Modified laminar bone did not stop sauropods from achieving large body sizes

An almost complete dinosaur femur found in the Baynshire Formation (late Cenomanian to Santonian; Mongolia) in 1963 during the Polish–Mongolian Paleontological Expeditions is described here for the first time. The morphology of the femur and bone histology suggest that the specimen was a representative of the Titanosauriformes, the predominant sauropod clade during the Cretaceous. Bone tissue exclusive to this clade, modified laminar bone that indicates a reduced growth rate, is identified in the thin sections taken from the femur. Based on its bone histology, the already ca. 20-meter-long specimen appears to be a subadult. This specimen achieved a significantly larger size compared with other Titanosauriformes with modified lamellar bone at a similar growth stage.

1963年波兰-蒙古古生物考察期间在拜恩希尔组（晚森诺曼期至桑托期；蒙古）发现的一具近乎完整的恐龙股骨，在此首次得到描述。股骨的形态学特征与骨组织学分析表明，该标本属于泰坦巨龙形类（Titanosauriformes）——白垩纪时期占主导地位的蜥脚类恐龙支系。在股骨的薄片样本中，发现了该支系特有的骨组织——改良层状骨（modified laminar bone），这一特征表明其生长速率有所降低。根据骨组织学特征判断，这具体长已达约20米的标本应为亚成体。与其他处于相似生长阶段且具有改良层状骨的泰坦巨龙形类相比，该标本的体型显著更大。