ENT 100 Lecture Notes - Lecture 7: Hexapoda, Protura, Diplura
Document Summary
Crustaceans are proposed to by an insect ancestor/sister group. Have two primary body parts, head and the rest. Jaws have single articulation, very small support for jaw so cannot power down on food. Oldest insect fossil: 8mm long without abdominal leglets; possibly monophyletic, jaw with two attachment points. More than a single jaw articulation is what separates true insects from other hexapods. Need fine textured mud or fine volcanic ash. Don"t need all three, they can work together though. Mineral deposits leaking into organism create internal cast, replace soft parts with minerals. Preserved in sedimentary rock and impression is left. Animals preserved in tar pits/lakes; relatively recent (about 50,000 years ago) Based on fossils, insects are some of the slowest speciators, they have the potential to speciate quickly due to exoskeleton, they just do not. Attempts to extract and sequence dna from amber preserved insects, but none of them have been repeatable. First parasitic insects, flowering plants, social insects, butterflies.
