It is subdivided into the Triassic, Jurassic, and Cretaceous periods. Phylogenetic analyses estimated the origin of the newt subfamily in the Late Cretaceous to Eocene. Danxia landform is formed from red-coloured sandstones and conglomerates of largely Cretaceous age. There were three general dinosaur faunas in the Late Cretaceous. The sea was wider in Jurassic than in Cretaceous period. The thick limestones, which predominate in The Bahamas, date back to the Cretaceous. The family Kalligrammatidae lived from the Jurassic to Aptian (Lower Cretaceous) periods. Tropeognathus is a genus of large pterosaurs from the late Early Cretaceous of South America. The Athens schist is a soft reddish rock dating from the upper Cretaceous. Fossil mackerel shark teeth date to the Early Cretaceous. Countershading existed in marine reptiles in the Cretaceous period. This group became extinct at the end of the Early Cretaceous epoch. Many fossil sites worldwide contain beetles from the Cretaceous. Marine reptiles were less numerous after mass extinction at the end of the Cretaceous. Gavialidae is estimated to have diverged from Crocodylidae in the Late Cretaceous about 80 mya.