Skip to main content Accessibility help

We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.

Close cookie message
×
Hostname: page-component-586b7cd67f-gb8f7 Total loading time: 0 Render date: 2024-11-25T08:14:54.663Z Has data issue: false hasContentIssue false

7 - Reassessing the Morphological Foundations of the Pythonomorph Hypothesis

from Part II - Palaeontology and the Marine-Origin Hypothesis

Published online by Cambridge University Press:  30 July 2022

By
Michael J. Polcyn ,
Bruno G. Augusta  and
Hussam Zaher
Edited by
David J. Gower  and
Hussam Zaher
David J. Gower
Affiliation:
Natural History Museum, London
Hussam Zaher
Affiliation:
Universidade de São Paulo
Get access

Summary

This chapter assesses morphological characters proposed to support the Pythonomorph Hypothesis— a purported close relationship between snakes and mosasaurians. With an emphasis on early diverging (non-mosasaurid) mosasaurians and mosaurids, new morphological data (including from high-resolution CT) for well-preserved dolichosaurid and mosasaurid fossils are presented. Details of the skull and mandibles are interpreted as supporting the monophyly of Mosasauria as the proximal outgroup of Varanoidea, to the exclusion of snakes. However, mosasaurians do deviate from the typical varanoid condition in aspects of their infraorbital foramen, ventral part of the lacrimal and its relationship with the prefrontal, anterior ramus of the ectopterygoid and its contact with the maxilla and jugal, lack of plicidentine, and (at least in early diverging mosasaurians) anguinoidean tooth replacement. We consider most characters previously reported as supporting the Pythonomorph Hypothesis to be problematic, because of incomplete fossil preparation, artefacts of taphonomy, limited comparisons, misinterpretations of anatomy, incomplete taxon sampling, or inadequate character formulation and/or scoring.

Keywords

morphologysystematicsphylogenysnakesmarine PythonomorphamosasaursfossilsVaranoidea
Type
Chapter
Information
The Origin and Early Evolutionary History of Snakes , pp. 125 - 156
Publisher: Cambridge University Press
Print publication year: 2022

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Townsend, T. M., Larson, A., Louis, E., and Macey, J. R., Molecular phylogenetics of Squamata: the position of snakes, amphisbaenians, and dibamids, and the root of the squamate tree. Systematic Biology, 53 (2004), 735–757.Google Scholar
Burbrink, F. T., Grazziotin, F. G., Pyron, R.A., et al., Interrogating genomic-scale data for Squamata (lizards, snakes, and amphisbaenians) shows no support for key traditional morphological relationships. Systematic Biology, 69 (2020), 502–520.Google Scholar
Estes, R., de Queiroz, K., and Gauthier, J. A.. Phylogenetic relationships within Squamata. In Estes, R. and Pregill, G. K., eds., Phylogenetic Relationships of the Lizard Families (Stanford, California: Stanford University Press, 1988), pp. 119–281.Google Scholar
Lee, M. S. Y., Convergent evolution and character correlation in burrowing reptiles: towards a resolution of squamate relationships. Biological Journal of the Linnean Society, 65 (1998), 369–453.Google Scholar
Conrad, J. L., Phylogeny and systematics of Squamata (Reptilia) based on morphology. Bulletin of the American Museum of Natural History, 310 (2008), 1–182.Google Scholar
Rieppel, O. and Zaher, H., The intramandibular joint in squamates, and the phylogenetic relationships of the fossil snake Pachyrhachis problematicus Haas. Fieldiana Geology, 43 (2000), 1–69.Google Scholar
Gauthier, J. A., Kearney, M., Maisano, J. A., Rieppel, O., and Behlke, A., Assembling the squamate tree of life: Perspectives from the phenotype and the fossil record. Bulletin of the Peabody Museum of Natural History, 53 (2012), 3–308.Google Scholar
Mulder, E. W. A., Maastricht Cretaceous finds and Dutch pioneers in vertebrate palaeontology. In Touret, J. L. R. and Visser, R. P. W., eds., Dutch Pioneers of the Earth Sciences (Amsterdam: Royal Netherlands Academy of Arts and Sciences, 2004), pp. 165–176.Google Scholar
Camper, A. G., Lettre de A.G. Camper à G. Cuvier sur les ossemens fossiles de la montagne de St. Pierre, à Maëstricht. Journal de Physique, de Chimie, et d’Histoire Naturelle, 51 (1800), 278–291.Google Scholar
Cuvier, G., Sur le grand animal fossile des carrières de Maestricht. Annales du Museum National d’Histoire Naturelle, 12 (1808), 145–176.Google Scholar
Cope, E. D., On the reptilian orders, Pythonomorpha and Streptosauria. Proceedings of the Boston Society of Natural History, 12 (1869), 250–266.Google Scholar
Camp, C. L., Classification of the lizards. Bulletin of the American Museum of Natural History, 48 (1923), 289–481.Google Scholar
Russell, D. A., Systematics and morphololgy of American mosasaurs (Reptilia, Sauria). Bulletin of the Peabody Museum of Natural History, 23 (1967), 1–241.Google Scholar
Nopcsa, F., Über die varanusartigen lacerten Istriens. Beiträge zur Paläontologie Österreich-Ungarns und des Orients, 15 (1903), 31–42.Google Scholar
Nopcsa, F., Eidolosaurus und Pachyophis: Zwei neue Neocom-Reptilien. Palaeontographica, 65 (1923), 99–154.Google Scholar
McDowell, S. B. and Bogert, C. M., The systematic position of Lanthanotus and the affinities of the anguinomorphan lizards. Bulletin of the American Museum of Natural History, 105 (1954), 1–142.Google Scholar
Lee, M. S. Y., The phylogeny of varanoid lizards and the affinities of snakes. Philosophical Transactions of the Royal Society of London, B352 (1997), 53–91.CrossRefGoogle Scholar
Caldwell, M. W. and Lee, M. S. Y., A snake with legs from the marine Cretaceous of the Middle East. Nature, 386 (1997), 705–709.Google Scholar
Lee, M. S. Y. and Caldwell, M. W., Anatomy and relationships of Pachyrhachis problematicus, a primitive snake with hindlimbs. Philosophical Transactions of the Royal Society of London. B353 (1998), 1521–1552.CrossRefGoogle Scholar
Lee, M. S. Y., Bell, G. L., and Caldwell, M. W., The origin of snake feeding. Nature, 400 (1999), 655–659.Google Scholar
Zaher, H., The phylogenetic position of Pachyrhachis within snakes (Squamata, Lepidosauria). Journal of Vertebrate Paleontology, 18 (1998), 1–3.Google Scholar
Zaher, H. and Rieppel, O., Tooth implantation and replacement in squamates, with special reference to mosasaur lizards and snakes. American Museum Novitates, 3271 (1999), 1–19.Google Scholar
Zaher, H. and Rieppel, O., The phylogenetic relationships of Pachyrhachis problematicus, and the evolution of limblessness in snakes (Lepidosauria, Squamata). Comptes Rendus de Séances de l’Académie des Sciences (Série IIA), Earth and Planetary Science, 329 (1999), 831–837.Google Scholar
Rieppel, O. and Zaher, H., The braincases of mosasaurs and Varanus, and the relationships of snakes. Zoological Journal of the Linnean Society, 129 (2000), 489–514.Google Scholar
Rieppel, O. and Kearney, M., The origin of snakes: limits of a scientific debate. Biologist (London), 48 (2001), 110–114.Google ScholarPubMed
Caldwell, M. W. and Cooper, J. A., Redescription, palaeobiogeography and palaeoecology of Coniasaurus crassidens Owen, 1850 (Squamata) from the Lower Chalk (Cretaceous; Cenomanian) of SE England. Zoological Journal of the Linnean Society, 127 (1999), 423–452.CrossRefGoogle Scholar
Caldwell, M. W., Description and phylogenetic relationships of a new species of Coniasaurus Owen, 1850 (Squamata). Journal of Vertebrate Paleontology, 19 (1999), 438–455.Google Scholar
Caldwell, M. W., On the aquatic squamate Dolichosaurus longicollis Owen, 1850 (Cenomanian, Upper Cretaceous), and the evolution of elongate necks in squamates. Journal of Vertebrate Paleontology, 20 (2000), 720–735.CrossRefGoogle Scholar
Caldwell, M. W., A new species of Pontosaurus (Squamata, Pythonomorpha) from the Upper Cretaceous of Lebanon and a phylogenetic analysis of Pythonomorpha. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, 34 (2006), 1–42.Google Scholar
Pierce, S. E. and Caldwell, M. W., Redescription and phylogenetic position of the Adriatic (Upper Cretaceous; Cenomanian) dolichosaur Pontosaurus lesinensis (Kornhuber, 1873). Journal of Vertebrate Paleontology, 24 (2004), 373–386.CrossRefGoogle Scholar
Paparella, I., Palci, A., Nicosia, U., and Caldwell, M. W., A new fossil marine lizard with soft tissues from the Late Cretaceous of southern Italy. Royal Society Open Science, 5 (2018), 172411.CrossRefGoogle ScholarPubMed
Garberoglio, F. F., Apesteguía, S., Simões, T. R., et al., New skulls and skeletons of the Cretaceous legged snake Najash, and the evolution of the modern snake body plan. Science Advances, 5 (2019), eaax5833.Google Scholar
Mekarski, M. C., Japundžić, D., Krizmanić, K., and Caldwell, M. W., Description of a new basal mosasauroid from the Late Cretaceous of Croatia, with comments on the evolution of the mosasauroid forelimb. Journal of Vertebrate Paleontology, 39 (2019), e1577872.CrossRefGoogle Scholar
Caldwell, M. W., Carroll, R. L., and Kaiser, H., The pectoral girdle and forelimb of Carsosaurus marchesetti [sic] (Aigialosauridae), with a preliminary phylogenetic analysis of mosasauroids and varanoids. Journal of Vertebrate Paleontology, 15 (1995), 516–531.Google Scholar
Bell, G. L., Jr. A phylogenetic revision of North American and Adriatic Mosasauroidea. In Callaway, J. M. and Nicholls, E. L., eds., Ancient Marine Reptiles (New York: Academic Press, 1997), pp. 293–332.Google Scholar
Palci, A. and Caldwell, M. W., Redescription of Acteosaurus tommasinii von Meyer, 1860, and a discussion of evolutionary trends within the clade Ophidiomorpha. Journal of Vertebrate Paleontology, 30 (2010), 94–108.CrossRefGoogle Scholar
deBraga, M. and Carroll, R. L., The origin of mosasaurs as a model of macroevolutionary patterns and processes. Evolutionary Biology, 27 (1993), 245–322.Google Scholar
Caldwell, M. W., Squamate phylogeny and the relationships of snakes and mosasauroids. Zoological Journal of the Linnean Society, 125 (1999), 115–147.Google Scholar
Páramo-Fonseca, M. E., Yaguarasaurus columbianus (Reptilia, Mosasauridae), a primitive mosasaur from the Turonian (Upper Cretaceous) of Colombia. Historical Biology, 14 (2000), 121–131.Google Scholar
Lee, M. S. Y. and Caldwell, M. W., Adriosaurus and the affinities of mosasaurs, dolichosaurs, and snakes. Journal of Paleontology, 74 (2000), 915–937.Google Scholar
Konishi, T. and Caldwell, M. W., New specimens of Platecarpus planifrons (Cope, 1874) (Squamata: Mosasauridae) and a revised taxonomy of the genus. Journal of Vertebrate Paleontology, 27 (2007), 59–72.Google Scholar
Bardet, N., Pereda Suberbiola, X., and Jalil, N.-E., A new mosasauroid (Squamata) from the Late Cretaceous (Turonian) of Morocco. Comptes Rendus Palevol, 2 (2003), 607–616.Google Scholar
Camp, C. L., California mosasaurs. Memoirs of the University of California, 13 (1942), 1–68.Google Scholar
Rieppel, O., Gauthier, J. A., and Maisano, J. A., Comparative morphology of the dermal palate in squamate reptiles, with comments on phylogenetic implications. Zoological Journal of the Linnean Society, 152 (2008), 131–152.Google Scholar
Conrad, J. L., Skull, mandible, and hyoid of Shinisaurus crocodilurus Ahl (Squamata, Anguimorpha). Zoological Journal of the Linnean Society, 141 (2004), 399–434.CrossRefGoogle Scholar
Bell, B. A., Murry, P. A., and Osten, L. W., Coniasaurus Owen, 1850 from North America. Journal of Paleontology, 56 (1982), 520–534.Google Scholar
Polcyn, M. J. and Bell, G. L., Jr., Russelosaurus coheni, n. gen., n. sp., a 92 million-year-old mosasaur from Texas (USA), and the definition of the parafamily Russellosaurina. Netherlands Journal of Geosciences, 84 (2005), 321–334.CrossRefGoogle Scholar
Dortangs, R. W., Schulp, A. S., Mulder, E. W. A., et al., A large new mosasaur from the Upper Cretaceous of The Netherlands. Netherlands Journal of Geosciences, 81 (2002), 1–8.Google Scholar
Rieppel, O. and Zaher, H., Re-building the bridge between mosasaurs and snakes. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 221 (2001), 111–132.CrossRefGoogle Scholar
Konishi, T., Caldwell, M. W., Nishimura, T., Sakurai, K., and Tanoue, K., A new halisaurine mosasaur (Squamata: Halisaurinae) from Japan: the first record in the western Pacific realm and the first documented insights into binocular vision in mosasaurs. Journal of Systematic Palaeontology, 14 (2016), 809–839.Google Scholar
Polcyn, M. J., Lindgren, J., Bardet, N., et al., Description of new specimens of Halisaurus arambourgi Bardet & Pereda Suberbiola, 2005 and the relationships of Halisaurinae. Bulletin de la Société Géologique de France, 183 (2012), 123–136.Google Scholar
Christensen, C. B., Christensen-Dalsgaard, J., Brandt, C., and Madsen, P. T., Hearing with an atympanic ear: good vibration and poor sound-pressure detection in the royal python, Python regius . Journal of Experimental Biology, 215 (2012), 331–342.Google Scholar
Holliday, C. M., Gardner, N. M., Paesani, S. M., Douthitt, M., and Ratliff, J. L., Microanatomy of the mandibular symphysis in lizards: patterns in fiber orientation and Meckel’s cartilage and their significance in cranial evolution. Anatomical Record, 293 (2010), 1350–1359.Google Scholar
Lessmann, M. H., Zur labialen Pleurodontie an Lacertilier-Gebissen. Anatomischer Anzeiger, 99 (1952), 35–67.Google Scholar
Bertin, T. J., Thivichon-Prince, B., LeBlanc, A. R., Caldwell, M. W., and Viriot, L., Current perspectives on tooth implantation, attachment, and replacement in Amniota. Frontiers in Physiology, 9 (2018), 1630.Google Scholar
Gauthier, J. A., Fossil xenosaurid and anguid lizards from the early Eocene Wasatch Formation, southeast Wyoming, and a revision of the Anguioidea. Contributions to Geology, University of Wyoming, 21 (1982), 7–54.Google Scholar
Polcyn, M. J., Tchernov, E., and Jacobs, L. L., The Cretaceous biogeography of the eastern Mediterranean with a description of a new basal mosasauroid from ‘Ein Yabrud, Israel. In Tomida, Y., Rich, T. H. and Vickers-Rich, P., eds., Proceedings of the Second Gondwanan Dinosaur Symposium (National Science Museum Monograph 15), (Tokyo: National Science Museum, 1999), pp. 259–290.Google Scholar
Haber, A. and Polcyn, M. J., A new marine varanoid from the Cenomanian of the Middle East. Netherlands Journal of Geosciences, 84 (2005), 247–255.Google Scholar
Rieppel, O., Tooth replacement in anguinomorph lizards. Zoomorphologie, 91 (1978), 77–90.Google Scholar
Kelley, N. P. and Pyenson, N. D., Evolutionary innovation and ecology in marine tetrapods from the Triassic to the Anthropocene. Science, 348 (2015), aaa3716.Google Scholar
Houssaye, A., Palaeoecological and morphofunctional interpretation of bone mass increase: an example in Late Cretaceous shallow marine squamates. Biological Reviews, 88 (2013), 117–139.Google Scholar
Caldwell, M. W., Ontogeny and phylogeny of the mesopodial skeleton in mosasauroid reptiles. Zoological Journal of the Linnean Society, 116 (1996), 407–436.Google Scholar
Rieppel, O., Helveticosaurus zollingeri Peyer (Reptilia, Diapsida) skeletal paedomorphosis, functional anatomy and systematic affinities. Palaeontographica Abteilung A, Paläozoologie, Stratigraphie, 208 (1989), 123–152.Google Scholar
Bell, G. L. and Polcyn, M. J., Dallasaurus turneri, a new primitive mosasauroid from the Middle Turonian of Texas and comments on the phylogeny of Mosasauridae (Squamata). Netherlands Journal of Geosciences, 84 (2005), 177–194.Google Scholar
Sullivan, C., The role of calcaneal ‘heel’ as a propulsive lever in basal archosaurs and extant monitor lizards. Journal of Vertebrate Paleontology, 30 (2010), 1422–1432.CrossRefGoogle Scholar
Houssaye, A., Lindgren, J., Pellegrini, R., et al., Microanatomical and histological features in the long bones of mosasaurine mosasaurs (Reptilia, Squamata) – implications for aquatic adaptation and growth rates. PLoS ONE, 8 (2013), e76741.CrossRefGoogle Scholar
Rieppel, O., Zaher, H., Tchernov, E., and Polcyn, M. J., The anatomy and relationships of Haasiophis terrasanctus, a fossil snake with well-developed hind limbs from the Mid-Cretaceous of the Middle East. Journal of Paleontology, 77 (2003), 536–558.Google Scholar

Save book to Kindle

To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×