Sizes are given with a range, but no one knows the real size of each crocodiles. They are the largest reptiles to live on Earth at present. However, some ancient crocodiles even reached sizes surpassing most of the large theropod dinosaurs. The candidates for the largest crocodylomorphs are given
Sarcosuchus imperator - Sarcosuchus (/ˌsɑːrkoʊˈsuːkəs/; meaning "flesh crocodile") is an extinct genus of crocodyliform and distant relative of living crocodylians that lived 112 - 94 million years ago. It dates from the early Cretaceous Period of what is now Africa and South America and is one of the largest crocodile-like reptiles that ever lived. It was almost twice as long as the modern saltwater crocodile and weighed up to 8 tonnes. It has thought that this crocodylimorph actually reached sizes of up to 12 meters; however current; recent size estimates has given the animal 9.5 meters as maximum lenght and 4.7 tons, as maximum weight. 
Purussaurus brasiliensis - Purussaurus is an extinct genus of giant caiman that lived in South America during the Miocene epoch, 8 million years ago. It is known from skull material found in the Brazilian and Peruvian Amazon, Colombian Villavieja Formation, and northern Venezuela. It is estimated from to be 11 meters.
Mourasuchus amazonensis - Mourasuchus is a genus of large carnivorous caiman from Miocene-age (Tortonian stage, 8 million years ago) wetland suggests that niche partitioning was efficient, which would have limited interspecific competition. It estimated to being able to grew up to 12 meters.
Deinosuchus riogradensis - Although Deinosuchus was far larger than any modern crocodile or alligator, with the largest adults measuring 12 m (39 ft) in total length, its overall appearance was fairly similar to its smaller relatives. It had large, robust teeth built for crushing, and its back was covered with thick hemispherical osteoderms. One study indicated Deinosuchus may have lived for up to 50 years, growing at a rate similar to that of modern crocodilians, but maintaining this growth over a much longer time.
Deinosuchus rugosus - Being almost same as it's another species of it's genus, it was just a little bit smaller but more robustly built and most common of the 2 species. It mainly lived in America. It probably can reach sizes of up to 11.6 meters.
Rhamphosuchus crassidens - Rhamphosuchus ("Beak crocodile") is an extinct relative of the modern false gharial. It inhabited what is now the Indian sub-continent in the Miocene. It is only known from incomplete sets of fossils, mostly teeth and skulls. Older estimates say it could reach sizes of up to 18 meters, but modern estimates show a much smaller size of 11.4 metres.
Gryposuchus croizati - Gryposuchus is an extinct genus of gavialoid crocodilian. It is the type genus of the subfamily Gryposuchinae. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the early and middle Miocene epoch. One recently described species, G. croizati, grew to an estimated length of 10.6 metres (35 ft).
Euthecodon brumpti - Euthecodon is an extinct genus of long-snouted crocodyline crocodilians. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya. It existed from the Early Miocene to the Early Pleistocene. The species E. brumpti can reach sizes of up to 10.4 meters.
Stomatosuchus inermis - Stomatosuchus inermis ("Weaponless mouth crocodile") was a 10 metres (33 ft) long stomatosuchid neosuchian from the Late Cretaceous (Cenomanian) of Egypt. Unlike most other crocodyliforms, it is difficult to determine exactly what S. inermis ate. Its flattened skull had a long, flat, lid-like snout, which was lined with small, conical teeth. The mandible may have been toothless and may have supported a pelican-like throat pouch.
Fasolasuchus tenax - Fasolasuchus is an extinct genus of rauisuchid. Fossils have been found from Argentina that date back to the Rhaetian stage of the Late Triassic, making it one of the last rauisuchians to have existed before the order became extinct at the end of the Triassic. Fasolasuchus tenax could have reached sizes of up to 10 meters and possibly the largest non dinosaurian land animal, but recent studies show that it was; most likely; primarily aquatic.