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Saber-toothed cat

    The term '''saber-toothed cat''' describes numerous cat-like species of the that lived during various parts of the Cenozoic that evolved their saber-toothed characteristics entirely independently The saber-tooth morphology (biology)|morphology is an excellent example of convergent evolution as it occurred repeatedly and independently in at least four distinct mammalian groups

    Saber-tooth genera

    The genera of sabre-toothed cats along with the regions and time periods where they have been found is summarized here:
    '''Genus Name''' '''Number of Species''' '''Times''' '''Regions'''
    ''Smilodon'' 4 25 MYA to 11000 YA North America
    ''Hoplophoneus'' 5 337 MYA to 238 MYA North and South America
    ''Homotherium'' 1 3 MYA to 10000 YA Europe and Asia
    ''Thylacosmilus'' (marsupial) 1 10 MYA to 1.8 MYA Australia
    ''Metailurus'' 1 15 MYA to 8 MYA China and Eastern Europe
    ''Machairodus'' (Ancestral to ''Homotherium'') 5 15 MYA to 2 MYA Africa Europe Asia and North America
    ''Megantereon'' 2 3 MYA - 9000 Years Ago Africa Eurasia and North America
    ''Dinofelis'' 5 5 MYA to 1.5 MYA Africa Eurasia and North America
    ''Paramachairodus'' 2 20-15 MYA to 9 MYA Spain
    ''Xenosmilus'' (1 specimen) 1 1 MYA (?) Central Florida

    Saber-tooth evolutionary tree

    All saber-tooth mammals lived between 9000 and 337 million years ago but the evolutionary lines that lead to the various saber-tooth genera started to diverge much earlier
    The lineage that led to Thylacosmilus was the first to split off in the late Cretaceous It is a marsupial and thus more closely related to kangaroos and opossums than the felines The creodonts diverged next and then the nimravids before they blossoming of the truly feline saber-tooths
    • Class Mammalia
      • Subclass Marsupialia (diverged ? MYA in the Cretaceous)
        • Order Sparassodonta (an extinct South American group of marsupials)
          • Family Borhyaenidae (South American marsupial carnivores)
          • Thylacosmilus
      • Subclass Placentalia
        • Order Creodonta (diverged ? MYA in the Paleocene)
          • Family Hyaenodontidae
            • ?Hyaenodontid genus
        • Order Carnivora
          • Family Nimravidae (diverged from the felioformes 48–55 MYA in the late Eocene)
            • Hoplophoneus
          • Family Felidae (true cats)
            • Subfamily Machairodontinae (diverged ? MYA in the ?)
              • Tribe Homotheriini
                • Homotherium
                • Machairodus
                • Xenosmilus
              • Tribe Metailurini
                • Dinofelis
                • Metailurus
              • Tribe Smilodontini
                • Megantereon
                • Paramachairodus
                • Smilodon

    Why such large teeth?

    The most dramatic feature common to all of the so-called saber-toothed cats is their enlarged upper canines While it is generally agreed upon that they were used in hunting the exact way they were used has been debated since the 1880s when Smilodon was first described


    Some paleontologists believe that the primary purpose is to grab and hold large prey This is not well supported by evidence however as it has been shown that saber-teeth used in this way may be broken relatively easily and fossil skulls with broken saber-teeth are rare


    A more accepted hypothesis suggests that saber-teeth were used for a shearing bite to the throat or abdomen of large prey (Akersten 1985) or to deliver deep stab wounds from which the prey would eventually bleed to death


    Another possible use was as a social display structure (like most horns and antlers) If this is the case it would support the theory that sabertooths were social animals

    External links