Entomology 10

Fossil damselfly from Florissant shales, Colorado (Tertiary Period)

Evolution and Biogeography

I. Phylogenetic relationships among extant insects

1. Hexopoda: Entognathous classes/orders: mouthparts recessed in pouch
2. Insecta: Apterygote (wingless) orders
3. Pterygota: Winged: Paleopterous (fixed wings); Intromissive copulation
4. Neoptera: Wing folding
5. Endopterygota: Complete metamorphosis

II. Fossil insects

1. Oldest: Devonian >360 MYA - Springtails; Archeognatha
   Upper Carboniferous >285 MYA - many Pterygota
2. Extinct taxa: About 50% gone by Triassic >245 MYA
   Rest during Mesozoic 245-65 MYA
3. Major radiations: Carboniferous 360-285 MYA; Permian 285-245 MYA and Cretaceous 145-65 MYA for infraordinal taxa
4. Correlations with other major taxa
   • Pre Devonian 600-400 MYA- First land plants & animals;
     Scorpions, Millipedes
   • Devonian 400-360 MYA- Seed ferns; first insects, spiders;
     Eurypterids (marine)
   • Carboniferous 360-285 MYA- Ferns; Amphibian specialization; first Reptiles,
     Pterygota: Paleoptera and Neoptera
   • Permian 285-245 MYA- Conifers; Reptiles diversify; Many insect orders go extinct, modern orders appear; first Endopterygota
   • Mesozoic 245-65 MYA- Ginkos, Cycads, Angiosperm radiation; Age of Reptiles; first Mammals, Birds; Neoptera dominant, many modern insect families; Amber fossils
   • Tertiary 65-1 MYA- Insect fauna similar to present by mid Tertiary; Amber fossils.

III. Amber insects and biotechnology

1. Age - commercial value - fakes
2. DNA extraction & replication - Jurassic Park
   • Comparisons between fossil and modern taxa
     • Termites & Stingless bees (40 MYA)
     • Weevils (120 MYA)

IV. Biogeography

1. Biogeographic regions
2. Why do insects occur where they do today?
   • Disjunct patterns
   • Evolution
   • Extinction
   • Continental Drift
   • Dispersal
     • Active
     • Passive
       Human assisted: Accidental; Intentional

Readings in Gullan, P.J. and Cranston, P. S. (1994). The Insects: An Outline of Entomology:

• Read: pp. 10 (1.4); pp. 184-189 (7.2 & 7.3)
  
• Review: pp. 192-197 (7.5)

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