Salt glands in the Jurassic metriorhynchid Geosaurus: implications for the evolution of osmoregulation in Mesozoic marine crocodyliforms (original) (raw)
Abstract
The presence of salt-excreting glands in extinct marine sauropsids has been long suspected based on skull morphology. Previously, we described for the first time the natural casts of salt-excreting glands in the head of the Jurassic metriorhynchid crocodyliform Geosaurus araucanensis from the Tithonian of the Vaca Muerta Formation in the Neuquén Basin (Argentina). In the present study, salt-excreting glands are identified in three new individuals (adult, a sub-adult and a juvenile) referable to the same species. New material provides significant information on the salt glands form and function and permit integration of evolutionary scenarios proposed on a physiological basis in extant taxa with evidence from the fossil record. G. araucanensis represents an advanced stage of the basic physiological model to marine adaptations in reptiles. G. araucanensis salt glands were hypertrophied. On this basis, it can be hypothesized that these glands had a high excretory capability. This stage implies that G. araucanensis (like extant pelagic reptiles, e.g. cheloniids) could have maintained constant plasma osmolality even when seawater or osmoconforming prey were ingested. A gradual model of marine adaptation in crocodyliforms based on physiology (freshwater to coastal/estuarine to estuarine /marine to pelagic life) is congruent with the phylogeny of crocodyliforms based on skeletal morphology. The fossil record suggests that the stage of marine pelagic adaptation was achieved by the Early Middle Jurassic. Salt gland size in the juvenile suggests that juveniles were, like adults, pelagic.
Access this article
Subscribe and save
- Get 10 units per month
- Download Article/Chapter or eBook
- 1 Unit = 1 Article or 1 Chapter
- Cancel anytime Subscribe now
Buy Now
Price excludes VAT (USA)
Tax calculation will be finalised during checkout.
Instant access to the full article PDF.
References
- Dunson WA (1976) Salt glands in reptiles. In: Gans C (ed) Biology of the reptilia, vol 5. Academic, London, pp 413–445
- Dunson WA, Mazzotti FJ (1989) Salinity as a limiting factor in the distribution of reptiles in Florida bay: a theory for the estuarine origin of marine snakes and turtles. Bull Mar Sci 44:229–244
Google Scholar - Fernández M, Gasparini Z (2000) Salt glands in a Tithonian metriorhynchid crocodyliform and their physiological significance. Lethaia 33:269–276
Article Google Scholar - Gandola R, Buffetaut E, Monaghan N, Dyke G (2006) Salt glands in the fossil Crocodile Metriorhynchus. J Vertebr Paleontol 26:1009–1010
Article Google Scholar - Gasparini Z, Dellapé D (1976) Un nuevo cocodrilo marino (Thalattosuchia, Metriorhynchidae) de la Formación Vaca Muerta (Jurásico, Tithoniano) de la provincia del Neuquén. Act I Congr Geol Chileno Santiago 1:C1–C21
Google Scholar - Gasparini Z, Spalletti L, Fernández M, de la Fuente M (1999) Tithonian marine reptiles from the Neuquén basin: diversity and paleoenvironments. Revue Paléobiol 18:335–345
Google Scholar - Gasparini Z, Pol D, Spalletti L (2006) An unusual marine Crocodyliform from the Jurassic–Cretaceous boundary of Patagonia. Science 311:70–73
Article PubMed CAS Google Scholar - Jackson K, Butler DG, Brooks DR (1996) Habitat and phylogeny influence salinity discrimination in crocodilians: implications for osmoregulatory physiology and historical biogeography. Biol J Linn Soc 58:371–383
Article Google Scholar - Hazard LC (2001) Ion secretion by salt glands of Desert Iguanas (Dipsosaurus dorsalis). Phys Biochem Zool 74:22–31
Article CAS Google Scholar - Hazard LC (2004) Sodium and potassium secretion by iguana salt glands: acclimation or adaptation? In: Alberts A, Carter RL, Hayes WB, Martins E (eds) Iguanas: biology and conservation. University of California Press, California, pp 84–93
- Hirayama R (1998) Oldest known sea turtle. Nature 92:705–708
Article CAS Google Scholar - Hopson JA (1979) Paleoneurology. In: Gans C, Northcutt RG, Ulinski P (eds) Biology of the Reptilia, vol 9. Academic, London, pp 39–146
- Hua S, de Buffrenil V (1996) Bone histology as a clue in the interpretation of functional adaptations in the Thalattosuchia (Reptilia, Crocodylia). J Vertebr Paleontol 16:703–717
Article Google Scholar - Marples BJ (1932) The structure and development of the nasal glands of birds. Proc Zool Soc Lond 2:829–844
Google Scholar - Mazzotti FJ, Dunson WA (1989) Osmoregulation in Crocodilians. Am Zool 29:903–920
Google Scholar - Peaker M, Linzell JL (1975) Salt glands in birds and reptiles. Cambridge University Press, London
Google Scholar - Schmidt-Nielsen K, Fange R (1958) Salt glands in marine reptiles. Nature 4638:783–785
Article Google Scholar - Staaland H (1967) Anatomical and physiological adaptations of the nasal glands of Charadriiformes birds. Comp Biochem Phys 23:933–944
Article CAS Google Scholar - Tapplin LE, Griggs GC (1981) Salt glands in the tongue of the Estuarine Crocodile, Crocodylus porosus. Science 212:1045–1047
Article Google Scholar - Witmer LM (1995a) The extant phylogenetic bracket and the importance of reconstructing soft tissue in fossils. In: Thomason J (ed) Functional morphology in vertebrate paleontology. Cambridge University Press, Cambridge, pp 19–33
Google Scholar - Witmer LM (1995b) Homology of facial structures in extant archosaurs (birds and crocodilians), with special reference to paranasal pneumaticity and nasal conchae. J Morphol 225:269–327
Article Google Scholar - Witmer LM (1997) The evolution of the antorbital cavity of Archosaurs: a study in soft- tissue reconstruction in the fossil record with an analysis of function of pneumaticity. Soc Vertebr Paleontol Mem 3:1–73
Google Scholar
Acknowledgements
We thank L. Witmer for suggestions on an early draft. The paper benefited from comments by D. Pol, C. McHenry and an anonymous reviewer. Financial support received from Agencia Nacional de Promociones Científicas y Tecnológicas de Argentina (PICT 25276), Consejo Nacional de Investigaciones Científicas y Tecnológicas de Argentina (PIP 5156/4) and Universidad Nacional de La Plata (N 463) is gratefully acknowledged.
Author information
Authors and Affiliations
- Departamento Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, 1900, La Plata, Argentina
Marta Fernández & Zulma Gasparini
Authors
- Marta Fernández
You can also search for this author inPubMed Google Scholar - Zulma Gasparini
You can also search for this author inPubMed Google Scholar
Corresponding author
Correspondence toMarta Fernández.
Additional information
Communicated by G. Mayr
Rights and permissions
About this article
Cite this article
Fernández, M., Gasparini, Z. Salt glands in the Jurassic metriorhynchid Geosaurus: implications for the evolution of osmoregulation in Mesozoic marine crocodyliforms.Naturwissenschaften 95, 79–84 (2008). https://doi.org/10.1007/s00114-007-0296-1
- Received: 30 April 2007
- Revised: 28 June 2007
- Accepted: 07 July 2007
- Published: 22 August 2007
- Issue Date: January 2008
- DOI: https://doi.org/10.1007/s00114-007-0296-1