Myrmecoleon is an animal from Medieval bestiaries, also referenced in some sources as a Formicaleon, Formicaleun or Mirmicioleon.
There are two interpretations of what a Myrmecoleon is. In one version, the ant-lion is so called because it is the "lion of ants", a large ant or small animal that hides in the dust and kills ants. In the other version, it is a beast that is the result of a mating between a lion and an ant. It has the face of a lion and the body of an ant, with each part having its appropriate nature. Because the lion part will only eat meat and the ant part can only digest grain, the ant-lion starves.
The ant-lion story may come from a mistranslation of a word in the Septuagint version of the Old Testament, from the book of Job. The word in Hebrew is lajisch, an uncommon word for lion, which in other translations of Job is rendered as either lion or tiger; in the Septuagint it is translated as mermecolion, ant-lion.
"A beast with the front of a lion and the back of an ant. It is the result of a lion and ant mating, but because the lion part eats meat and the ant part eats vegetables, it will die of starvation. It was born from a mistranslation of the Bible."
"A monster whose front half is a lion and rear half is an ant. It is said to be born when a male lion impregnates an ant egg. Because its father is carnivorous and its mother herbivorous, it eats nothing and dies of starvation. It was apparently a mistranslation of "old lion" in the Book of Job that gave rise to this strange creature."