白垩纪伤齿龙竖直成对螺旋排列产卵方式

A Cretaceous troodontid laid her pairs of eggs vertically and arranged spirally in a nest

伤齿龙类(troodontids)与其他恐龙不同,生蛋时将蛋竖直插入巢穴内松软泥沙里。此窝产自中国浙江天台盆地上白垩统赤城山组地层的恐龙蛋化石,显示该种恐龙每次产2枚蛋,从巢穴中心开始,向外依次螺旋排列,每窝可超过20枚。暗示雌性伤齿龙类与雌性盗蛋龙类一样,有1对均具输卵功能的输卵管,一次又一次地在一个固定巢穴生蛋,并时常照看这些蛋。此外,伤齿龙类恐龙的蛋壳像某些现代鸟类的蛋壳一样坚固,足以承受其插入泥沙时的压力。而其他一些恐龙的蛋壳更像某些现代爬行类的蛋壳,是韧性的,在重力作用下往往呈扁球形。

Unlike other dinosaurs,the troodontids laid their eggs standing up in loose sands or muddy soil.The clutch of fossil troodontid eggs in the Upper Cretaceous Chichengshan Formation from Tiantai Basin,Zhejiang Province,China indicated that these creatures produced a pair of eggs every time in open nests and covered them with sands or muddy soil and laid their eggs starting at the center of the nest,then screwed in turn outward laying more than 20 eggs per nest.It suggests that a female troodontid had a pair of functional oviducts as that of oviraptorosaurs,and laid her eggs again and again in a single nest and perhaps looked after these eggs frequently.The troodontid eggshell,furthermore,was rigid as that of some modern bird eggs and strong enough to resist pressure while the eggs were forced into sands and muddy soil when they were laid.Some of the other dinosaur eggshells,in contrast,were stretchable as those of some modern reptiles.