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Hyaenodontidae ("Hyena teeth") is a family of the extinct predatory mammals. The Hyaenodontids were important mammalian predators that arose during the late Paleocene and persisted well into the Miocene.〔 (1988): ''Dissopsalis'', a middle and late Miocene proviverrine creodont (Mammalia) from Pakistan and Kenya. ''Journal of Vertebrate Paleontology'' 48(1): 25-45.〕 They were considerably more widespread and successful than the oxyaenids, the other clade once considered part of Creodonta,.〔 (1985): ''The Field Guide to Prehistoric Life.'' Facts on File Publications, New York. ISBN 0-8160-1125-7〕 ==General Characteristics== Characterized by long skulls, slender jaws, slim bodies, and a tendency to walk on their toes rather than flat-footed (plantigrade), they generally ranged in size from 30 to 140 cm at the shoulder.〔 While ''Hyaenodon gigas'', the largest ''Hyaenodon'' species, was as much as 1.4 m high at the shoulder, 10 feet long and weighed about 500 kg, most were in the 5–15 kg range, equivalent to a mid-sized dog.〔 Fossil evidence of their skulls shows that they had a particularly acute sense of smell, while their teeth were adapted for shearing, rather than crushing.〔 Because of their size range, it is probable that different species hunted in different ways, which allowed them to fill many different predatory niches. Smaller ones would hunt in packs during the night like wolves, and bigger, fiercer ones would hunt alone during the daylight, using their sheer size and their mighty jaws as their principal weapon. The carnassials in a hyaenodontid are generally the second upper and third lower molars. However, some hyaenodontids possessed as many as three sequential pairs of carnassials or carnassial-like molar teeth in their jaws.〔Wang, Xiaoming; and Tedford, Richard H. Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press, 2008. p15〕 Hyaenodontids (like all creodonts) lacked post-carnassial crushing molar teeth (such as those found in many carnivoran families, especially the Canidae and Ursidae), and thus lacked dental versatility for processing any foods other than meat.〔Wang, Xiaoming; and Tedford, Richard H. Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press, 2008. p15-7〕 Hyaenodontids are very unusual in regards to their tooth replacement. Studies on ''Hyaenodon'' show that juveniles took 3–4 years in the last stage of tooth eruption, implying a very long adolescent phase. In North American forms, the first upper premolar erupts before the first upper molar, while European forms show an earlier eruption of the first upper molar.〔 At least one hyaenodontid lineage, Apterodontinae, was specialised for aquatic, otter-like habits.〔Camille Grohé, Michael Morlo, Yaowalak Chaimanee, Cécile Blondel, Pauline Coster, Xavier Valentin, Mustapha Salem, Awad A. Bilal, Jean-Jacques Jaeger, and Michel Brunet, New Apterodontinae (Hyaenodontida) from the Eocene Locality of Dur At-Talah (Libya): Systematic, Paleoecological and Phylogenetical Implications, Published online 2012 Nov 21. doi: 10.1371/journal.pone.0049054〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hyaenodontidae」の詳細全文を読む スポンサード リンク
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