.16-123 (1991). J. remained very poorly explored. A revie$ of seamount biota 7. Clark, M.. Jacobs,L. L.. &Dorms, W. R Mammal-likedentition in a Mesozoic uocndylian. Science 244. 1064-1066 (1989). @ and biogeography reported a total of 597 invertebrate species 8. Gomani.E. M.AcrocodyIiformfrom theEarly Cretaceous dinosaurbeds, northernMalaw¡.l Vertebr. recorded from seamounts worldwide since the CharZengm expedi- PaleontoL 17,280-294 (1997). tion of Most reports, based on a single taxonomic group, 9. 1872. Medem, F. Osteología aaneal, distribución geográfica y ecologia de MeInriosuchlisniser (Spix) were extremely limited: 5 seamounts of the estimated more than (Crocodylia, Alligatoridae). Rw. Amd Colomb. Cieirc Emd W y Nat lt.5-19 (1963). J. 10. Balouet, C. & Buffetaut, E. Mekosucltis inexpenanrs, n.g., usp., aocodilien nouveaude I'Holocene 30,000 seamountsin the world's oceans4"accounted for 72% of the de Nouvelle Calédonie. C R. Acad. Sci. 304,853-856 (1987). species recorded. Only 15% of the species occurring on seamounts 11. W~llis,P. M. A New crocodilians fmm the Late Oligocene White Hunter Site, Riversleigh; north- were considered potential seamount endemics. Here we report the western Queensland. Me~nQld Mus. 41,423-438 (1997). discovery of more than macro- and megafaunal species from 12. Cawalho, I. S. &Campos, D. A Um mamífero triconodonte do Cretáceo Inferior do Madào, 850 BmiL An. Arad Bru. Cienc 60,437-446 (1988). seamounts in the Tasman Sea and southeast Coral Sea, of which 13. Canalho. L S. Candidodon:um crocodilo com heterodontia(Notosuchia, CretáceoInferior - Brasil). 29-3496 are new to science and potential seamount endemics. An. Amd Bras. Cienc. 6633'1-345 (1994). Low species overlap between seamounts in different portions of 14. Wu, X -C., Sues, H. -D.&Sun, A. A plant-eating crocodyliformreptile from the Cretaceousof Cllink Nanrre 376.678480 (1995). the region indicates that the seamounts in clusters or along ridge J. 15. Benf0n.M. I. &Clark, M. in ThePhylo*~yandCInsrificntion ofthe TetrapodsVol. 1 (ed. Bcuton,M. systems function as 'island groups' or 'chains,' leading to highly J.) 295-338 (Clarendon, Oxford. 1988). localized species distributions and apparent speciation between 16. Krause, D. W., Prad G. V. R., Koenigwald,W. von, SAN, A & Grine. E E. Cosmopolitanism groups or ridge systems that is exceptional for the deep sea. These among Gondiv&n Late Creraceous m3mmals. Nnture 390,504-507 (1997). S. this 17. Sampron. D. et aL Predatory dinosaur remains fromMada&car: implications for the Cretaceous results have substantial implications for the conservation of biogeobphy of Gondwana. Science 280,1048-1051 (1998). fauna, which is threatened by fishing activity'. C. 18. Buckley, 6. A., Brochu. A. &Krause, D. WIHy&rdiversityand the paleobiogeographicorigins of Whereas previous studies of the seamount fauna have often the iate Cretaceous crocodyliforms 0fMadagascar.J. Vertebr.PakontoL 17 (suppl. (1997). 3). 35A focused on particular taxa, the present study sought to describe 19. Iordansky, N. N. in Biology ofthe Reptilia Vol. 4 (eds Gans, C &Parsons, T. S.) 201-262 (Academic, New York, 1973). the benthic community as a whole and enlisted broad taxonomic (J. 20. Gans, C Biomechanics:An Approach to Vkiebmte Biology B. Lippinmtt, Philadelphia. 1974). support (see Acknowledgements). In all, 516 species of fish and The J. 21. Wake, M.H. in SLuIl VOL 3 (edsHanken, & Hau, B. IC) 197-240 (University of Chicago, macro-invertebrates were obtained from 6 seamounts along the Chicago, 1993). 22. Schumacher,G.-H.inBiolog)'oftheReprilinVol.4(edsGans, C. &Parsons,T.S.)101-199 (Academic, Norfolk Ridge, 108 from 4 seamounts on the Lord Howe Rise, and NewYÖrk. 1973). 297 from 14 seamounts south of Tasmania (Table 1, Fig. 1).Thirty- 23. Hott0n.N. III Asurveyofadaptive relationships ofdentition to diet in theNorth AmeriunIguanidae. six per cent of species from the Norfolk Ridge seamounts were new Am. Mid. Nat 53,138-114 (1955). to science and not known from sampling of the open seafloor and 24. Suffi,H.-D. &Reisz, R. R Origins and earlyevolutionof herbivory in tetrapods. TrendsEcoLEVO% 13, 141-145 (1998). are therefore potential endemic species, along with 31% of species 25. Galton, P. M. in The Dinosauria (eds Weisbampel, D. B., Dodson, P. & Osmóska, H.) 456-483 (Unk from the Lord Howe seamounts and between 16 and 33% from the California. Berkeley, 1990). Tasmanian seamounts. 26. Coombs, W. P. &Maryanska, T. in The Dinosauria (cds Weisbampel, D. B., Dodson, P. & Osmólska. H.) 456-483 (Univ. California, Berkeley, 1990). - Over the range of sampling carried out on Norfolk and Lord 27. Swofford, D. L. PAW': PhyfogeneticAnalysirUn'ngParsimony (*and Other Methods], Version 4.0bZa. Howe Ridges, we found a linear relationship between number of (SinauerAssociates. Sunderland, Massachusetts, 1999). species recorded from each seamount and the number of samples íñ6~käiion-is-äSdäEdë obtained there (Fig. 2). This relationship implies that the greater SuippE,mGtäG on'N&ë's WÕrlp I.M;ide Web site (http://www.nature.com) or as paper copy from the London editorial office of Nature. number of species obtained from seamounts on Norfolk Ridge is -- I22 NATURE IVOL 405 JUNE 2000 I www.nature.com - .-. g44 l~l~lll~~~~~l~~~~ll' 0 10022029 letters to nature 150"E 165'E 180" 300 15"s 15"s A 250 200 150 30"s 30"s O0 1 BR LordHowe X Total Lord Howe 50 O 45"s 45% I 50 1 O0 Number of samples 150"E I65"E 180" of Figure 2 Relationship between the number species recorded at each seamount site of Figure 1Location'of seamount sampling sites (triangles)and topographic and and the number samples obtained from that site. oceanographic features mentioned in the text. Depths are given in fathoms (1 fathom = 1.83 m). owing to greater sampling effort there rather than greater species seamounts in that region (C = O). Thus there are significant
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  • Australian Natural HISTORY Lord Howe Island Is One of the Most Interesting and Beautiful Islands in the World
    AUSTRAliAN NATURAl HISTORY lord Howe Island is one of the most interesting and beautiful islands in the world. Its beauty is legendary. Recent visitors from the cruise ship, M.S. Lindblad Explorer. a well-travelled naturalist group seeking out-of­ the-way places. considered it perhaps the most beautiful island they had ever seen. The high. tree-covered hills to the north; the narrow. low cen­ tral portion (with which man has dealt most kindly); the turquoise lagoon bordered by breakers and a long. curving arch of beach; and the huge majesty of Mount Lidgbird and Mount Gower thrusting their peaks up from the Pacific to dominate the scene with white bosun birds etched against their dark basalt cliffs-a remarkable land- and seascape. The island is biologically interesting because it has rich and varied flora and fauna with an unusually high proportion of species found nowhere else. Its lovely lagoon has a flourishing coral reef - probably the southern­ most in the world. and there are many species of fish. coral. and other animals which have evolved in the area because of its relative isolation from the great coral reefs in the tropics to the north. Yet this unspoilt island with its rich natural values is not thousands of miles from anywhere- it is four hours by seaplane from Sydney, Australia's largest city. This special issue gathers together some of the interesting natural history of Lord Howe Island. By the time it appears. Lord Howe will have an airstrip, which is being built as I write. There is no doubt that it will be visually damaging.
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