Hermit crab on physical characteristics, genetic information, and combined data, support the longstanding hypothesis that the king crabs in the family Lithodidae are derived hermit crabs and should be classified as a family within Paguroidea. Other researchers have challenged this, asserting that the Lithodidae (king crabs) should be placed with the Hapalogastridae in a separate superfamily Lithodoidea. Six families are formally recognized in the superfamily Paguroidea, containing around 1100 species in total in 120 genera. The fossil record of "in situ" hermit crabs using gastropod shells stretches back to the Late Cretaceous. Before that time, at least some hermit crabs used ammonites'
Saw-billed hermit to the typical hummingbirds, Trochilinae (Hinkelmann, 1999). This, coupled with the considerable number of autapomorphies such as the unusual bill, suggest it is the most primitive species of the hermit lineage; a situation paralleled by the equally unusual tooth-billed hummingbird in the Trochilinae. Saw-billed hermit The saw-billed hermit ("Ramphodon naevius") is a hummingbird from southeastern Brazil, the only member of the genus Ramphodon. It is around 14–16 cm long and is one of the heaviest of the hermits; its straight bill has a hooked tip. It lives in humid forests, where it aggressively defends feeding routes ("trap-lines") from individuals of