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Spathicephalus
''Spathicephalus'' is an extinct genus of stem tetrapods (early four-limbed vertebrates) that lived during the middle of the Carboniferous Period. The genus includes two species: the type species ''S. mirus'' from Scotland, which is known from two mostly complete skulls and other cranial material, and the species ''S. pereger'' from Nova Scotia, which is known from a single fragment of the skull table. Based on the ''S. mirus'' material, the appearance of ''Spathicephalus'' is unlike that of any other early tetrapod, with a flattened, square-shaped skull and jaws lined with hundreds of very small chisel-like teeth. However, ''Spathicephalus'' shares several anatomical features with a family of stem tetrapods called Baphetidae, leading most paleontologists who have studied the genus to place it within a larger group called Baphetoidea, often as part of its own monotypic family Spathicephalidae. ''Spathicephalus'' is thought to have fed on aquatic invertebrates through a combination of suction feeding and filter feeding.
==History of study==
The type species of ''Spathicephalus'', ''S. mirus'', was named by paleontologist D. M. S. Watson in 1929. Watson described seven fossil specimens from an outcrop of the Rumbles Ironstone in the town of Loanhead in Midlothian, Scotland. The ironstone dates to the late Namurian stage (earliest Upper Carboniferous) and is part of the Limestone Coal Group. These specimens were discovered in the 1880s and include a mostly complete skull with the palate exposed, an impression of the underside of a skull roof, a right portion of the back of a skull, and various jaw fragments. At the time, ''Spathicephalus'' and other tetrapods from the Namurian of Scotland were some of the oldest tetrapods known, predating the better-known Late Carboniferous tetrapod assemblages of the British Coal Measures. In November 1974, Scottish paleontologist Stanley P. Wood discovered additional skull and jaw fragments of ''Spathicephalus'' in an open-pit mine (the Dora Open Cast Mine) near the town of Cowdenbeath in Fife. Wood found these fossils in a layer of siltstone that is the same age as the ironstone in Loanhead.
American paleontologist Donald Baird named a second species of ''Spathicephalus'', ''S. pereger'', from Nova Scotia in 1962.〔 Baird named ''S. pereger'' on the basis of an impression of the right half of a skull table that collectors from the Harvard Museum of Comparative Zoology found on a beach between Point Edward and Keating Cove on Cape Breton Island. The impression was preserved in siltstone from the Point Edward Formation, which dates to the latest Upper Carboniferous (equivalent to the early Namurian in Europe), meaning that ''S. pereger'' predates ''S. mirus'' by several million years.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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