Fossil middle triassic “sea cows” – placodont reptiles as macroalgae feeders along the north-western Tethys coastline with Pangaea and in the Germanic basin
Cajus G. Diedrich
DOI: 10.4236/ns.2011.31002   PDF    HTML     7,693 Downloads   16,345 Views   Citations


The descriptions of fossil Triassic marine pla- codonts as durophagous reptiles are revised through comparisons with the sirenia and basal proboscidean mammal and palaeoenvironment analyses. The jaws of placodonts are conver- gent with those of Halitherium/Dugong or Mo- eritherium in their general function. Whereas Halitherium possessed a horny oral pad and counterpart and a special rasp-like tongue to grind seagrass, as does the modern Dugong, placodonts had large teeth that covered their jaws to form a similar grinding pad. The sirenia also lost their anterior teeth during many Millions of years and built a horny pad instead and specialized tongue to fed mainly on seagrass, whereas placodonts had only macroalgae availa- ble. Indirect evidence for Triassic macroalgae is provided by benthic palaeocommunities from different layers and extended European regions in the Germanic Basin. Studies of tooth wear stages for Placodus indicate that anterior teeth may have been used in a similar manner to the procumbent front teeth of modern Dugong. Paraplacodus and Placodus seem to have used these teeth as spatulas to dig out seaplants. Cyamodus and other placodonts such as Placochelys had smaller or reduced anterior teeth. The scarcity of highly worn palatine or maxillary and lower jaw dentary Placodus or Cyamodus teeth (less then 0.5%) suggests that they had a relatively soft diet. The seaplants would only have been squeezed in a similar feeding strategy to that of modern Dugong feeding on seagrass without jaw rotation and grinding. The phylogenetic trend in tooth reduction within the placodonts Paraplacodus, Placodus, especially in Cyamodus but also Placochelys, and Henodus within 11 My appears to have been a result of this plant-feeding adaptation and may even explain the origin or at least close relationship of the earliest Upper Triassic turtles as toothless algae and jellyfish feeders, in terms of the long-term convergent development with the sirens.

Share and Cite:

Diedrich, C. (2011) Fossil middle triassic “sea cows” – placodont reptiles as macroalgae feeders along the north-western Tethys coastline with Pangaea and in the Germanic basin. Natural Science, 3, 9-27. doi: 10.4236/ns.2011.31002.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Diedrich, C. (2009b) The vertebrates of the Anisian/ Ladinian boundary (Middle Triassic) from Bissendorf (NW Germany) and their contribution to the anatomy, palaeoecology, and palaeobiogeography of the Germanic Basin reptiles. Palaeogeography Palaeoclimatology Palaeoecology, 273, 1-16. doi:10.1016/j.palaeo.2008.10.026
[2] Jaeckel, O. (1907) Placochelys placodonta aus der Obertrias des Bakony. Resultate der wissenschaftlichen Erforschung des Balaton, 1, 1-90.
[3] Rieppel, O. (2000) Sauropterygia I. Placodontia, Pachy- pleurosauria, Nothosauroidea, Pistosauroidea. Handbuch der Pal?oherpetologie, Teil 12A. München, Friedrich Pfeil.
[4] Oosterink, H.W., Berkelder, W., Jong, C., de Lankamp, J. and Winkelhorst, H. (2003) Sauriens uit de Onder- Muschelkalk van Winterswijk. Staringia, 11, 1-145.
[5] Kuhn-Schnyder, E. (1960) über Placodontier. Pal?ontologische Zeitschrift, 34, 91-102.
[6] Peyer, B. (1931a) Die Triasfauna der Tessiner Kalkaplen, III: Placodontia. Abhandlungen der Schweizerischen Pal?ontologischen Gesellschaft, 51, 1-25.
[7] Peyer, B. (1931b) Paraplacodus broilii nov. gen. nov. spec., ein neuer Placodontier aus der Tessiner Trias. Verhandlungen der Schweizerischen Naturforschenden Gesellschaft, 109, 1-219.
[8] Chun, L., Wu X.-C., Rieppel, O., Wang, L.T. and Zhao, L.Z. (2008) An ancestral turtle from the Late Triassic of southwestern China. Nature, 456, 497-501. doi:10.1038/nature07533
[9] Münster, G.G. (1830) über einige ausgezeichnete fossile Fischz?hne aus dem Muschelkalk bei Bayreuth: Bayreuth, Birner.
[10] Agassiz, L. (1833-1843) Recherches sur les Poissons fossiles: Neuchatel et Soleure.
[11] Wei?, G.W. (1937) Bayreuth als St?tte alter erdgeschichtlicher Entdeckungen: Bayreuth. Gauverlag Bayerische Ostmark GmbH.
[12] Owen, R., 1858, Description of the skull and teeth of the Placodus laticeps Owen with indications of other new species of Placodus and evidence of the saurian nature of that genus. Philosophical Transactions of the Royal Society London, 148, 169-182. doi:10.1098/rstl.1858.0009
[13] Diedrich, C. 2011. Palaeoenvironment, stratigraphy, facies and biodiversity of the marine reptile-rich Middle Triassic carbonates of the famous Bayreuth localities (Germany) in the Germanic Basin of Europe. (in review).
[14] Braun, C.W.F. (1862) über Placodus gigas Agassiz und Placodus andriani Münster. Programm zum Jahresbericht der k?niglichen Kreis-Landwirtschafts- und Gewerb eschule zu Bayreuth für das Schuljahr 1861/62. Bayreuth,Theodor Burger.
[15] Braun, C.W.F. (1863) über Placodus quinimolaris. Programm zum Jahresbericht der k?niglichen Kreis- Landwirtschafts- und Gewerbeschule zu Bayreuth für das Schuljahr 1862/63. Bayreuth,Theodor Burger.
[16] Meyer, H. von (1863b) Placodus andriani aus dem Muschelkalk der Gegend von Braunschweig. Palaeonto- graphica, 10, 57-61.
[17] Meyer, H. von (1847-1855) Zur Fauna der Vorwelt. 2 Abt. Die Saurier des Muschelkalkes mit Rücksicht auf die Saurier aus Buntem Sandstein und Keuper..Frankfurt a. Main.
[18] Meyer, H. von (1863a) Die Placodonten, eine Familie von Sauriern der Trias. Palaeontographica, 11, 175-291.
[19] Broili, F. (1912) Zur Osteologie des Sch?dels von Placodus. Palaeontographica, 59, 147-155
[20] Drevermann, F. (1924) Sch?del und Unterkiefer von Cyamodus. Abhandlungen der senckenbergischen naturforschenden Gesellschaft, 38, 291-309.
[21] Drevermann, F. (1933) Das Skelett von Placodus gigas Agassiz. Abhandlungen der senckenbergischen naturforschenden Gesellschaft, 38, 321-364.
[22] Huene, F. von (1933) Zur Lebensweise und Verwandts- chaft von Placodus. Abhandlungen der senckenbergis- chen naturforschenden Gesellschaft, 38, 367-382.
[23] Diedrich, C. (2010a) Palaeoecology of Placodus gigas (Reptilia) and other placodonts - Middle Triassic macroalgae feeders in the Germanic Basin of central Europe - and evidence for convergent evolution with Sirenia. Palaeogeography Palaeoclimatology Palaeoecology, 285, 287-306.
[24] Nosotti, S. and Pinna, G. (1996) Osteology of the skull of Cyamodus kuhnschnyderi n. sp., novelle espèce de Cyamodontidae (Reptilia, Placodontia) du Muschelkalk supérieur allemande. Comptes Rendues de l’Academie de Sciences Paris, 317, 847-850.
[25] Rieppel, O. and Hagdorn, H. (1999) A skull of Cyamodus kuhnschnyderi Nosotti & Pinna 1993, from the Muschelkalk of wasselonne (Alsace, France). Pal?ontologische Zeitschrift, 73, 377-383.
[26] Kuhn, O. (1969) Subclass Placodontomorpha Kuhn 1968. Handbuch Palaeoherpetologie, 9, 7-18.
[27] Suess, H.D. (1987) On the skull of Placodus and the relationships of the Placodontia. Journal of Vertebrate Paleontology, 7, 138-144.
[28] Rieppel, O. (1995) The Genus Placodus: Systematics, Morphology, Paleobiogeography, and Paleobiology. Fieldiana Geology NS, 31, 1-44.
[29] Westphal, F. (1988) Pflasterzahnsaurier (Placodonten) aus dem süddeutschen Muschelkalk (Mitteltrias). In: Hagdorn, H. (ed.), Neue Forschungen zur Erdgeschichte von Crailsheim. Muschelkalk. Sch?ntaler Symposium. Goldschneck-Verlag, Stuttgart, 151-165.
[30] Rieppel, O. and Zanon, R.T. (1997) The interrelation- ships of placodontia. Historical Biology, 12, 211-227.
[31] Diedrich, C. and Trostheide, F. (2007) Auf den Spuren der terresten Muschelkalksaurier und aquatischen Sauropterygier vom obersten R?t bis zum Mittleren Muschelkalk (Unter-/Mitteltrias) von Sachsen-Anhalt. Abhandlungen und Berichte zur Naturkunde Magdeburg, 30, 5-56.
[32] Diedrich, C. (2009a) Palaeogeographic evolution of the marine Middle Triassic marine Germanic Basin changements – with emphasis on the carbonate tidal flat and shallow marine habitats of reptiles in Central Pangaea. Global and Planetary Change, 65(2009), 27-55.
[33] Diedrich, C. (2008a) Millions of reptile tracks - Early to Middle Triassic carbonate tidal flat migration bridges of Central Europe. Palaeogeography, Palaeoclimatology, Palaeoecology, 259, 410-423.
[34] Diedrich, C. (2008b) The food of the miosiren Anomotherium langenwieschei (Siegfried) - indirect proof of seaweed or seagrass by xenomorphic oyster fixation structures in the Upper Oligocene (Neogene) of the Doberg, Bünde (NW Germany) and comparisons to modern Dugong dugon (Müller) feeding strategies. Senckenbergiana maritima, 38, 59-73.
[35] Thenius, E. (1979) Die Evolution der S?ugetiere. Stuttgart-New York, Gustav Fischer Verlag.
[36] Marsch, H. and Eisentraut, M. (1984) Die Gaumenfalten des Dugong. Zeitschrift für S?ugetierkunde, 49, 314-315.
[37] Lanyon, J.M. and Sanson, G.D. (2006a) Degenerate dentition of the dugong (Dugong dugon), or why a grazer does not need teeth: morphology, occlusion and wear of mouthparts. Journal of Zoology, 268, 133-152. doi:10.1111/j.1469-7998.2005.00004.x
[38] Lanyon, J.M. and Sanson, G.D. (2006b) Mechanical disruption of seagrass in the digestive tract of the dugong. Journal of Zoology, 270, 277-289.
[39] Domning, D.P. (1978) Sirenian evolution in the North Pacific Ocean. University of California. Geological Sciences, 118, 1-176.
[40] Fürsich, F.T. (1981) Die Palaeonucula strigilata/Den- talium undulatum-Faunengemeinschaft in Weichb?den der mittleren alpinen Trias. In: McKerrow, W.S. (ed.), Pal?o?kologie: Stuttgart, Franckh, 138-139.
[41] Hagdorn, H. (2004) Muschelkalkmuseum Ingelfingen. Edition Lattner.
[42] Furrer, H. (1993) Stratigraphie und Fazies der Trias/Jura-Grenzschichten in den Oberostalpinen Decken Graubündens. Dissertation University Zürich.
[43] Yiang, D.-J., Motani, R., Hao, W.-C., Rieppel, O., Sun, Y.-L., Schmitz, L. and Sun, Z.-Y. (2008) First Record of Placodontoidea (Reptilia, Sauropterygia, Placodontia) from the Eastern Tethys. Journal of Vertebrate Paleontology, 28, 904-908. doi:10.1671/0272-4634(2008)28[904:FROPRS]2.0.CO;2
[44] Domning, D.P. (2001) Sirenians, seagrasses, and Cenozoic ecological change in the Caribbean. Palaeogeography Palaeoclimatology Palaeoecology, 166, 27-50. doi:10.1016/S0031-0182(00)00200-5
[45] Aysel, V., Erdugan, H. and Okudan, E.?. (2006) Marine Algae and Seagrasses of Hatay (Mediterranean, Turkey). Journal of the Black Sea Meditteranean Environment, 12, 159-179.
[46] Domning, D.P. and Beatty, B.L. (2007) Use of Tusks in Feeding by Dugongid Sirenians: Observations and Tests of Hypotheses. Anatomic Record, 290, 523-538. doi:10.1002/ar.20540
[47] Erftemeijer, P.L.A., Djunarlin, M. and Mok, W. (1993) Stomach content analysis of a Dugong (Dugong dugon) from South Sulawesi, Indonesia. Australian Journal of Marine and Freshwater Research, 44, 229-233.
[48] Gohar, H.A.F. (1957) The Red Sea dugong. Marine Biological Station Al-Ghardaqa Red Sea, 9, 3-49.
[49] Reynolds, J.E. and Odell, D.K. (1991) Manatees and Dugongs. New York.
[50] Marsch, H. (2002) Dugong-Status Report and Action Plans for Countries and Territories. Nairobi: United Nations Evironment Programme, DEWA, RS.02.
[51] Ripple, J. (2002) Manatees and Dugongs of the World: Hong-Kong, Voyageur Press.
[52] Schubert-Klempnauer, H. (1975) Macroplacus raeticus n.g., n. sp. ein neuer Placodontier aus dem R?t der Bayrerischen Alpen. Mitteilungen der Bayrischen Staatssammlung für Pal?ontologie und Historische Geologie, 15, 33-55.
[53] Kozur, H.W. and Bachmann, G.H. (2008) Updated correlation of the Germanic Triassic with the Tethyan scale and assigned numeric ages. Berichte der Geologischen Bundesanstalt Wien, 76, 53-58.
[54] Gingerich, P.D., Domning, D.P., Blane, C.E. and Uhen, M.D. (1994) Cranial morphology of Protosiren fraasi (Mammalia, Sirenia) from the middle Eocene of Egypt: a new study using computed tomography. Contributions from the Museum of Paleontology, University of Michigan, 29, 41-67.
[55] Huene, F. von (1936). Henodus chelydrops, ein neuer Placodontier. Palaeontographica A, 84, 99-147.
[56] Reif, W. (1942) Erg?nzungen zum Panzerbau von Henodus chelydrops v. Huene. Palaeontographica A, 94, 31-42.
[57] Chun, L. and Rieppel, O. (2002) A new cyamodontoid placodont from Triassic of Guizhou, China. China Science Bulletin, 47(5), 403-407. doi:10.1360/02tb9094
[58] Buffeteaut, E. and Novak, M.A. (2008) Cyamodontid placodont (Reptilia: Sauropterygia) from the Triassic of Slovenia. Palaeontology, 51, 1301-1306. doi:10.1111/j.1475-4983.2008.00819.x
[59] Gaffney, E.S. (1990) The comparative osteology of the Triassic turtle Proganochelys. Bulletin of the American Museum of Natural History, 194, 1-263.
[60] Reisz, R.R., Jason, J. and Head, J.J. (2008) Palaeontology: Turtle origins out to sea. Nature, 456, 450-451. doi:10.1038/456450a
[61] Scheyer, T.M. (2008) Aging the oldest turtles: the placodont affinities of Priscochelys hegnabrunnensis. Naturwissenschaften, 95, 803. doi:10.1007/s00114-008-0386-8
[62] Aigner, T. and Bachmann, G.H. (1991) Sequence Stratigraphy of the German Muschelkalk. In: Hagdorn H, Seilacher, A. (eds). Muschelkalk, Sch?ntaler Symposium. Goldschneck-Verlag, Stuttgart, 15-18.
[63] Haas, J. and Budai T. (1999) Triassic sequence stratigraphy of the Transdanubian range. Geologica Carpathica, 50, 459-475. doi:10.1556/AGeol.45.2002.1.3
[64] Nagy, Z.R. and Csillag, G. (2002) Correlation of Upper Julian to Lower Tuvalian (Carnian) depositional cycles from the Balatonhenye. Barnag area, Balaton Highland, Hungary. Acta Geologica Hungaria, 45, 45-62.

Copyright © 2024 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.