Machimosaurus

{{short description|Genus of reptiles}} {{Automatic taxobox |fossil_range = {{Fossil range|154|130}} Kimmeridgian - Hauterivian? |image = Machimosaurus sp.jpg |image_caption = ''Machimosaurus mosae'' cast |taxon = Machimosaurus |authority = Von Meyer, 1837 |subdivision_ranks = Species |subdivision = * {{extinct}}'''''M. hugii''''' type Von Meyer (1837) * {{extinct}}'''''M. mosae''''' Sauvage and Lienard 1879 * {{extinct}}'''''M. nowackianus''''' (von Huene. 1938) * {{extinct}}'''''M. buffetauti''''' Young ''et al.'', 2015 * {{extinct}}'''''M. rex''''' Fanti ''et al.'', 2016<ref name=Fantietal>Federico Fanti, Tetsuto Miyashita, Luigi Cantelli, Fawsi Mnasri, Jihed Dridi, Michela Contessi, Andrea Cau. The largest thalattosuchian (Crocodylomorpha) supports teleosaurid survival across the Jurassic-Cretaceous boundary, Cretaceous Research, Available online 10 January 2016.</ref> |synonyms = *''Machinosaurus'' *''Madrimosaurus hugii'' (''sic'') }}

'''''Machimosaurus''''' is an extinct genus of machimosaurid crocodyliform from the Late Jurassic (Kimmeridgian and Tithonian) and Early Cretaceous.<ref name="news.nationalgeographic.com">{{cite web | url=http://news.nationalgeographic.com/2016/01/160111-ancient-crocodile-marine-largest-paleontology/ | archive-url=https://web.archive.org/web/20160112060450/http://news.nationalgeographic.com/2016/01/160111-ancient-crocodile-marine-largest-paleontology/ | archive-date=January 12, 2016 | title=Monster-Size Marine Crocodile Discovered | date=11 January 2016 }}</ref><ref name="sciencedirect.com">{{cite journal | doi=10.1016/j.cretres.2015.11.011 | volume=61 | title=The largest thalattosuchian (Crocodylomorpha) supports teleosaurid survival across the Jurassic-Cretaceous boundary | journal=Cretaceous Research | pages=263–274| year=2016 | last1=Fanti | first1=Federico | last2=Miyashita | first2=Tetsuto | last3=Cantelli | first3=Luigi | last4=Mnasri | first4=Fawsi | last5=Dridi | first5=Jihed | last6=Contessi | first6=Michela | last7=Cau | first7=Andrea | bibcode=2016CrRes..61..263F | hdl=11585/529635 | hdl-access=free }}</ref> The type species, '''''Machimosaurus hugii''''', was found in Switzerland. Other fossils have been found in England, France, Germany, Portugal, Switzerland and Tunisia.<ref name="news.nationalgeographic.com"/><ref name="Steel, 1973">Steel R. 1973. ''Crocodylia. Handbuch der Paläoherpetologie, Teil 16''. Stuttgart: Gustav Fischer Verlag,116 pp.</ref><ref>Mateus, O. 2013. Crocodylomorphs from the Mesozoic of Portugal and a new skull of eusuchian from the Late Cretaceous. Abstract book of Hwaseong International Dinosaurs Expedition Symposium, South Korea, pp: 66-68.</ref> '''''Machimosaurus rex''''' is the largest named teleosauroid and thalattosuchian, with an estimated length of up to {{cvt|7.15|m}} (skull length {{cvt|155|cm}}).<ref name=Youngetal/> ''Machimosaurus'' is the largest known crocodyliform of the Jurassic.<ref name="news.nationalgeographic.com"/><ref name="sciencedirect.com"/><ref name="Steel, 1973"/><ref name=Youngetal/>

==Discovery and species== thumb|left|Illustrations of the three European species Christian Erich Hermann von Meyer in 1837 named isolated conical, blunt teeth with numerous longitudinal lines from Switzerland, ''Madrimosaurus hugii''. However, in 1838, realising he had misspelled the name, he emended ''Madrimosaurus'' to ''Machimosaurus'', from the Greek ''machimoi'', ancient Egyptian troops deployed during the Ptolemaic Dynasty plus the ''-saurus'' suffix, literally meaning "pugnacious lizard".<ref name="Young et al. 2014"/> The teeth of ''Machimosaurus'', with their rounded, blunt apex and stout morphology make them characteristic and easily identifiable compared to other teleosaurid teeth.<ref name="Vignaud, 1997">{{cite journal | last1 = Vignaud | first1 = P | year = 1997 | title = La morphologie dentaire des Thalattosuchia (Crocodylia, Mesosuchia) | journal = Palaeovertebrata | volume = 26 | issue = 1/4| pages = 35–59 }}</ref>

The type species, ''M. hugii'', is known from the Kimmeridgian of Portugal, Spain, Tunisia and Switzerland.<ref name="news.nationalgeographic.com"/><ref name="Young et al. 2014"/> ''Machimosaurus ferox'' and ''M. interruptus'' were previously considered junior synonyms of ''M. hugii'',<ref name="Krebs, 1967">{{cite journal | last1 = Krebs | first1 = B | year = 1967 | title = Der Jura-Krokodilier Machimosaurus H. v. Meyer | journal = Paläontologische Zeitschrift | volume = 41 | issue = 1–2| pages = 46–55 | doi=10.1007/bf02998548| bibcode = 1967PalZ...41...46K | s2cid = 130110535 }}</ref><ref name="Buffetaut, 1982">{{cite journal | last1 = Buffetaut | first1 = E | year = 1982 | title = Le crocodilien Machimosaurus VON MEYER (Mesosuchia, Teleosauridae) dans le Kimmeridgien de l'Ain | journal = Bulletin Trimestrielle Société de la Géologique Normandie et Amis du Museum, Havre | volume = 69 | issue = 1/2| pages = 17–27 }}</ref> but have been recently considered possible synonyms of '''''Machimosaurus mosae'''''.<ref name="Young et al. 2014"/>

Krebs (1967),<ref name="Krebs, 1967"/> considered ''M. mosae'' (Lienard, 1876) to be a junior synonym of ''M. hugii'', but is considered a second valid species of the genus based on a nearly complete skeleton found from the late Kimmeridgian of France.<ref name="Young et al. 2014"/><ref name="Hua et al., 1996">{{cite journal | last1 = Hua | first1 = S | last2 = Vasse | first2 = D | last3 = Buffetaut | first3 = E | last4 = Martin | first4 = M | last5 = Mazin | first5 = J-M | last6 = Vadet | first6 = A | year = 1993 | title = Un squelette de ''Machimosaurus mosae Sauvage et Lienard,'' 1879 (Crocodylia, Thalattosuchia) dans le Kimméridgien du Boulonnais | journal = Comptes Rendus de l'Académie des Sciences, Série II | volume = 317 | issue = 6| pages = 851–856 }}</ref>

Two species also placed within ''Machimosaurus'' are ''M. bathonicus'' and ''M. rigauxi'', from the Bathonian of France.<ref name="Sauvage, 1874">{{cite journal | last1 = Sauvage | first1 = H-E | year = 1874 | title = Mémoire sur les dinosauriens et les crocodiliens des terrains jurassiques de Boulogne-sur-Mer | journal = Mémoires de la Société Géologique de France |series=Série 2 | volume = 10 | issue = 2| pages = 1–57 }}</ref> However, these are gracile species, lacking the characteristic blunted teeth of ''Machimosaurus'', and are probably referable to ''Steneosaurus''.<ref name="Young et al. 2014"/> thumb|upright|Skull Mark Young and his colleagues <ref name="Young et al. 2014">Young, M. T., Hua S., Steel L., Foffa D., Brusatte S. L., Thüring S., Mateus O., Ignacio-Ruiz Omeñaca J., Lepage Y., Havilk P., & Andrade M. B. (2014). Revision of the Late Jurassic teleosaurid genus Machimosaurus (Crocodylomorpha, Thalattosuchia). Royal Society Open Science. 1(140222), 1-42.</ref><ref>Young, M. T., Hua S., Steep L., Foffa D., Brusatte S. L., Thüring S., Mateus O., Ruiz-Omeñaca J. I., Havlik P., Lepage Y., & de Andrade M. B. (2015). Addendum to 'Revision of the Late Jurassic teleosaurid genus Machimosaurus (Crocodylomorpha, Thalattosuchia)'. Royal Society Open Science. 2, Number 2</ref> made a detailed revision of the genus and recognized four species: ''M. hugii'', ''M. mosae'', '''''M. nowackianus''''' from Harrar, Ethiopia, and a new species, '''''Machimosaurus buffetauti'''''. They hypothesized that ''Machimosaurus'' may have been analogous to the Pliocene–Holocene genus ''Crocodylus'' in having one large-bodied taxon suited to traversing marine barriers and additional, geographically limited taxa across its range.

The fossilized anterior portion of the lower jaw from the Late Jurassic (Oxfordian or Kimmeridgian) of Ethiopia referred to the pliosaur ''Simolestes nowackianus'', is in fact a large species of ''Machimosaurus''.<ref name="Bardet & Hua, 1996">{{cite journal | last1 = Bardet | first1 = N | last2 = Hua | first2 = S | year = 1996 | title = ''Simolestes nowackianus'' HUENE, 1938 from the Late Jurassic of Ethiopia is a teleosaurid crocodile, not a pliosaur | journal = Neues Jahrbuch für Geologie und Paläontologie, Monatshefte | volume = 1996 | pages = 65–71 | doi = 10.1127/njgpm/1996/1996/65 }}</ref> thumb|Diagram of the skull of ''M. rex'' in palatal view In 2016, a new species of ''Machimosaurus'' from Douiret Formation in Tunisia was described in the journal ''Cretaceous Research''. Named ''Machimosaurus rex'', it was the largest teleosauroid known at the time, estimated to be {{convert|9.6|m|ft|1|abbr=on}} in length (skull length {{convert|155|cm|in|abbr=on}}) based on a partial skeleton.<ref name="sciencedirect.com"/> ''M. rex'' was also the youngest teleosauroid known at the time. However, more recent estimates put ''M. hugii'' along with ''M. rex'' at about {{convert|6.9|-|7.15|m|ft|1|abbr=on}} long.<ref name=Youngetal>{{Cite journal|url=http://palaeo-electronica.org/content/2016/1554-teleosaurid-size-estimation|doi=10.26879/648|title=Big-headed marine crocodyliforms and why we must be cautious when using extant species as body length proxies for long-extinct relatives|year=2016|last1=Young|first1=MT|last2=Rabi|first2=M.|last3=Bell|first3=MA|last4=Foffa|first4=D.|last5=Steel|first5=L.|last6=Sachs|first6=S.|last7=Peyer|first7=K.|journal=Palaeontologia Electronica|volume=19|issue=3|pages=1–14|doi-access=free}}</ref> The discovery of ''M. rex'' indicates that teleosauroid crocodylomorphs survived the extinction event at the end of the Late Jurassic, but did not retain the biodiversity seen in the Jurassic. Moreover, an incomplete specimen from the Barremian of Colombia attributed to Teleosauroidea is not only the youngest known teleosauroid, but also the largest at about {{convert|9.6|m|ft|1|abbr=on}} long.<ref name="Cortes et al. 2019">Cortes D, Larsson HCE, Maxwell EE, Parra Ruge ML, Patarroyo P, Wilson JA. 2019. An Early Cretaceous teleosauroid (Crocodylomorpha: Thalattosuchia) from Colombia. Ameghiniana. doi:10.5710/AMGH.26.09. 2019.3269.</ref>

==Classification==

The phylogenetic relationships of the Machimosauridae were analyzed in a comprehensive analysis of teleosauroid relationships. The results of the analysis are shown below:<ref name=Johnson2020>{{cite journal |last1=Johnson |first1=Michela M. |last2=Young |first2=Mark T. |last3=Brusatte |first3=Stephen L. |title=The phylogenetics of Teleosauroidea (Crocodylomorpha, Thalattosuchia) and implications for their ecology and evolution |journal=PeerJ |date=2020 |volume=8 |article-number=e9808 | pmid=33083104| doi=10.7717/peerj.9808 |language=en |issn=2167-8359|doi-access=free |pmc=7548081 }} 50px Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref> {{Clade|{{clade |1=''Macrospondylus bollensis'' |2={{clade |1=''Clovesuurdameredeor stephani'' |2={{clade |1=''Charitomenosuchus leedsi'' |2={{clade |1=''Seldsienean megistorhynchus'' |2={{clade |1=''Deslongchampsina larteti'' |label2=Machimosaurinae |2={{clade |1={{clade |1=''Proexochokefalos hebertii'' |2=cf. ''Proexochokefalos bouchardi''}} |2={{clade |1=''Neosteneosaurus edwardsi'' |2=''Andrianavoay baroni'' |label3=Machimosaurini |3={{clade |1=''Lemmysuchus obtusidens'' |2=''Yvridiosuchus boutilieri'' |3={{clade |1='''''Machimosaurus buffetauti''''' |2={{clade |1='''''Machimosaurus mosae''''' |2={{clade |1='''''Machimosaurus rex''''' |2='''''Machimosaurus hugii'''''}}}}}}}}}}}}}}}}}}}}}}|label1=Machimosauridae}}

==Palaeobiology==

=== Niche partitioning === From the Kimmeridgian-age, semi-aquatic deposits of Oker, Lower Saxony, Germany two genera of teleosaurids (''Steneosaurus'' and ''Machimosaurus'') are known, in addition to the neosuchian genera ''Goniopholis'' and ''Theriosuchus''.<ref name="Karl et al., 2006">Karl H-V, Gröning E, Brauckmann C, Schwarz D, Knötschke N.2006. The Late Jurassic crocodiles of the Langenberg near Oker, Lower Saxony (Germany), and description of related materials (with remarks on the history of quarrying the "Langenberg Limestone" and "Obernkirchen Sandstone"). ''Clausthaler Geowissenschaften'' '''5''': 59-77.</ref> ''Machimosaurus'' and ''Steneosaurus'' are also found together in the same Tithonian-age deposits of western France.<ref name="Billon-Bruyat, et al., 2001">Billon-Bruyat J-P, Mazin J-M, Buffetaut E, Tong H, Abit D. 2001. New occurrence of vertebrate remains in the latest Jurassic of western France (Oléron island, Charente-Maritime). ''6th European Workshop on Vertebrate Palaeontology - Florence and Montevarchi (Italy) - September 19–22, 2001 Abstract Booklet'', p. 19</ref>

===Diet=== thumb|Tooth Bite marks on an early Kimmeridgian sauropod (''Amanzia'') femur from Switzerland match teeth known from ''Machimosaurus hugii'', also found in the same deposits. This suggests either scavenging on the sauropod's corpse, or active predation from the waters edge, much like living crocodilians.<ref name="Meyer & Thüring, 2003">{{cite journal | last1 = Meyer | first1 = CA | last2 = Thüring | first2 = CR | year = 2003 | title = Dinosaurs of Switzerland | journal = Comptes Rendus Palevol | volume = 2 | issue = 1| pages = 103–117 | doi=10.1016/s1631-0683(03)00005-8| bibcode = 2003CRPal...2..103M }}</ref> Kimmeridgian-age fossil turtles from "Solothurn Turtle Limestone" of northern Switzerland have bite marks, and splintered ''Machimosaurus'' teeth imbedded,<ref name="Meyer, 1991">{{cite journal | last1 = Meyer | first1 = CA | year = 1991 | title = Burial experiments with marine turtle carcasses and their paleoecological significance | journal = PALAIOS | volume = 6 | issue = 1| pages = 89–96 | doi=10.2307/3514956| jstor = 3514956 | bibcode = 1991Palai...6...89M }}</ref> while fossil turtles from the Late Jurassic of Germany also possess bite marks that match teeth of ''Machimosaurus'' found in the same deposit.<ref name="Tichy & Karl, 2004">{{cite journal | last1 = Tichy | first1 = G | last2 = Karl | first2 = H-V | year = 2004 | title = The structure of fossil teeth of chelonophagous crocodiles (Diapsida: Crocodylia) | journal = Studia Geologica Salmanticensia | volume = 40 | pages = 115–124 }}</ref>

Morphofunctional analysis on the skull of ''Machimosaurus'' strongly suggests they ate turtles (chelonophagy).<ref name="Krebs, 1967"/><ref name="Buffetaut, 1982"/> Morphological comparison of their teeth also confirms that they are adapted to seizing and crushing hard prey.<ref name="Vignaud, 1997"/><ref name="Massare, 1987">{{cite journal | last1 = Massare | first1 = JA | year = 1987 | title = Tooth morphology and prey preference of Mesozoic marine reptiles | journal = Journal of Vertebrate Paleontology | volume = 7 | issue = 2| pages = 121–137 | doi=10.1080/02724634.1987.10011647| bibcode = 1987JVPal...7..121M }}</ref>

===Locomotion=== Based on the vertebrae (zygapophysial) articulations, ''Machimosaurus'' is considered to have lived in open-seas, swimming by lateral undulations of the tail with the limbs used for steering and balancing. Head and neck depressing (downward moving) muscles would have been well-developed, as their attachment site on the skull (basioccipital tubera) were large. This would have greatly assisted ''Machimosaurus'' in diving.<ref name="Krebs, 1967"/>

==See also== {{Portal|Paleontology}} *List of marine reptiles

==References== {{Reflist|2}}

== External links== * [http://www.angellis.net/Web/PDfiles/repcrocs.pdf Angellis Net pdf] * [https://web.archive.org/web/20141020000838/http://paleopedia.free.fr/croco_thalattosuchia.html#Machimosaurus Images on French Paleopedia]

Category:Prehistoric pseudosuchian genera Category:Prehistoric marine crocodylomorphs Category:Early Cretaceous crocodylomorphs of Europe Category:Late Jurassic crocodylomorphs of Europe Category:Early Cretaceous crocodylomorphs of Africa Category:Late Jurassic genus first appearances Category:Early Cretaceous genus extinctions Category:Thalattosuchia Category:Fossil taxa described in 1837