Crassigyrinus, the "thick tadpole," was the rebellious teenager of  life's transition to land. This two- meter-long creature was one of the  first tetrapods, or animals with  four legs. You might not have  noticed, though, because of its tiny  limbs! Crassigyrinus' limbs were  likely vestigial because it had  readapted to a fully aquatic life- style. This left it with a slender, eel-like profile that was perfect for prowling the early Carboniferous waters it called home. Following the teenage trend of ungainly propor- tions, its head and jaws were gigan- tic in order to accommodate massive eyes and two rows of teeth. These adaptations made Crassigyrinus an  effective predator. Its streamlined  body helped it move swiftly through  the water, while its hefty head tore  into its prey of choice: small  vertebrates, like fish.  This wee beastie swam in the swamps and lakes of what is now Scotland.  Its large eyes were perfectly adept at peering through the murky water that it lived in, and may have also provided nocturnal vision for when it snuck out past curfew and tried  to go party at the pub. Other  frequenters of the Scottish swamps included Crassigyrinus' the small  fish that it feasted upon, anthra- cosaurs like Proterogyrinus,  terrestrial temnospondyls, and an  assortment of arthropods.