Ebersole Jun A, Ehret Dana J
McWane Science Center, Birmingham, AL, USA.
University of Alabama, Alabama Museum of Natural History, Tuscaloosa, AL, USA.
PeerJ. 2018 Jan 8;6:e4229. doi: 10.7717/peerj.4229. eCollection 2018.
Decades of collecting from exposures of the Upper Cretaceous Tombigbee Sand Member of the Eutaw Formation and Mooreville Chalk in Alabama, USA has produced large numbers of isolated () teeth. Many of these teeth had formerly been assigned to the extinct Late Cretaceous shark (Agassiz, 1843), a taxon that is now considered largely restricted to the Turonian of Europe. Recent studies have shed light on the diversity of Late Cretaceous (.) taxa, and here we recognize a new species from Alabama, . The teeth of sp. nov. appear aligned with the members of the species group, but can be distinguished from these other species by a combination of the following: anterior teeth with a more pronounced and triangular lingual root protuberance, broader triangular cusp, and a taller root relative to the height of the crown; anteriorly situated lateroposterior teeth have a distally inclined or hooked main cusp and more than one pair of lateral cusplets; and lateroposterior teeth have a strong distally hooked main cusp and a root that is largely symmetrical in basal view. At present, sp. nov. is stratigraphically confined to the Santonian/Campanian Sigal, 1952 and Brotzen, 1934 Planktonic Foraminiferal Zones within the Tombigbee Sand Member of the Eutaw Formation and Mooreville Chalk, and teeth have been collected from only four counties in central and western Alabama. The recognition of sp. nov. in Alabama adds to our knowledge on the diversity and distribution of Late Cretaceous otodontids in the region.
在美国阿拉巴马州，数十年来从尤塔组汤比格比砂岩段和穆尔维尔白垩层的上白垩统地层中采集到了大量孤立的（）牙齿。这些牙齿中有许多以前被归为已灭绝的晚白垩世鲨鱼（阿加西，1843年），这一分类群现在被认为主要局限于欧洲的土伦阶。最近的研究揭示了晚白垩世（.）分类群的多样性，在此我们确认了一种来自阿拉巴马州的新物种，。新物种的牙齿似乎与物种组的成员一致，但可以通过以下特征组合与其他物种区分开来：前牙有更明显的三角形舌侧牙根突起、更宽的三角形牙尖以及相对于冠高更高的牙根；位于前方的后外侧牙有向远端倾斜或钩状的主牙尖和不止一对外侧小牙尖；后外侧牙有强烈向远端钩状的主牙尖，且牙根在基部视图中基本对称。目前，新物种在地层上局限于尤塔组汤比格比砂岩段和穆尔维尔白垩层内的桑托阶/坎帕阶（西加尔，1952年；布罗岑，1934年）浮游有孔虫带，且仅在阿拉巴马州中部和西部的四个县采集到了牙齿。在阿拉巴马州确认新物种增加了我们对该地区晚白垩世耳齿鲨科多样性和分布的了解。
