Chiarenza Alfio Alessandro, Cau Andrea
Department of Earth Science and Engineering, Imperial College London , London , United Kingdom.
Earth, Life and Environmental Sciences, University of Bologna, Bologna, Italy; Geological and Palaeontological Museum "G. Capellini,"Bologna, Italy.
PeerJ. 2016 Feb 29;4:e1754. doi: 10.7717/peerj.1754. eCollection 2016.
We describe the partially preserved femur of a large-bodied theropod dinosaur from the Cenomanian "Kem Kem Compound Assemblage" (KKCA) of Morocco. The fossil is housed in the Museo Geologico e Paleontologico "Gaetano Giorgio Gemmellaro" in Palermo (Italy). The specimen is compared with the theropod fossil record from the KKCA and coeval assemblages from North Africa. The combination of a distally reclined head, a not prominent trochanteric shelf, distally placed lesser trochanter of stout, alariform shape, a stocky shaft with the fourth trochanter placed proximally, and rugose muscular insertion areas in the specimen distinguishes it from Carcharodontosaurus, Deltadromeus and Spinosaurus and supports referral to an abelisaurid. The estimated body size for the individual from which this femur was derived is comparable to Carnotaurus and Ekrixinatosaurus (up to 9 meters in length and 2 tons in body mass). This find confirms that abelisaurids had reached their largest body size in the "middle Cretaceous," and that large abelisaurids coexisted with other giant theropods in Africa. We review the taxonomic status of the theropods from the Cenomanian of North Africa, and provisionally restrict the Linnean binomina Carcharodontosaurus iguidensis and Spinosaurus aegyptiacus to the type specimens. Based on comparisons among the theropod records from the Aptian-Cenomanian of South America and Africa, a partial explanation for the so-called "Stromer's riddle" (namely, the coexistence of many large predatory dinosaurs in the "middle Cretaceous" record from North Africa) is offered in term of taphonomic artifacts among lineage records that were ecologically and environmentally non-overlapping. Although morphofunctional and stratigraphic evidence supports an ecological segregation between spinosaurids and the other lineages, the co-occurrence of abelisaurids and carcharodontosaurids, two groups showing several craniodental convergences that suggest direct resource competition, remains to be explained.
我们描述了来自摩洛哥塞诺曼阶“凯姆凯姆复合动物群”（KKCA）的一具大型兽脚亚目恐龙部分保存的股骨。该化石保存在巴勒莫（意大利）的“盖塔诺·乔治·杰梅拉罗”地质与古生物博物馆。将该标本与KKCA的兽脚亚目化石记录以及来自北非的同期动物群进行了比较。标本中远端倾斜的头部、不突出的转子嵴、粗壮且呈翼状的远端小转子、近端有第四转子的粗壮骨干以及有皱纹的肌肉附着区域的组合，使其有别于鲨齿龙、三角洲奔龙和棘龙，并支持将其归入阿贝力龙科。这具股骨所属个体的估计体型与食肉牛龙和埃氏猎龙相当（体长可达9米，体重2吨）。这一发现证实阿贝力龙科在“白垩纪中期”已达到其最大体型，并且大型阿贝力龙科与非洲的其他巨型兽脚亚目恐龙共存。我们回顾了北非塞诺曼阶兽脚亚目的分类地位，并暂时将林奈双名法中的伊吉迪鲨齿龙和埃及棘龙限定于模式标本。基于对南美洲和非洲阿普第阶 - 塞诺曼阶兽脚亚目记录的比较，从生态和环境不重叠的谱系记录中的埋藏学假象方面，对所谓的“施特罗默之谜”（即北非“白垩纪中期”记录中有许多大型掠食性恐龙共存）给出了部分解释。尽管形态功能和地层证据支持棘龙科与其他谱系之间存在生态隔离，但阿贝力龙科和鲨齿龙科这两个在颅齿方面有若干趋同特征表明存在直接资源竞争的类群的共存情况仍有待解释。
