Cricosaurus

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Cricosaurus
Skull of Cricosaurus suevicus in the State Museum for Natural History Stuttgart.

Skull of Cricosaurus suevicus in the State Museum for Natural History Stuttgart .

Temporal occurrence
Upper Jurassic to Lower Cretaceous
160 to 136 million years
Locations
Systematics
Crocodylomorpha
Mesoeucrocodylia
Thalattosuchia
Metriorhynchidae
Metriorhynchinae
Cricosaurus
Scientific name
Cricosaurus
Wagner , 1858

Cricosaurus is an extinct genus of marine crocodile relatives fromthe Metriorhynchidae family . The genus was described in 1858 by Johann Andreas Wagner on the basis of three skull finds from the Tithonian ( Upper Jurassic ) of Germany. The name Cricosaurus means "ring lizard" and is derived from ancient Greek .

Fossil specimens of Cricosaurus have come down to us from the Upper Jurassic of England , France , Switzerland and Germany . There are also remains in Argentina , in Mexico . and in Cuba .

Discovery history and classification

Historical reconstruction of C. suevicus by Williston , 1914

Cricosaurus was reclassified by Wagner in 1858 after describing another specimen in 1852.

Since then a number of other species have been named, including C. suevicus by Fraas in 1901, which was previously assigned to Geosaurus . A species originally described by Wagner in 1858, C. medius , was later reclassified as a junior synonym of Rhacheosaurus gracilis .

The original three skulls, which were all assigned to different species, were only insufficiently known, so that the genus was regarded in the past by various paleontologists as a junior synonym of Metriorhynchus , Geosaurus or Dakosaurus . Several phylogenetic analyzes could not confirm the monophyly of the genus Cricosaurus . However, a more comprehensive study was in 2009 show that the species of the genus described Cricosaurus were valid and in addition, some species with long snouts, previously as the genera Geosaurus , Enaliosuchus and Metriorhynchus , in reality, had been classified as belonging in more detail with the type species of Cricosaurus related were. These species were therefore assigned to the genus Cricosaurus .

A total of nine valid species have been described:

  • C. bambergensis (Sachs et al. 2019)
  • C. elegans (Wagner, 1852) ( type species )
  • C. gracilis (Philips, 1871)
  • C. macrospondylus (Koken, 1883)
  • C. suevicus (Fraas, 1901)
  • C. schroederi (Kuhn, 1936)
  • C. araucanensis (Gasparini & Dellapé, 1976)
  • C. vignaudi (Frey et al. , 2002)
  • C. saltillense (Buchy et al. , 2006)

Enaliosuchus is a synonym of Cricosaurus macrospondylus .

Cladogram according to Cau & Fanti (2010).

 Cricosaurus  

C. sp.


   

C. suevicus


   

C. saltillense


   

C. elegans


   

C. vignaudi


   

C. gracilis


   

C. araucanensis


   

C. schroederi


   

C. macrospondylus




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Paleobiology

Artist's impression of C. suevicus

All currently known species were three meters or less in length. Compared to recent crocodiles , Cricosaurus reached small to medium sizes. The animal's body was streamlined, and it also had a tail fin, making it a more efficient swimmer than modern crocodiles.

Salt glands

Recent studies of the fossil specimens of Cricosaurus araucanensis have shown that both juveniles and adults had well-developed salt glands. This means that the animals got along without fresh water from birth . Adult specimens of Metriorhynchus also had well-developed salt glands.

Niche division

Cricosaurus macrospondylus

Several species of the Metriorhynchidae are known from the Mörnsheim formation ( Solnhofen limestone , early Tithonium) in Bavaria: Dakosaurus maximus , Geosaurus giganteus , Cricosaurus suevicus and Rhacheosaurus gracilis . The thesis has been put forward that nesting enabled several species of crocodile relatives to coexist in the same habitat. The top predators of this formation seem to have been Dakosaurus and G. giganteus , which were very large and had a short mouth with serrated teeth. The various Cricosaurus species with their long mouths probably mainly fed on fish, although the lightly built Rhacheosaurus may have specialized in small prey. In addition to these four types of Metriorhynchiden, a medium-sized type of Teleosaurid Steneosaurus existed at the same time.

Both C. suevicus and Dakosaurus maximus are known from the somewhat older Nusplinger Plattenkalk (upper Kimmeridgian ) in southern Germany . As in the Solnhofen limestone, C. suevicus fed on fish, while Dakosaurus maximus was at the top of the food chain.

proof

  1. ↑ a b Andreas Wagner : On the knowledge of the dinosaurs from the lithographic slate. In: Treatises of the Mathematical-Physical Class of the Royal Bavarian Academy of Sciences. Vol. 8, Department 2, 1858, ISSN  0176-7038 , pp. 415-528, digitized .
  2. ↑ a b Rodney Steel: Crocodylia (= Handbook of Paleoherpetology. Vol. 16). Pfeil et al., Munich et al. 1973, ISBN 3-437-30141-1 .
  3. ↑ Zulma Brandoni de Gasparini, Daniel Dellapé: Un nuevo cocodrilo marino (Thalattosuchia, Metriorhynchidae) de la Formacion Vaca Muerta (Jurasico, Tithoniano) de la Provincia de Neuquen (Republica Argentina). In: Congreso Geológico Chileno. Actas. 1, Vol. 1, 1976, ZDB -ID 50377-0 , pp. C1-C21, digitized version (PDF; 428.92 kB) .
  4. ^ Eberhard Frey , Marie-Celine Buchy, Wolfgang Stinnesbeck, José Guadalupe López-Oliva: Geosaurus vignaudi n.sp. (Crocodyliformes: Thalattosuchia), first evidence of metriorhynchid crocodilians in the Late Jurassic (Tithonian) of central-east Mexico (State of Puebla). In: Canadian Journal of Earth Sciences. Vol. 39, No. 10, 2002, ISSN  0008-4077 , pp. 1467-1483, doi : 10.1139 / e02-060 .
  5. ↑ Zulma Brandoni de Gasparini, Manuel Iturralde-Vinent: Metriorhynchid crocodiles (Crocodyliformes) from the Oxfordian of Western Cuba. In: New Yearbook for Geology and Paleontology. Monthly books. No. 9, 2001, ISSN  0028-3630 , pp. 534-542.
  6. ↑ Andreas Wagner: Newly found dinosaur remains from the lithographic slate and the upper Jurassic limestone. In: Treatises of the Mathematical-Physical Class of the Royal Bavarian Academy of Sciences. Vol. 6, Department 3, 1852, pp. 661-710, digitized .
  7. ↑ Eberhard Fraas : The sea crocodiles (Thalattosuchia ng) a new group of dinosaurs of the Jura formation. In: Annual books of the Association for Patriotic Natural History in Württemberg. Vol. 57, 1901, ISSN  0368-4717 , pp. 409-418.
  8. ^ A b Mark Thomas Young, Marco Brandalize de Andrade: What is Geosaurus? Redescription of Geosaurus giganteus (Thalattosuchia: Metriorhynchidae) from the Upper Jurassic of Bayern, Germany. In: Zoological Journal of the Linnean Society. Vol. 157, No. 3, 2009, ISSN  0024-4082 , pp. 551-585, doi : 10.1111 / j.1096-3642.2009.00536.x .
  9. ↑ Mark Thomas Young: The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia). In: Journal of Vertebrate Paleontology. Vol. 27, Supplement to No. 3 = Program and Abstracts 67th Annual Meeting Society of Vertebrate Paleontology, The Jackson School of Geosciences University of Texas Austin, Texas, USA, October 17-20, 2007 , 2007, ISSN  0272-4634 , p 170A.
  10. ^ Sven Sachs, Mark Young, Pascal Abel, Heinrich Mallison. A new species of the metriorhynchid crocodylomorph Cricosaurus from the Upper Jurassic of southern Germany. Acta Palaeontologica Polonica, 2019; 64 DOI: 10.4202 / app.00541.2018
  11. ↑ Ernst Koken : The reptiles of the north German lower chalk. In: Journal of the German Geological Society. Vol. 35, 1883, pp. 735-827, digitized .
  12. ↑ Andrea Cau, Federico Fanti: The oldest known metriorhynchid crocodylian from the Middle Jurassic of North-eastern Italy: Neptunidraco ammoniticus gen. Et sp. nov. In: Gondwana Research . Vol. 19, No. 2, 2011, ISSN  1342-937X , pp. 550-565, doi : 10.1016 / j.gr.2010.07.007 .
  13. ↑ Judy A. Massare: swimming capabilities of Mesozoic marine reptiles; implications for method of predation. In: Paleobiology. Vol. 14, No. 2, 1988, ISSN  0094-8373 , pp. 187-205.
  14. ↑ Marta Fernández, Zulma Gasparini: Salt glands in a Tithonian metriorhynchid crocodyliform and their physiological significance. In: Lethaia. Vol. 33, No. 4, 2000, ISSN  0024-1164 , pp. 269-276, doi : 10.1080 / 002411600750053835 .
  15. ^ Marta Fernández, Zulma Gasparini: Salt glands in the Jurassic metriorhynchid Geosaurus: implications for the evolution of osmoregulation in Mesozoic marine crocodyliforms. In: The natural sciences . Vol. 95, No. 1, 2008, pp. 79-84, doi : 10.1007 / s00114-007-0296-1 .
  16. ↑ Robert Gandola, Éric Buffetaut , Nigel Monaghan, Gareth Dyke : Salt glands in the fossil crocodile Metriorhynchus. In: Journal of Vertebrate Paleontology. Vol. 26, No. 4, 2006, pp. 1009-1010, doi : 10.1671 / 0272-4634 (2006) 26 [1009: SGITFC] 2.0.CO; 2 .
  17. ↑ Marco Brandalise de Andrade, Mark Thomas Young: High diversity of thalattosuchian crocodylians and the niche partition in the Solnhofen Sea ( Memento from June 3, 2011 in the Internet Archive ). In: The 56th Symposium of Vertebrate Palaeontology and Comparative Anatomy. 2008.
  18. ↑ Gerd Dietl, Olga Dietl, Günter Schweigert, Rolf Hugger: The Nusplinger Plattenkalk (Weißer Jura ζ) - excavation campaign 1999. In: Annuals of the Society for Natural History in Württemberg. 156, 2000, ISSN  0368-2307 , pp. 5-26.