Metriorhynchids
Fossil rangeMiddle Jurassic-Early Cretaceous,
TaxonMetriorhynchidae
AuthorityFitzinger, 1843
Subdivision ranksGenera
Subdivision
Synonyms

Metriorhynchidae is an extinct family of specialized, aquatic metriorhynchoid crocodyliforms from the Middle Jurassic to the Early Cretaceous period (Bajocian to 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] They represent the most marine adapted of all archosaurs.

Description

Metriorhynchids are fully aquatic crocodyliforms. Their forelimbs were small and paddle-like, and unlike living crocodylians, they lost their osteoderms ("armour scutes"). Their body shape maximised hydrodynamy (swimming efficiency), as they did have a shark-like tail fluke.[6] Like ichthyosaurs and plesiosaurs, metriorhynchids developed smooth, scaleless skin.[7] However, unlike those marine reptiles, they were poikilothermic with little to no endothermic ability.[8]

Metriorhynchids were the only group of archosaurs to become fully adapted to the marine realm, becoming pelagic in lifestyle.[9] 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.[10] 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.[11][12] 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).[13] The family has a wide geographic distribution, with material found in Argentina, Chile, Cuba, England, France, Germany, Italy, Mexico, Poland, Russia, Switzerland and Czech Republic.[9][5][14]

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,[15][16][17] Dakosaurus[15] and Cricosaurus[15] 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[15][16][18] and Teleidosaurus[15][17] 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][19][20] Metriorhynchidae is a node-based taxon defined in the PhyloCode by Mark T. Young and colleagues in 2024 as "the smallest clade within Metriorhynchoidea containing Thalattosuchus superciliosus, Gracilineustes leedsi, Metriorhynchus brevirostris, Rhacheosaurus gracilis, and Geosaurus giganteus" [21] The cladogram below follows the topology from the 2020 analyses by Young et al. and reduced to genera only.[13][22]

List of genera

The type genus of the family Metriorhynchidae is Metriorhynchus from the Middle to Late Jurassic.[22] 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.[23]

Within this family, the genus Neustosaurus and Enaliosuchus are considered nomen dubium ("doubtful name").[24]

The genus Capelliniosuchus was once thought to be a metriorhynchid similar to Dakosaurus.[25] However, it was later found to be a mosasaur.[26]

GenusStatusAuthorAgeLocationDescriptionSynonymsImages
Ambayrac, 1913late OxfordianFrance.Sometimes considered to be a nomen dubium.
ValidWagner, 1858middle Oxfordian to upper ValanginianArgentina, Chile, Cuba, England, France, Germany, Mexico, Russia and Switzerland.
Validvon Quenstedt, 1856upper Kimmeridgian to lower BerriasianArgentina, England, France, Germany, Mexico, Poland, Switzerland and possibly Russia.
nomen dubium[29]Koken, 1883ValanginianGermany.
ValidCuvier, 1824upper Kimmeridgian to upper ValanginianFrance, Germany, Italy and Switzerland.
  • Brachytaenius
  • Halilimnosaurus
ValidYoung et al., 2010middle Callovian to lower KimmeridgianEngland and France.
ValidParrilla-Bel et al., 2013middle Callovian to KimmeridgianSpain and Mexico.
Validvon Meyer, 1832lower Kimmeridgian.France.
ValidCau & Fanti, 2011earliest BathonianItaly.
nomen dubiumValanginian— potential senior synonym of Enaliosuchus
ValidOwen, 1884late Kimmeridgian to early TithonianEngland and possibly Spain.
ValidRusconi, 1948upper TithonianArgentina and Chile.
Validvon Meyer, 1831lower TithonianGermany.
ValidLydekker, 1890middle Callovian to lower OxfordianEngland and France.
ValidYoung et al., 2020lower Callovian to lower OxfordianEngland and France.
ValidAndrade et al., 2010Kimmeridgian to TithonianEngland.
ValidYoung et al., 2013CallovianEngland.

Subclades

Summary of the phylogenetic definitions of metriorhynchid subclades shown in the classification section. These are based on Young and colleagues 2024.[21]

NameNamed byDefinition
DakosaurinaYoung et al., 2024[21]The largest clade within Metriorhynchidae containing Dakosaurus maximus, but not Metriorhynchus brevirostris, Geosaurus giganteus, Plesiosuchus manselii, and Torvoneustes carpenteri.
GeosaurinaBonaparte, 1845The largest clade within Metriorhynchidae containing Geosaurus giganteus, but not Metriorhynchus brevirostris, Plesiosuchus manselii, Torvoneustes carpenteri, and Dakosaurus maximus.
GeosaurinaeBonaparte, 1845The largest clade within Metriorhynchidae containing Geosaurus giganteus, but not Rhacheosaurus gracilis, Metriorhynchus brevirostris, and Gracilineustes leedsi.
GeosauriniBonaparte, 1845The smallest clade within Metriorhynchidae containing Tyrannoneustes lythrodectikos, Geosaurus giganteus, Torvoneustes carpenteri, and Dakosaurus maximus.
MetriorhynchidaeFitzinger, 1843The smallest clade within Metriorhynchoidea containing Thalattosuchus superciliosus, Gracilineustes leedsi, Metriorhynchus brevirostris, Rhacheosaurus gracilis, and Geosaurus giganteus.
MetriorhynchinaeLydekker, 1888The smallest clade within Metriorhynchidae containing Rhacheosaurus gracilis, Metriorhynchus brevirostris, and Gracilineustes leedsi.
PlesiosuchinaYoung et al.,2014The largest clade within Metriorhynchidae containing Plesiosuchus manselii, but not Metriorhynchus brevirostris, Geosaurus giganteus, Torvoneustes carpenteri, and Dakosaurus maximus.
RhacheosauriniYoung et al., 2011The largest clade within Metriorhynchidae containing Rhacheosaurus gracilis, but not Metriorhynchus brevirostris and Gracilineustes leedsi.

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). p. 206.
  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. Bibcode:2015CrRes..56..608C. doi:10.1016/j.cretres.2015.07.001. hdl:2318/1537833
  3. ^ Fitzinger LJFJ. 1843. Systema Reptilium. Wien: Braumüller et Seidel, 106 pp.
  4. ^ Mark T. Young & 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
  5. ^ Mark T. Young; Stephen L. Brusatte; Marcello Ruta; 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
  6. ^ Fraas E (1902). "Die Meer-Krocodilier (Thalattosuchia) des oberen Jura unter specieller Berücksichtigung von Dacosaurus und Geosaurus". Palaeontographica. 49: 1–72.
  7. ^ Spindler, Frederik; Lauer, René; Tischlinger, Helmut; Mäuser, Matthias (2021-07-05). "The integument of pelagic crocodylomorphs (Thalattosuchia: Metriorhynchidae)". Palaeontologia Electronica. 24 (2): 1–41. doi:10.26879/1099. ISSN 1094-8074
  8. ^ Séon, Nicolas; Vincent, Peggy; Delsett, Lene L. (April 16, 2025). "Reassessment of body temperature and thermoregulation strategies in Mesozoic marine reptiles". Paleobiology
  9. ^ Steel R. 1973. Crocodylia. Handbuch der Paläoherpetologie, Teil 16. Stuttgart: Gustav Fischer Verlag,116 pp.
  10. ^ 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. hdl:11336/66599
  11. ^ Spindler, Frederik (2019). Live Birth in a Jurassic Marine Crocodile [abstract]. In: Abstracts of the 90th Annual Meeting of the Paläontologische Gesellschaft. SNSB - BSPG, München. p. 141. ISBN 978-3-946705-07-9. Archived 2023-05-17 at the Wayback Machine.
  12. ^ Spindler, Frederik (2019). When Bavaria was the Ancient Caribbean – Plattenkalk Fossil Treasures from Painten [abstract]. In: Abstracts of the 90th Annual Meeting of the Paläontologische Gesellschaft. SNSB - BSPG, München. p. 10. ISBN 978-3-946705-07-9. Archived 2023-05-17 at the Wayback Machine.
  13. ^ 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. hdl:11336/137182
  14. ^ Daniel Madzia, Sven Sachs, Mark T. Young, Alexander Lukeneder, Petr Skupien (2021). "Evidence of two lineages of metriorhynchid crocodylomorphs in the Lower Cretaceous of the Czech Republic". Acta Palaeontologica Polonica. 66 (2): 1-11. doi:10.4202/app.00801.2020. Archived 2021-05-21 at the Wayback Machine.
  15. ^ Young MT (2007). "The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia)". Journal of Vertebrate Paleontology. 27 (3): 170A. doi:10.1080/02724634.2007.10010458
  16. ^ 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. Bibcode:2008Palgy..51.1307W. doi:10.1111/j.1475-4983.2008.00818.x
  17. ^ Mueller-Töwe IJ (2005). "Phylogenetic relationships of the Thalattosuchia". Zitteliana. A45: 211–213.
  18. ^ Gasparini Z, Pol D, Spalletti LA (2006). "An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia". Science. 311 (5757): 70–73. Bibcode:2006Sci...311...70G. doi:10.1126/science.1120803. hdl:11336/73480. PMID 16282526. S2CID 10312971
  19. ^ 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. Bibcode:2011GondR..19..550C. doi:10.1016/j.gr.2010.07.007
  20. ^ Mark T. Young; Mark A. Bell; 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
  21. ^ Young, Mark T.; Wilberg, Eric W.; Johnson, Michela M.; Herrera, Yanina; De Andrade, Marco Brandalise; Brignon, Arnaud; Sachs, Sven; Abel, Pascal; Foffa, Davide; Fernández, Marta S.; Vignaud, Patrick; Cowgill, Thomas; Brusatte, Stephen L. (2024). "The history, systematics, and nomenclature of Thalattosuchia (Archosauria: Crocodylomorpha)". Zoological Journal of the Linnean Society. 200 (2): 547–617. doi:10.1093/zoolinnean/zlad165
  22. ^ Young, M.T., Brignon, A., Sachs, S., Hornung J.J., Foffa, D., Kitson, J.J.N., Johnson, M.M., Steel, L. (November 2020). "Cutting the Gordian knot: a historical and taxonomic revision of the Jurassic crocodylomorph Metriorhynchus". Zoological Journal of the Linnean Society. 192 (2): 510–553. doi:10.1093/zoolinnean/zlaa092
  23. ^ Stéphane Hua (May 2020). "A new specimen of Teleidosaurus calvadosii (Eudes-Deslongchamps, 1866) (Crocodylia, Thalattosuchia) from the Middle Jurassic of France". Annales de Paléontologie. 106 (4). Bibcode:2020AnPal.10602423H. doi:10.1016/j.annpal.2020.102423
  24. ^ Buffetaut E (1982). "Radiation évolutive, paléoécologie et biogéographie des Crocodiliens mésosuchienes". Mémoires de la Société Géologique de France. 142: 1–88.
  25. ^ 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.
  26. ^ Fanti, Federico; Cau, Andrea; Negri, Alessandra (2014-05-01). "A giant mosasaur (Reptilia, Squamata) with an unusually twisted dentition from the Argille Scagliose Complex (late Campanian) of Northern Italy". Cretaceous Research. 49: 91–104. Bibcode:2014CrRes..49...91F. doi:10.1016/j.cretres.2014.01.003. ISSN 0195-6671
  27. ^ Quenstedt FA. 1856. Sonst und Jetzt: Populäre Vortäge über Geologie. Tübingen: Laupp, 131.
  28. ^ Koken E (1883). "Die reptilian der norddeutschen unteren Kreide". Zeitschrift der Deutschen Geologischen Gesellschaft. 35: 735–827.
  29. ^ 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. Bibcode:2020CrRes.11404479S. doi:10.1016/j.cretres.2020.104479. hdl:20.500.11820/c52d1d56-1bf3-4aae-b2e1-38c85eed44fa. S2CID 218996914
  30. ^ 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
  31. ^ 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
  32. ^ 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. Bibcode:2010JVPal..30.1451D. doi:10.1080/02724634.2010.501442. hdl:11336/69039. S2CID 83985855