Handout: Geological Time Scale - Get to know the Eras and Periods!
Cladistic Overview of Taxa:
-----Examples from Ch. 9: Eryops, Cacops, aistopods, Diplocaulus
-----Cacops was probably related to extant subgroup, Lissamphibia (frogs, salamanders, etc.)
-----stem fossils: "anthracosaurs" including Seymouria and the lizard-like Westlothiana
-----Synapsida (including mammals)
-----Sauropsida (or Reptilia if this taxon rediagnosed as clade)
----------Turtles (or recent change as subgroup of diapsids, e.g., p. 173)
----------Diapsida (including lizards, crocodiles, and birds)
The split between lissamphibians and amniotes came very early after tetrapods first invaded terrestrial habitats. (See the links under "The First Amphibians" in the HOL Ch. 8 links.)
Taxa from Ch. 10 that you should learn to recognize:
Diapsids (not many in Paleozoic Era, but note Petrolacosaurus)
Synapsids (the ones we will cover are referred to as "pelycosaurs," which is a "stem" or paraphyletic grouping that gives rise to the later therapsid clade)
-----ophiacodonts: Archaeothyris, Ophiacodon
-----sphenacodonts: Haptodus, Dimetrodon, therapsids (including us)
1. Describe briefly how the climate and world geography was changing from the Permian to the Triassic, the time which includes the world's most dramatic "P/T" extinction event.
2. Most of this chapter is on the synapsid amniotes. How is this group characterized with respect to novelties of its skull? What is a likely function of these novelties?
3. How did the worldwide habitat of synapsids differ in the Permian vs. the Triassic?
4. How did the dietary diversity of synapsids differ in the Permian vs. the Triassic?
5. What factors important in order to feed on land plants?
6. Describe how Paleozoic synapsids, such as Dimetrodon, thermoregulated (see pp. 160-162 and Fig. 10.12)
7. Contrast this with thermoregulation in Triassic therapsids.
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