The groups of the animals that played a major role in the late Cretaceous period but were absent in the Paleocene world.
Answer to Problem 1RQ
Ammonoids, rudist, and marine reptiles were common during the Cretaceous period, but these organisms became extinct in the Paleogene world.
Explanation of Solution
Paleogene life was very similar to modern life. There was no special alteration in the Paleogenic life apart from the expansion of the taxonomic group in all parts of the Earth. However, the origin of Paleogene life by the end of the Cretaceous period marked a huge shift in the history of life on the Earth.
Ammonoids and belemnoids were swimming carnivores during the Cretaceous period. Very rare belemnoids were able to survive and all the ammonoid undergwent extinction in the Paleogene life. Moreover, rudist and marine reptile also disappeared from the oceans in the Palaeogene period. These organisms were considered important during the late Cretaceous period.