Crown primates strepsirrhines tarsiers platyrrhines

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Chapter 1 / Exercise 013
Biology
Martin/Solomon
Expert Verified
Crown Primates Strepsirrhines Tarsiers Platyrrhines Catarrhines Stem Primates Plesiadapiforms† Last common ancestor of living primates (the earliest crown primate)
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Biology
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Chapter 1 / Exercise 013
Biology
Martin/Solomon
Expert Verified
2 Station 1: The Paleocene – Plesiadapiforms, the Stem Primates (1 pt.) The Order Primates includes all living primates and their extinct relatives back to the last common ancestor of strepsirrhines and haplorhines (“crown primates”). It also includes the now extinct plesiadapiforms (“stem primates”). Although plesiadapiforms are not the direct ancestors of living primates, their close relationship with the last common ancestor of living primates can tell us important information about early primate adaptations. (See the figure on Page 1.) 1. Compare and record the dental formulae of the plesiadapiform cast and the galago (a strepsirrhine). Is the plesiadapiform dental formula apomorphic (derived) or plesiomorphic (primitive) compared to the galago? ( Note: the plesiadapiform has procumbent incisors (not a toothcomb) and the galago has a toothcomb which includes its 1 st canine.) 2. Look at the handout on the plesiadapiform Carpolestes simpsoni . Does the hallux (big toe) of Carpolestes have more symplesiomorphic features shared with the tree shrew, or synapomorphic features shared with the euprimate? List at least one feature you considered. Station 2: The Eocene – Early Crown Primates (1 pt.) Two extinct superfamilies, Adapoidea and Omomyoidea, group the earliest crown primates. Adapoids are thought to be ancestral to present day strepsirrhines, while omomyoids are most likely ancestral to tarsiers and anthropoids. Many species of adapoids and omomyoids were sympatric (lived in the same place and time) and have been found throughout North America and Europe. Compare the adapoid skull cast with the lemur and tarsier skulls. ( NOTE: the adapid cast is poorly molded and falsely shows post-orbital closure ) 1. List two traits the adapid and the lemur share. A. __________________________________________ B. __________________________________________ 2. List two differences between the adapid and the tarsier skulls. (Do not use the absolute overall size as a difference. Relative sizes of features on the skulls are more useful. Additionally, please do not list the sagittal crest as a difference.) A. __________________________________________ B. __________________________________________
3 Station 3: The Oligocene – Early Anthropoids (2 pts.) The second half of the Eocene and beginning of the Oligocene epochs, between ~43-33 mya, is marked by a great deal of geologic and climatic change. During this time the first anthropoids (monkeys and apes) appear in the fossil record, and seem to have quickly diversified into platyrrhines and catarrhines by around 40 mya. This early anthropoid diversification is well- documented in the Fayum Depression of Egypt. Examine the dental casts of Aegyptopithecus and Parapithecus . Compare them with the modern capuchin (platyrrhine) and macaque (catarrhine) skulls in order to answer the following questions: 1. From the fossil evidence, is Aegyptopithecus a platyrrhine or a catarrhine? List one synapomorphy that supports your answer. 2. Is the dental formula of Parapithecus apomorphic (derived) or plesiomorphic (primitive)? What is the relevance of finding an anthropoid with this dental formula in Egypt? ( Hint: think

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