page_title: Postosuchus
section_title: Skull
hierarchical_section_title: Postosuchus / Description / Skull
caption_attribution_description: English: Petrified Forest National Park. Arizona. Dinosaur Fossil.
context_page_description: Postosuchus, meaning "Crocodile from Post", is an extinct genus of rauisuchid reptiles comprising two species, P. kirkpatricki and P. alisonae, that lived in what is now North America during the Late Triassic. Postosuchus is a member of the clade Pseudosuchia, the lineage of archosaurs that includes modern crocodilians. Its name refers to Post Quarry, a place in Texas where many fossils of the type species, P. kirkpatricki, were found. It was one of the apex predators of its area during the Triassic, larger than the small dinosaur predators of its time. It was a hunter which probably preyed on large large bulky herbivores like dicynodonts and many other creatures smaller than itself.
  The skeleton of Postosuchus is large and robust with a deep skull and a long tail. The total body length is about 4 to 5 metres. The extreme shortness of the forelimbs relative to the hind limbs, the very small hands, and measurements of the vertebrae suggest that Postosuchus may have been committed to bipedal locomotion.
context_section_description: The skull of Postosuchus was constructed narrow in front and extended wide and deep behind. It was 55 cm in length and 21 cm broad and deep. There are many fenestrae (openings) present in the bones that lighten the skull, providing space for the muscles. Like more derived archosaurs, the lower jaw had mandibular fenestrae (openings at the lower jaw), formed by the junction of the dentary with other jaw bones (surangular and angular). Postosuchus had very good long distant sight, due to large orbits, supporting large and sharp eyes, and strong olfaction provided by elongated nostrils. Inside the skull, under the nostrils, there was a hollow that may have contained the Jacobson's organ, an olfactory sensory organ sometimes referred as the "sixth sense". The jaws held large and sharp serrated teeth, of which some were developed even larger to operate as hooked sabers. A complete tooth found among Postosuchus remains in North Carolina measured about 7.2 cm in height. Postosuchus possessed heterodonty dentition, which means each tooth was different in size and shape from the others. The upper jaw contained seventeen teeth, with each premaxilla bearing only four teeth and each maxilla thirteen teeth. In the lower jaw were over thirty teeth. Replacement activity in Postosuchus was different from that of crocodiles, since the replacement tooth didn't fit directly in the pulp cavity of the old tooth, but grew until resorption of the old tooth was complete.
caption: Skull cast
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