The name means "pancake crocodile" from the Greek λαγανον, laganon ("pancake") and σοῦχος, souchos ("crocodile") in reference to the shallow depth of the skull, which is characteristic of all stomatosuchids. It has been nicknamed "PancakeCroc" by Paul Sereno and Hans Larsson, who first described the genus in a monograph published in ZooKeys in 2009 along with other Saharan crocodyliformes such as Anatosuchus and Kaprosuchus.
The type species is L. thaumastos from the Cenomanian-age Echkar Formation in Niger. A second species, L. maghrebensis, is known from the Kem Kem Beds in Morocco, which are also Cenomanian in age.
According to Sereno, L. thaumastos was an approximately 6 meters (20 feet) long, squat fish-eater with a 1 meters (3.3 feet) flat head. It would have stayed motionless for hours, waiting for prey to swim into its open jaws with spike-shaped teeth.