LATE CRETACEOUS TROODONTID EGGS FROM TIANTAI,ZHEJIANG

The unique nesting and egg-laying behaviors of troodontids differ from those of other dinosaurs in that troodontids laid their eggs standing up in sands or muddy soil.The clutches of fossil troodontid eggs have been unearthed from the Mid-Upper Cretaceous sedimentary sequences in Inner Mongolia,Henan and Guangdong.The fossil skeletons of troodontid were found in the Lower Cretaceous strata of Inner Mongolia and Liaoning provinces.Here,we describe a clutch of fossil troodontid eggs in the Cretaceous Chichengshan Formation from Tiantai Basin,Zhejiang Province.The specimens we discovered indicate that the troodontid egg-shell was as rigid as that of some modern bird eggs and was sufficiently strong to resist the pressure while the egg was forced into sands and muddy soil when it was laid.Most other dinosaur eggshells,in contrast,were stretchable as some modern reptile eggs.Dinosaur eggs with stretchable egg-shell are preserved as flattened,circular or oval in outline.In other words,the procreant system of troodontid resembled,to some extent,some modern birds in egg-shell formation.More-over,the troodontid eggs in nest stood aslant more or less outwards.This suggested that an adult female troodontid faced outwards while laying eggs vigilantly.This behavior could be an adaptation to severe competition.

Project Supported:

Clc Number:

Q91