Water Reptiles of the Past and Present

Name: Water Reptiles of the Past and Present
Author: Williston, Samuel Wendell

Williston, Samuel Wendell

Aquatic reptiles; Aquatic reptiles, Fossil

Order =CHELONIA=
        Temporal region imperforate. Head and limbs more or less
        retractile within a box formed chiefly by the exoskeleton.
        Suborder =Pleurodira=     Triassic to recent.
                 =Cryptodira=     Jurassic to recent.
                 =Trionychoidea=  Cretaceous to recent.

    Order =THEROMORPHA=
        Primitive reptiles with notochordal vertebrae, perforate
        temporal region, persistent intercentra; two coracoids;
        plate-like pelvis with median vacuity; no free
        dermosupraoccipitals in skull; longer legs and neck;
        phalangeal formula 2, 3, 4, 5, 3(4).
        Suborder =Pelycosauria= (_sens. lat._) Permocarboniferous,
                                                  North America, Europe.
                  =Dromasauria=                 Upper Permian, Africa.
                  =Dinocephalia=                Middle and Upper
                                                      Permian, Africa.

    Order =THERAPSIDA=
        Reptiles with a single temporal perforation on each side;
        vertebrae not notochordal; intercentra not persistent;
        pelvis with vacuity; skull bones reduced; teeth heterodont;
        phalangeal formula, 2, 3, 3, 3, 3.
        Suborder =Anomodontia=    Permo-Trias, Africa, North America.
                 =Therocephalia=  Upper Permian, Africa.
                 =Theriodontia=   Trias, Africa.

    Order =SAUROPTERYGIA=
        Aquatic reptiles with a single temporal vacuity; no
        supratemporal bone, or quadratojugal; ribs single-headed,
        diapophysial; coracoids large, meeting in middle line,
        single; neck long, tail short.
        Suborder =Nothosauria=   Triassic, Europe.
                 =Plesiosauria=  Triassic to close of Cretaceous,
                                                      cosmopolitan.

    ⃰Order =PROGANOSAURIA=
        Primitive aquatic reptiles; single (? upper) temporal
        perforation; neck elongate; nares posterior; vertebrae
        notochordal; intercentra persistent; pelvis plate-like;
        phalangeal formula 2, 3, 4, 5, 4(6). Permocarboniferous,
        Africa, South America.

    Order =ICHTHYOSAURIA=
        Reptiles with all aquatic adaptations; a single, upper
        temporal perforation; both supratemporal and squamosal
        present; a single coracoid. Middle Triassic to Benton
        Cretaceous, cosmopolitan.

    ⃰Order =PROTOROSAURIA=
        A single, upper temporal vacuity, quadrate fixed (neck
        vertebrae elongate); bones hollow; cervical ribs
        single-headed, articulating with centrum; pelvis plate-like.
        Permian, North America, Europe.

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Water Reptiles of the Past and Present

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