What did early vertebrates look like?

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Unit 2: Major Vertebrate Transitions
I. Vertebrate innovations: where do they come from? II. Early vertebrates and the challenges of, and tools for studying them. III. Relationship of vertebrates with their close relatives. IV. Important transitions/synapomorphies of clades in the lineage of vertebrates. Outline: Vertebrate Origins
General Vertebrate Morphology: Vertebrate body plan is ______________ Made of repeating structures ( Serially homologous ) Ex: Each vertebra is part of a unique segment Some segments are similar to each other and some are individualized. Vertebrate Embryo Vertebrate Adult Vertebrate Morphological Innovations
General Mechanisms of Morphological Change: 1. _____________________________________ Number of vertebrae varies from vertebrate to vertebrate. Carroll et al. 2005 Vertebrate Morphological Innovations
General Mechanisms of Morphological Change: 2. _____________________________________ (Diversification of repeated parts within an individual) Pharyngeal Gill Arches all the same Some Pharyngeal Gill Arches individualized and formed Jaws… Or parts of Ear Carroll et al. 2005 Vertebrate Morphological Innovations
…but have diversified and perform many different functions. Tetrapod forelimbs are homologous! Carroll et al. 2005 Vertebrate Morphological Innovations General Mechanisms of Morphological Change: 3. _____________________________________ (Divergence of a structure between taxa) Homologous structures : features that are shared because they were present in the common ancestor
Ex: Feathers arose from epithelial cells Carroll et al. 2005 Vertebrate Morphological Innovations General Mechanisms of Morphological Change: 4. _____________________________________ Novelty : new character, pattern, or body plan that evolved from pre-existing material or arose de novo, and became adapted to a new purpose
Carroll et al. 2005 Vertebrate Morphological Innovations General Mechanisms of Morphological Change: 1. Changes in the number of repeating parts 2. Diversification of serially homologous parts 3. Diversification of homologous parts between lineages 4. Appearance of novelties
What did early vertebrates look like?
Some Fossils Molecular Data using DNA from extant species

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