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Figure 2 in Nanotyrannus, a new genus of pygmy tyrannosaur, from the latest Cretaceous of Montana

Bakker, R. T.,; Williams, M.; Currie, P. J.


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{
  "publisher": "Zenodo", 
  "DOI": "10.5281/zenodo.3358013", 
  "container_title": "Hunteria", 
  "title": "Figure 2 in Nanotyrannus, a new genus of pygmy tyrannosaur, from the latest Cretaceous of Montana", 
  "issued": {
    "date-parts": [
      [
        1988, 
        12, 
        31
      ]
    ]
  }, 
  "abstract": "Figure 2\u2014Branching diagram of the tyrannosaurids and fheir close allies, with lateral views of the skulls shown in correct stratigraphic sequence. Nodes and the derived characters that define them: 1) Neotheropoda (Late Jurassic- Latest Cretaceous) \u2014 premaxillary tooth crowns strongly assymmetrical, with inner (lingual) face nearly flat and outer (buccal) face strongly convex; premax. symphysis U-shaped in dorsal view; intramandibular joint fully developed, with anterior prong of the angular penetrating into the cavity between the dentary and splenial. 2) Ceratosauridae (Late Jurassic) \u2014 premaxillary tooth count reduced to three; premaxillary incisors with thick, strong sulci and ridges on the inner face. 3) Advanced neotheropods (Late Jurassic-Latest Cretaceous) \u2014 occiput much deeper above the foramen magnum, as seen in posterior view; accessory antorbital fenestra present; posterior shafts of cervical ribs do not overlap one another; presacral column compresssed fore- to-aft relative to femur length; scapula blade very narrow throughout its length. 4) Allosauridae (LateJurassic) \u2014 parocdpital process bent downwards strongly; basituber with a deep notch in the posterior-ventral edge for the ilio-costalis cervicis-capitis muscle; sphenethmoid ossification weak. 5) Very advanced neotheropods (Early Cretaceous-Latest Cretaceous) \u2014 ascending process of astragulus very tall, wide transversely and thin front-to-back; nasals narrow. 6) Dromaeosauridae (Early Cretaceous-Latest Cretaceous (Deinonychus) \u2014 pubis turned backwards; second hindclaw very large and sickle-shaped; distal half of tail encased within basketwork of bony rods developed from chevrons and prezygapophyses. 7) Tyrannosauroidea (Early Cretaceous-Latest Cretaceous) \u2014 paroccipital process very deep top-to-bottom at the root; large excavation around the fenestra ovalis and pneumatization of the paroccipital root. 8) Acrocanthosaurids (Early Cretaceous) \u2014 neural spine of cervicals and dorsals elongated. 9) Advanced tvrannosauroids (Late Cretaceous) \u2014 occiput deeper above the supraoccipital wedge; metatarsal bundle very long and compressed side-to-side, with strong pinching of the proximal end of metatarsal III. 10) Ornithomimids + tro\u00f6dontids + birds +?oviraptorids (?Latest Jurassic-Latest Cretaceous) \u2014 periotic region with large depression and highly pneumatic. 11) Tyrannosauridae (Late Cretaceous) \u2014 adductor muscle scar developed forward over the frontals to a position opposite the orbits; squamosal-quadratojugal suture very long, straight and nearly parallel to the long axis of the skull, as seen in side view; supraoccipital ' wedge with two tabs of bone placed in tandem; first maxillary tooth like the four premaxillary teeth; all incisiform teeth very crowded and narrow across buccal face; parietal occipital wings very tall above the supraoccipital; large oval foramen in jugal. 12) Nanotyrannus (Latest Cretaceous, Lanciat Faunal Age) \u2014very wide basicranial boxwork with flat ventral floor; verv wide frontal-orbital region with very narrow snout; parietal wing of occiput with sharp angle between dorsal and lateral edges. 13) Rough-snouted tyrannosaurids (Late Cretaceous) \u2014 dorsal surface of nasals very rough, with irregular longitucinal striae and ridges. 14) Daspletosaurus torosus (Late Cretaceous, Judithan Faunal Age) \u2014 snout and mandible short front-toback and deep; teeth large and reduced in number; lachrimal horn developed into blunt triangular apex. 15) Tyrannosaurids with anterior pneumatic foramina in basicranial boxwork (Late Cretaceous). 16) Ahoramus (Late Cretaceous, Nemegt Fauna) \u2014 multiple oval hornlets on nasals. 17) Massive snouted tyrannosaurids with anterior basicranial foramina (Late Cretaceous) \u2014 snouts and mandibles short and deep; tooth count reduced. 18) New genus and species from the Horseshoe Canyon Formation Late Cretaceous) \u2014 orbit closed off from below by prong of postorbital. 19) Tyrannosaurids with large anterior foramina. 20) Gorgosaurus (Late Cretaceous, Judithan Faunal Age) \u2014 lachrimal horn developed into apex that is directed forward. 21) Tyrannosaurids with large foramina and wide basicrania (Late Cretaceous) \u2014 orbit closed off from below by postorbital; lachrimal and postorbital swollen above orbits; lachrimal swollen around pneumatic foramen; maxillary tooth row curved more strongly; maxillary tooth count reduced; mandible deeper; basicranial boxwork wider; first maxillary tooth enlarged. 22) Tarbosaurus (Late Cretaceous, Nemegt Fauna) \u2014 tooth crowns swollen and thick for their height. 23) Tyrannosaurus (Latest Cretaceous, Lancian Fauna) \u2014 teeth strongly procumbent; mandible very deep; lachrimal and postorbital very swollen above and behind orbit; muscle attachment surface, for anterior pterygoideus, at posterior-dorsal corner of antorbital fenestra eliminated by swelling oflachrimal; pneumatic foramen in lachrimal surrounded by grossly swollen bone; basicranium compressed fore-to-aft and basitubera displaced forward against basipterygoid processes", 
  "author": [
    {
      "family": "Bakker, R. T.,"
    }, 
    {
      "family": "Williams, M."
    }, 
    {
      "family": "Currie, P. J."
    }
  ], 
  "page": "1-30", 
  "volume": "1", 
  "type": "figure", 
  "id": "3358013"
}
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