Avalon explosion: proposed evolutionary radiation of Animalia, taking place around 575mya in the Ediacaran
had two main radiations of animal life: the rangeomorphs and the erniettomorphs
Cambrian explosion: refers to the interval of time in the Cambrian period when practically all major animal phyla started appearing in the fossil record
lasted between 13 and 25 million years
occurred around 538.8 million years ago
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Laggerstätten
Laggerstätte:sedimentary deposit that exhibits extraordinary fossils with exceptional preservation
two types: Konzentrat-Lagerstätten and Konservat-Lagerstätten
Konzentrat-Lagerstätten: concentration Lagerstätten, have a particular concentration of disarticulated organic hard parts, such as a bone bed
Konservat-Lagerstätten:conservationLagerstätten, known for exceptional preservation of fossilised organisms or traces
taphonomy varies
explain important moments in history and the evolution of life
sediment from toxic volcanic ash of submarine volcanoes and landslides
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Ancestors of Animals
common ancestors of plants and animals appeared 2500 million years ago
theoretically, there are three ways multicellular organisms could have evolved from protists:
different protists form symbioses to create a composite multicellular organism
products of asexual division stay together, and multicellularity comes from intermediate colonial stage
multinucleate protist evolve internal membranes around each nuclei
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Abundance of Invertebrates
1.3 million described invertebrate species, of which almost 90% are arthropods
most familiar groups include:
ANNELIDA (segmented worms),
ARTHROPODA (e.g., insects, spiders, crustaceans),
CNIDARIA (corals, sea anemones, jellyfish),
ECHINODERMATA (e.g., starfish and sea urchins),
KINORHYNCHA (mud dragons),
MOLLUSCA (e.g., snails, clams, squids),
NEMATODA (roundworms),
NEMATOMORPHA (horsehair worms),
PLATYHELMINTHS (flatworms),
PORIFERA (sponges),
PROTOZOA (e.g., amoeba),
ROTIFERA (wheel animals),
and TARDIGRADA (water bears)
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Haeckel's Tree
created in 1866
had three kingdoms: Animalia, Vegetabilia, and Protista
all microscopic organisms were known as Monera
Monera persisted as a group until 1977 when Carl Woese split Monera into Archaea and Bacteria
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Biological Symmetry
animals can be asymmetric, radially symmetrical, or bilaterally symmetrical
BILATERIA can be split into PROTOSTOMIA and DEUTEROSTOMIA
protostomes have their mouth form from the blastophore
deuterostomes have their anus form before their mouth
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