Cretaceous

adj. chalky; like chalk; pertaining to the Cretaceous era (Geology)

The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i.e. from 145.5 ± 4.0 million years ago (Ma)) to the beginning of the Paleocene epoch of the Tertiary Period (about 65.5 ± 0.3 Ma). The youngest and longest geological period of the Mesozoic, the Cretaceous constitutes about 80 million years. The end of the Cretaceous defines the boundary between the Mesozoic and Cenozoic eras.
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Noun
1. from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants
(synonym) Cretaceous period
(hypernym) period, geological period
(part-holonym) Mesozoic, Mesozoic era, Age of Reptiles

Adjective
1. abounding in chalk
(pertainym) chalk
2. of or relating to the Cretaceous geologic era; "cretaceous rocks"
(pertainym) Cretaceous, Cretaceous period

(a.)
Having the qualities of chalk; abounding with chalk; chalky; as, cretaceous rocks and formations. See Chalk.
  

144-65 Million Years Ago
The last period of the Mesozoic era may have seen more dinosaurs then ever before. The horned dinosaurs appeared, like the Triceratops and Centrosaurus. The armoured Anklyosaurus, duckbilled Parasaurolophus, and large carnivore Tyrannosaurus were a few of the quickly evolving dinosaurs. Birds became increasingly numerous & flowering plants were emerging. By the end of the Cretaceous period, all large and small ruling reptiles, except the crocodile went extinct.
Tyrannosaurus (rex) 
Corythosaurus (casuarius) 
Anatosaurus(anectens)
Parasaurolophus(walkeri) 
Carnotaurus(sastrei) 
Gallimimus(bullatus) 
Triceratops(prorsus) 
Tarbosaurus(baatar) 
see list of time periods

TYRANNOSAURUS rex
Best known of the dinosaurs, T-rex was one of the most awesome creatures that have walked on the earth. It was one of the largest meat - eating dinosaurs, having a skull up to 5ft long and many sharp teeth reaching lengths of 6in (15cm). The first complete T-rex skeleton was discovered in 1902, and many great examples have been unearthed over the last fifteen years.

TIME - 65 - 68MYA, Late Cretaceous period.
RANGE - USA Colorado, Montana, N. Dakota, New Mexico, Wyoming.
Canada Alberta, Saskatchewan.
DIET - The T-rex was a carnivore, especially fond of large herbivorous
dinosaurs.
SIZE - Height up to 20ft (6m) and lengths up to 49ft(15m)..
WEIGHT - 6.5 US tons.

see time period