Chinsamy Anusuya, Cerda Ignacio, Powell Jaime
University of Cape Town, Department of Biological Sciences, Private Bag X3, Rhodes Gift, 7700 South Africa.
CONICET, Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Museo Carlos Ameghino, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta) 8300, Cipolletti, Río Negro, Argentina.
Sci Rep. 2016 Apr 26;6:24858. doi: 10.1038/srep24858.
The presence of well-vascularised, endosteal bone in the medullary region of long bones of nonavian dinosaurs has been invoked as being homologous to medullary bone, a specialised bone tissue formed during ovulation in birds. However, similar bone tissues can result as a pathological response in modern birds and in nonavian dinosaurs, and has also been reported in an immature nonavian dinosaur. Here we report on the occurrence of well-vascularised endosteally formed bone tissue in three skeletal elements of armoured titanosaur sauropods from the Upper Cretaceous of Argentina: i) within the medullary cavity of a metatarsal, ii) inside a pneumatic cavity of a posterior caudal vertebra, iii) in intra-trabecular spaces in an osteoderm. We show that considering the criteria of location, origin (or development), and histology, these endosteally derived tissues in the saltasaurine titanosaurs could be described as either medullary bone or pathological bone. Furthermore, we show that similar endosteally formed well-vascularised bone tissue is fairly widely distributed among nondinosaurian Archosauriformes, and are not restricted to long bones, but can occur in the axial, and dermal skeleton. We propose that independent evidence is required to verify whether vascularised endosteal bone tissues in extinct archosaurs are pathological or reproductive in nature.
非鸟类恐龙长骨骨髓区域中存在血管丰富的骨内膜骨，这被认为与骨髓骨同源，骨髓骨是鸟类排卵期间形成的一种特殊骨组织。然而，类似的骨组织在现代鸟类和非鸟类恐龙中也可能作为病理反应出现，并且在一只未成熟的非鸟类恐龙中也有报道。在此，我们报告在阿根廷上白垩统的披甲泰坦巨龙类蜥脚类恐龙的三个骨骼元素中出现了血管丰富的骨内膜形成的骨组织：i）在一根跖骨的髓腔内；ii）在一枚尾椎骨的气腔内；iii）在一块皮内成骨的小梁间隙内。我们表明，考虑到位置、起源（或发育）和组织学标准，盐龙类泰坦巨龙中的这些骨内膜衍生组织可被描述为骨髓骨或病理骨。此外，我们表明，类似的由骨内膜形成的血管丰富的骨组织在非恐龙类主龙形类中分布相当广泛，并且不仅限于长骨，还可出现在轴骨骼和真皮骨骼中。我们提出，需要独立的证据来验证已灭绝主龙类中血管化的骨内膜骨组织在本质上是病理性的还是与繁殖相关的。
