|
Saurocephalus 〔Harlan, R. 1824. On a new fossil genus of the order Enalio Sauri, (of Conybeare). Journal of the Academy of Natural Sciences of Philadelphia. Series 1, 3(pt. 2): 331-337.〕 is an extinct genus of fishes within the family Saurodontidae Cope, 1871. Members of this family (saurodontids) were teleostean fishes restricted to the upper Cretaceous. They are placed within the Ichthyodectiformes, an extinct order of fish known from the middle Jurassic to the late Cretaceous with species found in almost every continent of the world. From among the almost 20 genera included in the order, saurodontids are more closely related to ''Gillicus'', ''Xiphactinus'', and ''Ichthyodectes''.〔Maisey, J. G.1991. Santana Fossils, an Illustrated Atlas. New Jersey, T.F.H. Publications Inc., 190–207.〕 Saurodontidae currently includes three genera, ''Saurodon'', ''Saurocephalus'', and ''Prosaurodon''. Members of the three genera were first collected from the upper Cretaceous Western Interior Sea of North America (Niobrara Formation). Consequent finds from elsewhere around the globe indicated saurodontids had a much wider geographical distribution including Europe and the Middle East where some of the best preserved and complete specimens come from the latest Maastrichtian of Jordan.〔Kaddumi, H. F. 2009. Saurodontids (Ichthyodectiformes: Saurocephalus) of Harrana with a description of a new species from the late Maastrichtian Muwaqqar Chalk Marl Formation. In: Fossils of the Harrana Fauna and the Adjacent Areas. Publications of the Eternal River Museum of Natural History, Amman, pp 215-231. 〕 Apparently, the three genera occurred at different time intervals. While the oldest might have been ''Saurodon'' known to occur as early as the late Coniacian, the youngest is ''Saurocephalus'' which first appeared during the early Campanian and continued on to the latest Maastrichtian. Although saurodontids were geographically widely distributed and continued until the end of the Cretaceous, they remained only moderately taxonomically diversified. Among the intriguing characters of saurodontid fishes which clearly distinguish them is the toothless unpaired bony predentary that projected from the lower jaw giving the fish a very characteristic appearance. The genus ''Saurocephalus'' is almost entirely represented by fragmentary specimens with the exception of a single complete and superbly well preserved specimen collected from latest Maastrichtian deposits of Jordan, ''Saurocephalus longicorpus''.〔 The complete material from Jordan offered an extensive amount of valuable information about ''Saurocephalus''.〔 With an elongate, torpedo-like body, saurocephalids were extremely fast open water formidable ambush predators. The morphology of their teeth and jaw structure suggest they were meat eaters. The closely set very sharp and firmly anchored teeth lined up along the upper and lower jaws acted together like sharp serrated scissors. The ventral extension of the upper jaw deep unto the sides of the lower jaw made the jaws perform like meat slicers. Saurocephalids were powerful and ferocious predators with powerful jaws capable of slicing and biting off large chunks of meat from their potential prey items. No doubt, fish was on top of the diet list. The large sizes attained by some saurocephalids which exceed two meters in length, may indicate they were capable of handling larger prey items such as smaller marine reptiles and sharks. To process large prey, they would cut them into smaller more manageable pieces using their powerful large jaws and sharp teeth. A close modern analogue of saurocephalids and to the matter saurodontids, would be barracudas (''Sphyraena barracuda'') known to ambush, ram, and stun their prey using the strong anterior projection of the dentary. Although not as notably elongate, the overall body outline of barracudas is similar to saurocephalids. == External links == *(Saurocephalus, Saurodon and Prosaurodon, sword-eels of the Late Cretaceous ) 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「Saurocephalus」の詳細全文を読む スポンサード リンク
|