Metriorhynchidae

Metriorhynchidae is an extinct family of specialized, aquatic metriorhynchoid crocodyliforms from the Middle Jurassic to the Early Cretaceous period (Bajocian to Valanginian stages, potentially as late as early Aptian[2]) of Europe, North America and South America. The name Metriorhynchidae was coined by the Austrian zoologist Leopold Fitzinger in 1843.[3] The group contains two subfamilies, the Metriorhynchinae and the Geosaurinae.[4][5]

Metriorhynchids
Temporal range: Middle Jurassic-Early Cretaceous, 170–135 Ma
Dakosaurus maximus skull, Staatliches Museum für Naturkunde Stuttgart
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Suborder: Thalattosuchia
Superfamily: Metriorhynchoidea
Family: Metriorhynchidae
Fitzinger, 1843
Subfamilies
Synonyms

Description

Metriorhynchids are fully aquatic crocodyliforms. Their forelimbs were small and paddle-like, and unlike living crocodilians, they lost their osteoderms ("armour scutes"). Their body shape maximised hydrodynamy (swimming efficiency), as they did have a shark-like tail fluke.[6]

Metriorhynchids were the only group of archosaurs to become fully adapted to the marine realm, becoming pelagic in lifestyle.[7] With tail flukes, reduced limb musculature, and long bones histologically comparable to other obligately aquatic animals, they were almost certainly incapable of terrestrial locomotion; combined with an unusually tall hip opening, as also seen in other obligately aquatic reptiles including the viviparous Keichousaurus, these characters suggest that metriorhynchids gave live birth.[8] A fossil of a pregnant Dakosaurus female recovered from the Late Jurassic Plattenkalk, Bavaria, preserves the complete skeleton of a neonate with small, paddle-like forelimbs unsuited for walking on land, similar to those of adults, further supporting live birth in metriorhynchids.[9][10] Recent research posits that despite their successful adaptation to a pelagic lifestyle, basal metriorhynchids were uniquely disadvantaged among aquatic tetrapods in evolving into sustained swimmers due to little to no posterodorsal retraction of the external nares (unlike other reptilian groups such as mesosaurs, phytosaurs, thalattosaurians, saurosphargids, ichthyosauriforms, sauropterygians, pleurosaurids or mosasauroids, as well as mammalian cetaceans or sirenians).[11]

The family has a wide geographic distribution, with material found in Argentina, Chile, Cuba, England, France, Germany, Italy, Mexico, Poland, Russia and Switzerland.[7][5]

Classification

Phylogenetic analyses published during the 2000s cast doubt on the idea that many traditional metriorhynchid genera formed natural groups (i.e., include all descendants of a common ancestor). The traditional species of Geosaurus,[12][13][14] Dakosaurus[12] and Cricosaurus[12] were found to represent unnatural groups, and the species traditionally classified in these genera were reshuffled in a study published in November 2009 by Mark T. Young and Marco Brandalise de Andrade.[4] The monophyly of Metriorhynchus [12][13][15] and Teleidosaurus[12][14] is also unsupported, and the species of these genera are pending reclassification.[4]

The classification presented by Young and Andrade in 2009 was approved in later studies of the Metriorhynchidae.[5][16][17] Metriorhynchidae is a node-based taxon defined in 2009 as the least inclusive clade consisting of Metriorhynchus geoffroyii and Geosaurus giganteus.[4] The cladogram below follows the topology from the 2020 analyses by Young et al. and reduced to genera only.[11][18]

 Metriorhynchidae 
 Metriorhynchinae 

Thalattosuchus

Gracilineustes

Maledictosuchus

Metriorhynchus

 Rhacheosaurini 

Cricosaurus

Rhacheosaurus

 Geosaurinae 

Neptunidraco

 Geosaurini 

Tyrannoneustes

Torvoneustes

'E-clade'

Purranisaurus

Ieldraan

Geosaurus

Dakosaurus

Plesiosuchus

Suchodus

List of genera

The type genus of the family Metriorhynchidae is Metriorhynchus from the Middle to Late Jurassic.[18] Other genera included within this family are Cricosaurus, Geosaurus, and Dakosaurus. Though once considered a metriorhynchid, Teleidosaurus has since been found to be slightly more distantly related to these animals within the superfamily Metriorhynchoidea.

Within this family, the genus Neustosaurus is considered nomen dubium ("doubtful name").[19]

The genus Capelliniosuchus was once thought to be a metriorhynchid similar to Dakosaurus.[20] However, Sirotti demonstrated that it is a junior synonym of Mosasaurus.[21]

Genus Status Author Age Location Description Synonyms Images
Ambayrac, 1913 late Oxfordian

France.

Sometimes considered to be a nomen dubium.
Valid Wagner, 1858 middle Oxfordian to upper Valanginian

Argentina, Chile, Cuba, England, France, Germany, Mexico, Russia and Switzerland.

Valid von Quenstedt, 1856 upper Kimmeridgian to lower Berriasian

Argentina, England, France, Germany, Mexico, Poland, Switzerland and possibly Russia.

nomen dubium[24] Koken, 1883 Valanginian

Germany.

Valid Cuvier, 1824 upper Kimmeridgian to upper Valanginian

France, Germany, Italy and Switzerland.

  • Brachytaenius
  • Halilimnosaurus
Valid Young et al., 2010 middle Callovian to lower Kimmeridgian

England and France.

Valid Parrilla-Bel et al., 2013 middle Callovian to Kimmeridgian

Spain and Mexico.

Valid von Meyer, 1832 lower Kimmeridgian.

France.

Valid Cau & Fanti, 2011 earliest Bathonian

Italy.

nomen dubium Valanginian potential senior synonym of Enaliosuchus
Valid Owen, 1884 late Kimmeridgian to early Tithonian

England and possibly Spain.

Valid Rusconi, 1948 upper Tithonian

Argentina and Chile.

Valid von Meyer, 1831 lower Tithonian

Germany.

Valid Lydekker, 1890 middle Callovian to lower Oxfordian

England and France.

Valid Young et al., 2020 lower Callovian to lower Oxfordian

England and France.

Valid Andrade et al., 2010 Kimmeridgian to Tithonian

England.

Valid Young et al., 2013 Callovian

England.

See also

References

  1. Andrews CW. 1913. A descriptive catalogue of the marine reptiles of the Oxford Clay, Part Two. London: British Museum (Natural History), 206 pp.
  2. Alfio A. Chiarenza, Davide Foffa, Mark T. Young, Gianni Insacco, Andrea Cau, Giorgio Carnevale, Rita Catanzariti (2015). "The youngest record of metriorhynchid crocodylomorphs, with implications for the extinction of Thalattosuchia". Cretaceous Research. 56: 608–616. doi:10.1016/j.cretres.2015.07.001.CS1 maint: uses authors parameter (link)
  3. Fitzinger LJFJ. 1843. Systema Reptilium. Wien: Braumüller et Seidel, 106 pp.
  4. Mark T. Young and Marco Brandalise de Andrade (2009). "What is Geosaurus? Redescription of Geosaurus giganteus (Thalattosuchia: Metriorhynchidae) from the Upper Jurassic of Bayern, Germany". Zoological Journal of the Linnean Society. 157 (3): 551–585. doi:10.1111/j.1096-3642.2009.00536.x.CS1 maint: uses authors parameter (link)
  5. Mark T. Young, Stephen L. Brusatte, Marcello Ruta and Marco Brandalise de Andrade (2010). "The evolution of Metriorhynchoidea (Mesoeucrocodylia, Thalattosuchia): an integrated approach using geometrics morphometrics, analysis of disparity and biomechanics". Zoological Journal of the Linnean Society. 158 (4): 801–859. doi:10.1111/j.1096-3642.2009.00571.x.CS1 maint: uses authors parameter (link)
  6. Fraas E (1902). "Die Meer-Krocodilier (Thalattosuchia) des oberen Jura unter specieller Berücksichtigung von Dacosaurus und Geosaurus". Palaeontographica. 49: 1–72.
  7. Steel R. 1973. Crocodylia. Handbuch der Paläoherpetologie, Teil 16. Stuttgart: Gustav Fischer Verlag,116 pp.
  8. Herrera, Y.; Fernandez, M.S.; Lamas, S.G.; Campos, L.; Talevi, M.; Gasparini, Z. (2017). "Morphology of the sacral region and reproductive strategies of Metriorhynchidae: a counter-inductive approach". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 106 (4): 247–255. doi:10.1017/S1755691016000165.
  9. Spindler, Frederik. Live Birth in a Jurassic Marine Crocodile [abstract]. In: Abstracts of the 90th Annual Meeting of the Paläontologische Gesellschaft, Munich 2019; 2019 Sept 15–18; Munich. Germany: PalGest; 2019. Abstract ID 102.
  10. Spindler, Frederik. When Bavaria was the Ancient Caribbean – Plattenkalk Fossil Treasures from Painten [abstract]. In: Abstracts of the 90th Annual Meeting of the Paläontologische Gesellschaft, Munich 2019; 2019 Sept 15–18; Munich. Germany: PalGest; 2019. Abstract ID 110.
  11. Young, M.T.; Sachs, S.; Abel, P.; Foffa, D.; Herrera, Y.; Kitson, J.J.N. (2020). "Convergent evolution and possible constraint in the posterodorsal retraction of the external nares in pelagic crocodylomorphs". Zoological Journal of the Linnean Society. 189 (2): 494–520. doi:10.1093/zoolinnean/zlaa021.
  12. Young MT (2007). "The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia)". Journal of Vertebrate Paleontology. 27 (3): 170A. doi:10.1080/02724634.2007.10010458.
  13. Wilkinson LE, Young MT, Benton MJ (2008). "A new metriorhynchid crocodilian (Mesoeucrocodylia: Thalattosuchia) from the Kimmeridgian (Upper Jurassic) of Wiltshire, UK". Palaeontology. 51 (6): 1307–1333. doi:10.1111/j.1475-4983.2008.00818.x.
  14. Mueller-Töwe IJ (2005). "Phylogenetic relationships of the Thalattosuchia". Zitteliana. A45: 211–213.
  15. Gasparini Z, Pol D, Spalletti LA (2006). "An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia". Science. 311 (5757): 70–73. doi:10.1126/science.1120803. PMID 16282526.
  16. Andrea Cau; Federico Fanti (2011). "The oldest known metriorhynchid crocodylian from the Middle Jurassic of North-eastern Italy: Neptunidraco ammoniticus gen. et sp. nov". Gondwana Research. 19 (2): 550–565. doi:10.1016/j.gr.2010.07.007.
  17. Mark T. Young, Mark A. Bell and Stephen L. Brusatte (2011). "Craniofacial form and function in Metriorhynchidae (Crocodylomorpha: Thalattosuchia): modelling phenotypic evolution with maximum-likelihood methods". Biology Letters. 7 (6): 913–916. doi:10.1098/rsbl.2011.0357. PMC 3210659. PMID 21543396.CS1 maint: uses authors parameter (link)
  18. Young, M.T., Brignon, A., Sachs, S., Hornung J.J., Foffa, D., Kitson, J.J.N., Johnson, M.M., and Steel, L. 2020. Cutting the Gordian knot: a historical and taxonomic revision of the Jurassic crocodylomorph Metriorhynchus. Zoological Journal of the Linnean Society, zlaa092. https://doi.org/10.1093/zoolinnean/zlaa092.
  19. Buffetaut E (1982). "Radiation évolutive, paléoécologie et biogéographie des Crocodiliens mésosuchienes". Mémoires de la Société Géologique de France. 142: 1–88.
  20. Simonelli V (1896). "Intoro agli avanzi di coccodrilliano scoperti a San Valentino (provincial di Reggio Emilia) nel 1886". Atli della Reale Accademia dei Lincei, Series Qunita Rendiconti. 5 (2): 11–18.
  21. Sirotti A. 1989. Mosasaurus hoffmanni Mantell, 1828 (Reptilia) nelle <<argille scagliose>> di S. Valentino (Reggio E.). Atti della società dei naturalisti e matematici di Modena 120: 135-146.
  22. Quenstedt FA. 1856. Sonst und Jetzt: Populäre Vortäge über Geologie. Tübingen: Laupp, 131.
  23. Koken E (1883). "Die reptilian der norddeutschen unteren Kreide". Zeitschrift Deutschen Geologischen Gesellschaft. 35: 735–827.
  24. Sachs S, Young MT, Hornung JJ (2020). "The enigma of Enaliosuchus, and a reassessment of the Lower Cretaceous fossil record of Metriorhynchidae". Cretaceous Research. 114: 104479.CS1 maint: multiple names: authors list (link)
  25. Cuvier G. 1824. Sur les ossements fossiles de crocodiles, 5. In: Dufour & D'Occagne, eds. Recherches sur les ossements fossiles, 2nd édition. Paris: 143-160
  26. Young Mark T., Brusatte Stephen L., Ruta M., Andrade Marco B. (2009). "The evolution of Metriorhynchoidea (Mesoeucrocodylia, Thalattosuchia): an integrated approach using geometrics morphometrics, analysis of disparity and biomechanics". Zoological Journal of the Linnean Society. 158 (4): 801–859. doi:10.1111/j.1096-3642.2009.00571.x.CS1 maint: multiple names: authors list (link)
  27. Andrade, M.B.D.; Young, M.T.; Desojo, J.B.; Brusatte, S.L. (2010). "The evolution of extreme hypercarnivory in Metriorhynchidae (Mesoeucrocodylia: Thalattosuchia) based on evidence from microscopic denticle morphology". Journal of Vertebrate Paleontology. 30 (5): 1451–1465. doi:10.1080/02724634.2010.501442.
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