Jiranrai of Left Alxa Banner, Inner Mongolia possesses an open
and undulating terrain. From the northern border of the salt pond
to the mountain appears the stratum of the Mesozoic Era in the
geological history, especially the sediment formed during the Early
Cretaceous Period and the Late Cretaceous Period, which is widely
distributed and very thick and is regarded as a "graveyard" where
ancient reptiles including dinosaurs are forever sleeping. In the
past decades, paleontologists at home and abroad have conducted
several investigations here and discovered a lot of dinosaur
fossils of the Cretaceous Period, including the well-know
Maortuensis and Tashuikouensis. But what makes the paleontologists
gasp with admiration is that a total of four sets of complete
fossil skeleton of Probactrosaurus have been found, which is a
miracle in the history of Probactrosaurus excavation.
What should be noticed is that in Jirantai three broods of
dinosaur fossil eggs were unearthed, from which twenty-seven intact
fossil eggs and many shell fragments were found. The shape of these
fossil eggs is quite unique; they are round fossil eggs, which are
not easily seen at home. What's more, they are big, with the
biggest diameter as 140 millimeters, comparable with a relatively
small ostrich egg. With air holes structured like a honeycomb,
dinosaur eggs of this kind is a new type in paleontology, named as
"Jirantai Honeycomb Egg", which is distinguished among the dinosaur
egg fossils at home and abroad.
According to experts, in the same area of Jirantai lie the
"forerunners" of dinosaur family living in the Early Cretaceous
Period130 million years ago as well as the "descendants" of the
thriving dinosaur family in the Late Cretaceous Period 70 million
years ago. The stratum and fossils here are not only like a set of
systematic and well-preserved archives but also like a perfect
natural museum, which recreate the scene of billions of years ago
when dinosaurs were originating, evolving, thriving and
declining.