Aquilolamna (Ah-quill-oh-lamb-nah), also called the “eagle shark,” was a cartilaginous fish that lived during the Late Cretaceous period. While unrelated to manta rays, this fish sports giant pectoral fins and a torpedo-shaped body. It was probably a filter feeder, sifting plankton from the seawater with its large mouth like modern basking and whale sharks. Its similarities to manta rays are the result of convergent evolution, where two lineages evolve similar body features to exploit similar resources in their environment. Unlike mantas, however, Aquilolamna likely glided through the water using its tail for propulsion rather than relying on flapping its pectoral fins. What exactly Aquilolamna is remains a bit of a mystery. Currently, one of the best ways to determine cartilaginous fish relationships is by looking at their teeth, but the only known fossil of Aquilolamna lacks these. Whether the teeth are yet to be found, or Aquilolamna lacked teeth altogether, is still unknown. Perhaps the taxonomic placement of this strange fish will be discovered in your lifetime! Aquilolamna is known from the Agua Nueva Formation in Mexico, which preserves a variety of marine animals from the Late Cretaceous. Data from this formation tells us Aquilolamna lived alongside polycotylid plesiosaurs, mosasaurs, ammonites, plenty of small fish, and the crushing-mouthed shark Ptychodus.