The mosasaurs are another group of extinct marine lizards which lived in [Cretaceous] seas. Some of these great reptiles grew to be as much as 50 feet long, and their great gaping jaws were filled with many sharp recurved teeth ([Pl. 41]). Mosasaurs were present in the great Cretaceous seas which covered many parts of Texas, and their remains have been reported from both north and central Texas. One such skeleton was found near Austin, and its skull is on display in the Texas Memorial Museum.
Plesiosaurs.—
The plesiosaurs were marine reptiles which were characterized by a broad turtle-like body, paddle-like flippers, and a long neck and tail ([Pl. 41]). These reptiles were not as streamlined or well equipped for swimming as the ichthyosaurs or mosasaurs, but the long serpent-like neck was probably very useful in helping the reptile catch fish and other small animals for food. Plesiosaur remains range from middle [Triassic] to late [Cretaceous] in age, and they have been found in Cretaceous rocks in Texas. A short-necked plesiosaur which was collected from Upper Cretaceous rocks near Waco is on display in the Strecker Museum at Baylor University in Waco.
Phytosaurs.—
The phytosaurs were a group of crocodile-like reptiles which ranged from 6 to 25 feet in length ([Pl. 42]). They resembled the crocodiles both in appearance and in their mode of life, but this similarity is only superficial, and the phytosaurs and crocodiles are two distinct groups of reptiles.
The phytosaurs are exclusively [Triassic] in age and their remains have been collected from Triassic rocks along the eastern margin of the High Plains of Texas.
Crocodiles and alligators.—
These reptiles adapted themselves to the same type [habitat] that was occupied by the phytosaurs, which preceded them. Crocodiles and alligators were much larger and more abundant during [Cretaceous] and [Cenozoic] time than they are today; the crocodiles first appeared in the Cretaceous and the alligators in the [Tertiary]. The remains of both crocodiles and alligators have been found in Texas, and one such crocodile (Phobosuchus) represents the remains of the largest crocodile yet discovered ([Pl. 43]). This specimen probably had an overall length of 40 to 50 feet, and its massive skull was 6 feet long and possessed exceptionally strong jaws. The remains of this great beast were collected from exposures of Upper Cretaceous rocks along the Rio Grande in Trans-Pecos Texas.
Pterosaurs.—
These were [Mesozoic] reptiles with bat-like wings supported by arms and long thin “fingers” ([Pl. 42]). The pterosaurs were well adapted to life in the air, and their light-weight bodies and wide skin-covered wings enabled them to soar or glide for great distances. The earliest known pterosaurs were found in lower [Triassic] rocks, and the group became extinct by the end of the [Cretaceous]. During this time certain of these creatures attained a wingspread of as much as 27 feet, but their bodies were small and light.