Farke Andrew A, Phillips George E
Raymond M. Alf Museum of Paleontology, Claremont, CA, USA.
Mississippi Museum of Natural Science, Mississippi Department of Wildlife, Fisheries, and Parks, Jackson, MS, USA.
PeerJ. 2017 May 23;5:e3342. doi: 10.7717/peerj.3342. eCollection 2017.
Ceratopsids ("horned dinosaurs") are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.
角龙科（“有角恐龙”）在北美洲西部和亚洲被发现，这种分布反映出白垩纪晚期两个大陆之间推测存在的陆桥连接。然而，此前在北美洲东部尚未发现这个类群，可能是由于合适年代和沉积环境的露头有限，以及在白垩纪晚期的大部分时间里，北美洲东部和西部被西部内陆海道分隔开来。来自密西西比州尤宁县猫头鹰溪组（马斯特里赫特晚期）的一枚齿骨牙齿，是北美洲东部首次报道的角龙科化石。这颗牙齿展现出角龙科典型的一系列特征，包括双根和突出的、刀片状的隆脊。基于化石的年代，我们推测这与角龙科在白垩纪最晚期扩散到北美洲东部相符，大概是在西部内陆海道退缩后北美洲两半重新连接之后。
