BIOL 2400 Lecture Notes - Lecture 4: Opabinia, Pikaia, Phanerozoic
25 Dec 2014
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The cambrian explosion: anthropods bilateral symmetry segmented bodies: many appendages jointed legs hard exoskeletons. Cambrian (511-542 mya) burgess shale gave exceptional preservation (lagerst tte) . Trilobites in burgess shale you can see appendages: paleozoic, arthropod, olenoides serratus fossils suggested they molted their sa. Aysheaia fossil: marine onychophoran, walcott thought this species was an annelid worm modern (land) Ottoia: which phylum is this? priapulid worm fossil modern. Opabina regalis hypothesis: increase in predation pressure mid-cambrian constrained large morphological changes? predators trunk. = another species: was a large swimming predator (preyed on crustaceans) Anomalocaris laggania different from canadensis but same species different head shape, arm morphology, no fantail. Anomalocaris saron from the 515 mya lagerstatten in chenjiang china shows armed anterior appendages and prominent eyes central gut and dark paried structures. Wiwaxia: may be a polychaete or a mollusc? had an exoskeleton with scales .
