1.   In consequence, amphibian fossils become very scarce indeed in later geological periods and there are long gaps in their fossil history.

2.   For almost a century Archaeopteryx has been alone on its perch as the early bird of the Jurassic geological period.

3.   He published many research papers on various geological periods.

4.   Previous generations of scientists had thought that chordates evolved in the later Ordovician geological period.

5.   Palaeontology is the science which deals with the life of past geological periods as known from fossil remains.

6.   The extinction marked the end of the Permian geological period and was followed by the rise of the dinosaurs during the Triassic period.